Classic Alfa Forums

I have a 310.16 Arna 1.5 engine in need of a rebore. What is best to do? I was told 1.7 8v pistons 87mm bore could be used =a 1.6 engine. Or should I go for a slight oversize.
Cheers Bikerboab

Source your pistons first, - oversize pistons can be hard to find, then bore to what you have.
John.

That's the plan John. Thankyou

1.5 and 1.7 blocks are not the same castings, both have 5.5-6mm thick cylinder walls and if you bore a 1.5 block to 87mm only 4mm is left. This could be ok for a road car but I read about a racer that had cracked walls after one season.

I've heard similar stories to that Bert, but, also had some very encouraging word on the same work from the horses mouth so to speak.

Tom, BLS, built many engines this way before usable 1.7 blocks were common place, for both road and pretty high spec race use, and never had any unexpected failures due to thin walls or over stressed castings.

He did agree that there were a small number of stories of failures around back in the day, but could not pin point the reasoning having had no similar experience himself.

I'm currently involved in a race car build that will be utilising the very same engine build, and i am not expecting any problems from it, mainly because it was originally a BLS prepared block!