Main Bearing Clearances Too

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I don't see any reason for these to more than .0025", although I do know guys who like .003" on strip only cars.
 
I tried an engine with .004- .0045 once. It had 5 psi pressure when it was normal running temp at idle! I told the machinist this was to much clearance before I installed it, he said it would be alright, well I dropped the truck off to him because he said "It must be a bad oil pump". He put a pump in it, then I showed up a little to early and caught him putting straight 50W oil in it, I told go ahead, it won't make a difference. Cranked it up 60 psi cold. 5 psi hot. Then He wouldn't stand behind it, told me to bad! Luckily it was my truck and not a customers. From then on when I would crank it up, it had that death rattle until it had oil pressure. Not telling you what to do but I wouldn't run accept it..
 
With what you posted for pressure, I am seriously thinking there is an issue. Is this a HV pump? What pan? NO way should the mains be that large IMO. I shoot for .0025, with .003 as max on the mains. I've run as tight as .001 with no issue on mains but over .0035 is too large IMO. You should be hemoraging oil out there and it should show on the gage. Again, what do the bearings look like? Can you post some pics? Especially #4 main and the rods it feeds.
 
ill try to get some pics for you.I have a high volume pump and milidon 8 qt pan with their pick up tube ect.i had a windage tray but discussed it with Ryan at SD and he said leave it out.I did.And the pressure never drops below 35-40 at idle.Of course idle is 1200
 
Funny thing about oil pressure tho is it's resistance to flow you're measuring. So if you have stock passages but a big volume pump pushing, you can have great pressure shown on the gage which is tapped off the passage that feends the mains. But the rods are fed thru the mains. So you can be bleeding off oil thru big clearances there and it doesnt get to the rods. It's mostly at high rpm and the rod bearings will show some wear and heat marking/discoloration. If you have the hard bearings with a coating, you may not see heat marking but you might see wear especially on the centers of the shells. Are the mains full groove? Were the main passages enlarged?
 
No full grove mains and the passages havent been enlarged.Well i guess i'll order some +1 bearings.Any recommendations on bearings?The ones in there now are part# MS540HX for the mains and # CB481HXN on the rods..0040-.0043 on mains and .0039-.0042 on the rods.Thanks guys.I believe their Clevites
 
Instead of replacing all, I would just go to full grooved mains, .001" oversize. I think that would take care of what I consider the biggest issue, which is too much main clearance and not fully grooved. I typically wont use fully grooved but I think your rpm and rod clearances will do better with full time oiling. I apologize I was trying to get the most recent Mahle catalog (Clevite) and something's up with my Adobe and I gotta run. Stay with the H series, but find the .001"OS with full grooves.
 
Thanks Moper.I'll get on that.Think i'll have to remike everything,or should i be ok with the .001 oversize knowing that i miked everything a month ago,and that putting these in will bring it into specs?Thanks again.Have to get this thing ready for the Pinks All Out in September so we can keep getting some Mopars in there.
 
megacab said:
Thanks Moper.I'll get on that.Think i'll have to remike everything,or should i be ok with the .001 oversize knowing that i miked everything a month ago,and that putting these in will bring it into specs?Thanks again.Have to get this thing ready for the Pinks All Out in September so we can keep getting some Mopars in there.
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I would remic them to make sure the new bearings are right.
 
megacab said:
ill try to get some pics for you.I have a high volume pump and milidon 8 qt pan with their pick up tube ect.i had a windage tray but discussed it with Ryan at SD and he said leave it out.I did.And the pressure never drops below 35-40 at idle.Of course idle is 1200
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I'm curious why they said to leave the windage tray out? I have a custom pan that holds 8 quarts and it uses a windage tray on my 415 stroker. I believe in the small block stroker book he mentions not using a windage tray. Thanks for the info. Jayson
 
I believe they said the way the small block skirt is on the bottom there wasnt a need.He said leaving out the windage tray has made more power everytime in everyone they have tested.Being they build tons of radical smallblock Moars making awesome power i took their word.But i had it in previously about a year ago.Even the local guy who has me running these crazy clearances builds some really strong running motors,placing consistantly in the top of the drag series around here.He swears by the clearances,but their Chevys.He's not real familar with Mopars abd im sure their all different
 
Some guys like the tray, some don't If it's a race car, I think a high dollar tray awith a scraper and a baffled pan is the only way to fly. The cheaper trays can catch oil around the crank. The factory one should have the slots enlarged (bent open further) to help that. With a deep pan, you are not so worried about whipping the oil as you are to get it out away from the crank as soon as possible. The bigger oil delivery systems will dump more oil on the crank, and running no tray probably helps get it off it faser rather than trapping it there.

Mega... EVRY TIME a bearing is change the journals should be mic'd. There's nothing saying you didnt got a 4:30Friday bearing or something that was mis-boxed. Check it all. Every time. Period. I think if you measured and got the same .004+ clearance than the .001" OS bearing will bring you in nicely where you want to be. Use an inside mic and check the main bore too. You should see something like .004" when figured top to bottom, but more at the parting lines with it properly torqued. Also check the crank journal for taper.
 
I also realised that my pump was just a standard Melling with a high pressure MP spring kit i installed a while back.So im going to grab a high volume
 
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