Not fully understanding what is meant by "IA1" block. Presuming it might relate to the early first run of blocks I offer this for a FWIW.
Here is a thread from 2005 where there was a discussion regarding the lifter tie bar making contact contact with the lifter bore pad on the block. This was first run, block number 17.
Note comment in post #9
https://forums.maxperformanceinc.com...d.php?t=425138
Later blocks were changed to correct the situation. In addition the website assembly notes were changed.
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'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 )
Old information here:
http://www.hotrod.com/articles/0712p...tiac-trans-am/
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