l-82 corvette heads

[capriceowns]

Will L-82 vette heads work on my 1987 305? Im getting a deal off my dads friend, for L-82 heads(about 80,000 miles on them) a weiand manifold and edelbrock carb. I probably wont get the carb since my Q-jet works better now.

But can L-82 heads work? i dont wanna lose any compression,m the guy said they have like 75 or 74 cc chambers.

im working on a mild 350 build up to put into my caprice, but if i can use some of the parts now itll be more fun

[silicon212]

Originally Posted by capriceowns

Will L-82 vette heads work on my 1987 305? Im getting a deal off my dads friend, for L-82 heads(about 80,000 miles on them) a weiand manifold and edelbrock carb. I probably wont get the carb since my Q-jet works better now.

But can L-82 heads work? i dont wanna lose any compression,m the guy said they have like 75 or 74 cc chambers.

im working on a mild 350 build up to put into my caprice, but if i can use some of the parts now itll be more fun

L82 heads will do two negative things to your 305:
#1, they will drop the compression ratio into the 7s,
#2, they have valves that are large enough to interfere with the cylinder bore.

They also have the wrong intake manifold interface (center bolt angle).

In short, they may be OK for a 350, but no good for a 305. There are better heads for your 305.

[capriceowns]

Originally Posted by silicon212

L82 heads will do two negative things to your 305:
#1, they will drop the compression ratio into the 7s,
#2, they have valves that are large enough to interfere with the cylinder bore.

They also have the wrong intake manifold interface (center bolt angle).

In short, they may be OK for a 350, but no good for a 305. There are better heads for your 305.

will they do fine on my 350?

[96capricemgr]

They are VERY unlikely to be of any performance value. Just because something comes off a Vette does not mean it was in any way special. Nothing was making any power in 82.

[Blue Bowtie]

Yes, 1987 was the "split" year for the 72° intake bolts in the center two positions. The heads would bolt to the block just fine, and the Weiand intake will obviously bolt to the old heads with no problems. However, the old heads might be '882 castings, and even if they aren't, they are similar. They are oversized chambers (76cc), have weenie little valves (1.94/1.50), and can be thin in critical areas due to core shift that was common in those castings. Basically, you have two good mud anchors, or one anchor and one door stop, wheel chocks for truck equipped with dual rears (so long as you pull the rocker studs), or any combination of the above.

There is a another negative with those heads - The port runner volumes are comparatively puny. If your '87 has '187 castings, they already flow waaaay better than the "big bad Corvette" heads, plus the chambers are 58cc so you can maintain some decent compression and power.

I usually take them OFF 350s in favor of better heads. As a matter of fact, I installed similar heads to '187s ('416) on this L-81 350 as a performance improvement, after a little porting, valve enlargement, and a cam more suited to a Corvette than a Biscayne:

[Blue Bowtie]

ARRRGH! Once again, Dwayne gets done in a sentence what takes me a paragraph.

[capriceowns]

So these heads arent good for me at all? I thought they have the 2.02 intake and the larger exhaust.

So im better off using my 305 heads on my 350? I could save some dough by just having them rebuilt and shaved a little then slapping them on my 350.

[silicon212]

Originally Posted by capriceowns

So these heads arent good for me at all? I thought they have the 2.02 intake and the larger exhaust.

The size of the valves are only a part of the story - then you have intake volume, exhaust volume, flow numbers etc. There are some 1.94/1.5 valved heads that flow much better than the 2.02/1.6 882s, 993s etc. The 492s in my own car are one such head (mine have "puny" [hi there, Blue Bowtie!]1.94/1.5s). These also came in 2.02/1.6s and were factory on the 1970 LT-1.

[capriceowns]

Ah i see.

So rebuilding my 305 heads are using them on my 350 is better.

Whats the maximum valve size I can have in my 305 heads? Were can I find the casting #'s

will bigger valves make a difference?

[silicon212]

Originally Posted by capriceowns

Ah i see.

So rebuilding my 305 heads are using them on my 350 is better.

Whats the maximum valve size I can have in my 305 heads? Were can I find the casting #'s

will bigger valves make a difference?

Bigger valves will help it breathe better. The casting number is usually somewhere under the rocker covers - between valvesprings. Usually a 7 digit number, can be 6. The last three digits are what are used to refer to a design - i.e. '492', 3991492.

Some 305 castings can be modified to take 1.94/1.5s, some cannot. Blue Bowtie has the casting # head and some pics of 1.94s installed in these 305 heads. The biggest issue with the chambers and larger valves on the 305 heads is something called "shrouding", where the part of the valve closest to the chamber won't flow. Unshrouding involves removing some material in this area to free up the flow.

Also, a 58cc chambered head on a 350 will almost certainly demand a deep-dish piston to keep compression ratios down low enough for the engine to run on 87 octane.

[96capricemgr]

Do not get carried away with valve size. I think most of us understand the LT1 makes BIG power compared to the older smallblocks right.
Well many of the LT1 head shops use stock 1.94/1.50 valves on basic work with great results and some only go to 2.00/1.56 on high effort stuff.
All guesses, estimates and calculations based on 1/4 mile performance place my car around 400rwhp on a stock 100K LT1 shortblock, rev limiter set about 6400rpms shifts commanded between 6-6100rpms. Valves in my worked GM castings are just 2.00/1.56. Using both asumed drivetrain losses and calculating based off the injector duty cycles this is around 480fwhp, if I can get that power with these "small" valves I really don't think a stock shortblock gen is going to gain much from bigger valves.

Blue, what other handle might I know you under?

[Blue Bowtie]

Know this guy?

[kdrolt]

http://www.thirdgen.org/techboard/tb...-headflow.html

What you want from a head is a runner that has large enough volume to suit your needs (170 cc runners are fine for your use on the street), adequate flow past the valves (this could be improved on the 305 heads --- by porting), and very importantly you want a fast burn closed-style chamber with squish regions... and a centrally-located spark plug. The 305 heads have many of these features. The 1982 Vette heads have only large valves, so they will flow well (for stock heads) but they won't burn the fuel as efficiently as the 305 heads will.

I agree with most of what's already been said above. IMO rebuilding the 305 heads is the right way to go (new valve guides, new springs, DIY porting, and back cut on the valves). No need to make the valves larger because the gains are very small as compared to the cost. DIY porting is the best bang for the buck, as shown in the above thread. HTH.