piston to cylinder tolerance

Knuckledragger

Knuckledragger

Knuckledragger
Joined
Jun 4, 2009
Messages
236
i got a 2nd gen 12v ive been goin through for a friend. i took the block to the machine shop to get the bores freshened up. the machinist called me today and told me he could clean and match the bores at .005 over. my question is will that be ok to go back with stock pistons and rings or will i have to go over. this truck will be a daily driver that hauls about 1500 lbs with a welder and equipment. im going to do some minor mods to it for a little more power (i.e.tune afc and slide plate). i was thinkin the extra clearance would help with the added heat. any advise? thanks
 
If it was mine I'd do it, my next one will have .008 vise the stock clearance, keeps them from scuffing as much at high EGT's and abuse.

Jim
 
I'd run it. As Jim said the piston to wall clearance is better on the loose side. .005" is a conservative #.
 
Ive still stuck em at .010", so dont be to concerned. Keeping better control over the temp's is the better advise though.
 
Thanks for the info! Snedge im trying to get my parts list together and get back with you but ive been to busy. im trying to fing a used timing housing as the old one met the kdp
 
Knuckledragger said:
Thanks for the info! Snedge im trying to get my parts list together and get back with you but ive been to busy. im trying to fing a used timing housing as the old one met the kdp
Click to expand...

Jeff has new aftermarket housings for an affordable price.
 
That would be like .009" or .011"? That's way too loose for a street driver IMO. IIRC the factory spec is .004" to .006". My cylinders are bored for .005"-.006" clearance
 
Snedge said:
I'd run it. As Jim said the piston to wall clearance is better on the loose side. .005" is a conservative #.
Click to expand...

My 6.7 block is nearly new and i have new pistons with the coated skirts(Swain). Is the .004 to .006 number still ok?
 
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