Correct Heads on LT-1

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Jul 9, 2010 | 03:48 PM

CoolShark

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From: Gotham City CA

Correct Heads on LT-1

I am getting my engine gone through and found two different head numbers. It is a matching number block and has the correct intake and card, but one head is a 3998993 and the other is a 3973487X. According to my books, they should both be 3973487. I get all kinds of info from different sites for '72 LT-1's. Any info from the experts here?

I also posted this in tech

Jul 9, 2010 | 04:07 PM

Easy Mike

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From: Southbound

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I'm no expert, but my NCRS Specifications Guide lists the 487 heads for the 72 LT-1s. The 993 heads are shown for the 200hp base engine but unverified and for 73 and later L-48s.

Jul 9, 2010 | 04:28 PM

84compuvette

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Quote:

Originally Posted by Easy Mike

I'm no expert, but my NCRS Specifications Guide lists the 487 heads for the 72 LT-1s. The 993 heads are shown for the 200hp base engine but unverified and for 73 and later L-48s.

Same info I have. 72 LT-1 should have 487X. My '71 L48 original engine has 487 (non-X) factory heads on it.

Jul 10, 2010 | 12:15 AM

Solid LT1

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From: Fremont CA

487X, I have a pair, what casting date you looking for?

Jul 10, 2010 | 09:53 AM

Mike Ward

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Are the casting dates on each head prior to the assembly date of the engine?

Jul 10, 2010 | 06:24 PM

CoolShark

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According to the books I have, it should have 487 non-X heads. My VIN is 1Z37L2S511xxx Did they change mid-year?

Jul 10, 2010 | 07:23 PM

2000HdTp

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The NCRS guide states that the X shows up on later 1972 3973487 base and LT1 cylinder heads. I have 2 LT1's and they both have the 3973487(X) heads and one was built in March and the other one in June of 1972. I hope this helps.