piston deck clearence
 

i know you have to check and confirm but...is it safe to assume that most pontiac blocks are going to run .015 to .020 on the hole with non stock parts?

the 455 i just assembled..probably gonna un assemble. measure at .020 on all 4 corners.

the 400 i test fit, .020 on one side, .015 to .020 on the other. kinda odd.

now i just test fit a 467 stroker, .020 i could feel the drag on feel gauges...i did fit .023 in once, but i think i was pushing up on my straight edge so i called it .020 with the other 3 corners. if i missed it by .003, i think its still gonna be a improvent.

455 an 400 both use stock cranks, eagle h beams, ross flat tops with the 455 being the power adder version


the 467 being a eagle forged crank and h beams with mahle flat tops

Instead of feeler gauges, do you have a dial indicator that you can setup to confirm the measurements?

I think mine ended up around .003 to .005 in the hole with Ross pistons and Eagle crank/rods.

i do, and since the 455 is assembled...ill see if it backs uo the .020. ...even by eye, i can see my blocks are nowhere near .003-.005

With non stock parts it a “who knows “ condition .

In terms of what I have seen with a stock short block in terms of 4 bbl motors is 389-400 deck clearance is real close to .023” , a 455 will be about .019” to .021”.

The exact clearance hinges on if you have tapped the bearing clearance down out of the rod big end.

I don’t drive myself nuts anymore since I am not looking to run in a NHRA stock or SS class.

As such if I am within .008” of where I want to be ( provided there’s enough PTVC) I call it a day and move on.

I have a 1970 / 350 that i checked the deck one time and at opposite corners .005-.007 and .017-.019 its like the block was sitting not so perfect in the cutting machine, i left it alone

make sure you check near piston pin center line to thwart effects from piston rocking