Question about overboring ?
10-23-2004, 08:42 PM
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Question about overboring ? Hi ppl
Ive got a sbc 350 block here (i know its not an ls1 block but this q relates to all motors out there) and it was recently bored out 30thou over and all machined up with the good bits. I originally had a decent bottom end for it, but ive sold that bottom end now so ive just got the bare block again.
Now my question is, with the block being 30thou up, can i just go buy any set of 30thou pistons out there and drop them in?
im confused coz im not really sure if the machine shop did the bores exactly to match the pistons i had (which of course were 30 up) or its just a general procedure to go exactly to the 30thou up and all pistons will fit that bore and have roughly the same piston to bore clearance...
Any help please let me know!
thanks
Ive got a sbc 350 block here (i know its not an ls1 block but this q relates to all motors out there) and it was recently bored out 30thou over and all machined up with the good bits. I originally had a decent bottom end for it, but ive sold that bottom end now so ive just got the bare block again.
Now my question is, with the block being 30thou up, can i just go buy any set of 30thou pistons out there and drop them in?
im confused coz im not really sure if the machine shop did the bores exactly to match the pistons i had (which of course were 30 up) or its just a general procedure to go exactly to the 30thou up and all pistons will fit that bore and have roughly the same piston to bore clearance...
Any help please let me know!
thanks
10-23-2004, 08:51 PM
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a shelf .030+ will fit...it will not be an optimal fit..when you have a block bored, send the pistons you will use..the shop should do final hone for each piston by dedicated hole...you possibly can do some honing to the shelf pistons after the fact...but there are other things you must know before ordering like...deck height...pin height...chamber size & shape...valve lift & size...power adder or not...ring pkg...piston weight...do you intend to balance the rotating assbly?..if so, send the block with the pistons, or better yet, have the shop get the pistons for you...they'll appreciate that and so will you in the end
10-23-2004, 09:15 PM
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thanks for thge reply bryan.
Yeah thats what i was thinking, the block would of got bored to suit the previous pistons.
Is it possible it could be a little too bored out for the next set i buy? like assuming i get a set of 30thou pistons, and the block from the previous bore is sitting at 31thou up (as an example) would this be too much?
I just want them to fit and not rattle and have too much clearance... i definately plan to get it balanced again (different bottom end compared to the previous one)
Yeah thats what i was thinking, the block would of got bored to suit the previous pistons.
Is it possible it could be a little too bored out for the next set i buy? like assuming i get a set of 30thou pistons, and the block from the previous bore is sitting at 31thou up (as an example) would this be too much?
I just want them to fit and not rattle and have too much clearance... i definately plan to get it balanced again (different bottom end compared to the previous one)
10-24-2004, 01:43 AM
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from reading your question & between the lines(no offense)...let your engine builder order your pistons when he does the balance...take your block to him also...but to answer your question, no it aint that big a deal....in fact, i like loose in the hole...loose is less friction....loose is good to a point...heat expands stuff...if youre juicin it loose is real good...a good engine builder can do wonders...youre gonna spend the money anyway, spend it with him