Chevy Nova Forum banner

1 - 20 of 25 Posts

·
Registered
Joined
·
2,638 Posts
Discussion Starter #1
So my wagon currently has a Magnum 280 Comp Cam. I get like 10mpg. I'm sick of it. Here's the basic specs:

Camel hump heads
~9.5-10:1 compression
Stock exhaust manifolds
Edelbrock Performer EPS intake
Holley 600 with mech. secondaries
TH350 with about a 3.08-3.31 rear gear

What are some hydraulic flat tappet grinds that you guys use to get decent gas mileage. I had a 72 Nova a long time ago that got 20mpg with a mild RV cam that I didn't know the specs on. I would like to get somewhere around here with the TH350 then step up to a 2004R and get even better fwy mileage. Please chime in on what you think would work best. I'm also adding power brakes, so a bit more vacuum would help. I'm thinking that something in the 212*-220* @.050 and about .450" lift is what I'd need on a 110*-114* LSA. Thanks
 

·
Premium Member
Joined
·
2,921 Posts
have you tried a different carb? get rid of the DP and try a VS carb first. see what kind of improvement that makes before all the work of switching cams..IMO
 

·
Premium Member
Joined
·
3,563 Posts
I'm thinking that something in the 212*-220* @.050 and about .450" lift is what I'd need on a 110*-114* LSA. Thanks
I think you are on the right track. Call Comp Cams' hotline and talk to them, they can advise better than anyone on any message board.

204/214 @0.050 on a 112* angle would be my guess. I'd go with the Comp Cams Extreme Energy cam line.

FYI - the stock manifolds are holding back your mileage. Headers would help. If you want to keep the manifolds - look into a split pattern cam with a slightly longer exhaust duration to help get the spent gasses out of the cylinders.
 

·
Premium Member
Joined
·
3,563 Posts
have you tried a different carb? get rid of the DP and try a VS carb first. see what kind of improvement that makes before all the work of switching cams..IMO
Yeah, I found that odd as well... a EPS manifold with a DP? If you like Holley carbs, their Street Avenger is set up for the best mileage.
 

·
Registered
Joined
·
2,638 Posts
Discussion Starter #5
I guess I'll try a different carb first then. That's just a little bit of bending lines. I didn't think the 600 was bad on gas. It's an old 600. It doesn't tend to run rich, and I keep my foot out of it. My race car with the o/d gets better gas mileage actually.
 

·
Premium Member
Joined
·
3,563 Posts
I guess I'll try a different carb first then. That's just a little bit of bending lines. I didn't think the 600 was bad on gas. It's an old 600. It doesn't tend to run rich, and I keep my foot out of it. My race car with the o/d gets better gas mileage actually.
Well, the cam swap to something smaller will help a bunch. If you have the time to experiment, the cam would be a good start since you are basically living off the primary jets on your 600.
 

·
Registered
Joined
·
2,638 Posts
Discussion Starter #7
i could be wrong on the carb. there's just a single inlet on the drivers side. i just figured because it has two bowls that it's a double pumper. there's a link between the first and second fuel bowl for fuel, and it's for sure a mechanical secondary carb. how much improvement would i see with one of the 570 street avenger carbs? they're 350$ on summit. i'd rather borrow one and find out first before buying.
 

·
Registered
Joined
·
162 Posts
Check out the summit brand of cams # SUM-1102 or # SUM-1103.....they should both work for what you are looking for imo
 

·
Registered
Joined
·
2,638 Posts
Discussion Starter #9
Well, the cam swap to something smaller will help a bunch. If you have the time to experiment, the cam would be a good start since you are basically living off the primary jets on your 600.
that was my thinking as well. the cam swap is easier, but cheaper. i figure between gaskets and everything i'll be out about $300. the problem is that it's a LONG JOB! Radiator, water pump, oil pan, intake manifold, rockers, rocker adjustment, TDC, removing grill, etc, etc, etc...

I've swapped cams in a 3rd gen car by removing the grill. Will it be easy enough to do the same on my 66 wagon?
 

·
Registered
Joined
·
308 Posts
May I suggest a wideband o2 setup I Have had mine for a while (fast one that reads both banks) With my 74 i click off low 12s with the over drive but I can lean out the carb to the 17 18 range on the meter and get wicked milage on the highway
Just a thought By the time you get a new carb you could buy a wideband setup and tune anycar you own by just switching the meter around
Josh
 

·
Registered
Joined
·
2,638 Posts
Discussion Starter #11
May I suggest a wideband o2 setup I Have had mine for a while (fast one that reads both banks) With my 74 i click off low 12s with the over drive but I can lean out the carb to the 17 18 range on the meter and get wicked milage on the highway
Just a thought By the time you get a new carb you could buy a wideband setup and tune anycar you own by just switching the meter around
Josh
how much are you talking about spending?
 

·
Registered
Joined
·
4,612 Posts
umm

isn't the 280 magnum about 230 @.050 ??? I had an elgin 204/214-112 cam in my tow vehicle's 305 with headers and 2.5 pipe. It would get about 15 mpg in a van, I tried the smaller cam with 194/205, couldn't tell much difference
 

·
Registered
Joined
·
2,638 Posts
Discussion Starter #13
isn't the 280 magnum about 230 @.050 ??? I had an elgin 204/214-112 cam in my tow vehicle's 305 with headers and 2.5 pipe. It would get about 15 mpg in a van, I tried the smaller cam with 194/205, couldn't tell much difference
Yes, it is. Maybe a carb change is in order? And maybe an o/d would help too...
 

·
Registered
Joined
·
308 Posts
last time i looked aroound you could find a lm1 from innovative for 200 or less heck my fast that reads both banks was only like 3 or 400 but you dont really need to read both banks one is good enough for most stuff
A lot of people dont seem to have them and maybe its the cost but ive been able to get about any carb running on my car prety well with it
its nice to know if tha motors lean or rich without pulling plugs and thats not that acurate anyways http://www.rpmoutlet.com/mt.htm
im sure with some looking you may find it cheeper i really like the fast setup because it can data log a run so you know what the cars doing during the burnout and going down the track without guessing
with everything ive bought and spent money on the wideband I think was the best money spent so far and that includes gears the motor and the tko
BEST OF LUCK
Josh
 

·
Registered
Joined
·
2,146 Posts
I like the Comp 268 cam or a GM L-82 cam I've used them both in a 350 having the cam 2* advanced at the cam seemed to help more on the bottom end. In a 383 or 400 I'd go straight up. Play with jetting and timing too and I also suggest some 1 5/8" headers.
 

·
Registered
Joined
·
1,725 Posts
1. Find a GM Aluminum spreadbore ( QJet ) intake manifold .
2. Get a good Q-jet from Cliff Ruggles (unless you know how to do it yourself)
3. Call Bullet Cams http://www.bulletcams.com/ and have the guys get you the correct cam profile for YOUR car.
4. Have the ignition curve checked and mapped out, and correct it.
5. Correctly match your components, and you'll have great throttle response, power and fuel economy.
 

·
Registered
Joined
·
1,989 Posts
Put some rhoads lifters in it to bleed off some low rpm duration and increase some vaccum, that would be the cheap and easy route.
 

·
Registered
Joined
·
2,638 Posts
Discussion Starter #19
Lots of advice, thanks guys. Mike, that cam is not cheap, but if it works, it works. I will look into everything that was mentioned. Sounds like I'm not the only one who's had this problem. I bought the car with the cam that's in it, and if I built it I might have done things differently. Headers are probably not gonna happen unless I can find a set that makes plug changes not terrible. I'll be doing some more homework on this...
 

·
Premium Member
Joined
·
667 Posts
Lots of advice, thanks guys. Mike, that cam is not cheap, but if it works, it works. I will look into everything that was mentioned. Sounds like I'm not the only one who's had this problem. I bought the car with the cam that's in it, and if I built it I might have done things differently. Headers are probably not gonna happen unless I can find a set that makes plug changes not terrible. I'll be doing some more homework on this...
I've got a set of 1 1/2 primary tube headers for $100:yes:
 
1 - 20 of 25 Posts
Top