My 402 heads are listed for "366/427" - The 1947 - Present Chevrolet & GMC Truck Message Board Network

davepl · 01-02-2012, 04:35 PM

The casting numbers on the cylinder heads for my 70 GMC 402 are 3975950, which at every source I've checked shows them as

1968-70 366/427 2.06/1.72 Closed Chamber

The block is TO42TTBG, which is 402. Now I'm a little confused, because the 366/427 are tall-deck engines and the intake manifold wouldn't fit, even if you could mix and match tall deck heads with a short deck block.

Are the sites I've checked all wrong, or do I have the wrong heads on this truck?

Thanks!
Dave

01-02-2012, 04:35 PM	#1
davepl Registered User Join Date: Aug 2006 Location: Redmond, WA Posts: 6,332	My 402 heads are listed for "366/427" The casting numbers on the cylinder heads for my 70 GMC 402 are 3975950, which at every source I've checked shows them as 1968-70 366/427 2.06/1.72 Closed Chamber The block is TO42TTBG, which is 402. Now I'm a little confused, because the 366/427 are tall-deck engines and the intake manifold wouldn't fit, even if you could mix and match tall deck heads with a short deck block. Are the sites I've checked all wrong, or do I have the wrong heads on this truck? Thanks! Dave __________________ 1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible

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