Posted By: BigFish69
engine builders whats max clearence on mains - 04/27/13 09:28 PM
What would be max main bearing clearence on rb race motor I have .00375 to .004 on the mains to loose ?
Thanks
Thanks
engine builders whats max clearence on mains
Posted By: dOc …
Re: engine builders whats max clearence on mains - 04/27/13 10:28 PM
I wouldn't like 4 ... but maybe it would be OK using STRAIGHT-50 weight oil .. 
Posted By: W5DART66
Re: engine builders whats max clearence on mains - 04/27/13 10:31 PM
If that's with dial bore gauge and you are sure about the number run it. it will be fine.
Posted By: Performance Only
Re: engine builders whats max clearence on mains - 04/27/13 11:26 PM
Quote:
What would be max main bearing clearence on rb race motor I have .00375 to .004 on the mains to loose ?
Thanks
I'll answer the question with a question. How did you get to that clearance? Either the crank is undersize or the main housings are bigger than spec. Before i'd say run it, i'd want to know which it is and how much power is the engine going to make. If the housing bores are out of spec, fix them. that's your bearing crush. If those are okay and it's just the crank being on the small side i'd say have at it on a serious combo.
Posted By: dvw
Re: engine builders whats max clearence on mains - 04/28/13 12:22 AM
For what its worth my line hone was off so we set it at the tight end of the crank bore housing dimension. Mains ended up at .0025". I wanted more so I switched bearing manufactures(no info in front of me as I'm overseas) and got.0028"-.0029". Even though the rod journals were .001" undersize I still only had .0018" on the rods. Had BME resize the rods and ended up with .004" rod clearance. I didn't like the oil pressure so I switched the rod bearings to .001" under, rods now at .003". That really didn't do much for pressure. I ended up tightening the oil pump relief valve spring. Upped the pressure from 45 to 60 at 7000. I probably should have left the clearnce at .004". It's really about oil flow not pressure.
Doug
Doug
Posted By: RickRoss
Re: engine builders whats max clearence on mains - 04/28/13 01:02 AM
U need a small block
Posted By: Cab_Burge
Re: engine builders whats max clearence on mains - 04/28/13 01:45 AM
Quote:Not in my opinion, as long as there is no other problems. I have bought used fuel crank that where not cracked and used them with those clearances on my own pump gas street motors with no real problems to speak of( 18 lbs oil pressure with hot (190+ F)5W20 Valvoline at 800 RPM idling in gear, 65 lbs at 6500 RPM with the same oil temps three minutes later
What would be max main bearing clearence on rb race motor I have .00375 to .004 on the mains to loose ?
Thanks
