4.0 overbore

[swynx]

picking up a spare ohv 4.0 for the truck on the cheap, im not sure how many miles or what condition. basicly its whatever comes into the family junkyard. ill pull it and hand the father in law 100$.

i have 2 sets of heads for a ohv 4.0, ill probably have a set port n polished. i planned on doing probably a simple 410 cam.

i was on rockauto and they offer a .20 overbore pistons and piston rings... i assume this would be smart as for better sealing. although ive never done anything, dealing with pistons or rings. but i know they deal with compression and oil control. ive read a lot of "rednecks" add this in there build thread like there adding power. but really its essential to a engine rebuild.

^^assuming i would need to take the block to the napa machine shop and have it bored .20 over?

also assuming im on the right track for a fresh engine?

also ive seen the 4.3 stroker kit, and not really digging the price on that, but if theres anything else i should/could do for some power or reliablity thats say around 500$, im totally willing to wait a payday to throw it in.

 

[Angie]

hi, i have done a 410 build before and didn't bore the block. the 4.0's i own and work on are ohv's and they are torque monsters on their own accord. if your truck doesn't burn any oil as it stands now, why go through the hassle of tearing out the bottom end? not broke don't fix it... unless you are planning on a full rebuild? all bearings, gaskets, rings, ... even then you are adding extra costs with boring the block and now adding over sized pistons. for what you are asking about there are no half ways, it will be all or nothing.

if your goal is just some easy fast more power, then just do the top end for now with heads, & cam. you don't know the history of the motor, however I would venture to guess the bottom end is in fairly good condition. these are strong motors as long as taken proper treatments.

my $0.02 of advice, please keep this updated as your progress along.

cheers,

 

[jeremysdad]

Iirc, the 4.0's are about bored as much as the block will take stock. I think they can safely take a .010 bore?

Read it somewhere here from someone that knows more than me about it. lol