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Howard Jones · 04-02-04, 04:32 PM

Ya, I guess it is a problem getting something heavy like a motor across the Alantic and still keep the buget inline. This is pretty much our problem with the chassis's. They are expensive to ship to the USA and so I guess this is part of the reason why GT40's are rare item over here.

But I still think that even if it costs a little more, I would take the time and try and find a block that is on its orginal bore to rebuild before I started down the road of trying to go to 40 thou on a 302.
Now, I know it can and has been done, sometimes after a sonic check has reveiled a nice thick cylinder wall, but most of the time the cylinder wall just ends up very thin, or the boring process uncovers a block that is beyond repair after spending good money on what was a used up block.

I can only say what I would do, and that would be to try and find another block before I spent any real money on the 30 over one. At 350Hp this motor is in the margin when it comes to thin cylinder walls @ 40 thou over.
Can it be honed at 30 over and try to find some "big" 30 over pistons that will fit the honed bore corectly. I used to go thru all the pistons at the Yamaha shop with a mic to find the smallest ones when I bored my race bikes so that I could get one more bore out of them in the end.

Anyway, good luck.

04-02-04, 04:32 PM	#10 (permalink)
Howard Jones 10 tenths Join Date: Jun 2002 GT40: San Francisco Bay Area California USA Posts: 1,911 Rep Power: 26	Re: rebore 302 Ya, I guess it is a problem getting something heavy like a motor across the Alantic and still keep the buget inline. This is pretty much our problem with the chassis's. They are expensive to ship to the USA and so I guess this is part of the reason why GT40's are rare item over here. But I still think that even if it costs a little more, I would take the time and try and find a block that is on its orginal bore to rebuild before I started down the road of trying to go to 40 thou on a 302. Now, I know it can and has been done, sometimes after a sonic check has reveiled a nice thick cylinder wall, but most of the time the cylinder wall just ends up very thin, or the boring process uncovers a block that is beyond repair after spending good money on what was a used up block. I can only say what I would do, and that would be to try and find another block before I spent any real money on the 30 over one. At 350Hp this motor is in the margin when it comes to thin cylinder walls @ 40 thou over. Can it be honed at 30 over and try to find some "big" 30 over pistons that will fit the honed bore corectly. I used to go thru all the pistons at the Yamaha shop with a mic to find the smallest ones when I bored my race bikes so that I could get one more bore out of them in the end. Anyway, good luck.