making rod bearing last longer

dmc919 · Nov 24, 2008

what do yall suggest to make rod bearings last longer for a stock 302 that will see a sustained 6k rpm's?

BlownFiveLiter · Nov 24, 2008

Frequent oil changes?

I'd be more concerned about making the rod bolts last longer with sustained 6K RPM.

enyawix · Nov 24, 2008

A high Quality Synthetic 20/50 engine oil you get what you pay for.

Amsoil is at the top of my list.

MustangLX-5.0 · Nov 25, 2008

I'd be concerned more about the timing chain.Read below so you understand what I'm getting at.

A few year ago I sold my 89 GT to a friend of mine.He used to "get on it" quite often.One night I was hanging out and we went for a ride.Came to a light and a mitsu 3000 gt all ragged out sat next to him.Light turns green...both him and my friend start gettin on the gas real good..2nd gear comes around and 3 seconds later the rpm's instantly shot up to 6500 for at least 2 seconds then the engine just died.Rolled off to some side street.Looked under and there was oil all coming out from the timing chain area at the oil pan.Part of the pan was broke.

Tore the engine all down.The timing chain had broke.Worse yet..The crank broke about haflway.2 of the main caps snapped right off the block.The rod for the front left piston twisted up like a pretzel.

I never figured out the sole cause of all of this.Why the engine sped to 6500 then shut off (tach was only at 3500 when it happened).Broken timing chain maybe.But could breaking a timing chain cause the crank to snap? or did the crank / main caps causing the crank to slide forwards...thus causing the demise of the timing chain??? Never know.

All I do know is...if you don't rebuild the internals with better quality parts,it's not gonna handle 6k+ rpms constantly.These motors werent built for it from the factory.Any stang motorhead knows this.

1987stangman · Nov 25, 2008

Yea, it's not like your motor is going to make total peak HP at 6K. What is the reason it will see 6K? And why is rod bearings you main area of concern?

Brian@PAR · Nov 25, 2008

Well I can't argue with the timing chain and it's lack of strength but you can spin these to 7K with little more than good rod bolts. Now sustained 6000 RPM's may be a different story with a 50 oz motor but I'm not convinced they will not handle it.

Last year I parted out a 306 that came out of a road racing Mustang. The motor had 20 races on it and routinely bounced of the 7400 RPM revlimiter. This was a stock racing class. It had a stock crank balanced at 28, main studs, stock rods with ARP wavelocks and aftermarket forged flat tops. Now this was in a Mexican block so I'm sure that helped with durability (really big main caps) but the rest was stock.

Another example of crazy fast stock parts. 255 crank in a Mexican block turning 9K. This is an internally balanced drag motor that runs low 9's N/A. This is a long rod motor and I would bet the pistons were lightened even more but would anyone think a stock crank could turn that high?

Oh yeah about the original question Good oil, good pressure and good rod bolts equals 7000 RPM shift points at the drags and no excessive wear on rod bearings.

enyawix · Nov 25, 2008

it may be 351w time. I never did like having to spin high rpm to make power.

dmc919 · Nov 26, 2008

i'm running castrol gtx 10w-40, i had an old account here and seems like everythings been reset. the motor sustains 6k rpm's because it's in a mud racing truck, hold between 5-6k rpm for about 30 seconds. usually about 5 runs per event. after about 3 events "15 runs" i notice sparkley oil, drop pan and it's rod bearings. it's the only problem i've had with this engine. i'm on my second crank. first one was ground 2 times before i changed cranks. oil pressure is 50psi idle and 75psi 3k plus.

Black1987Stang · Nov 26, 2008

I would say theres something not right....
I would be more worried about the bearing clearances, bearing type and material, and so forth....They make different kinds of bearings, some are made for higher rpms like your running. For ex. I believe the Clevite H series bearings is for that and P series is for stockish application or vice versa....but if the clearance isn't right it's going to eat bearings.

Theres Tons of people that bring these motors to 6k all the time and have over 100k on the odometer and aren't eating bearings..for example the stang I just bought, it got beat the piss out of it and the only damage is deformed valve stems (had to file down the lip cuz the valves wouldnt pull out of the head) from the valves floating....Did you measure the oil clearance between the bearings? clean out all the oil passages INSIDE the crank and Inside the block? all you need is a passageway from the pump to the first journal to get partially clogged and it will ruin it for all 8 rod bearings. and of course good oil and rod bolts cant hurt...

Rick 91GT · Nov 26, 2008

The H-series bearings will actually eat up a stock crank, they are very hard and amde for the 4340 with the large radius/chamfer. I would looking into a coated bearing like a Calico and then build it with the proper clearances, and pressure/volume oil pump.

dmc919 · Nov 27, 2008

ok, thanks for the help. i've been using Sealed Power rod bearings from advance auto parts. thought all rod bearings were equal, lol.

enyawix · Nov 30, 2008

dmc919 said:
ok, thanks for the help. i've been using Sealed Power rod bearings from advance auto parts. thought all rod bearings were equal, lol.

I do not race that much and also have Sealed Power bearings. I want want to know about the Clevite P series bearings.

Brian@PAR · Dec 1, 2008

Take a look at this for an analysis of bearing failures. It will help you figure out what is going on.

http://mahleclevite.com/publications/CL77-3-402.pdf

Here is their catalog that talks about the different bearings.

http://mahleclevite.com/publications/EB-40-07.pdf

P bearings (the performance ones not the passenger car bearings) have higher crush and higher eccentricity to allow for cap deflection at high RPM's. I would doubt you need the P's though.

enyawix · Dec 1, 2008

What did you use to build your site? I tried to look at you site but it acts very strange in Firefox and Opera. I do not have access to IE.

Brian@PAR · Dec 1, 2008

Hmm I'm not a designer and did it myself. I never tested it in FireFox. I guess I should have doen that though.

I used a program called site spinner for the main site the store is done in another program.

You can get IE6 here
Download details: Internet Explorer 6 Service Pack 1

I'll have to see what is up in firefox. Thanks for the feedback.

making rod bearing last longer

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