Bearing clearances for a purpose build motor

Jerryl

Tall Unvaccinated Chinese Guy
Joined
Dec 14, 2004
Looking to be able to shift at an honest 5800-6000 rpm with blue printed HV pump, 99% street, 5w30.
What main and rod clearances do you recommend? :confused:
 
Well my persoanl opinion and one that has so far worked with my customers engines.

I prefer not to use and HV oil pump. A goos stocker will last 100,000 plus so I see no need. I personally beleive it puts excessive stress on the cam and front cam bearing. Of course there are plenty that have so this is personal.

Not sure why you chose a 5-30, pretty llight oil. Again I prefer a 10-30 for my applications. Again I am mostly building street strip and DR cars.

As for clearances. They call for .0015 to .002. I will say I use a 0017 to 0018 for all my performance engines. I will be a little more lenient on a purely street engine.

Hope this helps
 
I like the HV pumps as long as the engine can use it. Oil pressure is useless without flow but if you build an engine that can flow the oil you'll get better cooling of the bearings. Running a standard pump on a looser engine is kinda like trying to run a small turbo on a big engine. It'll only make so much pressure. If it can keep up great. If it can't then step it up. A 0w-30, 5w-30 and a 10w-30 oil are the exact same thickness at operating temp. You just need to decide how thick you want the oil when it's cold.

I worked my front cover over (earls front cover mods) and made sure the clearances in my pump were good. I used an HV pump. I opened up the mains to match the block (I think I only did this to the centers) and I used the TA performance dual groove cam bearings that relocate where the oil gets introduced on the cam journal. If you get those make sure you follow the instructions instead of going for hole alignment like you would on normal cam bearings. :mad: Anyway, I made sure my oil passageways didn't have anything like the cover gasket hanging into them and in general just eliminated as many lips as possible. I set my mains/rods out to around .023-.025. End result? I run a 0w-20 oil and on start up I have around 80 psi of pressure. After driving it comes down to about 20 psi stopped in drive and as soon as I hit the gas it climbs fast. Oh yeah, I still haven't gotten around to installing an oil cooler.
 
Well my persoanl opinion and one that has so far worked with my customers engines.

I prefer not to use and HV oil pump. A goos stocker will last 100,000 plus so I see no need. I personally beleive it puts excessive stress on the cam and front cam bearing. Of course there are plenty that have so this is personal.

Not sure why you chose a 5-30, pretty llight oil. Again I prefer a 10-30 for my applications. Again I am mostly building street strip and DR cars.

As for clearances. They call for .0015 to .002. I will say I use a 0017 to 0018 for all my performance engines. I will be a little more lenient on a purely street engine.

Hope this helps
Thans for the input.
It is appreciated. See response below.

I like the HV pumps as long as the engine can use it. Oil pressure is useless without flow but if you build an engine that can flow the oil you'll get better cooling of the bearings. Running a standard pump on a looser engine is kinda like trying to run a small turbo on a big engine. It'll only make so much pressure. If it can keep up great. If it can't then step it up. A 0w-30, 5w-30 and a 10w-30 oil are the exact same thickness at operating temp. You just need to decide how thick you want the oil when it's cold.

I worked my front cover over (earls front cover mods) and made sure the clearances in my pump were good. I used an HV pump. I opened up the mains to match the block (I think I only did this to the centers) and I used the TA performance dual groove cam bearings that relocate where the oil gets introduced on the cam journal. If you get those make sure you follow the instructions instead of going for hole alignment like you would on normal cam bearings. :mad: Anyway, I made sure my oil passageways didn't have anything like the cover gasket hanging into them and in general just eliminated as many lips as possible. I set my mains/rods out to around .023-.025. End result? I run a 0w-20 oil and on start up I have around 80 psi of pressure. After driving it comes down to about 20 psi stopped in drive and as soon as I hit the gas it climbs fast. Oh yeah, I still haven't gotten around to installing an oil cooler.

Those are exactly my thoughts.
I run the thinner oil, for two reasons; To get less load on the cam bearing, and get oil to the bearings faster.
The main oil feed is enlarged as well.
Typical oil pressure is 70-75 cold, and 20 hot idle.

I had also completed the “Earl’s mods” on the front cover and have run it for 4 years. End clearance is about 0.0015", carefully trimmed the gasket, etc.
Front cam bearing looked GREAT! :cool:

I would like to shoot for 0.0017-0.0018 mains and 0.0017-0.0019 rods.
Thoughts?

Thanks for the input!
 
Just for fun I'll say again that I went over .002 and have great pressure with a fairly light oil. :cool:
 
I agree. .018 on the rods and .020 on the mains here, and have 20psi hot idle with 5w30 synthetic.
 
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