Main bearings small block chevy,rocket block
 

Hi I have a 427 olds rocket block chevy engine that keeps tearing up #2& 4 main bearings after 2 burnouts. I have had the block line honed,a callies crank at first, had it turn twice due to bearing failure & just put a eagle crank in it with the same results. New four stage drysump oil pump & line also.All the rest of the bearings are ok. Any ideas would be great.

How long have you had this engine? What is the stroke, bore and deck height, fuel system and fuel, and any other info you have. I had a 463 with a olds rocket block, dry sump, injected on alcohol and also had main bearing problems. Mine was a 4.250 stroke with a 6.030 aluminum rod. top side of rod bearings would be a little hammered but never into the copper. Tell me what you can and we will go from there! Thanks,Don

Hi It has a 4.125 bore, 4 inch stroke,6.125 GRP alum rods,9.325 deck. It is alchol injected. I have a 5 spd lenco trans. The rod bearing seem to be ok but not much run time to tell. Rons twin terminators.New motor never made to the track. Made ten dyno pulls with no problems.
Thanks Mike

What is the new motor and how much power dit it make? Mine only had 1 Terminator on it and could not get the egts above 1000 degrees. What are your incremential times. I bet with a 5 speed its realy fast!

427 small block ,it made 750 hp @ 7500 .It is in a2800 pound 69 camaro 8.90@ 160.Had same combination in my last motor with no main bearing problems but kept losing #3 rod so i got a new block.I shift it at 8000 rpm.Would like to get it back on the track this year.

200 runs is the most i ever got before i lost #4 main bearing. I always managed to catch it by looking at the screen filters in the oil pan. Bad thing about a dry sump you lose a main bearing but oil pressure still at 80 lbs. Good luck with the new block!

Could be lack of oil return holes to the bottom. Those blocks don't have much for oil drain back holes. Could be pumping the oil pan dry, with not enough time to drain back. I have seen this before with those blocks. Otherwise, there should be no issue. Those are a dry sump or wet sump block, so, if you run it wet, you need to add some extra drain back holes in the lifter valley. They do that, so, when you dry sump it, you can keep the oil where you want it.


Frank
Advanced Performance
www.get-ap.com

How many oil resrictors? On my wet sump setup I needed to put four total in the galleys to control oil flow to the lifters and such. If you want more details I can provide them.

Dart has since updated the new Iron Eagle blocks to easily restrict the hole.

pwmax is correct..i have a rocket block and the oil drain back holes are way to small...i lost some bearing in 2 passes so we put screens in between the cam bearings in the lifter galley...problem solved

My block is a dry sump

Hey Mike, mine was a dry sump also, if you are trying to keep the excess oil out of the engine i dont think the drian holes in the lifter valley would be the problem. I think part of my problem was it had 16-1 compression and a 4.250 stoke. When my engine builder built it he had never built a SBC with a 4.250 stroke and wasnt sure it wouldnt try to throw the the rods right out of the block. The only problem i ever had was main bearings and im not sure it wasnt the rocket block. I had a freind with a 454 with a 4.125 stroke in a dart block with no problems and he is still running it after 5 years.

Do you have a suction line from the lifter valley? if not you will fill it up with oil.We have built many engines using this block with no problems. Bill

Yes one line in lifter galley & 3 on oil pan. What clearance do you run on the main bearings?

We use .003/.0032 with .0025 / .0028 on the rods.most drag racers don't get the oil temp up high enough before making a run and cold oil doesn't flow very well,this problem is worse in a dry sump engine where the oil isn't in the engine very long. you need light weight oil and a heater on your dry sump tank to get the oil above 160 deg before making a run,we use Gibbs XP3 which is a full synthetic 10/30 weight in normally aspirated engines and XP6 in the blown, turbo and heavy N20 engines. its 15/50 Bill