What main bearings for a high performance engine?
- Thread starter maca
- Start date
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Duane
Well-Known Member
Tell us about the build an maybe we can help with oil pressure.
Some of the guitar Jones mods like tubing the block and restricting the flow to the cam bearings and rockers help boost the oil pressure. Need to know more about the build.
Hey mate over the last couple of years I've posted on several forums including this one chased this low oil pressure problem. I think I've given up and just accepted it as the bearings don't show terrible wear when I strip the motor down. I've checked bearing clearances, used high-volume oil pumps and standard ones, checked the oil gallery plugs etc. I just can't seem to find a reason why the oil pressure is so low. I've taken it into professional engine build shops and they still can't find the problem either. I've spent so much money chasing it that I've just about given up on it. Once I rebuild this engine I was thinking of using my oil priming tool to get oil pressure with the valley and heads off. Maybe I will be able to see something then. I'm going to try a third oil pressure gauge just in case I got unlucky with the first two.
Duane
Well-Known Member
Unless you have some kind of casting flaw in your block, there is no rocket science to your oil pressure issue.
You asked earlier what block mods you should do which tells me you are not familiar with some common sbm oiling mods that would help your oil pressure.
That's why I asked for more info on the motor. Not just bearing clearances, but roller cam or not roller, tubed or bushed lifter bores etc. There should not really be a mystery to the pressure problem imho.
Thanks for your reply mate
My other magnum engine and a friend with a magnum engine have average or pressure of around 60 PSI at full throttle and 40 at idle so there does seem to be an issue with this engine.
It's a complete standard magnum bottom end. With standard crank bearings and rods. I used to run the standard roller lifters and still had oil pressure problems but now I run solid lifters and cam. I contacted a Mopar performance engine building shop and they said they could do some oil modifications for me that would improve oil into the bearings but probably would not improve oil pressure.
Duane
Well-Known Member
60 psi and 40 at idle is not that bad. That's a very good idle pressure imho.
Yes that's my friends and my other magnum engine. The one were discussing has next to no oil pressure.
Duane
Well-Known Member
Like I said, need info.
Sorry I listed the details above. What other details will affect oil pressure. Happy to list anything else.
It's a complete standard magnum bottom end. With standard crank bearings and rods. I used to run the standard roller lifters and still had oil pressure problems but now I run solid lifters and cam.
Duane
Well-Known Member
Lifter bore wear/ excessive leakage.
If this is the motor that makes 800 horse you should tube or bush the lifter bores, and restrict cam bearing oiling. Are any oil galley plugs missing? Low oil pressure means excessive oil leakage somewhere. Was this engine rebuilt?
Yes this is the engine that makes that horsepower. I did rebuild it in the past but still left it at standard bore as there was not much wear through the engine. I am taking the cylinders out 20 thou now. It didn't have excessive lifter bore wear and I had the machine Shop measure them and check them and they were still standard size. All gallery plugs are in place and triple checked. The main bearing clearances where 1 to 1.5 thou with the rear one being at 2 thou. I spent 2 years chasing the oil pressure problem on several forums trying different thingstand eventually gave up in frustration. I am going to speak to a Mopar performance shop this week about boiling modifications and I'll mention the ones you suggested. Thanks
Hey Duane
Thanks for suggesting the oiling mods. I went and saw that performance shop and they ran through different oil mods that will definitely help my engine and oil pressure. I'm going to take the block down to them and get them to do it for me. I feel a bit more confident now that they may fix the problem.
Duane
Well-Known Member
Ok good luck to you.
Heck I ordered .020 main bearings yesterday morning and it looks like they won’t be here till next Wednesday. Some of the .020 bearings were listed at a 4-1-19 ship date.
j par
Well-hung Member
When I was a kid my buddy and I would pack the tow bar kits at this tow bar manufacturing place we work for and we would always add extra nuts and bolts and washers and laughed that they would be confused when they had everything together with extra nuts and bolts left over, but we would never do anything like put two Bolts and no nuts...
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