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Author Topic:   Oilin' Catastrophe
DirtDobber
Dirt Maniac

Total posts: 118
posted November 08, 2005 06:37 PM  
Okay I am frustrated....
Three engine now and three failures!?

The #7 and 8 rods and spining the bearings and I am loosing oil pressure. Why??

Engine 1 detonated-- #6 rod pulled in two but the rod blued and the bearing was as thin as paper wrapped a couple of time around the crank. Poor crank it was soo young. This motor was all stock execpt for "large bore."

Engine 2 was all stock period. Spun rod NO high rpms. Had not even been raced and oil pressure gone.

Engine 3 was a well built heart - I thought. KB pistons, Eagle rods, high end bearings because I thought my failure were related to bearings and steel forged crank. Oh yea I installed oil restictors on this one.

Although I bought new oil pumps for all of these applications I always used the melling 55HV.

I have built more than dozen engine with no failures (knocking on wood here!!!) So what's up??

This is the first time I have used oil restrictors though. And after looking though my Motor Manual I am not sure I like them. After all the Chevy rod bearings are oiled after the main bearings and the main bearings are oiled after the cam bearings and the right foot mashed the throttle and the rear tires go uh!

I searched for more info on oil pump selection but....?

help????

Jason



dirttrackin94
Dirt Forum Racer

Total posts: 100
posted November 08, 2005 09:02 PM  
THERE ARE ONLY SO MANY POSSIBILITIES IT COULD BE,AND SOUNDS LIKE THEY ARE ALL FROM THE SAME THING.WITHOUT SEEING IT AND TAKING A GUESS I WOULD SAY ONE THERE WAS NOT ENOUGH CLEARENCE,TWO THERE WAS AN OUT OF ROUND CRANK OR ROD,AND THREE THE ENGINE WAS PUT TOGETHER DIRTY..

I USE A MELLINGS M55HV OIL PUMP AND OIL RESTRICTORS AS WELL AS VENT TUBES IN ALL MY MOTORS AND HAVE HAD ZERO FAILURES SO FAR.ALL MY MOTORS CARRY 90 PSI OIL WHEN COLD AND 50-60 PSI UNDER RACE CONDITIONS,AND ABOUT 7300 RPM,HAVE SEEN AS MUCH AS 8500 AT TIMES..

Eljojo
Dirt Forum Champ
Total posts: 985
posted November 09, 2005 04:23 AM  
I'd just make a bet that you used the same pan and pick up on all three mills. Did you ever check the clearance between them? I had a motor get a dent in the pan and restrict the flow at higher rpms.

modracer02
Dirt Roller

Total posts: 5
posted November 09, 2005 09:56 AM  
I would say the rod side clearence is to tight.

DirtDobber
Dirt Maniac

Total posts: 118
posted November 09, 2005 06:53 PM  
I have a clean area I do my assemblys. It is a really nice area.

Put together too tight - - maybe. I am installing the bearing on the loose side of tolerances I think. .002 mains - .0015 rods sides are .010 Should I allow more???

No on the oil pan. three different ones. and I was shown a way to put a 5/8 half inch drive inpact socket on the pick up, then tap the tube to snugg it in place. Next put the pan on slowly and it will push the pick up in place. Finish installation. Maybe to close?? I'll check..

I found a questionable spot on the camshaft of one I am working on tonight. The rear cam bearing was installed with the hole up. The rest were installed hole down (toward the crank.)


Thanks!!!

Leaf
Dirt Full Roller

Total posts: 62
posted November 09, 2005 07:42 PM  
pick up should be off the pan not pushed up and tight to the pan...

put the pick up on and use a simple tape measure from the block rails and check the height.

you want 1\4 inch of clearance

Cam brg hole just needs to be in the groove not covered. I like them on a side myself and all the same but it shouldnt matter.

Side clearance of rods should be a mpre, I prefer .020+.

hamer36
Dirt Maniac

Total posts: 197
posted November 09, 2005 07:42 PM  
mains .025
rods .022
side .018-.020

dirttrackin94
Dirt Forum Racer

Total posts: 100
posted November 09, 2005 09:27 PM  
sounds like a combination of the pickup being too close and the rod and main clearences being too tight.i clearance mine at..

mains .030
rods .025
side .016-.020

like i said before i have never had a problem.i turn it alot of rpm and always have exellent oil psi..like said before the pickup needs to be atleast a 1/4'' from bottom or it wont pickup right.

oldfordmod
Dirt Full Roller

Total posts: 53
posted November 10, 2005 08:36 AM  
A simple way to check the oil pump to pickup clearence is using kids modeling clay and sitting the pan on the engine with the gasket in place. It gives me a betterr feeling than measuring. Also, if you're using a stock size pan, that Milings HV pump could be pumping the pan dry.

leapinlizard
Dirt Freak

Total posts: 413
posted November 10, 2005 12:21 PM  
Can you post a picture of all the bearings?

nothing wrong with .0015

James Ott
Dirt Maniac

Total posts: 151
posted November 10, 2005 03:52 PM  
Hey!!!
mains .030
rods .025
side .016-.020
Don't sound right!
How about Mains .003 Rods .0025 Side .016-.020

FATBOY90
Dirt Full Roller

Total posts: 55
posted November 10, 2005 04:33 PM  
rods .022, main .008. are you stroking the motor?

------------------
FATASS RACING

Blackgold
Dirt Full Roller

Total posts: 71
posted November 10, 2005 05:27 PM  
I'll bet your're not getting oil to the bearings. The first 2 circle track engines that I built spun the 7 & 8 bearings. The 3rd engine I built, I put in oil restrictors and used a right side kick out and baffled oil pan. Haven't had a bearing problem since. Also used the HV55 pump. The post that said that your pick-up is too close to the bottom of pan probably is right on.

Panky AMCA 21
Dirt Roller

Total posts: 11
posted November 10, 2005 07:28 PM  
Heres one out of left feild.
Check your crank tunell.
We had a 3 engines go to lunch in 4 meetings suffering similar symptoms. After taking it to 2 differant machine shops the problem was located & found to that the crank tunell was line bored wrong,on an angle and was starving the rear bearing for oil. My new machine shop straightened up the tunell, we reassembled and did 38 race meetings before blowing head gasket.
Just a thought from experiance.

DirtDobber
Dirt Maniac

Total posts: 118
posted November 10, 2005 07:38 PM  
Can't seem to get the pic posted.

[This message has been edited by DirtDobber (edited November 10, 2005).]

dirttrackin94
Dirt Forum Racer

Total posts: 100
posted November 10, 2005 09:20 PM  
lmao,sorry james ott,i wasnt paying attention,you know what i meant..lol~

Kromulous
Dirt Forum Champ
Total posts: 822
posted November 11, 2005 06:38 AM  
Bearing clearances are way to tight for a dirt track engine. That and your oil pump needs to be up off the pan at least 1/4" minimum.

The guys above cover it already.


Krom.

mike9
Dirt Forum Racer

Total posts: 78
posted November 11, 2005 07:11 AM  
i think the problem is using the pan to push the pickup down once its down ir would be right up against the pan and you wouldnt get the oil flow you need i run mine with 3/8 - 1/2 inch pickup to pan clearance

street31
Dirt Roller

Total posts: 13
posted November 13, 2005 07:29 PM  
easy way to measure pan pickup height
1. measure from the pan rail to the bottom of the pan (stock pan 7.25)
now lay a straight edge on the pickup tube installed and measure from pickup tube to pan rail and adjust pickup tube to 7 inches and then when you install gasket you will be 3/8 off the bottom.
correct me if i read right .0015 clearance on bearings? 1 and a half thousanths bearing clearance will not work in a race motor unless you are using a stock volumn pump as you will over heat the oil trying to squeeze it through that little of a clearance.
002-0025 on rods
002-003 on mains
018-020 side clearance

DirtDobber
Dirt Maniac

Total posts: 118
posted November 14, 2005 07:04 PM  
Geesh! Well Okay I will "Loosen er up!!"

Thanks all looks good to me.

Okay what about looser? Does any one go much looser than this?? What would be too loose here??

By the way I think I understand now. I had not enough clearance and was maybe running too thick oil.

Jason

DirtDobber
Dirt Maniac

Total posts: 118
posted December 03, 2005 05:51 AM  
.003 on the mains
.0025 on the rods
.020 side clearance

I am guessing that is .020 total - which would mean stock is .004 - So .020 minus the .004 would be .016 and that leaves .004 per side of each rod to be removed.

OR is more taken off of one side
OR is all of it taken off of one side.

Ya see I am going to have to find a new machinist because the one I have been using this year did not tell me about this and does not seem to care. After looking at some of the work my machinist in Texas did, he just clearanced them and I never knew. But I can't tell exacty where they were clearanced, I can just measure the difference....

Just trying to get this one right ya know

{----------and thanks for the help!!--------}

[This message has been edited by DirtDobber (edited December 03, 2005).]

[This message has been edited by DirtDobber (edited December 03, 2005).]

Eljojo
Dirt Forum Champ
Total posts: 985
posted December 03, 2005 08:53 AM  
Dirtdobber, I know how you feel about a machinst that doesn't seem to care. I remodeled my machinists house here in TN and threw in a **** -load of extras for a trade on some machine work. Boy did I find out what that cat wa made of! The Eagle "H" beams had a cat on them, the SRP pistons came with some cast iron rings. and the crank (oh lemme tell ya about the crank!) there was a balance problem there... race on Saturday night, pull the motor on Sunday, replace the main bearings, spend Sunday afternoon, three or four nights in the shop wrenching, and finish it on Saturday. Race it on Saturday night (repeat) I asked him about re balanceing and he said (you know what) happens!
Good luck finding a reliable/reputable machinist!
Be sure to set that oil pick up about 3/8ths off the floor of the pan.

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