Author Topic: Help me with a block number for a possible SD  (Read 2537 times)

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Offline doeslayer

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Help me with a block number for a possible SD
« on: June 17, 2006, 02:49:17 PM »
Just purchased A 81 Trans Am that someone has put a 455 big block in that he claims is an SD and turbo 400 trannny. I don't  beleive that it's a true SD but he's got it painted up like a Super Duty with the Blue and white paint job.The heads say 6X on the side along with F146      DN     GM2.  The only Number I've been able to find on the block so far is0496947  X7. Does anyone know where I might be able to find out more info on this motor so I'll really know what I've got .I have'nt been able to even find the displacement number stamped on the side because of the headers so for all I know it might just be a 400. Thanks in advance.

Offline Zulu

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Help me with a block number for a possible SD
« Reply #1 on: June 17, 2006, 11:02:57 PM »
Based upon the numbers that you posted, it looks as if you have a 1976 400 with 6X heads. X7 was an engine code used on the 400 in 1976 and 1978 (and probably some other years???) but since the head date code suggest 1976 then the rest of the engine probably is also.

The 6X-4 heads were used on 350's in 1976 and the 6X-8 heads were used on the 400 that year (both heads were used in subsequent years also). The date code on the heads (F146) suggest that the heads are from 1976. F=June, 14=14th, 6=1976.

The 0496947 is something like an intake manifold casting number for a 1976 engine but I couldn't find that exact number so I'm not sure.

Anyway, from the few numbers posted, it's looking most like a 1976 400.

Here are some diagrams which might be useful in helping you locate various numbers.
http://groups.msn.com/TransAm1978/engineidentifiers.msnw
http://groups.msn.com/TransAm1978/cylinderheadid.msnw
The diagrams are for 1978 TA's so the numbers themselves won't match but the locations of the numbers would be the same on a 76 engine and heads. Post any numbers that you might find and we'll help decode everything for you.

Hope this helps.

Oh, and Welcome to 78TA.com.

Added: After some further research, I discovered that the X7 engine code was used on a 1973 455 engine also but not the SD. So it is possible that you have a 455. All could be answered if you were able to get at that CID casting (driver's side of block towards the front). A 455 with either 6X-4 or 6X-8 heads is not a bad combo.
 1978 TA W72 4sdp, WS6, Orig Owner -
- If there's nothing to do, I believe in doing nothing -

Offline doeslayer

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Help me with a block number for a possible SD
« Reply #2 on: June 18, 2006, 02:45:00 PM »
Thanks for the info.Not what I was truely wishing for I did'nt really think that I had found A true SD in a relatively solid car for 3000.00 The car has a sub par paint job that could have a lot better body work but the interior has been recovered in the past couple of years so I'm pretty happy with my purchase.Does anyone know where I might be able to purchase new tailight lenses and a fuel door for the 80-81 cars? They don't sell them in Year One,Classic Industries or Ames.

Offline Eagle 1

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Help me with a block number for a possible SD
« Reply #3 on: June 18, 2006, 06:48:50 PM »
I have a used tailight assembly and door that is in pretty good shape.  PM me if your interested.
" He done good didnt he Fred?"
"I'm in pursuit of a black Trans Am. He's all mine so stay outta the way."