Broken rod bolt

General engine tech -- Drag Racing to Circle Track

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KnightEngines
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Re: Broken rod bolt

Post by KnightEngines » Tue Oct 17, 2017 6:05 pm

^ this here is the man to listen too when it comes to Clevo's, he's been turning them waay too hard for a long time & knows how to make them live.
Knows how to make HP with them too........

PS, TuffXF - got some 4V's coming in soon, open chambers welded solid, doing tongues & epoxy on the intake, tongues on the exhaust & carving a pressure recovery chamber into them, customer found an old guy that can weld iron like I can weld alloy without it being too hard to grind. Aim is a factory casting headed engine making 750+ & streetable...........

1972ho
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Re: Broken rod bolt

Post by 1972ho » Tue Oct 17, 2017 6:22 pm

The mains are .0025,rods .0030 mains are clevite MS-1010P .020 rods are CB831-.020;Rods are eagle 5780 torque to 63ft#; lifters are ceramic hydraulic lifter bores are bushed with cam restrictions external balance and I shift at 7200 thur the lights at 8100 or so.

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Re: Broken rod bolt

Post by KnightEngines » Tue Oct 17, 2017 6:57 pm

Mains are too tight, like .001" too tight - clevo turning to 8k rpm wants .0035" on the mains - even a tad more wouldn't hurt it.
The stock crank flexes, that flex will have the crank riding the bearings (hence the wiped mains), as soon as you have contact on the main brgs you restrict flow to the rods & the rod brgs get hurt.

The eagle rods are turds for something turning this hard, chances are pretty good they closed up top to bottom from spreading the journal & reduced brg clearance.

Get some real rods, even some Scat Pro I beams will be an order of magnitude better than the eagles (I've turned the good Scat I beams past 8000 making 600+hp many times with zero issues, just be sure to get the 7/16" rod bolts).
Put it back together with .0035-.004" mains clearance & .003" rod brg clearance.

If the budget will allow internally balance the crank with Mallory metal - internal balance will significantly reduce crank whip at high rpm.

Get a vac pump on it, pull 8-10" of vac, that'll help with drainback, windage & oil aeration.
Look at the sump, make it BIG.
If you haven't already then open up the drains in the valley to 3/4" & add another 2.
You may well be running the sump dry at the end off a pass with those rpm, getting the oil back where it's needed, getting air out of it & having a large volume available in the sump will reduce the likelihood of sucking air and/or aerated oil playing havoc with bearings.
Pickup height should be 6-10mm from bottom of sump, 8mm is ideal, more than that & you're wasting sump capacity, less & you risk cavitation at the pickup.

You're turning this thing hard, you can't just treat it like a hot streeter, it needs to be built with the limitations of the large clevo mains, stock crank, limited drainback & windage in mind.

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Re: Broken rod bolt

Post by tuffxf » Tue Oct 17, 2017 7:25 pm

Gday
Thanks for the reply
What were the mains last time, full 3/4 or half groove?
Tk is right
With the crank ext balanced, hopefully it is only 28 oz!
The mains want to be the 3.5 - 3.7, i use the eagle rods too, there is better for sure, i run them 3.2 - 3.3 with the h series bearings.
Every time i closed my clearances up they come out looking ordinary.
Use the std pump with a 100 psi spring, relief valve will be shut when warm and pick your oil weight to achieve 75 psi on a pass,
The guys in the old days used to run full groove bearings to make the rods live, they were correct but i dont know if they understood why.
The stock crank has a timing issue to 2 and 7 rod bearing.
You can fit a full set of full grooved bearings as they did back in the day or what i do is fit fully grooved to no 2 and 4 main only.
You need to run the oil pressure up reasonably high.
Most people now days say you dont need to do much to the oiling system , reason is most use aftermarket cranks which all have the rod oil timing like a sbc.
The lifter bushes are a great idea as they can bleed heaps of oil here, if you've bushed the lifters run an external hose from oil point at the front to the oil pressure port at the rear as the bushes do intrude into the gallery a fair bit.
Your pushing boundaries at those rpm with the ext balanced crank but with a good balancer it can be done, not right but☺
You also need to get into the habit of cutting the filter every meeting, any bearing metal is not good.
You will pick up a problem early before it hurts anything
And need to make sure youre not putting too much oil up to the top end.
Cheers

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Re: Broken rod bolt

Post by KnightEngines » Tue Oct 17, 2017 7:45 pm

The guys in the old days used to run full groove bearings to make the rods live, they were correct but i dont know if they understood why.
The stock crank has a timing issue to 2 and 7 rod bearing.
You can fit a full set of full grooved bearings as they did back in the day or what i do is fit fully grooved to no 2 and 4 main only.
I just learned something, thanks!

Subaru's have a similar oil hole phasing issue, they run fully grooved main brgs, but the oil holes are in the wrong location on the pins, I made up some drill guide jigs to locate off the original oil holes to redrill the rod pins in the right spot, made one for #3 main as well, with the mains & rod pins redrilled it turns it into a straight shot oiling system & the munted rod bearing problem goes away.

1972ho
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Re: Broken rod bolt

Post by 1972ho » Tue Oct 17, 2017 8:12 pm

This happen to be a stock eliminator cleveland so there are only limited things on the list I can do, the eagle rod is the approved rod for this engine,no vacuum pumps not to sure about the external oil line,I run a innovator west balancer and I can only run a stock type oil pan but the inside can be modified.

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Re: Broken rod bolt

Post by KnightEngines » Tue Oct 17, 2017 8:23 pm

If you can run a vac-u-pan it'd be better than nothing.
Short of that you can vent off from the valley instead of the covers & use a large dia breather (like over 1").

If you're stuck with a stock appearing sump then spend some time on a crank scraper, windage tray & baffles. You can also move the pickup further back in the sump to where G forces are pushing the oil during a pass - make the most of the oil you can fit in it. Often you can overfill the sump a little, when it's running there is oil in the heads & valley, so a little extra in the sump is often ok.
You can test how much extra oil you can run on an engine dyno, fill it the usual amount, check the dipstick for aeration straight after a pull.
Add oil & recheck for aeration, keep going till you either see aeration or drop HP - both are indicators you've got too much in there.

With the eagle rods, if you must run them then cycle the bolts a few times & check roundness, hone as required to match all the sizes & get them round. Plan on a teardown after 20-30 passes, check the rods again & hone as required - once they've been run a bit & the bolts cycled they should settle & quit moving so much on the sizing & roundness.

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Re: Broken rod bolt

Post by KnightEngines » Tue Oct 17, 2017 8:26 pm

Also - depending on just how hard they look at the car you may be able to get away with running the breathers to a catch tank on an inner fender with a hidden line going through the fender to a hidden electric motor driven vac pump.

tuffxf
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Re: Broken rod bolt

Post by tuffxf » Tue Oct 17, 2017 8:31 pm

Gday ,
The old mains, full or half groove??
Those rods will be ok if they are sized properly and the bolts are good, 63ft lbs is correct for the 8740 bolts but only if you are using the old style arp moly lube, if the new stuff it will not have enough stretch.
The rods can either be finished round but look at a few different style bearings you want ones that are a lot thinner at the sides near the parting line,
They are going to pull in, or get the rods finished out of round if you cant find what you want bearing wise.
Good luck, good to see you racing a clevo
I think a screen windage tray is a better deal than a solid tray specially with the stock pan.
And dont use the thin oils
Cheers

1972ho
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Re: Broken rod bolt

Post by 1972ho » Tue Oct 17, 2017 9:05 pm

Yea you are right on that Gibbs oil I tried it once made 6 passes that weekend with oil pressure at idle was like 10- 15 psi but 65 at 8000 got home and had copper in the oil and the mains were down to the copper.

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