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YH 237356

Found a 400 I might buy for parts or possibly build. Anyone tell me what those numbers tell us about this particular engine?
 

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Found here Pontiac Power
Chart explains the other numbers. The date code off the rear of the block at the distributor will halp narrow it down

YH B-body 70 455 360 Turbo 400 L-75 1x4 9799140 4 HO
YH B-body 69 428 360 Turbo 400 1x4 9792968 2 int seat 45
YH A-body 75 400 170 Turbo 350 L-65 R 1x2 500557 2
YH A-body 77 301 135 Turbo 350 L-27 Y 1x2 525934 2
YH A-body 74 400 175 Turbo 400 L-65 R 1x2 481988 2
YH B-body 74 400 175 Turbo 400 L-65 R 1x2 481988 2
YH B-body 72 455 200 Turbo 400 L-75 U 1x2 485428 2
YH B-body 75 400 170 Turbo 350 L-65 R 1x2 500557 2
YH B-body 75 400 170 Turbo 350 L-65 R 1x2 500557 2
YH B-body 78 400 180 Turbo 350 L-78 Z 1x4 568557 2
YH B-body 65 421 338 Turbo 400 1x4 9778791 4
YH B-body 66 421 338 Turbo 400 1x4 9782611 4
YH B-body 67 428 360 Turbo 400 1x4 9786135 4
YH B-body 68 428 375 Turbo 400 1x4 9792968 4
YH F-body 74 400 175 Turbo 400 L-65 R 1x2 481988 2
YH F-body 77 301 135 Turbo 350 L-27 Y 1x2 525934 2
 

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If it's a 400 then it has to be one of these.

1974 400 190 HP YH A 8.0 255 4X 1-2 7044066 Block Casting # 481988
1975 400 170 HP YH A 7.6 266 5C 1-2 7045160 Block Casting # 481988/500557
1978 400 180 HP YH A 7.7 471 6X 1-4 17058264 Block Casting # 568557/500557

None of them a superior block in and of itself, but as we have learned, any 400 can be made to be a quality street motor. If the 78 is complete 6X heads are a good street head for the pump gas currently available.

Just my 2 cents.
:D
 

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YH 237356

Found a 400 I might buy for parts or possibly build. Anyone tell me what those numbers tell us about this particular engine?
As others already mentioned, having the 4-character date code from the top rear of the block next to the distributor is key. That will nail down the model year, and from that we'll know which "YH" you have. In case you didn't already know, the date code will be one alphabetic character followed by 3 numeric characters.

Bear
 
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