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Old 08-02-2004, 08:41 PM   #1
mrcorvette79
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Default Cylinder Head Specifications

I've exhausted most of the information I have collected (books, manuals,etc.) trying to find the original cylinder head specifications for my 1979 L-82 small block. Every article tells you what you can put on as far as replacements but I would like to know what I'm starting out with,
ie: combustion chamber size
intake and exhaust valve size
runner size

I know the compression ratio is 8.9:1 but the rest

Any and all help will be greatly appreciated. Information will help me make the correct descision new parts, heads , cam, intake, carb.
Thanks, Marc
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Old 08-02-2004, 08:46 PM   #2
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marc,
i think the heads for your car are a 462624. should be a 76 cc combustion chamber with a 1.94 intake valve and a 1.500 exhaust valve. i'm not sure of the intake port volume but i think its in the 150's.
if you run a 70 LT-1 piston with these heads you can get just under 10:1 compression. port matching , a 3 angle valve job and some pocket porting really help these heads. see ya! steve
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Old 08-02-2004, 08:54 PM   #3
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and port match to intake man.
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Old 08-02-2004, 08:58 PM   #4
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Thanks Steve, I've made a copy of your information to keep in my book. I'd hate to make a choice based on no information without trying to find out something. Wouldn't be a great feeling to spend the money on porting or new cylinder heads and have the engine run lazy. There's still alot I need to learn. Thanks, take care
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Old 08-02-2004, 09:00 PM   #5
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Your 79 L-82 heads should be 624's with 76cc chambers and 2.02 intakes and 1.6 exhaust.
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Old 08-02-2004, 09:07 PM   #6
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best bet is port yourself or buy new heads
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Old 08-02-2004, 09:09 PM   #7
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Well, the next question would be can I make the stock heads perform better with porting using the existing Performer Intake and Q-jet 795 cfm with hot air, or do I need to move up to the RPM intake and a larger carb to get the full potential.
Thanks, dazed and most of the time confused, Marc
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Old 08-03-2004, 10:36 AM   #8
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One of the resons all the articles talk about what to replace them with is because the magazines want to sell advertising to replacement parts sellers.

But the other main reason is that the "624" heads are truly poor heads. I know you did not ask this but here goes:

They were troublesome from the start. These heads are "lightweight" castings that are crack prone. They do not flow very well either. 76cc chambers, valve size is probably 1.9" intake and 1.5" exhaust. The L-82 had the big valves (2.02" and 1.6") in the early configurations but the valve size was made smaller at some time during the later 70's. They still had the screw-in studs and guideplates but that is about the only thing going for them.

You could rebuild them and do a pocket porting job on them but they will still be inferior to most any other head. Get an estimate on the cost of a valve job plus any additional work and add it up quick. You are very close to the cost of a much better, reliable, brand new part. If your old heads need any parts or additional work, the cost will be higher.

You could put them on the shelf and get a pair of the Edelbrock heads and be done with it. High quality pieces in my experience.

I have my '80 L-82 almost back together now. The only mod in the engine will be aftermarket heads and roller tip rockers. Everything else will be stock.

-Mark.
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Old 08-03-2004, 10:46 AM   #9
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I agree, I found my John Lingenfelter book and he states alot of the same concerns about the 624 heads. Not really worth the time to improve but they would be a great teaching tool during the winter months practicing some porting techniques. Do you have any thoughts on the World Products S/R Torquer heads. Similar specs to the Edelbrocks but in cast iron. The reason I want to go with iron is the front is already too light as it is. Any more and the handling will suffer.
Thanks for the information, Marc
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Old 08-03-2004, 11:11 AM   #10
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The 624's on my 79 came with 2.02/1.6 The stock aluminum intake outperforms the Edel performer in dyno testing. The stock carb is more than enough to support 500 hp motors. People that know Q-jets have know problem using them on pretty fast cars.

The major problem with L-82's is lack of compression. I spent lot's of money doing the P&P screw in studs and guide plates bigger springs for high lift cams.

I really don't believe that you can make the front end to light on a 79 Vette. Go to a certified scales and drive the front tires on the scales and weigh the front end. then weigh the rear end.

I've done it and i have an extremely lightened front end. You want rear weight bias to make it handle
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Old 08-03-2004, 01:00 PM   #11
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I have to agree with GKull here. I spent 800.00 making a set of 992 heads work at thier best and they still were not as good as a set of WP Sportman II's. Save yourself the heartache and buy good cylinder heads from the start.
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Old 08-03-2004, 01:31 PM   #12
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Marc,
The WP SR Torquers are not bad heads.

I personaly like the Dart Iron Eagle 180's much better though. Better flow and better valve guides by far and about the same $. Your valve jobs will last much longer with bronze guides over the cast iron guides in the World Products heads. You might need to clean up the castings a bit when you get them out of the box. I had pretty big cutter lips in the valve bowls when I bought mine. I had a few other adjustments here and there but no big deal. Either head will out perform the "624"s and still be reasonable in $.

I got a set of Dart IE 200's with 64cc Chambers for less than $750 to my door assembled. Gives me about 10.4 C/R using the thin fel-pro shim gasket and a .025" deck with the factory forged flat-tops.

-Mark.
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Old 08-03-2004, 01:42 PM   #13
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Good information from everyone on this subject. Would just a cylinder head change be enough or would the addition of a good cam set finish off the package.
The Sportsman II's have a 200 cc port volume, thats not too much is it? I don't want to take away from low end torque. In fact I want more torque, the Va. Beach area has limited open roads so it's mostly a stoplight playground.
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Old 08-05-2004, 03:29 PM   #14
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Default L-82 cam

The L-82 cam is really pretty good it's the same grind as the 325/350 hp of the 70's era. The only difference is those motors used higher flowing heads with 64 cc chamber to get the compression up.

Shop around for 180 ish cc intakes and 64 cc chambers without a cam change and you will feel the difference especially if you have a shift kitted TH350 or 4 speed.
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Old 08-05-2004, 06:45 PM   #15
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BOB, is correct with his info on valve and port size.
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Old 08-05-2004, 07:22 PM   #16
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Marc, i had the 78 l82 block, you need new heads just like you said, the 79 heads were crap right along with the dished pistons that it came with, if your interested the reason they did this is because of the emissions onslaught during the late 70's early 80's in which car manufacturers scrambled to find ways to reduce emissions with not really looking for performance anymore. Anyways, i would suggest a 64cc head, like other have. The ones that i considered till i decided to go aluminum was the vortec ones straight from gm performance parts, i dont know much about the wp heads so therefore i cannot compare them, but from the people that i have seen with these heads they have loved them, and with that 64 cc head it will make that compression ratio go much higher(just like other have said). The cam is ok, if you are really looking to make this thing a screamer, i would personally replace it while your digging around in the engine if you have the means, if you know what i mean . But, most def. replace the heads if you havent already figured that one out, hah, and then start looking at the cam, then intake, then carb, cuz those q-jets, if tuned right, run well. Have fun!!

Head addy.
http://www.gmpartsdepot.com/store/pr...Category_ID=57
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Old 08-05-2004, 07:22 PM
 
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