1978 L-82 performance mod questions
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1978 L-82 performance mod questions
Ok this week starts my quest to get to 300hp. My L82 already has an Accel distributor from previous owner. I am putting on Hedman Headers and new exhaust (cat free) with new mufflers this week. Since I am doing a little at a time, I thought about replacing the stock fuel pump with a Holley at the same time this week. Would that be worth it or should i just wait until the OE goes bad? Regardless, my next plan is to replace intake (Edelbrock) and Holley carb (600 or 650) and then heads and cam.
I would appreciate feedback on fuel pump, carb size, and other obvious things I am missing.
thanks in advance
I would appreciate feedback on fuel pump, carb size, and other obvious things I am missing.
thanks in advance
Race Director
Joined: Jan 2000
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From: San Jose CA
Fuel pump won't make a difference as long as yours is in good shape.
I don't think the intake will be worth a whole lot either. If your q-jet is in bad shape and out of tune, the Holley will help some but not much. I'd leave the intake tract alone until you do the heads and cam.
Hell, with an L-82 and full blown headers and exhaust, you should be able to get close to 300 hp as is.
Just verify that the carb and ignition are tuned well.
I don't think the intake will be worth a whole lot either. If your q-jet is in bad shape and out of tune, the Holley will help some but not much. I'd leave the intake tract alone until you do the heads and cam.
Hell, with an L-82 and full blown headers and exhaust, you should be able to get close to 300 hp as is.
Just verify that the carb and ignition are tuned well.
Le Mans Master
Joined: Mar 2008
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From: Oxford MA-----You just lost the game!!!!
Fuel pump won't make a difference as long as yours is in good shape.
I don't think the intake will be worth a whole lot either. If your q-jet is in bad shape and out of tune, the Holley will help some but not much. I'd leave the intake tract alone until you do the heads and cam.
Hell, with an L-82 and full blown headers and exhaust, you should be able to get close to 300 hp as is.
Just verify that the carb and ignition are tuned well.
I don't think the intake will be worth a whole lot either. If your q-jet is in bad shape and out of tune, the Holley will help some but not much. I'd leave the intake tract alone until you do the heads and cam.
Hell, with an L-82 and full blown headers and exhaust, you should be able to get close to 300 hp as is.
Just verify that the carb and ignition are tuned well.
The L82 has the big cam and big valves, free up the exhaust, tweak the spark advance and stock carb, it'll wake right up.
Scott
Le Mans Master
Joined: Apr 2005
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From: Seattle Area WA
Your Q-jet will flow 750cfm, rebuild it and leave it in place as well as the manifold. A fuel pump is a waste of money. Is that Accel distributor a HEI style? A stock HEI is hard to beat, regardless of which one you use, make sure that your distributor has been recurved to bring the timing in 36 degrees by 3,000 RPM with the vacum hose disconnected and plugged.
Le Mans Master
Joined: Nov 1999
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From: San Diego CA
pretty much agree with everything said above.
Fuel pump - waste of money.
Edelbrock manifold & holley carb - not much gain
headers and exhaust - excellent first step.
I read an article about the prepping of the actual indy pace car in 78 (the backup car actually) they said that removing the original highly restrictive factory pellet convertor was worth 25 hp alone.
Headers and duals with no convertor along with a proper tune will get you well on your way to 300 hp.
After that your heads are your next issue, even though they have large valves, they do not flow terribly well compared to , well, just about anything you can buy today, even a set of bone stock low lift vortec heads outflow the original thin wall L82 castings.
There may be some small gains to be had with an edelbrock (assuming performer) intake, stick with the qjet.
Fuel pump - waste of money.
Edelbrock manifold & holley carb - not much gain
headers and exhaust - excellent first step.
I read an article about the prepping of the actual indy pace car in 78 (the backup car actually) they said that removing the original highly restrictive factory pellet convertor was worth 25 hp alone.
Headers and duals with no convertor along with a proper tune will get you well on your way to 300 hp.
After that your heads are your next issue, even though they have large valves, they do not flow terribly well compared to , well, just about anything you can buy today, even a set of bone stock low lift vortec heads outflow the original thin wall L82 castings.
There may be some small gains to be had with an edelbrock (assuming performer) intake, stick with the qjet.
Le Mans Master
Joined: Oct 2007
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From: RI, Now Franklin/Nashville TN
Agree with everything stated above. I have actually done what you are suggesting to my bone stock internally L-82 4 speed. I have a 4175 Holley (25 years now, just rebuilt it myself), stock aluminum OEM intake, zero pollution control, Shorty headers, 2.5 true duals with Monza Turbo mufflers, K&N air filter in the OEM housing, and roller rockers. The engine is sooo much faster than when stock. Forget the intake (and carb if the Qjet runs ok) and do the rest. I am thinking about the heads and cam but probably if the OEM ones crack at some point but I doubt it since the car now runs at 175 degress with the Dewitts aluminum radiator versus the stock temperature of 225-235 degrees which I believe greatly contributed to the head cracking issue. Hope that helps!
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Le Mans Master
Joined: Oct 2010
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From: melbourne florida
2023 C3 of the Year Finalist - Modified
if you do the timing chain advance the cam timing 4 degrees which the factory did for emissions and it will REALLY wake up kind of like Washington, get the retard out
Le Mans Master
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From: RI, Now Franklin/Nashville TN
Jeff
Le Mans Master
Joined: Oct 2010
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From: melbourne florida
2023 C3 of the Year Finalist - Modified
all the companies have adjustable timing chain sets no more difficult than a standard set, if you change cams you may just want to install it straight up but the L-82 really wakes up if advanced 4degrees
Le Mans Master
Joined: Oct 2007
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From: RI, Now Franklin/Nashville TN
[QUOTE=7t9l82;1576739290]all the companies have adjustable timing chain sets no more difficult than a standard set, if you change cams you may just want to install it straight up but the L-82 really wakes up if advanced 4degrees[/QUOT
I don't know anything about adustable timing chains but companies like comp cams sells timing advance shims/buttons that require drilling the timing gears-not that simple. Originally I thought my marks would not be aligned when I take the case off and could just line the marks up for advancement but I guess that is not the case. How exactly did you advance your cam and where did you get the adjustable timing chain?
I don't know anything about adustable timing chains but companies like comp cams sells timing advance shims/buttons that require drilling the timing gears-not that simple. Originally I thought my marks would not be aligned when I take the case off and could just line the marks up for advancement but I guess that is not the case. How exactly did you advance your cam and where did you get the adjustable timing chain?
Le Mans Master
Joined: Oct 2010
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From: melbourne florida
2023 C3 of the Year Finalist - Modified
summit racing mine is made by cloyes. the drill and bushing type is more for a pro builder. the adjustable sets are stupid simple. just because you haven't heard of it doesn't mean it does not exist.
Le Mans Master
Joined: Oct 2007
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From: RI, Now Franklin/Nashville TN
You are absolutely correct-my ignorance and thanx to everyone alerting me to this option. I guess I am surprised that when I searched Summit Racing's website for timing chains, this option did not come up (I found it though when searching for adjustable timing chains). My error and thanx to all of you for the info. Did not mean any foul here!
Le Mans Master
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From: melbourne florida
2023 C3 of the Year Finalist - Modified
good luck . i beleive you will be very pleased! my 78 with a few modifications would always out run a friends l-82 with a 268 cam! these motors were really under appreciated
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This is exactly what I am looking for in my 77 L82 350!!!
Last edited by USMuscle; Feb 9, 2011 at 01:54 PM.
Race Director
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From: California
Some good opinions.... my question is, are you just shooting for 300.... or are you on a quest to even more hp... like 500-550hp..... power is addictive,.....
imho, if you are on your way to 500+hp, then forward think.... a RPM airgap from Edelbrock would be good, im running a BG Mighty Demon 750.... etc.... dont buy twice, like I and so many others have. The stock carb and intake are fine for 300..... not more.
I would go crazy with only 300hp.... just not near enough fro me,,,, jmho
good luck, Paul
imho, if you are on your way to 500+hp, then forward think.... a RPM airgap from Edelbrock would be good, im running a BG Mighty Demon 750.... etc.... dont buy twice, like I and so many others have. The stock carb and intake are fine for 300..... not more.
I would go crazy with only 300hp.... just not near enough fro me,,,, jmho
good luck, Paul
Le Mans Master
Joined: Oct 2010
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From: melbourne florida
2023 C3 of the Year Finalist - Modified
500 h.p. from a small block wont be very streetable. people need to focus on what they want the car to do,a500 h.p. engine wont guarantee anything. you can't say a 500 h.p. motor. will make my car go 11.0 it doesn't mean anything! ill beat your 500h.p. car with my 350 h.p. car because its been set up correctly for the combination. a motor is a small part of how a car performs, see where I'm going with this? 500 h.p. doesn't impress me even a little. if your looking for that kind of power this thread is a waste of your time
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Thanks for the part #'s. Any advise on the difference between the two (besides 3 X's the price!). FYI, I personally am looking for 350 HP at most...