70 LS5 intake question

[Norris W.]

I've always thought my 70 LS5 air roadster had the original intake. The casting date is consistent with the heads and the build date on the car. One of the other Corvette websites I play on had an LS5 differences discussion for different years and someone made the statement that the 70's had alum. intakes while teh 71's and newer had cast iron. I was prepared to contradict this because of my car, but looked it up in my old NCRS spec guide (over 10 yrs old) and sho' nuff, it says aluminum. I've always had it in my mind that the only oval port big block factory intakes in aluminum were the 68 & 69 390's.

[Clem Z.]

Re: 70 LS5 intake question

my specs list 1970 454 390HP manifold #3955287,1971 454 425 HP manifold #3967474 aluminum,1971 454 365HP manifold #3955287,1972 454 270 HP manifold # 6263753. since the 3967474 is the only one listed as alumimum i would guess that the others are cast iron. these specs come from the NHRA spec books

[Joe L.]

Re: 70 LS5 intake question

Norris-----

The 1970 Corvette LS-5 intake manifold, GM casting #3955287, was a CAST IRON manifold. The 1968-69 Corvette L-36 manifolds were the ONLY 4 barrel carb, aluminum, oval port manifolds which Chevrolet ever used in PRODUCTION.

After 1969, the only aluminum manifold used on any Corvette big block was the rectangular port GM CASTING #3963569. This manifold was also used on other 70-71 Chevrolets with LS-6 or L-78.

[Norris W.]

Re: 70 LS5 intake question

Thanks for the replies guys. Joe, your response was exactly what I thought I remembered. I assume the NCRS Spec Guide has been corrected by now???? Mine says First Edition, First Printing, Summer 1989.

[Jack H.]

Re: 70 LS5 intake question

The JG book is now in it's third edition--your library needs an update, visit our 'sponsor' at the STORE on this site. It reads:

"Small block engines use cast iron intake manifolds, except LT1 which is aluminum. 1970-72 big block intakes are cast iron, except LS6 which is aluminum."