Carb too big?? [Archive] - Chevy Nova Forum

: Carb too big??


Millertime
28th-March-2011, 10:23 PM
I bought my car with the 350 engine already built. I just installed a new MSD ignition setup trying to get my car to run smooth. During my research i found out the carb on my car is a Holley Part# R4781-5 or 850CFM!! Isn't a 850 carb big on a 350??

levisnteeshirt
28th-March-2011, 11:09 PM
yes it is ,,,, unless it has some serious compression , and is a full race engine ,, i would take it off


give us some details on the motor

big dog ss
28th-March-2011, 11:12 PM
I bought my car with the 350 engine already built. I just installed a new MSD ignition setup trying to get my car to run smooth. During my research i found out the carb on my car is a Holley Part# R4781-5 or 850CFM!! Isn't a 850 carb big on a 350??

depends on what has been done to the engine.. a modified 350 can handle a 850.. what are the specs on your engine?

photoman
29th-March-2011, 10:32 AM
That's listed as a 4150. Is it vac or mech secondary?

levisnteeshirt
29th-March-2011, 11:00 AM
i had a 800 dp on a mild 350 a while ,, a 600dp or a 750 vs did way better

Millertime
29th-March-2011, 02:00 PM
That's listed as a 4150. Is it vac or mech secondary?

mechanical, im going to upgrade my spark plug wires and battery and see if i can get the spark to keep up with all the fuel.

levisnteeshirt
29th-March-2011, 02:22 PM
smell your oil from time to time ,, make sure it doesn't start to smell like gas

bracketchev1221
29th-March-2011, 03:08 PM
It's too big. Plain and simple. I ran an 850 on a 615hp 383. On my 465 hp 355, a 750 killed an 850 in back to back comparison.

Millertime
29th-March-2011, 04:09 PM
can you rejet the carb? or is my only safe option to just buy a smaller carb?

big dog ss
29th-March-2011, 05:57 PM
if you have a mild 350 sb i would get another carb..:yes:

Plowman
29th-March-2011, 07:10 PM
Smokey Yunick ram intake - Smokey said one 850 carb on a 302 is enough. I was going to run the intake on a 350 cu inch engine with an 850 cfm carb.

levisnteeshirt
29th-March-2011, 07:33 PM
smokey yunicks 302's were 12.5 or more compression ,, 8000 + rpm engines ,,, ran for short periods before the oil was changed ,, things like that

testcase
29th-March-2011, 07:37 PM
Smokey Yunick ram intake - Smokey said one 850 carb on a 302 is enough. .

Enough for it and the 283 sitting next to it....

It would take a BUNCH of RPM to make that work.

Zman
29th-March-2011, 08:04 PM
IMO, 850 CFM Mechanical is WAAAAY to big for a mild 350.
If the car has auto trans, you would be much better off with maybe a 600-650 cfm Vacuum Secondary. DPs don't work well unless you have a built auto with higher stall converter.

balljoint
29th-March-2011, 08:20 PM
I bought my car with the 350 engine already built. I just installed a new MSD ignition setup trying to get my car to run smooth. During my research i found out the carb on my car is a Holley Part# R4781-5 or 850CFM!! Isn't a 850 carb big on a 350??

There are alot of myths about carb cfm,there are small blocks that run 1000cfm domanators and love it,I have seen small blocks with high rise intakes with dual 600 cfms x2=1200 cfm ,while others cannot make a 600 1850 work right ,I have a 780 holley on a 355 and the engine loves it ,there are some guys who say you can make any size cfm carb work on a small block,and some that say 500cfm is all that is needed,some say the more air you can push through intake the better,who really knows? How does the car run with that carb? Is it the carb or igntion or a mech issue? The carb may or may not be right for that engine ,just saying.:chev:

testcase
29th-March-2011, 09:34 PM
IMO, 850 CFM Mechanical is WAAAAY to big for a mild 350.
If the car has auto trans, you would be much better off with maybe a 600-650 cfm Vacuum Secondary. DPs don't work well unless you have a built auto with higher stall converter.

I would disagree, I have had much better luck with a properly tuned DP in almost any auto combo.
A lot of people think the "bog" at launch is a DP over fueling when in fact the opposite is true.
On a mild 350 we have had a lot of success with a 650 or 750 DP. The last one I tuned out for a customer we switched from a 600 vacum carb to a 650 DP. 67 Camaro, stock 350, turbo 350 w/shift kit, stock convertor, stock 3.55 gears.

Substainual pick up in 60 foot times and as I recall nearly a tenth in the 1/8.
I don't have my note book with me to give the exact numbers.

RED67
29th-March-2011, 10:09 PM
can you rejet the carb? or is my only safe option to just buy a smaller carb?

Check out the carb and make sure it's not damaged or modified incorrectly :(
Put stock Holley jets for your carb in it,make sure the power valve is what Holley recomends to start with,,,set the float levels and enjoy your car.:yes:
Small issues you'll have fun learning how to tune out. These same guys here will help you.
If you where having to buy a new carb,,and we're talking about a street car,,yup 650 or 750 DP would be the choice. But since you have this one, run it,,your not going to "Black Out" :eek: from disapointment. :D And you won't be the first guy to put a 850DP on a 350 Chevy,,by mistake or any other reason:no:
Many of the early "Stock" cars came with big carbs,,,340SB Plymoth and Dodge had 850 cfm Thermo Quads,,,,,,,,,some of the Q-Jets where 850cfm on "Bone" stock engines,with stock intakes and cast exhaust manifolds :eek:

RUN IT :yes: And enjoy it :turn:

levisnteeshirt
30th-March-2011, 10:22 AM
these " big carbs " are vacume secondary ,,, an 850 dp is all in ,,,,

i posted i had a 800 dp on a mild 350 and i didn't like it much ,,, that a 600 dp or a 750 vs did way better. How do i know this ?? Because i had the 600 dp on it first , and i traded it for the 800 and 750 vs. I fugured it was a 2 for 1 deal anyway so why not ?? i ran the 800 dp a week and took it off, put the 750 vs on and kept it on. The 800 was sluggish and got horrible mileage ,, the 600 dp got around 15 mpg. The 750 vs didn't do bad ,, but not as snappy as the 600 dp.

this was a 71 350 , 462 heads , Lunati 230 @ .050 , 450 lift , 114 LSA ,, 1981 vintage cam , original torker intake , headers/turbo mufflers

Plowman
30th-March-2011, 06:21 PM
these " big carbs " are vacume secondary ,,, an 850 dp is all in ,,,,

i posted i had a 800 dp on a mild 350 and i didn't like it much ,,, that a 600 dp or a 750 vs did way better. How do i know this ?? Because i had the 600 dp on it first , and i traded it for the 800 and 750 vs. I fugured it was a 2 for 1 deal anyway so why not ?? i ran the 800 dp a week and took it off, put the 750 vs on and kept it on. The 800 was sluggish and got horrible mileage ,, the 600 dp got around 15 mpg. The 750 vs didn't do bad ,, but not as snappy as the 600 dp.

this was a 71 350 , 462 heads , Lunati 230 @ .050 , 450 lift , 114 LSA ,, 1981 vintage cam , original torker intake , headers/turbo mufflers
You told us that your street driven Tunnel Ram ran the same way,tuning it will tell.

Plowman
30th-March-2011, 06:42 PM
smokey yunicks 302's were 12.5 or more compression ,, 8000 + rpm engines ,,, ran for short periods before the oil was changed ,, things like that

Smokey Yunick Ram was made and has a G.M.part# on it. Then Edelbrock made it for years. It is still street driven today.

RED67
30th-March-2011, 07:56 PM
[QUOTE=levisnteeshirt;1585787]these " big carbs " are vacume secondary ,,, an 850 dp is all in ,,,,

i posted i had a 800 dp on a mild 350 and i didn't like it much ,,, that a 600 dp or a 750 vs did way better. How do i know this ?? Because i had the 600 dp on it first , and i traded it for the 800 and 750 vs. I fugured it was a 2 for 1 deal anyway so why not ?? i ran the 800 dp a week and took it off, put the 750 vs on and kept it on. The 800 was sluggish and got horrible mileage ,, the 600 dp got around 15 mpg. The 750 vs didn't do bad ,, but not as snappy as the 600 dp.

this was a 71 350 , 462 heads , Lunati 230 @ .050 , 450 lift , 114 LSA ,, 1981 vintage cam , original torker intake , headers/turbo muffler

:rotfl: You failed to mention the small primarys on a spread bore carb too but who's keeping score ?
Most of us here have had at least one SBC with a big Holley carb on it :yes:,,,my first one was a 800DP on a '67 327 in 1975 :D sure ran sweet.

Judging from the above maybe you can help our friend find the stock jets and power valves for his new 800 Holley fed 350 Chevy.

Run it,,Enjoy it. :devil:

levisnteeshirt
30th-March-2011, 08:17 PM
hard to enjoy pulling the dipstick and smelling gas in the oil ,,, ,,,,

the smokey ram doesn't do too well from what i hear ,, unless its totally flogged ,,, some air dams added where needed ,,,, a bunch of dyno time ,,,,, they tried one for a EMC engine ,,, didn't do very well ,,, i'd say smokey let the intake out ,, he took to his grave how to make one work

balljoint
30th-March-2011, 08:28 PM
hard to enjoy pulling the dipstick and smelling gas in the oil ,,, ,,,,

the smokey ram doesn't do too well from what i hear ,, unless its totally flogged ,,, some air dams added where needed ,,,, a bunch of dyno time ,,,,, they tried one for a EMC engine ,,, didn't do very well ,,, i'd say smokey let the intake out ,, he took to his grave how to make one work

Please elaborate on the gas in the oil,caused by the intake? ,I am not familar with that intake design,I do no that smokey was a hard head and had alot of ideas on heads and blocks.

edp700
30th-March-2011, 09:59 PM
I had a 66 mustang with a 302 4 speed in it and i put a 750 double pumper on it and it ran great, for what it was. It had a small camshaft, a edelbrock performer intake and headers. It really just depends, you can tune the carb to run good. On a dyno, it might not make as much power as a 650 DP but you could make it run good.

pxtx
30th-March-2011, 10:02 PM
The gas inthe oil is probably talkign about either a overly rich tune, or an intake which the fuel can "fall out" of the airflow and "puddle" in the intake. Either scenario can be addressed and tuned out.

The SY1 intake is pretty cool, but me and my pop like running the old historic stuff so we're certainly biased. The cool factor steps up another notch when people say these competition set-ups don't run well on the street and we make it happen with good driveability AND power!

SY1 for reference:

http://i710.photobucket.com/albums/ww101/Plowman7/Tunnel%20Ram/SY1%20Intake/sy1intake.jpg

Note Smokey's recommendation here: 850, 800, 830 cfm DP carbs. Also note this was revised in 1985 so the intake came out about 1970 and was still being sold in the mid 1980's. Another cool part is that Smokey's contact info was listed to assist anyone in extracting maximum performance form the intake!

http://i710.photobucket.com/albums/ww101/Plowman7/Tunnel%20Ram/SY1%20Intake/edelbrockSY1read.jpg

Here is the inside of a stock SY1 intake.

http://i710.photobucket.com/albums/ww101/Plowman7/Tunnel%20Ram/SY1%20Intake/feb14148.jpg

Now, there was admittedly a bit of a puddle issue with the intake on the street, but Edelbrock is issue a kit to put some baffeling in the intake, as seen here:

http://i710.photobucket.com/albums/ww101/Plowman7/Tunnel%20Ram/SY1%20Intake/flowkit.jpg

I say run your 850 and learn to tune it.

levisnteeshirt
31st-March-2011, 10:04 AM
if just putting a big carb on something and having great results was all it took in this ,,, then hand me my tunnel ram ,, and i want 2 Big BO 1800 cfm dominators on my 350 290 hp crate motor

the deal is what work better ,,,, isn't it ???

i won a bet once that a 1050 would " idle " fine on a stock motor ,,, it idled fine ,, didn't run worth a crap

something with a small cam , and small heads , you might get a bigger carb to function , because it has greater air speed at low rpm , a stronger signal to the carb. When you try to shift the rpm range higher with cam timing to allow this , you loose these low speed characteristics , then carb sizing becomes more critical, especially with a small motor ,,

levisnteeshirt
31st-March-2011, 10:33 AM
You told us that your street driven Tunnel Ram ran the same way,tuning it will tell.

this was a different motor ,,,

RED67
31st-March-2011, 10:50 AM
if just putting a big carb on something and having great results was all it took in this ,,, then hand me my tunnel ram ,, and i want 2 Big BO 1800 cfm dominators on my 350 290 hp crate motor

the deal is what work better ,,,, isn't it ???

i won a bet once that a 1050 would " idle " fine on a stock motor ,,, it idled fine ,, didn't run worth a crap

something with a small cam , and small heads , you might get a bigger carb to function , because it has greater air speed at low rpm , a stronger signal to the carb. When you try to shift the rpm range higher with cam timing to allow this , you loose these low speed characteristics , then carb sizing becomes more critical, especially with a small motor ,,

Come on now,,,NPHNP,,,judging from post 18 and the above, help our friend out and share some of this vast technical knowledge in a positive way. Give him the stock Holley specs for his carb along with a few suggestions so he can get to work enjoying his 350 Chevy :turn: and you'll enjoy helping him tune up the 850DP.:yes:

Like was said in post 21,,most of us have had a big Holley on a small block Chevy,,and some of us have "Blundered Around" and got em running pretty good.

:devil:

Plowman
31st-March-2011, 10:53 AM
this was a different motor ,,,

Grumpy ran two 1050cfm on a 331cu.in. If you can't tune[only bolt on's],don't tell people it can't be done. Just help people out what you can do. People would like it more.

pxtx
31st-March-2011, 10:56 AM
I think we all can help the guy out a bit. A pic of the engine compartment from the passenger side may help us understand the fuel delivery system, and distributor setup.

We should also probably ask for the baseline data on how the ignition timing and advace are set-up.

Most importantly, where does the eingine need to be more smooth? Idle, part throttle, etc?

Wayne C.
31st-March-2011, 11:07 AM
I think all of our learned friends here at Steve's have shown and expressed the fact that "it can be done". Most of the people they have quoted are the "elite" of the drag racing sport, or some very seasoned veterans. That said I will chime in also. It can be done.
But since you are asking the question of weather or not the carb is too big, I have to believe that you are like most of us and not in the seasoned veteran, or elite of the drag racing sport. For the rest of the world you will probably have way better results by buying a 650 or at most 750 CFM carb, bolting it on and with minimul tuning go.
I have a 496 BBC with an 850 on it. I will probably end up with a 1000 CFM dominator or something like that, but I would rather "sneak up from this side as to starting out way over carb'd.
There, my two cents,
Wayne C. :cool:
http://s1119.photobucket.com/albums/k632/cooperhw/My%2066%20Nova%20Drag%20Car%202011/

levisnteeshirt
31st-March-2011, 11:18 AM
if i just had to get this 850 working on this motor ,,, this is what i'd do ,,, no mention of what intake ,, if there was ,, i missed it ,,, i'd get a true dual plane without any of the divider cut,, this functionally slpits the carb in half , so now we have two 425 cfm carbs ,,, i would remove the baseplate ,, and i would fill the area where the PCV port is with epoxy ,, the area with green in it

http://i424.photobucket.com/albums/pp329/levisnteeshirt/baseplate.jpg

if i needed a vacume port then i'd tap it from the intake

i would use manifold vacume for vacume advance ,, get an adjustable canister ,, and keep as much timing as i could in it

Plowman
31st-March-2011, 01:55 PM
To start with I would get a 1"carb spacer[less cash than a intake manifold]. Put a distributor curve kit in it and see what you got. I would just plug up or cap the PCV to see if it does anything[no epoxy].

photoman
31st-March-2011, 02:18 PM
mechanical, im going to upgrade my spark plug wires and battery and see if i can get the spark to keep up with all the fuel.

A mild 350 in a street car is going to run much better with a 600-750cfm vacuum secondary carb. You are on the right track with the plug wires. Make sure your ignition system is in top condition too. Confirm the timing/advance is optimal.

JRouche
1st-April-2011, 02:03 AM
Kinda funny reading all the posts saying yes, the 850 can be worked on to make it work.

Well yeah. Thats like saying I can make a man with a broken leg in a cast walk, give him a crutch. And thats what you will have, a crutch.

For the 350 a 650-750cfm carb is perfect. And Im not talking about a 9000rmp, 13:1 race engine that has a very narrow band width of power. Because for that engine it wont run smoothly, wont preform decently unless its turning 4500rpm+. And the high flowing 850 or larger CFM carb is perfect.

But do you plan on driving it on the street at 1500-2500 rpm sometimes?

If so the 650-750 cfm carb will have a more sensitive "carb signal". And that helps with low rpm driving. The smaller bores will increase the velocity of the incoming air and have a stronger venturi effect for the amount of air that your engine needs.

What does that give you? Throttle response at low to mid throttle blade tip over. And for street driving when you are mostly below 65% of your throttle usage its nice to have more throttle response.

And I havent even got into fuel econemy because well, many of us dont care about that so much as preformance. But with a higher air intake velocity you should see better econemy also. And yes, you can "detune" an 850 carb for econemy. But whats the point.

Think about intake air velocities. Its a big concern when you are dealing with the venturi effect. JR

Plowman
1st-April-2011, 07:22 AM
In 1970 G.M. put a 780cfm on a 350cu.in. and it ran fine. So if you use just the two barrel 35 per-cent of 90 per-cent of the drive time it should be fine. So if it is what you got,it can be tuned to work. But if it is to walk on or not to walk,most people will take the crutch for now.

levisnteeshirt
1st-April-2011, 10:12 AM
In 1970 G.M. put a 780cfm on a 350cu.in. and it ran fine. So if you use just the two barrel 35 per-cent of 90 per-cent of the drive time it should be fine. So if it is what you got,it can be tuned to work. But if it is to walk on or not to walk,most people will take the crutch for now.

vacume carb ,,, different animal

big dog ss
1st-April-2011, 01:15 PM
In 1970 G.M. put a 780cfm on a 350cu.in. and it ran fine. So if you use just the two barrel 35 per-cent of 90 per-cent of the drive time it should be fine. So if it is what you got,it can be tuned to work. But if it is to walk on or not to walk,most people will take the crutch for now.

also the 350 in 1970 was no "stock" engine.. the old 780 are excellent carbs i have several.. that same carb also cam on big blocks from factory.. as most know a vs carb will only give what the engine wants..

levisnteeshirt
1st-April-2011, 01:52 PM
an 850 dp ,, gives the driver what he imagines he wants ,, on a mild motor ,,,slow air speed , fuel dropping out ,,, oil being washed off the cyl walls ,, gas in the oil ,,, been there done it , got the tee shirt

pxtx
1st-April-2011, 03:12 PM
How do you know the motor is a mildly built 350?

levisnteeshirt
1st-April-2011, 03:19 PM
lemme tell ya about a friend i met a couple years ago ,,, 355, 14-1 , 230 darts , vic jr , 264/266 @ .050 cam ,,, 2200 lb tube frame S 10, 567 gear , 6300 stall , 32x14 tires ,,, it had a 750 hp carb on it ,, he bought a 850 pro systems carb ,,, the car didn't pick up at all ,, notta ,, none ,, can't remember what he paid for the carb but it wasn't cheap ,,,

Plowman
1st-April-2011, 04:08 PM
lemme tell ya about a friend i met a couple years ago ,,, 355, 14-1 , 230 darts , vic jr , 264/266 @ .050 cam ,,, 2200 lb tube frame S 10, 567 gear , 6300 stall , 32x14 tires ,,, it had a 750 hp carb on it ,, he bought a 850 pro systems carb ,,, the car didn't pick up at all ,, notta ,, none ,, can't remember what he paid for the carb but it wasn't cheap ,,,

That sounds like the way you tuned it and your cars. All you touch and tune sounds the same. I think all you tell is story or is it your tune.

levisnteeshirt
1st-April-2011, 04:15 PM
last motor i built ,,, 355 ,,, the shop that did it said " oh its got to have at least a 750 dp on it " ,,, i meesed with the 750 dp for a few years ,,, i got it decent ,,, it did alot better with a 650 dp on it ,,,, long story short ,,, a 650 dp on a 2 in spacer


i broke an axle with a 750 vs carb ,,, so they will make power too ,, they do need help out of the box though

Millertime
3rd-April-2011, 07:27 PM
http://i303.photobucket.com/albums/nn125/MillerJWcoins/IMG_0968.jpg

Here is the only pick of the engine bay i have right now. I just installed a Ready To Run Pro Billet MSD Distributor, SS Blaster Coil, 8.5 MM Super Conductor Wires, Duel Platinum Spark Plugs. I have an MSD timing tape ariving on tuesday, then i will post more about how the car is running. I want to make sure my timing is close before i play the guessing game too much.

Millertime
3rd-April-2011, 07:49 PM
http://i303.photobucket.com/albums/nn125/MillerJWcoins/MSD.jpg

Sorry about the small pic, i have a crappy phone

JRouche
3rd-April-2011, 11:02 PM
How do you know the motor is a mildly built 350?

Really? You think it might NOT be a mild 350. You havent been reading the original posters posts. It is pretty evident its a mild 350.

It started out as this "I bought my car with the 350 engine already built."

And then this. "im going to upgrade my spark plug wires and battery and see if i can get the spark to keep up with all the fuel. "

And.. "can you rejet the carb? or is my only safe option to just buy a smaller carb? "

And NO Millertime, Im not dissing you. Im just trying to point out that its pretty obvious what type of engine you have. It doesnt sound like a barn burner. Im thinking a MILD 350. Helps to read the entire post and ask the correct questions.

Id venture that its on the stock side of a 350 than a modified 350 just from the original posters remarks. And no matter if its been worked over it STILL sounds like a MILD 350. JR

Baddbob
3rd-April-2011, 11:07 PM
Most double pumpers are calibrated on the rich side for performance-it may be a little much for that 350. Simple test to see it you're overcarbed you can try disconnecting the secondary link and see how it runs just with the primary. What rpm is the idle set at?

levisnteeshirt
4th-April-2011, 08:09 AM
http://i303.photobucket.com/albums/nn125/MillerJWcoins/MSD.jpg

Sorry about the small pic, i have a crappy phone

i would do a compression check and see what the engine is pumping. I hope you have a good idea what cam is in it. That intake has 2 in of extra plenum , plus 2 in of extra plenum with the spacer. All of that makes the engine respond like it has even larger carburator.

Plowman
4th-April-2011, 06:27 PM
i would do a compression check and see what the engine is pumping. I hope you have a good idea what cam is in it. That intake has 2 in of extra plenum , plus 2 in of extra plenum with the spacer. All of that makes the engine respond like it has even larger carburator.

What numbers would you say is a good number for compression check? Tell "Millertime" what is the compression he needs or is looking for. Glass hood too I see. I think that would help,do not leave him hanging.

levisnteeshirt
4th-April-2011, 06:38 PM
i would do a compression check and see what the engine is pumping. I hope you have a good idea what cam is in it. That intake has 2 in of extra plenum , plus 2 in of extra plenum with the spacer. All of that makes the engine respond like it has even larger carburator.

to make this set up work ,, " good " ,, on a 355 ,, i'd be looking for around 180-200 psi ,,, minimum

if it isn't ,,, i'd maybe borrow a carb or 2 ,, smaller ones ,,, see what it liked ,, ,,, saw a 383 with around 145-150 psi ,, it seemed to do well with a 750dp ,,500 hp ,, hyd roller , ported dart 200's , around 10-1 static compression

pxtx
4th-April-2011, 09:27 PM
Really? You think it might NOT be a mild 350. You havent been reading the original posters posts. It is pretty evident its a mild 350.



Maybe my idea of mild is different, but this car seems like it could tip the scals to at least 51% drag race specific and 49% street car. When do your scales tip past mild?

Can't really see what type of heads you have here, can't get a good look at the end casting marks. Can you take a look under the valve covers and get some identification?
http://i303.photobucket.com/albums/nn125/MillerJWcoins/IMG_0968.jpg

Nice job on the ignition system upgrade. Those parts are a good compliment to any aggressive small block. You may want to check your distributor. Looks like it might be a tooth off. Ask if you don't know what I mean.

http://i303.photobucket.com/albums/nn125/MillerJWcoins/MSD.jpg

So far, the induction system seems to all compliment each component. Nice hood to bring in enough air and give the right clearance.

http://i303.photobucket.com/albums/nn125/MillerJWcoins/IMG_0962.jpg

I would get under the back of the car and check yoru gear ratio. If the car is in neutral and the rear tires are in the air, you should be able to spin 1 tire and both sides should travel in the same direction, like you are driving down the road. If not, ask what to do, if yes follow these instrucitons.

Mark the pinion and mark the housing and line up the marks. Turn 1 tire one complete revolution and count how many times the pinion turns. 4 and 1/2 times is approx a 4.56 gear, 3 times would be about a 3.08 gear. Do you follow the pattern?

In an email you wrote "All i know about the car is that the engine does have an agressive cam. I took the valve covers off and saw that it does have a real expensive set of rocker arms and springs. I have no idea what was done to the engine beyond that." Fair enough on a car you bought from a fellow who did not build the motor either. I wanted to put out this info because I am not so sure the conclusion everyone has made on your car is correct. Sure an 850 is a big carb, but it might not be as over carb'ed as some have assumed.

Your mission is to get a good handle on what your rear gear ratio is and try and get some identificaiton on the heads. Even a clear picture of the front of the driver side head may give us a casting mark to clue you in, but actual numbers from under the valve cover would be best.

Plowman
4th-April-2011, 09:44 PM
to make this set up work ,, " good " ,, on a 355 ,, i'd be looking for around 180-200 psi ,,, minimum

if it isn't ,,, i'd maybe borrow a carb or 2 ,, smaller ones ,,, see what it liked ,, ,,, saw a 383 with around 145-150 psi ,, it seemed to do well with a 750dp ,,500 hp ,, hyd roller , ported dart 200's , around 10-1 static compression

Is that compression "race gas" only.

asteeler4life
4th-April-2011, 09:48 PM
AN 850 IS WAY TOO BIG UNLESS YOU GOT RACING ON YOUR MIND. YOU'D DEFINITELY NEED MORE COMPRESSION. HOW MUCH COMPRESSION YOU GOT NOW ANYWAY ABOUT 10:1. YEAH THAT CARB IS TOO BIG, SEND IT TO ME. :eek:
I'D GET IT A PROPER HOME. :devil:
GOOD LUCK! :thumbsup:

Millertime
4th-April-2011, 10:35 PM
Can't really see what type of heads you have here, can't get a good look at the end casting marks. Can you take a look under the valve covers and get some identification?

Luck for you guys i took these picks when i changed my valve covers.

http://i303.photobucket.com/albums/nn125/MillerJWcoins/IMG_0948.jpg
http://i303.photobucket.com/albums/nn125/MillerJWcoins/IMG_0947.jpg

Sorry i havn't been talking more, i really want to get this figured out i have just been soo busy at work. Wednesday i will definatly check the gearing for you. Also, the reason the distributor looks off is because its not bolted down right now, you can turn it, i left it that way so its ready to tune when my timing tape comes in on wednesday. But which way would you turn it? Counterclockwise?

Thanks for everyones input and help.

pxtx
4th-April-2011, 11:12 PM
I did a quick search and came up with this:

W stands for World Products
NH is New Haven foundry which is out of business
I-037 designates they are World Sportsman heads, and are 200cc runners.

Most of those heads were 64cc combustion chamber with a 2.02-2.05 valve.

I classify these heads as above average for a "mild" sbc build. I wish I had them on my car.

Millertime
4th-April-2011, 11:19 PM
Can someone put this into english for me?

How would this effect fuel consumption in my engine. Sorry i dont know alot about heads.

levisnteeshirt
5th-April-2011, 08:29 AM
a 200cc head on a 350 is a pretty serious effort ,, ,,, the spacer and that intake with a 2 in rise cast in it , plus an 850 ,,, is not going to help your fuel mileage ,,, unless you have a 513 gear


nice lookin car ya got there

an 850 can support 600 hp ,,, thats when its in it own range for a 350 ,, a 600 hp 350 spins to 8000 rpm ,,, and pulls like hell doing it,,,, if you don't have this kind of motor ,, it would be to your benefit to swap it to something more inline with what your car needs ,,,, a 650dp will far more than most give them credit for

smell your oil ,,, does it smell like gasoline ?? if it starts doing this , yout oil is being dilutted by fuel , so its lubricating properties are being diminished ,,, ring wear will be accelerated , bearings , cam and lifters ,,, its a real bad losing situation ,,, been there done it , got the tee shirt ,,, wouldn't say it if i hadn't seen it ,,, feel the love for the engine ,, i laugh at these posters saying to run it ,,lol ,,, its toooooo bigggggggg

Plowman
5th-April-2011, 09:36 AM
a 200cc head on a 350 is a pretty serious effort ,, ,,, the spacer and that intake with a 2 in rise cast in it , plus an 850 ,,, is not going to help your fuel mileage ,,, unless you have a 513 gear


nice lookin car ya got there

an 850 can support 600 hp ,,, thats when its in it own range for a 350 ,, a 600 hp 350 spins to 8000 rpm ,,, and pulls like hell doing it,,,, if you don't have this kind of motor ,, it would be to your benefit to swap it to something more inline with what your car needs ,,,, a 650dp will far more than most give them credit for

smell your oil ,,, does it smell like gasoline ?? if it starts doing this , yout oil is being dilutted by fuel , so its lubricating properties are being diminished ,,, ring wear will be accelerated , bearings , cam and lifters ,,, its a real bad losing situation ,,, been there done it , got the tee shirt ,,, wouldn't say it if i hadn't seen it ,,, feel the love for the engine ,, i laugh at these posters saying to run it ,,lol ,,, its toooooo bigggggggg

Hey levisnteeshirt you drink beer. Is your glass half empty?

pxtx
5th-April-2011, 09:47 AM
All my experiences with fuel in the oil have not been from a carburetor that is too big, but rather from one which was malfunctioning.

Floats set too high, sunk float, dirt stuck in a needle and seat, blown power valve, too much fuel pressure- that type of thing. Basically things which can cause the fuel to run out of the carb and down into the intake, onto the piston and past the rings.

For the fuel to fall out of atomization and contaminate the oil form too much jet is significantly less likely but not entirely impossible.

I would expect the car to go a little flat from too much air (or lack of enough signal to the carb) rather than flood out the motor from too much fuel.

What is it that were are trying to tune out of the car again? I think Millertime was looking for more smoothness. Don't know how old the plugs are, and with no choke, he couldhave fouled some. The 850 should be relatively smooth, much like a 650 at idle, so was that area a problem, was it part throttle or was it WOT?

Let's try and get this back on track and understand what you are trying to improve.

If fuel economy needs to improve, let's talk about what it currently is/was and the gear you have and go from there. With a nice ignition tune that includes vacuum advance we'll get you a measurable improvement.

I have a pair of 600 cfm Holley's on a 327 with a X-Ram intake, 4 speed and 4.88 gears and I get 12 mpg. Just figured I would list that as a point of reference.

Plowman
5th-April-2011, 10:30 AM
1200cfm on a mild 327cu.in. is good than a 850cfm is ok or good for a mild 350cu.in.. So go with the MSD box.

levisnteeshirt
5th-April-2011, 12:49 PM
1200cfm on a mild 327cu.in. is good than a 850cfm is ok or good for a mild 350cu.in.. So go with the MSD box.

most likely 2 600 vs carbs ,, soo ,,, it acted like a 600 dp , and the extra volume was only drew in , if the motor pulled it ,,, ,,,

an 850dp is a serious carb ,, takes alot of motor to utilize it , ,,, if it was a 850 vs , or 870 vs ,,, that would be a different ball game ,,,

levisnteeshirt
5th-April-2011, 06:54 PM
http://www.youtube.com/watch?v=qP3DKyoIInA&feature=related

levisnteeshirt
5th-April-2011, 08:25 PM
i'm a good one to say anything about this ,,, look what i put a bid in on today ,,LOL

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=220762715165&viewitem=&sspagename=STRK%3AMEBIDX%3AIT

Millertime
5th-April-2011, 11:27 PM
So i got my timing tape installed and managed to get it idling at around 1000-1200 rpms with no back fire. I installed the 0 of the tape right on the line in the harmonic balancer. My problem is that to get it to idle, if my block is set up right it says i am pulling 55 degrees of timing at idle!!! Now i know this is wayyyy to high.

So my question is, am i off on the distributor, would it even run at 55 degree timing if im off a tooth? Or is the line on my harmonic ballencer just that far off. I just dont want to damage anything so im posting here first.

(pxtx i will still check my rear gears tomorow)

levisnteeshirt
6th-April-2011, 08:17 AM
one way to do a quick check is to see what the overlap looks like at TDC when #1 is not firing , but in overlap ,,,, there are 2 TDC events ,,, one when its preparing to fire , one where the valves are in overlap ,,,, roughly , the overlap " should " be split in overlap ,,,,, see when the intake and exhaust valve for #1 look like they are evenly open ,,, see how close it is to TDC when this occurs ,,,,, this only works perfect with a single pattern cam ,,, but its a good way to get a visual whats going on with the timing set/chain ,,,

with most cams ,, this should take place around 4 degrees ahead of TDC

another thing i'd do ,, is get a TDC tool ,, that screws into the spark plug hole ,, i'd take all the plugs out for this ,,,, insert the tool into the #1 spark plug hole ,, rotate it near TDC , it should bump the tool before TDC ,,, mark the balancer at the pointer where it does ,,, rotate it the opposite direction until it bumps the tool again ,, mark the balancer at the pointer where it stops ,,, measure the distance between the 2 marks , half way should be TDC on the balancer

Plowman
6th-April-2011, 08:46 AM
Make a piston stop. Take the white stuff out of a old spark plug,tap threads[3/8" nct]in it ,put a long bolt in taped spark plug and install in #1 cyl. Turn engine over by hand untill it stops,mark that spot. Turn engine other direction till it stops,mark it. Half the distance of the untraveled marks is true top dead center #1 cyl[mark the outside of the harmonic balancer and the lower part past the rubber,so you can tell if it spining].

Plowman
6th-April-2011, 09:00 AM
most likely 2 600 vs carbs ,, soo ,,, it acted like a 600 dp , and the extra volume was only drew in , if the motor pulled it ,,, ,,,

an 850dp is a serious carb ,, takes alot of motor to utilize it , ,,, if it was a 850 vs , or 870 vs ,,, that would be a different ball game ,,,
We put two 390cfm carbs on the 327cu.in. and went 16 seconds. We put two 600cfm carbs on same car and went 13 seconds. So we live it,I do not know what you do,but in the rest of the world the 600's work.

Plowman
6th-April-2011, 09:03 AM
i'm a good one to say anything about this ,,, look what i put a bid in on today ,,LOL

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=220762715165&viewitem=&sspagename=STRK%3AMEBIDX%3AIT

Are you going to put two 390cfm carbs on it?

levisnteeshirt
6th-April-2011, 05:52 PM
Are you going to put two 390cfm carbs on it?

tough question ,, to be honest i wish i hadn't put a bid on it ,,, but that is considered the best tunnel ram ever made ,, hatted to see it go by

might try 2 500 2 barrels , 2 600 vs carbs ,, or maybe 2 600 dp's ,, ( 5500 stall )

Plowman
6th-April-2011, 06:26 PM
I have six pack,two 3 barrels,950cfm,on a TR2 Edelbrock tunnel ram,and a bbc. Sounds good. Hope you fine the intake you want. Paul

Millertime
6th-April-2011, 06:49 PM
To start from the beginning... When i took out the old distributor i did mark it and installed the new distributor in the same place. When i tried starting it the car kept on backfiring even if i adjusted the timing. After doing some troubleshooting i found out that the MSD setup needs a constant 12.5 volts to work effectively and my old battery was only putting out between 12.3 -12.4 volts which means my car probably wasn’t getting the juice it needs to create enough spark for my carb. So i borrowed a battery charger and it didnt help, my battery was official dead. I've been using a battery i had out of my Mitsubishi Ralliart when i upgraded to a race battery to try and troubleshoot. I did order an Optima Redtop and it came in today so i will be installing that tonight. So after replacing the distributor, sparkplug wires, sparkplugs, battery and battery wire terminals hopefully my car will be good to go!

Back to the timing. I got home kind of late last night and didnt find TDC before i installed the MSD timing tape. I just lined up the 0 on the tape with the line on my balancer figuring that it was correct. After i posted last night i did a quick cloths hanger test and found out that my TDC is defiantly off from my balancer explaining why the reading was soo far off. So now tonight when i have more time im going to try and redefine TDC on my car again and install my tape correctly to get better readings. Also i do have the vacuumed plugged for now. My car is running and idling very good so i know my timing is really close.

You had asked what all i am working with. I have a basic $40 timing light special from Advanced Auto. Nothing special at all. I put on a MSD timing tape that i installed on wrong.

To give you more information about me so you know who you are working with. I am a Staff Sergeant in the Air Force. I'm an Electrical & Environmental specialist with MH-53 helicopter and CV-22 Osprey Tilt-rotor experience. I love mechanics and have experience working on imports and a few bikes. I can do any task with direction, i just dont have a lot of experience with older domestics and im trying to learn as much as possible. So if my questions sound dumb just bear with me.

So if i do get my tape on right what timing should i set if im idling at 1000 rpms? Thanks for your help and im sure i will have a million more questions.



Joel

Plowman
6th-April-2011, 09:28 PM
Set it with that camshaft 10 to 18 for starters. What you want is total at 3500rpm and the idle timing checked after total is set at 35 to 40 degrees advanced. You will need more info. But it should run.

Millertime
6th-April-2011, 10:10 PM
Got my car running! Even swapped in the lighter blue springs and it ran even better! One problem... When car is at WOT the car boggs down. It runs a lot faster at half throttle than at full throttle. So if anyone here is familiar with MSD distributors would putting a higher degree timing stop help, or is my only option to get a smaller carb?

Plowman
6th-April-2011, 10:59 PM
You have to make or buy a piston stop to get it.

levisnteeshirt
7th-April-2011, 07:04 AM
half throttle is better than full throttle ,,, hmmm ,, i would take the carb apart and clean it very good ,,,,

bottem line ,, there is only so much we can do ,, i wish i could reach through the keyboard and be there with you ,, i bet we could get it better than it is ,,,, i would look at the air bleeds ,,, make sure they're not plugged ,,, ,,, i would soak the metering blocks in a carb dipping solution to make sure nothing is stopped up ,,,, i would change the metering block gaskets , and the base plate gasket ,,, Holley gaskets will sometimes shrink over time ,, and a passage might become blocked ,, alot of things to look for

personally ,, your life will be alot more happy with a 3310, 750 vs holley carb ,,, there just about goof proof ,,,, they allow for modifications so you can build it some , learn about it ,,,, great carb for alot of street cars IMO

get a book and get educated on them too ,, a holley carb is like electronics ,, it has several circuits you have to learn how they function and how to control them to your benefit