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Post by stingerIII on Dec 16, 2013 22:44:46 GMT -5
Found my first post Scorpion Ultra lite Cuyuna 430 this summer .
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Post by kube1 on Dec 17, 2013 14:21:55 GMT -5
hmmm. . I would have thought that to be a bit out of round. . but according to the specs for the ultralight version, that is actually within spec. just seems kinda lopsided to me I agree, I think I'll just go ahead and bore over with new pistons. Just to be safe. I mean, why go half way right?
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Post by kube1 on Dec 18, 2013 13:30:18 GMT -5
OK, I am going to go ahead and get some cast pistons and rebore the cylinders. The thing is, i really have no idea on clearances. I have read a pile of forum posts, mostly made by scorp11, and I'm a little nervous as to what each side should be bored to. This is not going to be a race sled. I just want reliablity. I understand that the timing and fuel are very important. I am making the mag side a freeflow head. I'm just going to let a engine shop do the boring for me since they have right fixtures and equipment and it doesn't cost that much. In the past I just let the machinist measure the pistons and bore the right size but I'm not sure if that is going to be safe this time. I am going to to buy a set of SPX pistons since they are readily available and I've had good luck with them in the past. Am I worrying about nothing or do you guys have specific clearances that I should tell the shop to bore to?
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Post by kube1 on Dec 18, 2013 15:28:52 GMT -5
Ok, im looking at the cuyuna service manual and it states 0.005 to 0.010. Im thinking 0.005 on the mag side and 0.007 on the PTO side.
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Post by scorp11 on Dec 18, 2013 19:27:03 GMT -5
Ok, im looking at the cuyuna service manual and it states 0.005 to 0.010. Im thinking 0.005 on the mag side and 0.007 on the PTO side. Ok, im looking at the cuyuna service manual and it states 0.005 to 0.010. Im thinking 0.005 on the mag side and 0.007 on the PTO side. That is what I did my last cuyuna at with aftermarket pistons. I figured the PTO side would rattle a little but it did not. I think .006 would be ok too. I also added some ring end gap as well Specs from my last motor. Ran good until the stupid wrist pin clip broke an ear piece off that went through the engine and broke both rings.
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Post by kube1 on Dec 18, 2013 22:20:03 GMT -5
Thanks scorp11. Thats the advice I was looking for. I actually decided to just bore and hone it myself. I started making a fixture to hold the cylinders today but I won't get around to boring them out till the new year as I'll be on holidays.
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Post by speedbuff on Oct 18, 2017 9:00:43 GMT -5
I know its been a long time for this thread but any chance you could post a pic of youre boring jig?
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Post by speedbuff on Nov 12, 2017 15:35:54 GMT -5
when did the rockwells get replaced by cuyuna engines or better when did the tooling move to Crosby?will all pieces internals and such from a Rockwell 6 bolt swap with a cuyuna?
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