1978 corvette performance
Burning Brakes
Joined: Sep 2012
Posts: 818
Likes: 0
From: coon rapids mn
what exhaust system do you have ?I like the elderbrock performer intake ,retain the stock Q-jet .the comp cam extreme 268 hydraulic flat tappet cam is a good fit .you will need new springs and rocker arms for it .get some new weights and springs for your distributor .
Le Mans Master
Joined: Oct 2006
Posts: 8,940
Likes: 35
From: El Cajon California
Hello
I am in the same boat. I have a 1978 L-48 with single exhaust.
I bumped up the timing and monkeyed around with the dist weights.
I also installed a test pipe.
I also want to change the intake, cam and valve springs but I have a question.
Everyone recomends the comp cam 268 but I have a question. When I look up that cam on summitracing.com it says...
Basic Operating RPM Range:1,800-5,800
Why not use a cam that starts off idle?
Just curious?
I am in the same boat. I have a 1978 L-48 with single exhaust.
I bumped up the timing and monkeyed around with the dist weights.
I also installed a test pipe.
I also want to change the intake, cam and valve springs but I have a question.
Everyone recomends the comp cam 268 but I have a question. When I look up that cam on summitracing.com it says...
Basic Operating RPM Range:1,800-5,800
Why not use a cam that starts off idle?
Just curious?
Le Mans Master
Joined: Oct 2010
Posts: 6,929
Likes: 842
From: melbourne florida
2023 C3 of the Year Finalist - Modified
a lower rpm cam is more for pickup trucks and tow vehicles great if you want to lower your 0-30 times not so much overall performance.
for real performance i would recommend,moving.
for real performance i would recommend,moving.
Drifting
Joined: Sep 2010
Posts: 1,412
Likes: 50
From: Laguna Niguel California
If you are going far enough to replace the cam, get rid of those awful original heads. Bite the bullet and spend the money for AFR's and a hydraulic roller cam. Comp Cams makes a 262 that has a stronger lower end.
Melting Slicks
Joined: Oct 2011
Posts: 2,748
Likes: 90
From: Sacramento California
C2 of Year Finalist (performance mods) 2019
2018 C2 of Year Finalist
I did an L82 thread that answered a lot of your questions.
Exhaust is your number #1 performance roadblock.
Heads are second.
With new heads and exhaust, with everything else stock you would have a totally different car.
Exhaust is your number #1 performance roadblock.
Heads are second.
With new heads and exhaust, with everything else stock you would have a totally different car.
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Le Mans Master
Joined: Oct 2007
Posts: 7,444
Likes: 970
From: Tennessee/Rhode Island
Free Flowing Dual exhaust, proper tune, 180 operating temp, and proper distributor curve/timing will wake the motor up but it will never be a beast.
Really Good Heads and Roller cam will transform the car..
Really Good Heads and Roller cam will transform the car..
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
Distributor curve transformed my car and cost a few bucks. HP/$$ very high. Just guessing, 185hp->~195hp, but lots of torque down low added.
Next up is header and dual exhaust, just about the same gains but now you're looking at numbers approaching 1k. I'd guess this took me to the 210, 220 hp range. Again, guessing...
Heads and cam, but a mismatched combo (very low static CR) took me to 243rwhp, 280rwtq, but at the cost of a loss in torque down low. Faster when you punched it, not as much fun just cruising around though. At about $2k outlay...
And Now I've put a *fair bit* of cash into the motor I have now, built right from carb to pan and that's given me all the torque I was missing from before and more power on top... but not cheap at all.
Racer
Joined: Jul 2013
Posts: 257
Likes: 36
http://www.summitracing.com/parts/sm...-400/overview/
http://www.summitracing.com/parts/EDL-1806
Mike
Le Mans Master
Joined: Oct 2007
Posts: 7,444
Likes: 970
From: Tennessee/Rhode Island
x3
Distributor curve transformed my car and cost a few bucks. HP/$$ very high. Just guessing, 185hp->~195hp, but lots of torque down low added.
Next up is header and dual exhaust, just about the same gains but now you're looking at numbers approaching 1k. I'd guess this took me to the 210, 220 hp range. Again, guessing...
Heads and cam, but a mismatched combo (very low static CR) took me to 243rwhp, 280rwtq, but at the cost of a loss in torque down low. Faster when you punched it, not as much fun just cruising around though. At about $2k outlay...
And Now I've put a *fair bit* of cash into the motor I have now, built right from carb to pan and that's given me all the torque I was missing from before and more power on top... but not cheap at all.
Distributor curve transformed my car and cost a few bucks. HP/$$ very high. Just guessing, 185hp->~195hp, but lots of torque down low added.
Next up is header and dual exhaust, just about the same gains but now you're looking at numbers approaching 1k. I'd guess this took me to the 210, 220 hp range. Again, guessing...
Heads and cam, but a mismatched combo (very low static CR) took me to 243rwhp, 280rwtq, but at the cost of a loss in torque down low. Faster when you punched it, not as much fun just cruising around though. At about $2k outlay...
And Now I've put a *fair bit* of cash into the motor I have now, built right from carb to pan and that's given me all the torque I was missing from before and more power on top... but not cheap at all.
I started making changes in 1983 on my 78 L-82 4 speed:
1. First the usual stuff-richened up the carb, timing/distributor, removed all emissions, roller tipped rockers, lowered the operating temp from 225-240 to 175-180. Woke the car up a lot. Stock HP-220 NET HP.
2. Early 2000's-true 2.5 inch duals and free flowing mufflers and later shorty headers. Hit the dyno a couple of years ago with a weak #6 cylinder-233 RWHP which is apprx. 310-325 Gross HP.
3. Spring 2014-Totally rebuilt OEM L-82 block using reconditioned L-82 rods, L-82 crank, L-82 aluminum intake-everything else new including AFR 180 heads and roller cam. Expecting once the car gets on the dyno about 325-335 RWHP which would be about 100 more RWHP than the lightly modified L-82 before the rebuild. Should make about 450 GROSS HP and the Torque of many of the crate 383's since the crate motors generally do not use the best optimized parts for HP/Torque from those motors.
Rebuilding the L-82 with the best parts I could find was not cheap but I wanted an L-82 as much as feasible.
Last edited by jb78L-82; Oct 8, 2014 at 07:01 AM.