All Small Six 250 piston ring combo's for street

This relates to all small sixes
Robandhooch

Robandhooch

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Currently looking at pistons/rings for my 250 rebuild. Boring .020 as a light hone won't cut it on this job. Current candidates look like the 275NP, or the australian 3327H.

I really like the idea of the 3327, as it gives a slight increase in CR with the added 30 thou height, and the metric ring pack would shave some weigh on rings and less friction.

Thoughts, and even better would be wtf to get the ring pack in a 20 thou oversize?
 
Have you looked at the pistons for the early 80s 255 V8? They have a CH of 1.585 in., and will help increase the CR in the 250. Summit has 3.70 in. Silv-O-Lite cast pistons on their site for $207.99.
 
Last edited:
rocklord said:
Have you looked at the pistons for the early 80s 255 V8? They have a CH of 1.585 in., and will help increase the CR in the 250. Summit has 3.70 in. Silv-O-Lite cast pistons on their site for $207.99.
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Yeah I originally wanted to look into those, and looking at rockauto they're 400ish a set. I also for whatever reason can't seem to find the info on what that would leave me with between piston and deck. I know it's been a covered topic in here but i'm pretty awful at finding that info in here. Luckily the block is unmolested so it's factory still at this point till we do the bore.
 
The 250 with an OEM piston (CH 1.511") has a 0.123" piston recess. The 255 piston gives a 0.049" recess.
With a 62cc combustion chamber head, you would have around a 9.5CR
 
Not sure how, but I seem to have a taller block height than what is published here. The 255 is definitely the way to go, parts on order.
 
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