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Discussion Starter #1
Greetings,

Despite 2020 being what it was, I was finally able to get my nova on the road and to the track. I have owned it since 2004. As with all gear heads, I feel my track performance was underwhelming and searching for an outsider perspective on improving.

1967 Chevy II post car. Weighs 3020 with 6 point roll bar and bench seat. 3250 with me in it.
The powerplant is basically a time capsule from 1999. 400 SBC short rod with hypereutectic flat tops. Old dart iron eagle, heads 200 with a 2.08 valve. 64 cc. Lunatti solid BM .500/.515. 850 holley DP. Hooker super comp 1.625 thru 2.5 flowmasters. TH350 with 3500 stall, flashes to 4600. 12 bolt with 4.11 on 26 tall street et tire. 38 degrees timing, all in at 3000.
Best run was 12.46 @108.
1.72 sixty foot
7.91 eighth mile.

By my calculation it is making 320 at the wheels. I trap around 6200. I feel this combo should be 11.70 or better.
Plugs read coco brown, runs and street drives nice but not really a screamer like some of my 355's from the past. Cam is probably too small and the pistons are down .031 from deck.

Any feedback or criticism would be welcome. Thanks!!
 

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I had a similar motor in my 67 coupe, stock 406 short block, SP-II heads, Comp 224° HR cam, Q-jet, 1-5/8" headers with 2-1/2" collectors and x-pipe, 4.11 gears and a 700R4. 11.75 @ 117. 1.61 60ft, 7.50 @ 92 - 1/8
I would work on getting the 60' times down to the low 1.6 second range. You're giving up a lot right off the line.
What is your 1/8 mile speed?
 

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I'd agree with the camshaft being small. You didn't say anything about the lobe center but I'd go with more camshaft with 106-108. This will help with the 850 carburetor. Didn't say what diameter the converter is but the smaller the better. I once changed from a good ten inch converter to a eight inch and picked up three tenths touching nothing else. Anything you pick up in the first 60 foot will really improve your ET. Anything you can do to get a few pounds off will also help.
 

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Discussion Starter #4
I had a similar motor in my 67 coupe, stock 406 short block, SP-II heads, Comp 224° HR cam, Q-jet, 1-5/8" headers with 2-1/2" collectors and x-pipe, 4.11 gears and a 700R4. 11.75 @ 117. 1.61 60ft, 7.50 @ 92 - 1/8
I would work on getting the 60' times down to the low 1.6 second range. You're giving up a lot right off the line.
What is your 1/8 mile speed?
Hello Mike,
89 mph in 8th.
 

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I'd agree with the camshaft being small. You didn't say anything about the lobe center but I'd go with more camshaft with 106-108. This will help with the 850 carburetor. Didn't say what diameter the converter is but the smaller the better. I once changed from a good ten inch converter to a eight inch and picked up three tenths touching nothing else. Anything you pick up in the first 60 foot will really improve your ET. Anything you can do to get a few pounds off will also help.
9.5 converter set up by Quickdraw. Cam is an old lunnati on a 112 centerline. I can easily pull 120 pounds off as well
 

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Cam is rotten LSA, especially for a short rod 400, and not enough lift. Needs 106-108° LSA, 100-102° ICL when installed. Something around 250-260° @ .050 duration intake side .550"+ lift, and will like a 1.6 intake/1.5 exhaust rocker split set.If you like Lunati, something from the Tight Lash 2 or Drag Race cams list.
Remember, when you look at catalog description for recommended rpm range on a SBC cam, that is based on cam being used an a little 350, rpm range will be 500-600 rpm lower in a big 400.

Any port work been done to those heads, or just the 2.08" valve?? Any idea of the intake port flow numbers at all?
What intake manifold? Any carb spacer?

My similar 406 except 5.7" rods,... flat tops,zero decked, 10.8:1 compression, 68cc Sportsman II's w/2.055" valve and bowl blend, 254/260°@.050" Crower solid flat, .570/.575" lift with 1.6/1.5 rockers 106° LSA, 102° ICL, 1-3/4" x 3" Hedman Husler headers w/18" collector extensions, 2.5" Walker DynoMax turbo muffs, Vic Jr intake, 950 Holley, 1" open spacer, 4"x14" dia filter, mechanical clutch fan and water pump, 10" 3400 rpm converter, RMVB TH-400, 4.11 gear, 27 x 9" dirt track tire(American Racer, Street Stock Dirt L-60/15"), 3600 lb w/ driver '72 Nova.
Sixty Foot 1.68-1.72
11.44 @ 117 mph best, 67-6800 rpm shift, 6400 cross.... 11.90's short shifting @ 4800 rpm even when trying to slow it down to 12.0
Pump 93, drive 75 miles to track, race, drive home.
Also a mid 1990's combo, ...getting a fresh bullet at the moment.
 

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What’s the goal?

that sbc isn’t making much power with that mph. Yep. Need to get that 60’ down.

cam it too small. I tend to go conservative on cams because I like them to live and be enjoyable on the street. Maybe 240-250 duration less than .600 lift, dual plane rpm intake. I’d stay hydraulic. Even 210afr heads would wake that thing up. Converter And rear gear look ok. your car weight is good. It’s not heavy.
I’d make more power first then you could look at other things: weight, the converter if desired. Trap speed, rpm shift drop, etc
 

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Discussion Starter #8
Excellent responses guys!

I have few folks to bounce these things off of, so I really appreciate the feedback.

Goals?

I planned this out to run an 11.50 index class but still drive the car to town or to a show. 75/25 mix of racing first, driving second.
Do to the attendance at my local track, I have only 7 runs on it but have enough data to know my set up is down about 60 hp or so.
The heads......I got in a trade and they looked close to new condition in 2007. but the fella gave me a flow chart showing 256 at
.500 lift. I do not see evidence of porting or other work but haven't had the valves out either. Pocket port would be doable this winter if I dont upgrade to a promaxx 220 set.
I have a stealth intake that I milled out the divider plenum and has a one inch spacer.

The point of this post is game planning for next steps. I have 1500 to spend on up changing out the rotating assembly and cam, or staying with the current set up and buying the promaxx heads and a cam. When built in 1999, we had the rods resized with good bolts and it is balanced. The block is an 817 that had 20k miles (motorhome), so bore is std 4.125 but deck measured 9.031. I know this isn't helping quench and CR. It cranks at 175 psi.
 

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While I don't have a lot to share, I will say that this thread is helpful to the rest of us who are running an archaic 400 mill.
 

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I had a similar motor in my 67 coupe, stock 406 short block, SP-II heads, Comp 224° HR cam, Q-jet, 1-5/8" headers with 2-1/2" collectors and x-pipe, 4.11 gears and a 700R4. 11.75 @ 117. 1.61 60ft, 7.50 @ 92 - 1/8
I would work on getting the 60' times down to the low 1.6 second range. You're giving up a lot right off the line.
What is your 1/8 mile speed?
411977
 

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A few things I would change. A better head would help a lot, and definitely needs a better, bigger camshaft. Also I'm not feeling the Stealth intake, especially with the divider milled out. Depending on what you want more, power or drivability, you really couldn't go wrong with a Performer RPM airgap. If you want more top end and can lose some torque, then go Victor Jr. The 4.11 gearing is a fair compromise, but what rpm are you going through the traps at? The car might want a 4.33 or 4.56 gear. And lastly, are you running a full exhaust out the back or a short exhaust? Either way Stepping up to a 3 inch will help, and get rid of the Flowmaster. You want a muffler with a straight through design. Flowmaster are on the bottom of the list for making power.
 

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Based on the time slip I don’t see a big discrepancy in the numbers. Everything matches up. The car just appears down on power. Dropping the 60’ is not going to fix you’re issue. The 1/8 to 1/4 numbers pretty much match, and the 60’ I don’t feel is that far off for an honest mid 12 second car. The converter numbers are a little extreme that it flashes so much higher than stall, but I don’t know if that’s an advertised number. But it doesn’t seem like the converter is slipping too much at finish based on your mph numbers. I don’t want to pick a single cause but I agree I would expect more out of it. I don’t think it’s the heads since my friend and I ran a set of 64 cc world sportsman II 200 cc heads on a 355 with 10.5:1 compression and went 11.60. And this was a stock appearing 69 Camaro, not a gutted race car. However it did have an ultradyne solid flat tappet cam .518/.530 251/251. If changing t he heads is your desire I would get a cam made based on your heads, and car combo. I would also figure out your real compression ratio.
 

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Discussion Starter #13
A few things I would change. A better head would help a lot, and definitely needs a better, bigger camshaft. Also I'm not feeling the Stealth intake, especially with the divider milled out. Depending on what you want more, power or drivability, you really couldn't go wrong with a Performer RPM airgap. If you want more top end and can lose some torque, then go Victor Jr. The 4.11 gearing is a fair compromise, but what rpm are you going through the traps at? The car might want a 4.33 or 4.56 gear. And lastly, are you running a full exhaust out the back or a short exhaust? Either way Stepping up to a 3 inch will help, and get rid of the Flowmaster. You want a muffler with a straight through design. Flowmaster are on the bottom of the list for making power.
6200 rpm thru traps.

Converter flash was after run in high on return road.
I worry about to much more rpm with the short rods.....
 

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A few things I would change. A better head would help a lot, and definitely needs a better, bigger camshaft. Also I'm not feeling the Stealth intake, especially with the divider milled out. Depending on what you want more, power or drivability, you really couldn't go wrong with a Performer RPM airgap. If you want more top end and can lose some torque, then go Victor Jr. The 4.11 gearing is a fair compromise, but what rpm are you going through the traps at? The car might want a 4.33 or 4.56 gear. And lastly, are you running a full exhaust out the back or a short exhaust? Either way Stepping up to a 3 inch will help, and get rid of the Flowmaster. You want a muffler with a straight through design. Flowmaster are on the bottom of the list for making power.
Exhaust dumps at rear axles. I have thought of uncorking it and establishing a baseline, but like all of the response here, there isn't a smoking gun, nor will open headers make up the missing hp. I had a junk 355 with Sportsman 2 heads and crane 540 cam run the same et in a different nova back in the day.......unsure what to do with it.
 

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I don't like the Stealth intake choice either, and no amount of plenum work would help it, and neither would a different brand of dual plane liked an Air Gap....the runner cross section is just not larger enough in any dual plane for a 400" engine to breathe through.
With your converter, any supposed low end torque benefit from a dual plane is out the window anyway, you don't need it.
With the combo i outlined in my previous post, I was always looking for ways to trade off some low end for better top end power....it was capable of spinning the tires way more than needed. That's why the Vic Jr with a port match, 1" open spacer, big 950 carb, 1-3/4" headers....you've got to inhale and exhale 400"+, not a little weeny 350" like most SBC stuff is designed around. I always wanted to try a Victor 4x4 or Victor E on it since they were bigger plenum, or a Holley Strip Dom Dorton version.

Induction and exhaust has to be sized like it is a Big Block....because cubic inch-wise, it is.
 

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Discussion Starter #16
Thanks again for all of the information shared here. My opinion of this car underperforming was also validated.


Aftwr reading.....I feel that there is an air flow choke point in both intake and exhaust. The compression is also lower than I think it is. This winter I am pulling the heads and pocket port them and match up an open plenum intake. I know the dart are ok and there are much better heads, but these should work for 450-470 hp range. As mentioned the pistons are down the bore .031 and I used a .039 gasket. Since nobody sells a 400 steel shim, I plan to buy a 350 steel shim gasket(s) at .015, modify the bore dia, EDM the steam holes and help that compression issue. I manage a die shop and have access to machine tools. Cam change to a <.550 lift solid on a 106/108 lsa and switch over to electric wp and fan. Changing to 3 inch exhaust and a s

I will keep everyone updated on results. Thanks again!!
 

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Speedway Motors has a 4.165" bore steel shim in .024" thickness, no steam holes but that is an easy drill job. $10/ea
Speedway also sells a Mr Gasket solid copper 4.140" bore x .020" thickness gasket that doesn't need the block 0-ringed for use...same deal, drill the steam holes. Pricey little sucker though, at $60/ea



Check your deck close for flatness when planning to use a thin gasket....I've yet to see a virgin used 400 block that was flat, especially between the cylinders and near the two central exhaust valve section. It can be a sealing problem with shim gaskets.
That's the biggest reason I plan a zero deck from the start of any 400 build, as they are rarely flat enough to use as-is.

Sounds like you've got a decent plan though.

I also did a dirt simple, short rod 388" in a '76 Disco Nova,....
Home ported 2.02" 487X smogger heads, flat top Silvo-lite claimer hypers, no decking and .041 gasket for .065"-ish quench so just a hair over 9:1 comp, another Crower solid 268/276° @.050"(whopper!, but Dan Crower recommended it), .555"/.579" lift, 106° LSA in @ 100° ICL, 1.5 Crane roller rockers, Vic Jr, 780 Vacuum, 1-5/8" headers, 2.25" mandrel Hooker exhaust kit with Cyclone turbo muffs(Sonic Turbo?), 3000 stall, 4.10 gear, G-60/15 Amer Racer Tire Dirt Street Stock's @ 26" x 8", also all steel @ 3700 lbs(converted 6 cylinder car to 388 stroker).
1.86 Sixty Foot, ...it was weak off the line but big top end charge from that cam
12.65 @ 110 MPH
Pump 87
 

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I did a 400" small block in my car with (literally) thrown-together, "laying around" parts two years ago. Stock 4.125" bore, stock rods, stock 19.5cc dished pistons, and the slugs were 0.039-0.042" below deck. With a the already-deplorable quench height, 0.039" gasket and a 64cc(ish) 291 head, the "static" compression was calculated to be 9.05:1. With the very driver-friendly XE262 cam (.462/.469", 218/224°, 110° LSA), dynamic compression is 7.91:1.

Ironically, by keeping the cam small and "tame", it bleeds off so little compression between timing events that it needs premium to combat rattling with the awful quench and archaic head design. I wish I could have gone with a much bigger bumpstick, but I was afraid of pulling the rocker studs out of the cylinder heads. The components fit something of a 327-350" build more than a 400, but the parts were laying around, and I wanted a stump-puller for a light car, so...
 

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Greetings,

Despite 2020 being what it was, I was finally able to get my nova on the road and to the track. I have owned it since 2004. As with all gear heads, I feel my track performance was underwhelming and searching for an outsider perspective on improving.

1967 Chevy II post car. Weighs 3020 with 6 point roll bar and bench seat. 3250 with me in it.
The powerplant is basically a time capsule from 1999. 400 SBC short rod with hypereutectic flat tops. Old dart iron eagle, heads 200 with a 2.08 valve. 64 cc. Lunatti solid BM .500/.515. 850 holley DP. Hooker super comp 1.625 thru 2.5 flowmasters. TH350 with 3500 stall, flashes to 4600. 12 bolt with 4.11 on 26 tall street et tire. 38 degrees timing, all in at 3000.
Best run was 12.46 @108.
1.72 sixty foot
7.91 eighth mile.

By my calculation it is making 320 at the wheels. I trap around 6200. I feel this combo should be 11.70 or better.
Plugs read coco brown, runs and street drives nice but not really a screamer like some of my 355's from the past. Cam is probably too small and the pistons are down .031 from deck.

Any feedback or criticism would be welcome. Thanks!!
So there are a number of ways to approach this. You can throw money at it and change up your combination or you can work through your current combination to make sure you are getting as much out of it as possible b/4 make a major change to the combination. Most of us have not started with an optimum combination. Note that even if you change up your combination now, by changing heads and/or cam, etc. any other shortcomings may still be in place and could still limit the potential of the new combination. I suspect there is still more in your current combination, just as you do. You did not mention how the car ran in your 12.46 pass. Any bog?, Any breakup? Does it pull strong to your shift point? Are you running mechanical and or vacuum advance? Any tire spin? How many passes have you made? Was the car consistent? What was the DA when you made those passes? My car had been running consistent 11.7s-11.8s. I tuned the car for several years over maybe a couple hundred passes to get it to that ET, (with a lot of help and suggestions from folks on this site!). One day at the track, it would not go better than a low 12 second run. A friend suggested I check the mechanical advance, and sure enough, it was binding. I fixed that problem and it seemed to miraculously pick up the 4 tenths it had lost. I'm not suggesting that you shouldn't do the upgrades you want to do. But suppose you do all of that and it is still disappointing? If everything checks out good, I'd at least suggest you make a couple of passes with the headers uncorked, that might tell you a lot.
 

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Discussion Starter #20
So there are a number of ways to approach this. You can throw money at it and change up your combination or you can work through your current combination to make sure you are getting as much out of it as possible b/4 make a major change to the combination. Most of us have not started with an optimum combination. Note that even if you change up your combination now, by changing heads and/or cam, etc. any other shortcomings may still be in place and could still limit the potential of the new combination. I suspect there is still more in your current combination, just as you do. You did not mention how the car ran in your 12.46 pass. Any bog?, Any breakup? Does it pull strong to your shift point? Are you running mechanical and or vacuum advance? Any tire spin? How many passes have you made? Was the car consistent? What was the DA when you made those passes? My car had been running consistent 11.7s-11.8s. I tuned the car for several years over maybe a couple hundred passes to get it to that ET, (with a lot of help and suggestions from folks on this site!). One day at the track, it would not go better than a low 12 second run. A friend suggested I check the mechanical advance, and sure enough, it was binding. I fixed that problem and it seemed to miraculously pick up the 4 tenths it had lost. I'm not suggesting that you shouldn't do the upgrades you want to do. But suppose you do all of that and it is still disappointing? If everything checks out good, I'd at least suggest you make a couple of passes with the headers uncorked, that might tell you a lot.
Thanks for the feedback.

The car has made 7 passes since coming back to life. Our track has been packed and it has allotted for much test and tune. It has maybe 700 street miles on it as well. It doesnt run bad outside a gradual temperature rise and I could easily drive it to work daily outside the 4.11 gears. Maybe I am jumping to conclusions to soon.
Car leaves straight but has some spin. Drag radials seem inconsistent compared to slicks. I dont have a spotter. I ranged from 12.85 to 12.46. The latter time being after I eliminated a bent cam arm on the accelerator shaft. No bog and it pulls to 6200 pretty well. It doesnt scream like my 355,327s did but maybe that's the nature of a 400 sbc but I suspect I am not flowing the air efficiently.
 
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