Horse Power for 1982

[Evolution1980]

To sum up, I realized that my stock 350 did not need a 750 cfm carburetor. So i replaced it with a 600 cfm. My performance has increased dramatically.

Hmmm... :confused
I guess it's possible, but... If you had the OEM Qjet from the factory, I'm left to believe that it simply wasn't tuned properly and/or had worn parts. I can't think of any reason why a 600cfm should work any better than a 750cfm Qjet. Especially considering how small the primaries are on the 750 Qjet. But hey, whatever works for ya!

 

[minifridge1138]

It wasn't a Q-Jet. It was a Holley, but a true Quadra-Jet.
I will admit that the 750 was not tuned correctly. But I don't know if I would have ever been able to burn the amount of fuel it was pumping.

For carburetors, bigger does not always mean better. There is such a thing as too big.

 

[Evolution1980]

I will admit that the 750 was not tuned correctly. But I don't know if I would have ever been able to burn the amount of fuel it was pumping.

That's why it needs to be tuned correctly!

For carburetors, bigger does not always mean better. There is such a thing as too big.

Yep that is true, especially for pretty much any carb that isn't a Qjet. :cool
Glad ya got it all working out!
So then are you still looking for "mo' powah" upgrades? Or are you going to be satisfied for a while with the new grunt you've found?

 

[minifridge1138]

Yeah, i'll be happy for quite a while.
I'm sure that I could have tuned the 750 to perform well. But the previous owner abused it, so I'm pretty comfortable having a warranty and everything. After i finish some things (DeWitts radiator and wiring) I will come back to the carb, rebuild it, and see what it is like. But for now, i'm VERY happy.

Here is a link to a CFM calculator I found on the internet.
http://www.4secondsflat.com/Carb_CFM_Calculator.html

Basically, a 350 running at 100% Volumetric Efficiency, with a MAX RPM of 7000 needs a 708 cfm carb.

I don't want my car running at 7000 RPM's, so 750 is definitely too big. And there is NO WAY i'm at 100% VE.

So i think that 600 is better. (the calculator says i would need 588 cfm).

 

[Curtis]

Hey fridge, wanna run em?

 

[minifridge1138]

Not until i replace the radiator.
Someone went cheap with mine, it is a 2 core.

I'm going to order a dewitts in april. Just waiting for the next billing cycle on my credit card.

 

[GTR1999]

One thing I didn't see mentioned was the differential. Keep in mind the 80-82 were aluminum and weak. I've seen the stock engined cars with cracked bearing scaps and trashed parts. If you load it enough it will break, I know there are guys runnihng 400 hp with the stock rear ends but I would be cautious. If you plan to push the car hard you may want to consider a coversion to an early iron unit that can be built much stronger.

 

[Glensgages]

One thing I didn't see mentioned was the differential. Keep in mind the 80-82 were aluminum and weak. I've seen the stock engined cars with cracked bearing scaps and trashed parts. If you load it enough it will break, I know there are guys runnihng 400 hp with the stock rear ends but I would be cautious. If you plan to push the car hard you may want to consider a coversion to an early iron unit that can be built much stronger.

VanSteel in Clearwater, Fl., is less-than an hour-away, and we have already discussed 'back-dating' my Dana-44 center-section to pre-'79 standards:
basically, I think everything from the drive-shaft to the rear lug-nuts will be upgraded, but I'd still like to find a spool for this sucker.....

 

[Glensgages]

.....well..... quite a bit has happened since my last visit to this thread, and my priorities have changed.....


Despite winning a race at Bradenton in March of '07, the ol' Cease-Fire proved to be more inconsistent than it was slow, and after 2 more events (May & June, both First Round Runner-Ups..... ), I parked the car, and offered to help run the Series, offering tips to rookie racers, taking photographs, writing articles, and helping establish pairings before each round of Eliminations:
I decided I'd rather wait until I had a consistent car, capable of winning every time out, than beat my head off the wall with the '82.


(the house I own in Taxylvania has sat vecant for 15+ months, and in the current economy, who-knows when it'll get sold, and I don't want-to spend money to update this car until it is sold, and we have bought another place here )

Shortly after our season ended in September, we were told that Bradenton would no-longer host our monthly events, so I have no real-reason to turn this car into a strip-only piece anymore:
once we do find a house, I'll bring my 12-second '79 Z28 here, and begin racing it instead.....

...... but that doesn't mean I'll leave the '82 as-is.....
:nono

the wimpy 700R4 is leaking, and wouldn't stay in 3rd Gear under W-O-T, so it needs swapped-out (to a much-stronger THM350 ), and since I don't need to spend so-much money turning it into my 2nd 12-second racer, I can spend fewer dollars, and make it run like it should've from the factory
(I added 3.73 gears in late '03, so at-least that is accomplished already..... )

Because I'll keep the as-assembled L-83 short-block intact, I'll keep the RPM-limit self-imposed at 5500, and am planning on tossing the CFI, heads, and camshaft in-favor of better-matching pieces:
I'm thinking about a cam along-the-lines of CompCams' 270H, with a 650 cfm Holley double-pump carb sitting-atop a dual-plane intake (smallish-carb & dual-plane intake, to promote as-much bottom-end punch as possible with the low RPM limit ), but can't decide on which heads to purchase.....

the Scoggin-Dickey Performance upgraded iron vortec heads with 64cc chambers, or 58cc aluminum L98 heads, like those found on ZZ4 crate-motors.

I see the pros & cons of each as-such:

VORTEC HEADS ~ the head/intake kits from SDP, including a vortec-style RPM Air Gap intake, would cost just $1,100 complete, and result in a compression ratio approaching 10:1 (I believe the L-83 is 9.1:1 with the junk/OEM 76cc heads? )

L98/ZZ4 HEADS ~ the heads alone will cost $1250 from Pace Performance, but their 58cc chambers would raise the compression even-higher, probably close-to 10.8:1, and retain less heat than iron vortec heads
(I could save a few doallrs and use a 327-CID/365-HP intake I've had for almost 30 years with standard-port heads )

I guess my question, and concerns, are - - - - -

#1 - would an aluminum-headed motor live on the street with a short-duration cam and close-to 11:1 squeeze, or should I consider a longer-duration cam (and, if-so, how-long? ) ?
;help

#2 - would the power made from increasing the squeeze from 10:1 to 11:1 with smaller-chamber heads be worth it, as I try to maximize as-much HP & TQ below 5500 RPM?
:W

Any thoughts are greatly-appreciated!

 

[Hib Halverson]

Hey everyone,

I love my car. It looks great, and drives well. But it is not as fast as it looks. Currently i've got a 750 cfm Holley and a Holley dual plane manifold. What else can/should i do for more power and torque? I would love some suggestions from people with experience.

Here are my thoughts:
1) super charger / turbo charger (instant power, but my car already runs hot)
2) cam shaft, lifter, rocker arms
3) upgrade exhaust
4) upgrade heads

First, if the engine is stock, other than the 750 and the Holley intake, you've got way too much carburetor and probably too much intake.

In this order I'd
1) Forget a blower or a turbo
2) upgrade the exhaust with headers, true duals and retain your Flowmasters
3) Port the heads, change to a hydraulic roller cam and 1.6 roller rockers.

With the right parts, the right assembly and the right tune you can get to 350-375 hp fairly easily.

Tell us a little bit about how you converted an engine with computer controls to a non-computer engine.

 

[Curtis]

Hi Glenn,, just out of curiousity, i ran a vortec head engine with 10.0 to 1 compression with a XE 268 cam on my desktop dyno.. changing the compression to 11.0 to 1 gained about 11 lb.ft. and topped out at 4500 rpm.. the horsepower did better but topped at 6000 rpm (about 1000 rpm higher than the 10/1) with gain of 18 hp. I don't know that aluminum heads produce more power because they are aluminum, it may be they are just better against detonation in a street motor because they do not retain as much heat.. As far as best for the street, then you will lean towards the aluminum heads because you can run more advanced timing and stay out of detonation as a result of the lower heat retention.. The weight savings is always a plus. In the end, it is the heat that makes the power, suppose sort of like alcohol cars.. If the motor don't warm enough it makes no power. And on the other hand, money is always a worthy consideration. Let me know if there is anything I can do for you.. and good luck.

 

[Glensgages]

Let me know if there is anything I can do for you.. and good luck.

Thanks for the help to-date, Curtis..... even-though the car won't be raced on any regular basis, I figger I might-as-well build as-much snort into it as I can while it's apart, and thought running more squeeze would be a cheap-way to make power.

'Whenever' this goes-down, the local shop has a chassis dyno, and I'm sure we'll spin the drum, so I'll post the results here when they are official:
if anything-else rattles-around my head before we get-started, I may ask more questions here.

 

[minifridge1138]

First, if the engine is stock, other than the 750 and the Holley intake, you've got way too much carburetor and probably too much intake.
...
With the right parts, the right assembly and the right tune you can get to 350-375 hp fairly easily.

Tell us a little bit about how you converted an engine with computer controls to a non-computer engine.

No problem.

I've done a fair bit of work since i posted on this thread, so I'll start with what i've done lately. After that I'll describe the removal of the computer.
1) I have installed a 600 cfm holley. My gas mileage jumped from 14 highway to 23 highway. The 750 needed a rebuild so that is part of the improvement, but it was still too big for a 350 cid engine.
2) I installed hooker competition headers. This gave me a deeper sound, but not any noticeable power. I still need to replace the exhaust tubing from the header to the muffler with larger pipe.
3) I relocated the vacuum source for my distributor's advance. Thanks to JohnZ's explanation I am now using manifold vacuum. That really made a difference.
4) I bought a DeWitt's direct-fit radiator. I drove across Texas in July with the air conditioner on, and the temp never went above 210.

With all of that work, my car is running better than ever. Acceleration is smooth and consistent all the way up to 85 mph (that's where my speedometer ends).
I still feel that i'm lacking in low end torque, but that is largely due to the 2.73 rear end (which is the reason i get 23 mpg and can afford to drive the car).

How did I convert the car to run without a computer:
I was not the person that did the initial conversion. The previous owner actually removed the CrossFire. However, he was sloppy and made a lot of mistakes, so I have had to re-do most of his work and solve the problems left behind.

First you have to replace the Cross Fire with a carburetor and appropriate intake manifold. That is actually pretty straight forward. But it will leave you with a mess of unused wiring harnesses in your engine compartment. The can get in the way and don't look pretty, but they don't hurt anything by being there. You'll also need a distributor with a traditional vacuum advance. Again, this is a straight forward replacement. At this point, you now have intake and spark, but will need fuel. The stock fuel pump will not work, because the computer controls the fuel pump. I simply bought a mechanical fuel pump and installed it on the block. You could also buy an after-market electric fuel pump (or try to re-wire the original to work correctly). If you're not keeping the original fuel pump, then you will need to install a sending unit from an earlier corvette. At this point, you now have the 3 basic things you need to run: spark, air, and fuel. There will still be some miscellaneous things to do. For example, the torque converter in the 700 R4 will not lock up without the computer. You can get a torque converter lock-up kit for about to solve that problem and they range in price from $75 to $175.

I kept the description pretty brief just to give you an idea of what it takes. If anyone would like greater detail just ask. I think we all enjoy talking about our cars.

Personally i bought this car because i wanted a semi-project car. However, i do not recommend buying a car with a working CFI and replacing it with a carb. It is a pretty intense project all around (that means expensive). If you think the CFI is a piece of junk and want something better, i would recommend going with a newer TBI. There are a several options that will work with the stock computer. They'll give you better performance and are a much simpler project.

 

[Vette79]

After connecting the vacuum advance to straight manifold vacuum did you have to do anything else? What difference did you notice when connecting it to straight manifold vacuum?

 

[minifridge1138]

After connecting the vacuum advance to straight manifold vacuum did you have to do anything else? What difference did you notice when connecting it to straight manifold vacuum?

I adjusted the idle mixture on my carburetor.
I used a vacuum gauge and leaned it until i had maximum vacuum.

The difference was improved acceleration in mid and high throttle. It now reacts faster and smoother.
JohnZ has a GREAT article about vacuum advance and timing.

 

[Glensgages]

..... Let me know if there is anything I can do for you.....

Curtis..... if you could run me a few quick dyno-sims, it'd be much-appreciated:
this info won't be for my '82 Corvette, but for my '79 Z28, and as an emergency / back-up plan, should the 355" SBC, built in 1990, become un-hinged once I begin racing it again.....
hnoes

I'm thinking of this GMPP short-block

http://paceperformance.com/index.asp?PageAction=VIEWPROD&ProdID=183227

with these GMPP heads

http://paceperformance.com/index.asp?PageAction=VIEWPROD&ProdID=22702

I am figuring compression to be approx 9.8 / 10:1 with this combination.

Induction I'd consider would be Victor Jr and a 750 cfm Holley double-pump, and exhaust would be open-headers:
would like comparison of these 4 Comp Cams products -

270H (.470", 224* @ .050", 110* LSA )

280H (.480", 230* @ .050", 110* LSA )

286H (.490", 236* @ .050", 110* LSA )

292H (.501", 244* @ .050", 110* LSA )

RPM-limit for the Z28 will remain the same as now (5800 ), and would like to see which would be best for continued ET/MPH of 12.80s @ 105 on a budget, with a 2-bolt block, cast-iron crank, and production/junk rods, on readily-available 93-octane pump-gas.

for reference, current Z28 motor is 355" with 64cc iron Dart heads w/ 2.020"/1.600" valves (10.3:1 CR ), Victor/750 carb (as-above ), with 292H cam:
would be curious to see which combination most-closely resembles current set-up for-cheap.....
;help

 

[Curtis]

Single plane hi-flo intake, large tube open headers

Part # name rpm range rpm/HP rpm/torque
12-211-2 270H 1800-5800 4500/403 4500/470
5000/364 5000/383

12-212-2 280H 2000-6000 5500/488 5000/471
6000/384 5500/466

12-326-4 286H 2200-6200 6500/481 5000/463
7000/378 5500/455

12-213-3 292H 2500-6500 6500/473 5000/449
7000/473 5500/442

Single Plane Max-flo intake, large tube open headers

270H 5000/446 4500/484

280H 5500/491 4500/473

286H 6500/484 4500/455

292H 7000/476 4500/438

All ran with 750 4-bbl , 350 cu. In. , 9.8 compression , gasoline. Note that
A tunnel ram intake will get you another 25-40 hp. The head flo numbers
Were the ones listed on the web page for the heads selected.

 

[Curtis]

don't know why my chart appears like this.. just slide the second row of number to the right to line up columns again. example 5000/364 should line up under 4500/403, thus illustrating the power drop off. or i can email you good looking chart.

 

[Glensgages]

don't know why my chart appears like this.. just slide the second row of number to the right to line up columns again. example 5000/364 should line up under 4500/403, thus illustrating the power drop off. or i can email you good looking chart.

Please-do:

Glensgages@aol.com

 

[Glensgages]

I finally have some detailed results regarding my '82, and it's current performance capabilities.

After having moved to Florida in late '06, and having a house for-sale in Pennsy for almost 20 months, we took the '82 off the street to save money in early '07:
the house sold in early '08, we bought another house in August, and we decided we'd begin to drive the car again, but the original 700R4 would need rebuilt.

I towed the car to a racing-buddy's shop in Sarasota, RevXtreme, where Tracy Lewis and his crew would upgrade the transmission:
before I got home, Lewis called my cell-phone, saying
"..... oh, by-the-way..... we're taking-off the Cross Fire while we are at it....."



In it's place now sits a Holley 650 cfm double-pump carb, on-top of a Holley #300-48 Street Dominator intake, combined with an MSD ignition system:
the only additional work done to the L-83 was the use of CompCams 1.6:1 ratio rocker-arms.

Even-with the addition of 3.73 gears in '03 and a 'mysteriously-loud' at wide-open-throttle catalytic converter, the car would only run low 16s @ 84 MPH in the quarter-mile (it had run a best of 15.30 @ 89 on a very cold & windy day when I lived up-North, but that was a rarity):
upon completition, Lewis candidly told me "... it'll run 13s now..." , but my reaction was
:L

Lewis was kind-enough to invite me to join him for a test-and-tune session at Bradenton Motorsports Park in mid-November, so I towed the car to the track for it's maiden voyages:
I hadn't even driven the car around the block since it's return, so I had no-idea what to expect.

On the first run, I did a shabby burnout, left from idle, and shifted 2-3 after feeling a slight miss near 5200 RPM, yet the car responded with a 14.35 @ 97 MPH blast.


I removed the small, restrictive air-cleaner, raised the launch RPM to approx 1200, and lowered the 2-3 shift to 5000 RPM even (I think it'll pull straight to 5500 without the air-cleaner), and the car ripped-off 3 runs of 14.059, 14.044, and 14.062, all at over 95 MPH.
:W

Last week, we went to Orlando Speed World Dragway, and in slightly cooler/dryer air following a serious burnout, it ran 13.935 @ 99.14 MPH:
all of this achieved with the OEM L-83 long-block, exhaust manifolds, 2-1-2 pipes, with old-school BFG Radial T/A tires

We'll be racing the car again this week, at the 1/8-mile Sunshine Drag Strip in Clearwater, during the 2-day 'Big Turket Bracket Bash':
in it's previous configuration, the '82 ran 660' in the 10.2-10.4 range, but it currently runs 9-ohs, with a best of 8.938 @ 77.49 MPH

The car retains all of it's road-manners (except for the cruise-control, which we don't use), idles at 700 RPM in-Gear, and other-than shifting very firm, you'd never know it could run like a well-tuned C4, or a stock C5, but when you mat the skinny-pedal, you'd BETER have the car pointed where you want it to go:
no telling how-quick it'd run with vortec heads, more-aggressive cam, and headers with true-duals
(heck, it'd go quicker if I could manually hold the 700R4 in First Gear longer!)
hnoes

Special thanks to the gang at RevXtreme, who made the car's performance possible.