Rod & Main bearing life

[underdog]

How often should I replace the rod and main bearings?

I have a 383 SBC in a 3000# Chevelle. Scat crank 12:1 pistons using Rotella 30 weight changed every 40 passes or so. Got a 6 quart pan if that makes a difference.

Thanks

[want-a-be]

How many passes a year do you make?

Don

[underdog]

Hi Don

Still trying to get parts together for my rebuild. I make 80 to 100 passes. It depends on how many times I go RED !

I called Crane on that cam you suggested but they say it will not clear a stroker. I'll have to go to a roller and I'm not sure that's in the budget

[want-a-be]

Are you running steel or aluminum rods? Might hit with the extra 1/4" stroke, which is 1/8" closer to the cam....But I would think it should swing with a steel rod. I didn't have any problems with the 355 running aluminum rods. The next size down is also a pretty good cam.
Let me know if you need anything.

Don

[underdog]

I have Scat's 4340 forged H beam steel rods with 7/16 cap screws. They say they are profiled for strokers but I had to grind on the block to get them in. The cam I have now is a 106° Center.

While I have it out think I should replace the bearings? They were new last year and I still have good oil pressure, 40 at idle up to 80 running hard. I don't want to pull thef bottom out if I don't need to.

[want-a-be]

If this thing is on an engine stand then look at the mains and the rods bearings. If they are ok then I'd leave em. But there are some who believe...hey your there already whats a few hundred more bucks on the build. I will usually inspect them at least. If I take it all apart I'll remeasure them. If the clearances are where I left them then I'll clean everything up and reassemble.

I'd at least look at them if you're there though.

Don

[BIG CHIEF]

Also Keep in mind that we offer coating services that will help make the bearing life longer. The Top Fuel guys send us used bearings all the time so they don't have to buy new bearings for every run. Check out this video:

http://www.dartheads.com/products/dc-5-oil-shedding-coating.html?video=1

Thanks,

[Awesome Bill]

If the bearing clearences are correct, you can run almost forever. It is always depending up how much power your making, rpm your going to push it to and if any power adders are coming up. If the oil delievers the heavy metals to the bearings and always takes away the heat, you can run years, 5-10 and never hurt a bearing as long as you don't exceed the hp recommendations for your rods or do things like detonation, running hot, or not changing your oil. Oil is very cheap compared to engines, change it alot!

[Nova67ss]

I´ll Go with Bill, if all is ok the bearings will not "run down" because the oil film saves and do its job..

But a detonation or if U foams the oil the bearing hardly make´s one run down the strip..

A friend of me runs a V6 turbochaged car and we´re putin out a good 1275 - 1350 HP and we had some problem with disapearing oil (foaming) and that killed the main bearing instantly, STILL had good presure on low rpm

We solved (we think) the problem and now the engine livet tru 2 race´s and hits 7500 rpm every time..

[Awesome Bill]

detonation tries to knock the rod out of alignment with the cap. Usually pushes it to one side or the other depending on what side of the block it is. If detonation happens on a brand new engine, you could most likely have problems. A little detonation usually hurts nothing especially with the older engines. They tend to have just a little more room and the parts have already been broken in. I have engines that are 20 years old and still run perfect. These are hi-performance street engines. If you loose more than 10lbs of normal oil pressure, you have some sort of problem for sure. Always check gauge and oil filter first before pulling a good engine down for nothing!