Gramma's Car: the new project! - Page 16

**cook_dw** · #**151** 08-28-2015, 12:31 AM

Nice..

**njsteve** · #**152** 08-28-2015, 03:34 PM

Stopped by the shop to drop off the pistons and rings. The block has been bored and is awaiting the final honing to size.

**cook_dw** · #**153** 08-28-2015, 03:45 PM

Just curious do they use a torque plate on boring and honing?

**njsteve** · #**154** 08-28-2015, 04:14 PM

It's an old time shop - lots of experience. They do use torque plates for the Chevies but he says from his experience that there is no measurable distortion with Pontiac blocks when bored with a plate or without one. He indicated that it has to do with head bolt location in proximity to the bore walls. He said that the 400 small block Chevies were the worst for bore distortion due to the siamese bore walls and the close head bolt locations.

**cook_dw** · #**155** 08-28-2015, 04:38 PM

Interesting.. Did not take that into consideration..

**njsteve** · #**156** 08-31-2015, 10:32 PM

Rods are refinished and awaiting the crank to come back from cutting. Then the reciprocating assembly goes for balancing.

And the block is finished and home:

**njsteve** · #**157** 08-31-2015, 10:34 PM

Here's something interesting. There are stamped letters next to the bores. Are these for selective fit piston assemblies? "S", "M", and "L" for small, medium, and large? The 1975 350 block in Gramma's car had similar stampings on the deck surface as well, only they were the letter "P" next to each bore. The machinist said he has seen these on other Pontiac blocks over the years.

**Ryan1969Chevelle** · #**158** 08-31-2015, 11:03 PM

Cool, like Olds Select Fit!

Ryan

**njsteve** · #**159** 08-31-2015, 11:59 PM

One of the guys over at PY just responded with this chart for selective fit pistons for 1970 and 1971 Pontiacs. Looks like I was right!

**cook_dw** · #**160** 09-01-2015, 12:22 AM

Great info!!!

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