I have 1975 L82 with Edelbrock Performer intake,Headers,
2.5 duals, L82 cam , 1.6 rollertip rockers.
I can get some AFR 190 68cc CNCed heads cheap.
What Hp would they give me & what head gasket
should i use (flat top pistons)

 

wow, lucky you! I will comment on this because I also have a 75 L82 and am also considering the same (or similar) option and I've done a lot of research about this. One thing I can say is that AFR have a great reputation - I've really never heard anything but glowing praise about not only the flow numbers, but the actual dyno #'s and feedback from users, magazines - you may want to contact BeeJay, he has these heads in 195cc and I am pretty sure it took the car from 13 sec directly into the 11's.

I'm not sure I have enough experience to comment on exactly what your hp will go from and to, but here is what i have found. Sallee Chevrolet was offering a version of the GM crate engine called the AFR ZZ4 Sizzle. It was a zz4 bottom end (i.e. roughly the same as our L82), 10.25 compression ratio with flat top pistons and the AFR 195 cc runner with a 58CC chamber - that's how they get 10.25:1. The cam was the LT-4 hot cam, same as what BeeJay has. The engine pulled 440 Hp at 6000 rpm and 438 ft-lbs at 5500. And it's torque curve is the same or better at low rpm's as the zz4 crate engine, it just keeps on going past 5500 rpm like freight train - the zz4 engine is rapidly declining at 5500 rpm.

If your heads are like mine (72 cc / 8.5:1 or 76 cc / 9:1 (??) you will get some additional hp from the increase in compression ratio due to the 68 cc chamber - this will be felt across the entire powerband. The AFR heads will outflow any stock GM head hands down no matter what is done to them. So you should have a pretty healthy increase especially at the higher rpm's. I am not sure that a hydraulic tappet cam can get to the levels to truly use all of what the head could do though. Your cam and valvetrain may sign off above 5500 rpm no matter what head you have.

Also about your cam, with 1.5 ratio rockers, an L82 cam should be .46/.47" of lift at the valve (check me!). With 1.6 ratio you should be well into the low .5". Coincidently, that is roughly the lift of an LT-4 hot cam with 1.6 ratio - the LT-4 is a little more (.52/.53)and the roller cam gives more lift area under the curve, but it's pretty close I think. I am impressed that you got the stock L82 cam to work with 1.6 ratio rockers - I did not think this was possible, I never really considered it. I am in the (painful, but fun) beginning process of converting to the roller cam setup.

I think with flat top pistons, it is best to measure how far down into the block they are at TDC for your head gasket. Mine are typical and are .020" below the block deck. I think the best head gasket choice is when the quench zone is set correctly for your head, block, and compression ratio combination. These numbers vary with peoples opinions (also). I think the thinnest practical head gasket is .025" thick to seal an aluminum head. You can search Summit/fel-pro and there are really only a few thickness choices. The next most popular size up is .040". This actually may be too thick for the proper quench distance. Hopefully someone will point us both in the right direction on this one.

(Hey BeeJay, I didn't mean to be your biggest fan or anything, but I gotta say, you have it right on.)

Finally, and I am the very last person on this earth to give advice, but please say that you will take some of your good deal money and upgrade your brakes to the equivalent amount of performance you add. tires too. Learn from me, I've pretty much put every one of my three corvettes in the ditch by throwing cash under the hood and nowhere else. Talk to Keith at corvette engineering, he will provide you with everything you need with brakes and not sell you anything you do not. this isn't a sales plug, it's just the way he is.

 

 

This info is not really correct. The factory L82 cam is 222@ .050 duration and a lift of .450/.460. With 1.6 rockers this will give you a .480/.490. A definite improvement but these are also not true lifts at the valve. You will be in the .470 range at the valves. Still good but no where near the LT4 Hot cam. Also with a roller the lobe profile is much different than a flat tappet so the 2 cannot be compared. If you have the dollars for a roller cam definitly do it the power will be worth it.

As for the heads I ran a set of AFR 190 heads on my 350 then 383 for years. With a large solid flat tappet cam I was able to get 409 RWHP out of my 383. So the heads are sure capable of making HP. I have since stepped up to AFR 210s on mine.

 

When I built my 383, I 'settled' for cast iron heads but had them ported & polished.. I was tryng to save a few dollars but wasted them on the heads. My bottom end is all forged, including 6" H-Beam rods - my feelings were that if I wanted bigger heads later, I could always do that and still re use the bottom end.

I used a california smog legal cam, a Crane along with Crane 1.6 roller rockers. With that mild cam I was only at about 275HP at the wheels. It ran good for 20K miles but then came the AFR 195's

Moving to the smaller combustion chamber and getting rid of cast iron heads was a GREAT move for this project car. Not to mention the high-RPM power with the 195cc runners.

Now it's well over 300 RWHP and it's a lot more fun to drive. I'm up at 11:1 compression so it will ping if I run the A/C but that's about it.

I wish I had put the AFR 195's on it when I originally built it.

 

Someone call Bee Jay? Hey, are you getting a set of older AFR 190 cc heads, or newer AFR 195cc heads. I had the older 190cc heads, ported and polished. I was very happy with them and was never gonna buy heads again. But then the new AFR 195s came out. AFR, and a few people on this and other forums that I trust, told me that the as cast new 195s would significantly outperform my old ported and polished 190s. I sold the 190s with roller rockers for $1000 and bought the new 195s, and sure enough, they got me into the low, low, 13s. But now that I've said all of that, if you got a great deal on older 190s, go for it. When I bought my AFR 190s back in the early 90s, they were by far the best performance mod I had done yet. And I was already on my third cam. Igues in a nutshell, AFR 190s are a ton better than stock L-82 heads, newer AFR 195s are a ton better than older AFR 190s, especially with an LT4 Hot Cam and an Edelbrock RPM Air Gap manifold. The beuty of the 68cc heads you are considering is that you will have great compression. I'm gonna go to thin .015 head gaskets really soon just to get another .5 in compression. I guess the LT4 Hot Cam loves compression. I will get another 1 point in compression when I upgrade to a 383/396 block, but that is a way off. Keep us posted on what you do.

Hey David at Triumph, thanks for all of the propers. I read every word Gkull, Gordon, and Art (and a few others members I trust), say here, and on other Corvette forums. You weed thru the BS and you can get some really great advice here.
Bee Jay

 

i just got a set of the old 190 heads on a smoking deal myself. i don't know much about them but i did get some info from AFR. ever the salesmen, they tried to convince me i should just sell them off and buy the new fandango 195 eliminator heads. i had to convince them these are just perfect for me and what i'm doing. that said, i have some information and specs i'd be happy to share. just PM me and i'll send you a link.

 

Those are perfect for a hydraulic flat tappet 350 build with under .500 lift. They are capable of supporting close to 500 HP but flow is done @ .500 lift. Port size is good for 350 with matching intakes plentiful.