I have an 80 L82 true duals w/ 110 K easy miles and do mostly general cruising. Want more low end torque fun factor. Considering changing out top end to GMPP Vortec heads, Eldebrock Air Gap Perf RPM, which I would like to try myself. Hoping to get >400 tq. and >370HP

Q. Should I change out the L-82 cam at the same time?
Q. Do I need to rebuild the lower end at the same time?
Q. Timing chain has never been changed.
Q. Should this fit under an 80 stock hood?
Q. Can I stay with my LARS QJet with this combo or need Holley 4160 750cfm?

 

Theres a good chance the plastic teeth are gone on the silent timing sprockets.

If your going to do this much it might be worth it to rebuild the engine.

On the power vs low end torque. I suggest not getting too concerned with top max numbers. These are for drag racers. For street you want a fast rise at the low end even if it peaks lower it stays there as rpms rise. Superimpose a racing curve on this and the max numbers are higher but the used hp and torque numbers are lower, they peak rather than stay flat. Your generally driving below this racing hp curve. The engine hasn't started to produce yet for street RPMs.


Probably better for others to suggest a good street combo for you rather than a maxed power output. My BB is about what you want to achieve, since my levels are low for a BB imagine what you will compromise on a SB to reach them. I compromised high end max power for low and mid street usable power. You never hear about what hp and torque an engine provides at 1000-3000 rpm.

 

Cam - The L82 grind isn't bad but if you look at some of the newer ones out there, they make more lift with the same duration. Or you could go for slightly less duration and the same lift and build some low end torque.

Heads - Vortecs are good. Get the upgraded ones from scoggin's Dickey with springs that handle .525" lift. The stock Vortecs will only handle about .450" lift and the upgraded ones will give you more options later.

Manifold - If you go Vortec, you need a new manifold. The stock L-82 one is actually pretty good but you would have to look at other heads with a stock bolt pattern.

Carb - I like the Q-Jet but you may have to go with a Holley or Demon if you change the manifold. I always feel that an adaptor is not worth the hassle and you should match the carb to the mounting pad on the intake.

Other issues: New carb = new fuel line. Hood clearance. I don't think you have much. You can use a drop base airclearer but the air still has to get into the carb.

Oh, and replace the timimg chain while you got the engine apart. Cheap and easy insurance even if it looks good.

 

I have looked into upgrading my 80 for a little more performance. Your number one problem with any combination over stock will be a hood clearance problem. I was told by gm performance that the vortec set up of any kind will not fit under a stock hood. The only combination that seems to figure out to fit uner my stock hood is the combination from edelbrock. It is the performer series set up. It is not huge hp set up but it will work with our lower compression lower end blocks at 8.5 compression and gives about 310-320 hp. The only catch is not to use the edelbrock carb because it will not accept a drop base air cleaner which you will probabaly need with the 2101 intake manifold. Apparently a holley or road demon carb will both accept a drop base cleaner with the electric choke set up. Good Luck , I would be interested in what you choose and how it works out for you . Brent

 

For good bottom end, the Q jet is hard to beat. The tiny primaries were designed for this. Couple with a bottem end manifold like a good old spreadbore performer and you got a good combination, ( the air gap comes on at 1500+ rpm, the perfomer from idle) and it'll fit under your hood.

 

FYI...I have the holley sysm. max kit with a holley 750 mec. sec. dp carb and the holley power shot drop base air cleaner. All fit's under my stock hood with room to spare!!! And it make's 400+ hp for under $1500!! just some'm you may want to look at.

 

If you are into EFI a tpi swap would get your tons of low end torq up to 4500 rpm's, would work OK with the L82 cam but a shorter (less than 218 @ .050 lift) duration/higher lift cam would increase the torq. A set of 64 cc heads would also get you some more torq. If you can find a tpi out of vette with the l98 alum heads you would be at that 400 tq number but hp would be down around 300-325.

 

I would recommend a look at the Summit branded Iron Eagle heads, SUM-152123. They have a similar combustion chamber to the Vortecs but can use all the standard kit such as valve covers and intake. I've got them and I'm pleased with them. I'd recommend starting with that swap first and then evaluate it for a while and see if a hotter cam would really give you much more.

Personally, with as many miles as you've got, you're not long til you will need to consider a rebuild. The technology of 30 years ago wasn't engineered to have a production vehicle last longer than 100K miles.

 

Swap the cam and get a 750 speed demon, vortec heads and you'll be happy.

Les

 

At 110K miles it doesn't matter how easy they were. You need to pull the engine apart and do some serious clean up and restoration. Your cam bearings will need replacing...they will wear out even if you just idle the engine for 110K miles...and for that you need to pull the engine. Your timing gears and chain should be replaced as well as your oil pump...these items are relatively cheap while if they stop working like they should then your entire engine will be scrap with an expensive repair.

My vette had mostly easy miles, but my main and rod bearings showed .001" of wear...thus, out of tolerance and required replacing...and mine only had 50K miles on it.

 

Grayhook,How is the system max working for you?

 

So far... SWEET! just get'n it broke in good! about 550 mi. on it.
I've had no issue or problem with any thing but tunning it. And that's come around nicely. Just need to fine tune'n it a little more.
Boy that thing got some pull to it!
Got to get this thing to the track and see what it she'll do.

 

Grn 80 L-82,
The cam is likely to have a few worn lobes at this point so you need to put that on your list one way or another. My 80 L-82 had only about 45K miles on it at overhaul time. The bores looked great but the cam had a few worn spots on it even with the low mileage. This is not uncommon.

The bores are the BIG question here. If the bores are still good, you could just re-ring the bottom end, replace the cam and slap on a set of better heads. 64cc chambers will realy wake up that lazy engine and take advantage of all those good bottom end pieces the factory gave you. Either way you need to replace the timing chain.

If the block needs to be bored, I would have no question in my mind that it was time for a 383 stroker kit. You will need new pistons after a bore job anyway and the performance increase per dollar is difficult to match. The C3 is perfect for a 383 swap as it needs all the bottom end torque it can get. You can buy a 3.75" crank and stroker pistons then reuse the rods. I would probably put better rod bolts in there and have them all resized. You will need an externally balanced flywheel and damper along with a good balance job. Bolt on a set of modern chamber/old style heads and use the "Lars-buretor"/intake setup and you will be running strong. Keep the intake you have as it works pretty well and everything fits under the hood. It will save you a lot of fabrication time and some money too. It is not holding you back as much as you might think.

I know a guy that has a 383 with Edelbrock Performer heads and a stock 350/350 cam in his car. It is a torque monster Just pulls and pulls.

-Mark.

 

Well, lots to consider. I guess the summary is, if you are going to do the top end right I should redo the bottom end at the same time. So even if it seems like while the bottom end components may be ok, at 110K miles it is best to freshen up now including CAM, bearings, oil pump, and timing chain. For the top end it seems that the real limiting factor is the 80 stock hood clearance. A drop base air cleaner is a must, LARs Qjet should be OK to continue using, my existing intake may be best bet to fit under the hood or a new air gap RPM. Heads it seems like a 64cc head but maybe not a Vortec due to hood clearance. The Holly kit looks good but not sure if it will fit under an 80 hood?

 

The intake that came with the Holley kit is tall! if you use the Q-jet it may not fit! After i got this kit together i seen that with the 600 cfm edilebrock carb i was running it wasnt going to fit under the stock hood, so i got a high rise hood...Then brettmc built me this nice azz holley 750 dp carb and ( what a pickup in hp!) after i installed it i got a nice holley power shot air cleaner for it.(liked the blue filter ) then i got to look'n and tried put'n on the stock hood. wow it fit with a few inch's to spare.
i have no doubt it will fit in your 80 if you go with that setup.
Yeah,110K miles is a lot, it is best to freshen up now while you got it down!

 

Look at my wing nut....i can get another what? 1/2 inch there maybe... if i needed too.

 

Even my stock air breather. At least another 3/8 inch...
Yes, rebuild that motor. 110K is a lot of miles on these motors.

 

Greyhook, I saw the before and after video you have...WOW... that Holley kit looks like it has some great performance. Your original L-82 looks better than mine, I can't lay rubber unless I do a brake stand.