Compression ?

[Craig B]

When my motor had stock jugs with 64mm bore and 19cc dome it had 180 psi @ [sea level] . Now I have Driveline Cyls. with 19cc domes I'm @ 170 psi. What gives? Is it the bigger bore or the different porting  [as cast] in the jugs??? Just wanting to make sure it's ok. Thanks.

[rubberneck]

port timing most likely.  Even though kicking compression is reading lower my guess is your compression ratio is higher

[trickedcarbine]

^100%

[dirtydownunder]

what size bore are driveline cylinders ?

 

if its a brand spankin new build with very little run time. its gonna read a bit low till it breaks in.

[Craig B]

what size bore are driveline cylinders ?

 

if its a brand spankin new build with very little run time. its gonna read a bit low till it breaks in.

Driveline bore is 68mm. Has about 1hr. of run time on it.

[Craig B]

Thanks for the reply's. Kicking it over seems like it is a little harder than it before @ 64 mm 180 psi.

[gusto]

How do you like the cylinders and tell me about the power increase? 421 or stock stroke?

[Craig B]

So far I like them. I may have a problem with 1 head stud pulling out. Went to torque it to 20 ft. lbs. and it started to spin. Hope this isn't going to happen to all of them. May have to Timesert it.  It seams like it picked up good power. Stock stroke as of right now, but by the end of the month I am going to have someone go through the whole motor. My plans are +4 mil , some porting , trans mods and maybe a set of different pipes.