# 1970 Raiii 400 ??



## goat53 (Dec 13, 2006)

Need some help identiying 400 engine in 1970 GTO. I have searched everywhere and have a conflict, maybe someone can help. Engine cast code and date indicate 70 RAIII engine. Cast # 979914 built late 69 with 4 bolt mains. Heads are also late 69 and cast code 13. This indicates it is 70 RAIII engine in front of an automatic. 2 digit code on the front of the block is YD. can not find reference to YD anywhere on any engine . The code should be YZ according to my research on this engine. Anyone have any idea what YD is ?


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## red98gt (Sep 13, 2006)

Everything I can find says 1970 Bonneville.......but doesn't make sense if it's a 4 bolt block.

Try the Performance Years site. Much more traffic related to 60/70's Pontiacs.

http://performanceyears.com/newsite/index.html

Forums:

http://forums.performanceyears.com/forums/

Or one more resto site:
http://www.pontiacstreetperformance.com/


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## 05GTO (Oct 6, 2004)

Casting number 9799914 is listed for a 1970 400 or a 1970 400 RAIII with 4-bolt main, 

Letter code YD was used in 1970 for a 400 b-body (Prix, CAT and Bonn) with 290hp, automatic and a 2 bbl.

The letter code for a 1970 RAIII is WS for a manual and YZ for an automatic.


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## goat53 (Dec 13, 2006)

Thanks for info, that is about the same I came up with. casting # says it is RAIII with the 4 bolt mains but the YD says different. Should be YZ. Other info I have makes sense that with these heads being corect, at one time someone toasted the original RAIII block and made a RAIII out of this one.I have found out that all these blocks were tapped for 4 bolt but not always used. Other than the YD or YZ stamping the blocks were identical except for the 2 or 4 bolt issue. Different caming and heads designated HP. Again, thanks


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