crank/main bearing clearance

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35regal

35regal

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ok, my crank supply house is telling me one clearance, my machine shop has another preferd clearance. its a eagle 4340 crank, 418 motor with over 500 hp.this is a street/strip car, more time on the street. the smallest clearence is .0014, the largest is .0018. thanks for help!!!
 
i use to put most of the performance engines i built around 0.0025-0.0030 on mains, 0.0024-.0026 on rods Mopar,Ford,& GM

0.0018 is ok for a stocker but a little tight for my liking on any performance engine
 
the machnist thinks its to tight also, as well as fishy68, machinst isnt sure if he can polish this NEW EAGLE 4340 FROM RPM MACHINE to get desired clearance. you would think after buying new stuff you shouldnt have to machine it.$$$$$$$$$
 
35regal said:
ok, my crank supply house is telling me one clearance, my machine shop has another preferd clearance. its a eagle 4340 crank, 418 motor with over 500 hp.this is a street/strip car, more time on the street. the smallest clearence is .0014, the largest is .0018. thanks for help!!!
Click to expand...
That is TIGHT
 
well...if the rod clearance is tight, then hone the big ends of the rods a lil to get the clearance.
If the mains are tight...theres only 2 things you can do, polish/finish stone the crank OR run a line hone through the block, same idea as opening the big end of the rods.
 
Just have the machinist turn the crank. I understand those Chinese aftermarket cranks have some taper in the machining. Then you know the crank is right. Beats having the crank catch a bearing and spinning it. .002 min

Eagle is the worst manufacture of poor machine work on their cranks.
 
dodge freak said:
Just have the machinist turn the crank. I understand those Chinese aftermarket cranks have some taper in the machining. Then you know the crank is right. Beats having the crank catch a bearing and spinning it. .002 min

Eagle is the worst manufacture of poor machine work on their cranks.
Click to expand...

LOL almost every aftermarket crank is chinese.:read2:
 
Its like those Edelbrock heads. Take them all apart and you may find a tight valve guild, a poor valve seat, etc.

Hughes and other top shops do sell new heads that they have checked out and corrected. Cost a few hundred bucks more but they won't punch a hole in your piston by a valve stinking open.
 
I too believe that is a little tight. I shoot for .002 on a street motor. A little more if it's race only.
 
1wild&crazyguy said:
well...if the rod clearance is tight, then hone the big ends of the rods a lil to get the clearance.
If the mains are tight...theres only 2 things you can do, polish/finish stone the crank OR run a line hone through the block, same idea as opening the big end of the rods.
Click to expand...

I'm helping Brian put it together. Just got the crank dropped in and mains checked. haven't had a chance to do the rods yet. My back is acting up again so it'll be a couple more days till I can do that. The block is freshly align honed with ARP studs installed. Our machinist has always done things right in the past so I'd think it's right but the next step is to pull the crank back out and check the i.d. of the main bores to verify they are right.

Thanks for the tips and confirmation everyone.
 
dodge freak said:
Just have the machinist turn the crank. I understand those Chinese aftermarket cranks have some taper in the machining. Then you know the crank is right. Beats having the crank catch a bearing and spinning it. .002 min

Eagle is the worst manufacture of poor machine work on their cranks.
Click to expand...

I have read they aren't machined very good too but it doesn't have any taper to speak of. Just a little too big so the bearings are tight.
 
fishy68 said:
I'm helping Brian put it together. Just got the crank dropped in and mains checked. haven't had a chance to do the rods yet. My back is acting up again so it'll be a couple more days till I can do that. The block is freshly align honed with ARP studs installed. Our machinist has always done things right in the past so I'd think it's right but the next step is to pull the crank back out and check the i.d. of the main bores to verify they are right.

Thanks for the tips and confirmation everyone.
Click to expand...

whats the no.1 measure?, when you get a chance.
 
Mains or rods or both. I wouldn't sweat running it that way at all. I like mine a little tight. But I'd check those measurements carefully. How much taper on them? I've never seen an Eagle finished well enough to have them all within .0004.
 
moper said:
Mains or rods or both. I wouldn't sweat running it that way at all. I like mine a little tight. But I'd check those measurements carefully. How much taper on them? I've never seen an Eagle finished well enough to have them all within .0004.
Click to expand...

True, all the new engines out there run some pretty tight clearances lijke my turbo caliber. And I run that thing HARD!!!
 
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