Can an overbored block still use standard pistons/rings?

[RomanV]

Hi there.

If an engine block has been slightly overbored to remove minor scoring to the block, can the standard pistons/rings still be used?

Or will aftermarket ones be required?

This is for a red top 3sge.

Also, there is a block available for use that would only require honing, but it is from a previous generation 3sge. When the head gasket from the red top was overlayed to this block, one of the oil/water passages was slightly offset. Would it be possible, or a better option, to try and modify this block to suit? eg. Boring out the oil/water passage to mate up with the passage in the head. Or would I be better off over boring the red top block.

Cheers.

[Mr Revhead]

hmm bored or honed? how much did they take off?

[ee904age]

Depends what you mean by "slightly" bored. Generally anything more than a hone will reqiure oversized pistons. I would check with the workshop diong the job before going any further.

[ChaosAD]

You will need to get the pistons and bores measured with a micrometer to see if the piston-bore clearances are within specs.
If the bores were scored then chances are the pistons arent in the greatest shape either.
If they arent within spec then you could either hitup mr revhead for some new oversize pistons or Segedins for some tasty wiseco forgies.

Or you could try and find another block or bottem-end

[Celica RA45]

you can also sleeve the bore back to the std block dimensions and use the std pistons ,also as a note you cannot use a gen 3 block if you are going to use the vvti cam control as the gen 4 and 5 have a nother oil passage that feeds the solinoid for the cam control hope this helps

[RomanV]

Cool, thanks for the help.

[anthonym]

you can also sleeve the bore back to the std block dimensions and use the std pistons ,also as a note you cannot use a gen 3 block if you are going to use the vvti cam control as the gen 4 and 5 have a nother oil passage that feeds the solinoid for the cam control hope this helps

I have compared the gen 3 and redtop blocks fairly closely and I can't see any difference in the oil passages, where exactly is this extra oil passage?

Dave, if you decide to overbore the block to remove the score you will need to replace all 4 pistons with oversize pistons, you will need to check with Mr Revhead to see if Toyota manufacture the stock redtop pistons in oversizes. I would not recommend aftermarket forged pistons for a street engine.

[Mr Revhead]

fyi toyota do 0.5mm o/s for most engines, including this one

[ChaosAD]

Whats wrong with forgies in a street engine?

[Celica RA45]

the oil gallery is in between no 1 and no 2 cylinder on the exhaust side right next to a head bolt hole in the block ,so the 2nd head bolt hole on the exhaust side, you can see the the bulge where the oil gallery is coming off the main 1 that goes to the oil cooler assembly ,hope this helps

[Adamal]

Did you post that in the wrong thread?

[RomanV]

Nah he was referring to a comment that Nemesis made.

So...Theoretically speaking
If the VVTI mechanism were to be discarded for a set of fixed cams, this oil gallery would be irrelevant? As in, this is used to sense oil pressure to vary the VVTI?

Or does it still provide oil flow to the head?

Cheers.

[Celica RA45]

no its used to feed no 1 oil cam journal gallerys on inlet cam as the oil that comes from the cam no 5 journal doenst go right through you would have to modify the cam nad stop the oil from coming out of the vvti a bit technical but trd make cams and valve springs and lock ed vernier cam wheels