OK, newbie to Chevys here. I'm looking at a '73 L82 automatic. I'm looking for upgrade ideas from people with firsthand experience. I'm going with an L82 because the bottom end is built for much more power. I know the L48 can easily handle what my goals are, but I still like the idea of 4 bolt mains and forged vs cast internals. I don't want to pull the motor, so I'll be looking at top end upgrades. I would like between 350 and 425 hp, I don't want to have to upgrade the rest of the drive train, although, down the road, I will go with either a 4L80E or a 200-4R. I had a 200-4R in my '68 GTO with a built 469 (455+.060) and loved it. So I've been doing research and I'm looking at the AFR 195 Enforcer heads (groups thoughts on these heads?) What does the group think about the Edelbrock Performer manifold? Will it be a hindrance to reaching my goal? I've used the RPM in the past but it won't fit under the 'Vette hood. I'd like to go with a roller cam, what cam do you all recommend? Are there any block preperations necessary to go roller? I'll upgrade to an HEI ignition. As far as exhaust, what is the best, non header, manifold? What did they use for the '70 LT1? Are they decent options? Are they available for only an arm, I want to keep an arm and both legs. 😉 Everything I do will be bolt on so I don't mess with the originality should I or the next owner want to return it to original. I know a 383 stroker kit will get me where I want to be much easier, but I really don't want to pull the motor and open up the bottom end. Can I get to where I want to be with only top end upgrades?

I'm a Pontiac guy and I built a couple motors for my GTO, so I'm not a newbie to wrenching. I need to learn the intricacies of the Chevy vs Pontiac, I had my GTO for 25 years, so I got to know Pontiacs pretty well.

Thanks in advance

 

I would start with the simple things like: have Lars rebuild your q jet, keep your distributor and have it recurved and rebuilt by Jeff at advanceddistributors.com, add a 3.73 gear and you will notice a huge increase in performance ! I had a 76 L82 with T400 and 3.36 gear. Was pretty doggy until I got to mid range with the L82 cam. Also add a free flowing exhaust and you will like the results !

 

Thanks, Wil, this car has a 3.55:1. If/when I go with a 200-4R, 1st gear would be like a 400 with a 3.95. That should wake it up. When I finalize what I'm doing, I'll have the distributor and Q-Jet tuned for the application. I'll also get a torque converter to match the rpm range of the cam.

 

I agree with @wilcar
but i cannot wait to see what heads and roller cam do for you! Following…
fyi l82 stock, tuned..
Gross

 

Did the above to my stock 73 L82 4sp 3.55:1 rear plus tuned it following Lars tuning papers. Car pulls and takes off fast and strong.

Fran

 

Gr8one,

Looking at the stats of your original engine it shows 9 to1 compression. This factory data was usually estimated as close as possible but not written in stone. With the age of your short block, the actual C.R is more likely 8.5 - 8.8 at best.

I understand you don't want to get involved with the short block alterations. A lot more time & money. However, to double the H.P. you currently have is not likely going to happen with that poor C.R. To build some serious H.P. numbers, the C.R. should be 9.7 and above. How you chose to do that is up to you, crunching numbers, finding best bang for the buck, etc-etc. Smaller chamber heads are a given, but even then, you have to be realistic about H.P. outcome.

I recommend studying Dynamic Compression Ratio. The more common Static C.R is piston in bottom of cylinder squeezing to top. But in actuality, the Intake valve is still open when this event occurs. And for how long this happens is based in cam profile. Dynamic C.R. is where H.P. is made. Normally shoot for 7.9 - 8.5 on that.
There are a couple of DCR calculators on the internet to help you with the math. They do require lots of data to be entered.

On cam selection: Don't go by what somebody's engine has on here, that would be apples to oranges. No one has your exact set-up. Call the pros after you figure out which compo of parts you are installing.

And just for what it's worth. Two bolt mains and the webbing are good for well over 400 horse on SBC. Chevy didn't cheap out on iron down there.

 

As pointed out above and the fact the NHRA factored the L-82 at 315 horsepower back when these engines were new. Getting 400 horsepower out of one is pretty easy.
A good set of aftermarket small chamber beads and tuning helps a bunch and may be all you need to be happy.
The rpm airgap is a better intake aNd will fit under your hood.

 

I’ll ask this question, what is the condition of the engine? Has it been recently rebuilt or even been rebuilt at all??

If you start adding power to a tired engine, well I guess a new thread will be started…

 

The L82 ACHES for a real pair ov heads. AFR is hard to beat, but mind that final compression ratio. Select a head that will get you to the number you want. They make heads as small as 59cc chambers, and there have been MANY discussions on that exact topic in here, even recently. Try and get good quench (under .050"). Get GOOD long tube headers, a true 2.5" mandrel bent dual, with GOOD mufflers. I'd recommend a well-designed X-pipe. Then find a cam to match the heads, and the RPM range you're after. But absolutely do not compromise on the intake. Going with nice heads, a roller cam, and a real exhaust will be pointless if you try and make it breathe through a Performer. If you have to, get a bigger hood. If you like the stock scoop (i do), maybe someone makes a stock-looking hood thats just a bit taller?

Even with 425HP goal, you're not asking too much. Thats not even 50% more power than stock. It all starts with the heads.

 

AFR heads are a good choice as it an L-82 as a base engine. I might point out that the 195cc enforcers flow less than the 180cc eliminator "street". This means that more below peak torque power is going to be lost due to low velocity airflow to the chamber. Ultimately it will produce less power throughout than the 180 eliminators given everything else is the same and less torque throughout the entire RPM range of the engine. That of course comes with a price $$$ a 64cc chamber will net you about 10:1 CR.

https://www.airflowresearch.com/180c...cylinder-head/

https://www.airflowresearch.com/195c...cylinder-head/

No way I would choke the heads with a performer intake unless you want to do some porting to that intake and open it up. The RPM intake will do much better out of the box.

Then follow that up with long tube headers in the 1 3/4" primaries and 2 1/2" exhaust.

Cam really depends on where and how you want the power delivered. But at least something in the 275/275 advertised 222/222 @ .050 range. Not the old school L-82 cam as the lobes have long opening ramps and bleed off lots of CR during opening and closing.
I went roller and would never go back to flat tappet, but that'll cost about an additional $1000 all said and done over flat tappet. However you will never get a flat cam and can use whatever oil you choose vs only high zinc formulations for flat tappet.

Being the bottom end is not going to be touched, you may want to check the con rod clearances with some plastigauge and see how they're doing.

 

I originally built-up my 79 l-82. better flat H cam and heads. C/R has to be better. So I went to flat top forged -7 cc pistons and a .030 over bore and had it all balanced. It was a good 7200 rpm motor

 

A performer RPM intake WILL fit under a 73 hood with a drop base air cleaner.

 

ok, let's start over. you are looking at a 73 with an L82 cuz you like the forged crank and pistons. chebby engines are cheap and easy to upgrade. look at the CAR, not the engine. it is much harder to to rehab tired everything and weld up rusted windshield frames than it is to get a fresh engine to drop into a nicer car that has an L48 in it.

 

Agreed. Even a miled-up L31 Vortec pull-out with some basic upgrades would be a MASSIVE improvement. That was my original plan.