Hi all im just after a little bit of input as to whats a good clearance to run in my 4g64 main and rod bearings??

Bearing i am using are ACL bearings with 4g64 cranks and oliver extreme rods??

Thanks

Craig

 

what kind of rpm's are you planning on running?

 

No more than 8500rpm I would say

 

oil choice is more important imo.
I used 0.06mm (2.4thou ish) on my mains with 15W-50 Motul 300V

 

Thanks for the reply, 2.4 though sounds like a good enough oil clearance for a high reving engine as i was recommended to run my clearance than the standard spec

I have got all ACL race bearings that are the HX series so have a tiny bit extra clearance over standard bearings.

 

.002" should be plenty wide for the rods.

 

It depends on what you want to do with the motor. I've ran the x series acl bearings before and they worked ok, my oil pressure was lower than I would have expected so I had to step up to a 50 weight oil to keep them happy in my 2.3 build FYI.

 

I have seen a few people now using .002" for there clearance....but then earlier i was looking through another UK build of a 2.4 4g64 and he used .0025"

Car is going to be my daily drive but hopefully ill do some track time in it should all goto plan.

The crank is at the machine shop now being balanced and all the journals and oilways micro polished so when its back i can plastigauge everything to see what clearances i have and go from there......if they are to big i can just change the bearings to the non HX then check the clearances again.

The 4g64 crank is brand new and had II II II II stamped on it which i presume the size of the bearings that would of been fitted by

 

i dont know why people go so big, to me even .002" seems pretty loose.

 

The mitsi spec for the main bearings is between 0.03mm and 0.05mm and when you convert 0.05mm to thou it's just over .002"

 

Well the engine is now back together and i ended up with 2.5 though on the mains and 2 thou on the rod bearings

The company i use for all my machining work have said i will be fine with them clearances

 

what viscosity oil are you going to be running though?

 

Should work fine, just run a quality 20w50 or similar

 

Well either a 10w-50 or 15w-50

Will give them a try first an see what pressures I'm getting then if need be toto a thicker oil