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Author Topic:   Bone Stock sbc oil pressure dipping coming out of corners
Koolaid
Dirt Forum Racer

Total posts: 82
posted September 21, 2005 05:10 AM  
I'm running a 80-86 350 stock crate engine in an enduro car and have been fine up until the last two races. It has a stock pan running 20-50 oil. The problem is that the engine will hold a little over 40lbs all down the straight peaking at around 5000rpms (not turning it too hard). When I come out of 2 or 4 and open it up the pressure will drop right down to 20psi and then climb up to 40 before I get to mid track. This last race I tried a different brand oil filter and also slightly overfilled it thinking if everything was pumped to the top end then I'd have a little extra. I'm running a stock pan and the bypass has not been plugged. I've been lifting coming out of the corner and then getting on it to keep the pressure up. The gauge is hooked up at the back of the intake manifold on the top side of the block - would my readings be different at some other port? I know I'll get beat up for running a stock pan - I just wanted to get one more race out of this engine before we ditch it for a new engine (different style block that a different style pan goes on). Would 50w oil help this problem or plugging the bypass or still good pressure everywhere else in the engine and just not quite all the way up to the gauge? The engine is by no means new, but doesn't knock or rattle yet. Any ideas or thoughts would be appreciated - my new engine will have a different pan on it - we're just trying to avoid a $100 pan on this $250 engine for one race. Thanks for your time.

Flanndad
Dirt Freak

Total posts: 255
posted September 21, 2005 05:26 AM  
I wouldn't worry about 20 psi, The rule of thumb is 10psi for every 1,000rpm.
You are probally coming out of the turn between 2,000 and 3,000rpms. (which would be 20 to 30psi.

I would continue running the 20-50, add a little extra oil, run a good oil filter (no FRAM). And go for it..

Bearings are probally starting to go, cheap enduro motor, don't worry about it.
Keep cranking on it and see what happens....


dirt_mopar99
Dirt Forum Racer

Total posts: 94
posted September 21, 2005 08:02 PM  
I have always run 1 qt higher on my Chryslers.... just my 2 cents

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Speed Kills, Drive a Chevy and live forever!

mike9
Dirt Full Roller

Total posts: 72
posted September 21, 2005 08:08 PM  
i bet the oil pickup fell off the pump chevys are bad about that if it fell off it will **** some air as you accelerate and the oil goes to the back and right side as the g forces even out the oil cgoes back down in the pan and covers the hole the pickup tube goes in and the pressure comes back up you might check that

Koolaid
Dirt Forum Racer

Total posts: 82
posted September 26, 2005 05:03 AM  
Well I ended up pulling the engine this weekend for non-engine related things (trans) and pulled the pan just for grins. The mains and rod bearings are perfect - not a scratch in them - no sign of wear. Surprised the heck out of me for a junkyard engine I've beat on all season. The oil pump pickup tube didn't fall off - still firmly pressed in place. I think I'm just going to throw in a new oil pump and pickup, block the bypass in the filter adapter, and run it one last time this year. Is a Melling M-55 pickup and 55-S1 pickup what I want for a stock setup? I think higher pressure or higher volume would just make my problems worse? Thanks for your help.

Koolaid
Dirt Forum Racer

Total posts: 82
posted September 26, 2005 05:29 AM  
While I'm asking sbc questions:

When you replace the oil pump is it good practice to replace the shaft also? I know in Fords it was always cheap insurance, but wasn't sure on SBC's. I see a IS-55E with a steel shaft guide or an IS-55G & M-55005 that is a nylon guide and shaft for nylon guide - which is best?

sideways
Dirt Forum Champ
Total posts: 715
posted September 26, 2005 08:24 AM  
Run a stock volume and stock pressure pump.Cheap insurance to run the all steel pump rod.I have run both just feel better with the steel sleaved rod.Run a bolt on pick up also for racing they make a stock pan version for them. jmho

[This message has been edited by sideways (edited September 26, 2005).]

racer55
Dirt Newbie

Total posts: 3
posted October 16, 2005 12:03 AM  
you could also try using an oil accumulator but it may be out of your price range for that class.they do work though.

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