must be the heat I just cannot find it

[John G.]

have looked cover to cover in the Assembly Manual just cannot find casting number for exhaust manifold for 72 LT1 I suspect I do not have correct ones as no air holes and just cannot make out the casting numbers on the manifolds although they both look the same so were there different casting numbers for small blocks 70 through 72and was LT1 different? it's hot down under
john

[Dick W.]

Re: must be the heat I just cannot find it

have looked cover to cover in the Assembly Manual just cannot find casting number for exhaust manifold for 72 LT1 I suspect I do not have correct ones as no air holes and just cannot make out the casting numbers on the manifolds although they both look the same so were there different casting numbers for small blocks 70 through 72and was LT1 different? it's hot down under
john

You definitely have the wrong manifolds. LT-1 was definitely equipped with A.I.R.

[Paul D.]

Re: must be the heat I just cannot find it

John, I don't think you will find the #s in the AIM. Engines arrived at St Louis with manifolds in place and the AIM wouldn't give part #s for individual components of an assembly. According to my 4th edition TIM&JG, both manifolds are the same, but 2 possible numbers are listed. Both are stated as "w/AIR" and I cannot find any notes explaining the difference. The #s are 386711 and 3932461. Hopefully someone with more judging experience can add to the conversation. Chip.

[John G.]

Re: must be the heat I just cannot find it

John, I don't think you will find the #s in the AIM. Engines arrived at St Louis with manifolds in place and the AIM wouldn't give part #s for individual components of an assembly. According to my 4th edition TIM&JG, both manifolds are the same, but 2 possible numbers are listed. Both are stated as "w/AIR" and I cannot find any notes explaining the difference. The #s are 386711 and 3932461. Hopefully someone with more judging experience can add to the conversation. Chip.

I think one of the hard to read numbers is 3932461 will check tonight thanks Paul

[Paul O.]

Re: must be the heat I just cannot find it

As Paul stated 3932461 and the 386711 are the 2 manifolds # used and on ether sides of the engine. For 72 the Alternator bracket was changed and the bracket no longer was secured to the exhaust manifold hence the same manifold could be used ether side of the engine. Instead of side specific manifolds most likely a cost savings.

[Duke W.]

Re: must be the heat I just cannot find it

have looked cover to cover in the Assembly Manual just cannot find casting number for exhaust manifold for 72 LT1 I suspect I do not have correct ones as no air holes and just cannot make out the casting numbers on the manifolds although they both look the same so were there different casting numbers for small blocks 70 through 72and was LT1 different? it's hot down under
john

For future reference, John, remember that the AIM only shows parts that were installed at the final assembly plants. The manifolds were installed at the engine plant.

For the same reason we don't see brake disk/drum, or caliper/wheel cylinder numbers because the front knuckle and rear trailing arms were delivered to the plant as assemblies that included all the brake parts.

So we have to rely on parts books or anecdotal evidence in the judging guide to determine casting or part numbers of items that were delivered to the plant as part of a subassembly.

It's cool in Southern California, and it's gonna rain, tonight.

Duke

[John G.]

Re: must be the heat I just cannot find it

Thanks Duke I have misplaced my judging guide and I now recall some reference in it to these manifold casting numbers will have to hunt further
john

[Joe L.]

Re: must be the heat I just cannot find it

As Paul stated 3932461 and the 386711 are the 2 manifolds # used and on ether sides of the engine. For 72 the Alternator bracket was changed and the bracket no longer was secured to the exhaust manifold hence the same manifold could be used ether side of the engine. Instead of side specific manifolds most likely a cost savings.

Paul------


Unless someone has actually seen one, I don't think any manifold of GM #368711 was used. For one thing, I don't think that number, if it ever existed, would have been used as early as 1972. For another thing, I can't find any record of that number.

The GM #3932461 is the manifold used for most, if not all, 1972 small blocks. This manifold casting was finish-machined into both AIR and non-AIR configurations. The GM #3989036 may have been used for some 1972 applications. Although this manifold would support an AIR configuration, I don't know that it was ever actually machined for that use.

[John G.]

Re: must be the heat I just cannot find it

Paul------


Unless someone has actually seen one, I don't think any manifold of GM #368711 was used. For one thing, I don't think that number, if it ever existed, would have been used as early as 1972. For another thing, I can't find any record of that number.

The GM #3932461 is the manifold used for most, if not all, 1972 small blocks. This manifold casting was finish-machined into both AIR and non-AIR configurations. The GM #3989036 may have been used for some 1972 applications. Although this manifold would support an AIR configuration, I don't know that it was ever actually machined for that use.

Joe thanks for this I did not suspect any change to the manifolds and if air and non air were made I have the non air ones happy with this
john