#21  
Old 02-16-2020, 07:43 PM
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Quote:
Originally Posted by Jay S View Post
Hmmm....top photo is a w72 piston.

Bottom photo looks like a early 75, from one of the last 988 blocks?

Middle photo is what again? Out of what car???

Is this also a Warsak test?
Middle photo is clearly a 389 piston.

Pictured below are 1964 421 (left) and 389 pistons.

The 421 used larger valve reliefs to lower compression and match the compression of 389 engines, much like how 428 engines used dished pistons to maintain the same compression ratios of 400 engines while using the same cylinder heads.
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  #22  
Old 02-16-2020, 11:00 PM
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Yup, I screwed up.
First picture was labeled correctly as a '75 400 (WT) piston.
Second picture was a '67 400 (YC) piston.
Third picture was a '72 GTO 400 piston.

Now, the new 2 pictures are of the '78 YA and X7 pistons.
The flat top piston is from a '74 GTO (350).
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  #23  
Old 02-17-2020, 07:16 AM
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I am very happy we are all having this detailed discussion beacuse my main reason for posting these questions was to try to pin down how just a Cam change and the increase in compression over the 180 hp motor made for the bulk 30 hp gain in the TA motor.

It seams that from the responses posted here that not only was the 220 hp motor underrated, but so was the 180 hp motor !

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  #24  
Old 02-17-2020, 06:28 PM
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Quote:
Originally Posted by Region Warrior View Post
I still have a wz out of a totaled TA(had 1100 miles) back in summer of 78.
Has valve notches and chamfers around pistons.
Been apart after bout 10k miles sitting in corner of garage since 83. Never sold it after realizing vin # was punched and restamped...
DULP!
Not WZ, that's what my 67FB had.
The 78 is an X7(?). Has XX stampings and 6X-4 hds.

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