overboring, resurfacing and compression

[DSMatMSU]

i recently rebuilt my 6-bolt with 2g pistons... bored 20 over... at the same time my deck was VERY lightly decked... you can see where they just barely had to remove material, i dont know an exact amount, but they said they didnt have to do much... on the head, it was just resurfaced (1st, and only time)

now, would an overbored cyl, with reduced material on the block and head... would these two cancel each other out... or is the overbored piston going to give me the same compression as one that was not bored?? (this makes sense to me, but so does the other)... im just using a oem gasket, and didnt have any trouble settting my timing on the stock gears...

i need to get a new gauge, because mine wont zero out anymore, it stops at 30... so when i do compression tests i get numbers like 215, but at least its even.... *must, buy, new, gauge)

this has the possibilty of being a really stupid question but, im willing to learn...

 

[nickrule99]

I believe boring the cylinders wont affect your compression, becasue the pistons are designed with that in mind. A .040 overbored with 9.0:1 pitsons would have the same compression as a stock engine with 9.0:1 pistions.

So, since your taking away area when you decked the head, Id assume your compression will be a bit higher. Not to sure what numbers you'd expect, but Id assume they'd be a little higher.

Just something to feed you until someone who really knows what they're talking about chimes in.

 

[2bar]

Boring the block will not change the compression ratio in the cylinder. only the combustion chanber size such and decking the head or pistions will change the compression. You should not see much change if any in compression with just resurfacing the head. most machine shops do this all the time.