71 LT1 Heads

[Richard R.]

I'm looking at a 71 LT1 to purchase. Have had Mid Years for 30 years. A lot to learn about "real" LT1's. Question, the LT1 I'm looking at has double hump heads. I thought 70's had double hump, not 71 or 72.

[Ron G.]

Re: 71 LT1 Heads

Richard - 1970 LT-1's had the double bump heads. 1971 & 72 had what I refer to as a square with steps. At one point the heads were probably changed.

[Joe L.]

Re: 71 LT1 Heads

I'm looking at a 71 LT1 to purchase. Have had Mid Years for 30 years. A lot to learn about "real" LT1's. Question, the LT1 I'm looking at has double hump heads. I thought 70's had double hump, not 71 or 72.

Richard------


1971-72 LT-1 used cylinder heads, GM casting #3973487, with the symbol as shown below. However,just as with the "double hump" symbol heads, there were many variations of these heads used for many different 350 cid engine applications. So, this symbol on heads does not, at all, confirm that the heads are for an LT-1.

Why the change from the "double hump", last used for the 1970 model year? Well, for 1971 compression ratios were reduced across-the-board to enable the use of the then-new low octane unleaded regular gas. So, among other changes, combustion chambers were redesigned and increased in size.


1971-72LT1headsymbol 001.jpg

[Richard R.]

Re: 71 LT1 Heads

Ron,
Thank you for the reply. This car was Top Flighted 13 years ago, and you were one of the judges.