4mm motor squish?

[Valin]

I am about to throw my longrod 4mm motor together in the near future, and am wondering about what squish height should be run for a pump fuel setup. I'll be running a ProDesign coolhead with 21cc domes. I've looked a bit on this site, and it looks like alot of people are in the 35 thou range, which seems excessively tight for a pump fuel application. This is my first Banshee build. I have never built a motor this tiny, and on my other motors i'm in the 60 thou range.......

[spurdy]

I am about to throw my longrod 4mm motor together in the near future, and am wondering about what squish height should be run for a pump fuel setup. I'll be running a ProDesign coolhead with 21cc domes. I've looked a bit on this site, and it looks like alot of people are in the 35 thou range, which seems excessively tight for a pump fuel application. This is my first Banshee build. I have never built a motor this tiny, and on my other motors i'm in the 60 thou range.......

 

I am running 105 octane fuel and have mine set at 0.042". I know some guys run them pretty tight but I think most everyone is between 0.040" and 0.050".

 

SP

[rubberneck]

I just put together a 350 and the squish came out at .053. Jeff told me to run it as is and add a degree of timing. Runs good. Also, you didn't state elevation, but with 21 cc domes, im not sure you will be able to run pump gas on a 4mil motor. Check it before you run it for sure to make sure.

[sleeper06]

My stock cyl 4mil is .050,421 cub is .048,both on race gas though.I just put a stock stroke ported motor together with 21cc domes,Pump gas motor 145psi static comp .052 squish.I woulnt build a motor around squish,thats a non issue easily cured