SC apex ring gap? timing and fuel?

[polarcat71]

have a SC apex rebuilding it (as it never really ran, long story) sled only has like 500miles on it
18 lbs of boost, stock head gasket, installing low comp Carrillo pistons (bought from Hurricane), 1700' elevation (if that make a diff)
what is the correct piston end gaps (both top and lower comp rings)
also bought the valve timing jig from Hurricane to set the timing (not sure how to use it yet, any pointers would be great)

also when running what oct fuel should I use (its for lake racing and light trail riding.

 

[Macheater]

Did you ask Dave for specs?

 

[polarcat71]

Did you ask Dave for specs?

I emailed him a couple times, i know its his busy season and dont want to bother him too much. just fig someone on here has the answers as well.

 

[Macheater]

If your making 18psi you must be running at least a stage 2 blower. There's only a small handful of guys on here that have done that.
Message either sideshowbob or stone.

 

[polarcat71]

If your making 18psi you must be running at least a stage 2 blower. There's only a small handful of guys on here that have done that.
Message either sideshowbob or stone.

yes its is a 2b actually so there is supposedly even more with diff pulleys

 

[kinger]

What low CR ratio is it? 9:1 or 9.5:1? You are at least at 104 octane at 18psi even decompressed. I think the ring gaps are stock unless some clever engine builders have some tricks they don't want to reveal.

 

[polarcat71]

What low CR ratio is it? 9:1 or 9.5:1? You are at least at 104 octane at 18psi even decompressed. I think the ring gaps are stock unless some clever engine builders have some tricks they don't want to reveal.

pistons are 10:1 with stock head gasket
as for the ring gaps I just want to be sure. even if its within stock gaps specs should it be set in low, middle or upper spec. Book calls for top ring .010-.020 and 2nd ring .017-.023 so its a wide margin.

 

[kinger]

at 10:1 and 18 psi I did the math with the boost calc in the sticky and you will be at 100.3 octane needed.

I have no earthly business recommending ring gap, but I know under boosted conditions in all engines the rings get tighter with heat and compression. So I would love to hear from a apex specific builder, but if I had to pick I would error more to the larger side of the spec. Like .018 and 0.21 respectively. Should be a beast when done! Figures out to 320hp.