I only have the #'s book for small blocks and am about to get my grubby hands on a used 454. I want to decode the #'s first before driving 1000 miles to get it.

Block# 10069286 which I assume is 10068286 ( 90 454) stamping pad codes are GM3P CFD and L070. I assume L070 means Dec 7 1990. I hope this is still a Mark IV block.

The heads are stamped PASS casting # 3368781 date code J 8 73 one was marked J 81 73. I assume Oct 8 1973 for a date here. These sound like large oval port heads with small valves from a 74 Caprice or Chevelle. Mortec lists that casting #@ 73 - 85 oval port 454. Did light duty trucks still get the PASS code or was Truck for both tall deck and short deck heads?

Any help or comments are welcome

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Frank W
Forgotten Chevelles Rule
74 Laguna S-3 Motor in garage again !!!!!!!
Will work for a used 454, or any running 350 now
3.42 open rear, Posi in garage
73 Malibu Coupe mostly memories and some parts left in my garage
http://www.Chevellepages.com/folingo

I just need the suffix code decoded to see if it matches the block # and date code. Or does someone know of a web site with big block suffix codes TIA

You could always try www.mortec.com. (http://www.mortec.com.)

Good luck.


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Ian, Member #232
Canadian 66 Malibu SS
Gatineau, Quebec

btdt, they only have casting #'s http://www.chevelles.com/forum/frown.gif

I just got a nice book, Chevy Big Block parts interchange manual. Lots of good data, but the block casting# is not there. I am worried that this motor is a mark V based on the apparent date code L070 which would place it in the 91 model year.

I have only one Mark V casting # listed in my book, 10114182 91 up gen V 454. Anybody have more info about the mark V motors. The heads listed are nice large oval port heads, but they will not work with a stock mark V block according to my book. Anyone worked out that swap? The mark V block sounds beefy with the thicker casting, one piece rear seal and one piece oil pan gasket. But what heads would work with that motor?

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Frank W
Forgotten Chevelles Rule
74 Laguna S-3 Motor in garage again !!!!!!!
Will work for a used 454, or any running 350 now
3.42 open rear, Posi in garage
73 Malibu Coupe mostly memories and some parts left in my garage
http://www.Chevellepages.com/folingo