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Old 02-23-2021, 07:34 AM
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Tom Vaught Tom Vaught is offline
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Quote:
Originally Posted by PontiacJim1959 View Post
Here is a photo from the magazine article on the RA IV. Maybe Tom can ID the piston tops. I know magazines will toss in "parts" just to make the article up, but you can see the piston on the right has different valve reliefs. The article sounds like the piston on the left is the cast RA II piston, and the one on the right is the forged RA IV piston.

The article also states the RA IV forged pistons are 50 grams lighter than the old cast RA II pistons.
250 minus 50 says the piston combines weight would have been about 200 grams for the piston pin.

Notice the shallow cut on the piston on the right (in the general spark plug location)?

Tom V.

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