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They might not be big valve for 1980 L-82. I have a set (that are not original to my car) that have small valves, screw-in studs and guide plates. This car was very original in every way when I got it about 30 years ago but these heads puzzled me at tear down. Engine looked like it had never been apart with one other exception - .009" undersize crankshaft bearings. Where common folks would get a set of .009" undersize bearing shells I have NO idea. I suspected a factory rework but can not prove it one way or the other.
My stock 1980 L-82 came with the 882 heads. They had the bigger valves but overall didn’t flow very well, and I believe the chamber size was at 74cc. I swapped out to a set of 062 vortecs, and even though they had slightly smaller valves, the smaller chamber and larger runners really improved performance.
I’m asking because I’m considering building a second NHRA stock eliminator car out of it and the specs matter. NHRA has it listed as 1.94/1.50. But I can’t find a verified case of one coming with small valves. It makes no sense that the 80 would be rated at 5 hp more but have smaller valves
No L-82 came with the smaller valve L-48 heads including the very rare 1980 L-82 of which only 5,XXX were produced and only with an automatic, no 4 speed offered since GM did not want to EPA certify the 4 speed L-82's since the production numbers would be very small. The 78-80 L-82's (220-230 NET HP) are identical engines with the exception of mufflers (more free flowing from 78 to 79) and more efficient exhaust pipes in 80 (which is the additional 5 NET HP difference).
If your 80 L-82 has smaller valved heads now, it did not leave the factory that way (changed later or under warranty incorrectly) or someone changed them after 1980........
That’s my position as well. Unfortunately the MVMA sheet from 1980 that NHRA uses as their spec from the manufacturer says small valve (actually it doesn’t list the L82 separately when it comes to valve size). It’s now an uphill battle to get it changed.
I would not get too caught up with the NHRA about a 1980 C3....The Specs probably don't list the 882 bigger valve heads for the L82 since 95% of C1980 C3 production were base L-48's or the California ONLY 305 V8's. You stated that they only list the smaller valve heads (with no mention of the L-82 distinction) which indicates that they are not documenting the L-82 but only the base L-48 350. Another words the NHRA does not refer specifically to the L-82 engine which does NOT mean that the 80 L-82 had smaller valve heads, just that there is no documentation for the L-82's, from them.
BTW-My 1978 L-82 aluminum intake manifold has the EGR provision as well so not sure what you were referring to above about the 80 L-82 intake having an EGR provision, the 78-79 L-82's do as well.
NHRA lists the L82 and the heads. But their source document from GM has an error. I’ve dealt with NHRA for 20 years. This isn’t my first rodeo with them. Here’s our other stocker
NHRA lists the L82 and the heads. But their source document from GM has an error. I’ve dealt with NHRA for 20 years. This isn’t my first rodeo with them. Here’s our other stocker
I get what you need now...didn't read it carefully enough....
08-10-2018, 08:54 PM
L82 engine spec question
