1972 LT1 heads and performance vs 1970 LT1
 

What are the specifications for the factory heads on a 1972 350 LT1?

Intake and exhaust diameter?

- Combustion chamber size and design vs 70 350 LT1 and 72 base 350.

How do these engines perform in stock form compared against the 70 LT1(370 HP) or say even a 70 base engine 350? I had the base 300 hp 350 engine in a Chevelle with a Muncie M20 and it was impressive. That was 30 years ago, but I still remember the mid range of that motor. It would rev to about 6200 and stop. I think the hydraulic lifter cam would start to float about that RPM range.

Currently dealing on a 72 LT1 in the $20-22 range. I have just started the inspection and numbers process on the car. Will post pictures soon, as your opinions here are interesting and valuable.

I could be totally off base, but I think the heads are nearly identical.

The big difference is the decrease in compression ratio which was achieved by a change in the piston.

And, of course, the addition of the air pump crap.

All in all, though, I think the fundamentals of the engine are identical from 1970 to 1972.

The primary value of those heads is for restoration purposes. Beyond that, "performance" and 1960-1970's cylinder heads should not be used in the same sentance. They were good heads - fourty years ago.

It's been way too long since I played with these to remember exact specs. but there's not much difference between them other than '70 has a 64 cc combustion chamber and '71-72 had 76 cc chambers. Valves in both should be 2.02"/1.60".

I remember something about hardened valve seats on the 71-72.
Lower compression is easier on the wallet at fill up.
I cant speak for 70 power but the 71 LT1 is plenty fun.

All LT-! engines 70 through 72 had AIR crap. It cost a whopping 1 HP.

1970 engines had pink rods and much better that the following LT-1`s, Several years ago a set of 8 were $800.00 bucks...the heads have guide plates and screw in studs...the 71-72 engines also had a cam change and quite possibly be hydraulic .....and the reason Air could be ordered in 72....the solid lifter 370HP was not available if Air was ordered......The heads as far as I was concerned was the best available for SB engines...Being a simple engine swap I ordered one for my 62 and the cost complete, was $612.00 over the counter and delivered....all the engine lacked was the carb and coil through 'Art Moran Pontiac in 1970

the only diff was 70 had 11:1 compresion and small chamber heads, all year LT-1s had upgraded hardware, {rods, crank, pistons} soild lifters same cam, scwew ins guide plates big holly . and 72s had no ti, thats it.

Wrong wrong wrong---domestic U.S.A only corvettes had AIR installed. Export versions I.E Canadian versions had AIR delete options.How do I know, you ask. I own one with an original build sheet listing the AIR delete export option, listed

Can you post a pic of your build sheet? I am sure many of us would love to see it.

:thumbs:

LT-1 kid is 100 percent correct, and no the LT-1 never had a hydraulic cam, that was the L-82.:thumbs:

We have both a 70 and 72 LT-1 in our garage so maybe I can give some insight. The 186/492 casting 1970 LT-1 head is THE BEST head ever installed on a production line small block motor needing end bolt bosses for accessories. Even the base 350 motor was equipped with a variation of this head but lacked the screw in rocker studs guide plates big valves and combustion chamber rework for those big valves. Bolting on a set of 70 LT-1 heads was common practice for 71-72 owners back in the early 70's you would pick up 20-30HP and much more bottom end torque ( also raised your compression ratio almost a point.) The early heads actually will lose to the 71-72 heads on a flow bench comparison but there is more than flow happening in the cylinder. The closed chamber design is more efficient at combustion and helps create more power hence more NOX emissions so GM and all automakers had to modify their motors for changing emissions standards.

The late great John Ligenfelter onced tried to lobby the NHRA to allow Chevy Super Stock cars of the early 70's to use the early heads but failed. John made his reputation racing a 73 Vette sponsored by Graf Enterprises and once while competing at the US Nationals had a helicopter fly to his Decauter shop to source a replacement engine to continue competing (didn't have a Hollywood ending but the tale of his extreme effort lives on.) Johns advantage in using the Vette in Super Stock was the weight distribution, traction advantage of IRS and the giant oil pan the Corvette chassis allowed him to run.

glad you pointed out they unshrouded the valves, lots of people install bigger valves in their heads and lose power because of the curtain.:iagree:

:iagree: Many of us would just love to see that. Cars other than Corvettes exported to Canada and before 1969 are known to have 'smog delete' RPO KD1.

Never seen a Corvette with that option, in fact every original Canadian LT-! I've ever seen most definitely had AIR.