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This is the second time its happened. Mains and rod bearings are shiny silver tops and bottoms and doesnt seem to wear on the sides still dull silver. Ive changed everything but the dampner and the rods w pistons. The setup a 350 thats .040 with completely studed block. Boring and align honing was done. But what also puzzles me is the cam bearings wore un even on the top also. First time it happened new scat crank and new flywheel. Same thing. Whats up?
 

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Wear on the vertical axis is usually from detonation. It hammers the top half of the rod bearing and the bottom side of the mains.
 

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Are you shooting NOS?

I would change to ACL racing bearings and up the oil pressure.
Added oil pressure IE: HV HP pump will help with the high stress against the bearing.

Also there are a variety of Clevite bearing quality's.




LET the argument begin.:devil:

Al
 

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Discussion Starter #7
i am

Im still working on the 331 but this is a motor my buddy has in his 72 c-10. We were the ones that put it together and with the main studs arp said with their lube to torque the caps at 70 ft. lbs. We used clevite h series for the rod bearings and summit hi po main bearings. Summit guys said just throw the crank in it will work just fine. uh huh. just by the way everything is wore i was thinking it wasn't balanced right. Just my opinion. What do you guys think?
 

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hmm

i'm at my buddys shop often , i think he takes .002 off of the caps before he align-hones his blocks ,, he tells me some people don't. I'd look at the inside of the bore of the mains , and see if there is hone marks consistantly through this area
 

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What do you guys think?
Rods need to be resized. out of round rods can and will cause this.

Have crank turned by a quality machinist. Out of round journals and crank not straight may be a problem.

I would start with a fresh and quality surfaces.

Assemble engine and check clearances.

IMO
AL

PS: What has the oil pressure been?
What has the engine life been?
NOS?
High gear ratio in truck?

High gears, rpm or heavy towing and using a stock oil pan?
I would opt for a pan with more oil capacity.
 

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Discussion Starter #10
Nope

No nitrous, and its been over ten hours at least. Stock oil pan yes. Oil pressure is 50 at idle and b4 1500 its jump to 70 and stays there. No towing it his street rod and i believe 373 for gears
 

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No nitrous, and its been over ten hours at least. Stock oil pan yes. Oil pressure is 50 at idle and b4 1500 its jump to 70 and stays there. No towing it his street rod and i believe 373 for gears
Then there has to be other issues.
And not checking clearances, parts that are correct, IE: Straight, round & true, leaves a lot un-known.

Quality checks can seem redundant, but without them you have a crap shoot. Sometimes it works, sometimes it does not.

IMO, to much work not to take the steps to make it correct.

AL
 

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What heads and compression ratio? I think it's a combintaion of detonation and a machining issue. With a new crank you must have the journals checked for size and roundness, and they all require balancing, so if you just dropped it in, it's not right.
 

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Discussion Starter #13
ok

Well we got the rods on ebay and they have been resized with arp bolts but since they were cheap maybe not done right. The clearances were all goo and tight but maybe that because we just caught it in the right spot im not sure. He has 305 heads 58cc
 

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You're detonating, hammering the bearings. Have the rods resized again, have the crank turned, and either install some dished pistons or change the cylinder heads. Some people can get away with the really high compression, but most can't, especially if it's a mild engine. For a driver, try and get it down to around 10:1. You can get the same type of gas I can get here, so you'll be fine with that, but I wouldn't go much higher.
 

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This is the second time its happened. Mains and rod bearings are shiny silver tops and bottoms and doesnt seem to wear on the sides still dull silver. Ive changed everything but the dampner and the rods w pistons. The setup a 350 thats .040 with completely studed block. Boring and align honing was done. But what also puzzles me is the cam bearings wore un even on the top also. First time it happened new scat crank and new flywheel. Same thing. Whats up?
can you provide pics of the bearings? Be sure when you're assembling this time everything is CLEAN and recleaned. You should be using H bearings on the crank for its generous radiused journals. Be sure to check your clearances and also have the cam and crank checked for straightness. Does he have the correct balancer and flywheel/flexplate?

If its a detonation issue be sure the balancer is accurate at TDC. How much timing did you run and what is the static comp ratio? what gas did you use? what weight oil? were are the clearances coming out to be?
 

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Discussion Starter #16
guess

we found out that at least one of the studs on everymain could be taken out by hand. When we set the main down on we could still move it back and forth. Possibility? 10w40 oil correct flywheel but not sure on the balancer brand new cam also
 

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even new cams out of the box can be bent. Studs are only supposed to be installed hand tight. Are they all the way down in the holes? How do the main caps fit in the block? are they tight or loose?
 
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