spun bearings

[oldgold]

383 scat crank 5.7 stock floated rods speedpro flattop pistons 64cc head
rods 2.5 mains 2.0 clearances ran on engine stand 2 hours 2,000 rpm 65 psi oil pressure 150degrees water temp. installed in car ran again for 1 hr. took to track in warm up laps ran about 8 laps before oil pressure lite came on. tore down 2 spun bearings all new stuff why? sucking air in corners, oil pump trash only spun 2 bearings 3-4 if it was starved wouldnt bearings farthest away from pump be first to spin? block was line bored, crank was crack checked checked for straightness polished .

[Hendrens Racing Engines]

If I am reading this correctly you have .0025 rod clearance and .002 mains. thats .001 to tight on the mains. what is the rod side clearance?Bill

[dirty white boy]

3 an 4 or 5 an 6 was always the ones i had spin....i try not to do that no more,..cost to much...

[CNC BLOCKS]

383 scat crank 5.7 stock floated rods speedpro flattop pistons 64cc head
rods 2.5 mains 2.0 clearances ran on engine stand 2 hours 2,000 rpm 65 psi oil pressure 150degrees water temp. installed in car ran again for 1 hr. took to track in warm up laps ran about 8 laps before oil pressure lite came on. tore down 2 spun bearings all new stuff why? sucking air in corners, oil pump trash only spun 2 bearings 3-4 if it was starved wouldnt bearings farthest away from pump be first to spin? block was line bored, crank was crack checked checked for straightness polished .


What material was the crank and what bearings did you use. Was your oil filter bypass plugged??

Sounds like an oil issue because 3 and 4 rods are fed by different mains.

I have seen engines with tighter clearances on the rods and mains live and not have any problems!!

[SLM98]

What oil filter did you have on and what weight oil?

[fast_crew]

What did the main brgs look like? The rods are oiled from the mains... Does the oil pump spin freely?

[runyou-2]

oH boy...here we gooooooooooooooooooooo.....

[oldgold]

15 thousands on rod side clearance mr Hendren.
this is all cheap stuff ,scat crank, stock 5.7 rods floated, speedpro flattop hyperu cracktic pistons. oil filter bypass open oil plug under main cap wix/carquest filter. mains should be near .003? they were .002 mellings M55 hv stock pan (must run)

[CNC BLOCKS]

If you used a stock pick up and your cirle track racing that is most likely your problem as the pick is so big it does not take much to expose it to some air.

[Hendrens Racing Engines]

15 thousands on rod side clearance mr Hendren.
this is all cheap stuff ,scat crank, stock 5.7 rods floated, speedpro flattop hyperu cracktic pistons. oil filter bypass open oil plug under main cap wix/carquest filter. mains should be near .003? they were .002 mellings M55 hv stock pan (must run)

Normally you wont have a problem with to much clearance causing bearing problems but you sure will if there to tight. I assume because this was a low dollar build the block was not align honed,if not I would torque the caps on the block with no bearings and measure the main bores to make sure there on size and the correct cap is where it should be. I have seen many times where the caps were mixed up or numbered wrong. Bill

[hpontap]

A stock pan and an M55HV is more than likely what happened. You sucked the pan dry and starved the engine when you got on the track. Stock blueprinted O/P or an M55A would have been a better choice with a stock pan.

[oldgold]

this block was align honed , fresh bore job ,crank was crack checked ,checked for straightness, polished. rods were bought resized, and made floaters, pistons were new. i am concerned about grinding the crank ,resizing the rods and putting it back together and the same thing happening.wouldnt if the mains were out cause a main bearing problem or would a main bearing kinda live ok but show up on a rod .

[oldgold]

we use a stock pickup on our other engines and never have a oil pressure problem with stock pan and pickup. 3/8th off the bottom 20w 50 havoline oil wix filter.80psi cold 60psi at 6200 warm.2.5 on rods,2.5 on mains.bearings in our other motors look like new after our 20 shows. i am baffled at this point.

[oldgold]

you are thinking the hv pump is putting to much oil to the top
how do you get a good oil pressure with a stock pump ,i dont feel real good about 35-40 psi @5500 you end up with about 5-10psi on cautions.

[powerslide]

i wouldnt reuse the crank. bill told me awhile back if its cracked around the radi that you can fix it but just a matter of time before it breaks in two.(had a buddy fix his that spun and it busted in half after 8-10 races) probably get 2 new rods as well stock rods arent that high.

[hpontap]

Exactly, the HV pump is putting out a lot of oil and when you enter the turns, what little is left in the pan either runs to the front or climbs up the right side away from the pickup.
If you blueprint a stock GM pump or an M55A , if the bottem end is right, you will have plenty of oil pressure without sucking the stock pan dry.

[1Blacksheep]

Large Oil pressure fluxuation has alot to do with sloppy tolerance's and heavier wt oils. Its a ballance also that most professionals have found. HV means nothing if it doesn't have its match tolerance and capacity and usually ends up keeping the bypass well lubed.

[dirty white boy]

if 20/50 weight oil was cool,..with hv pump,an high rpms an 80 p.s.i. coulda just washed the barrings outta it....

[oldgold]

motor was run 1 hr before we arrived at track never went above 5500 170 coolant, 55-65 on track for 8 laps and it startrd to drop at 20 in the turns light came on and brought it in.

[anthonycacace]

motor was run 1 hr before we arrived at track never went above 5500 170 coolant, 55-65 on track for 8 laps and it started to drop at 20 in the turns light came on and brought it in.

Had something similar happen to an enduro motor once and it turned out to be a sticking piston pin. Although, I didn't have new rods or pistons, it was a new crank and bearings. I thought if you have to tare it apart anyway, may be worth a check.

[Hendrens Racing Engines]

motor was run 1 hr before we arrived at track never went above 5500 170 coolant, 55-65 on track for 8 laps and it startrd to drop at 20 in the turns light came on and brought it in.

Wet mag crank, grind if not cracked to low side of tolerance, check big end on rods, resize if necessary, grind out oil return holes in the back of block as large as you can get them. usually 70% larger than stock. ck oil return holes on heads for head gasket or block obstruction where they meet the block, grind out if necessary. install BRASS stand pipes in the center holes of the block one inch long, this will allow any crank case pressure a place to escape without fighting oil thats returning down the ground out end ones. assemble with .0025 rod and .003 main clearances,use 10/30 oil with your H.V. pump. go race it. Bill