Bearings clearance

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KB9GIB

KB9GIB

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Can someone tell me on a 340 bearing clearances stock crank & rods turned 20 using clevite P77 bearings what should the clearance be rod and mains. Thanks for any information in advance. KB9GIB
 
The clearances should be the same no matter what size bearing you are using.
 
KB9GIB said:
Can someone tell me on a 340 bearing clearances stock crank & rods turned 20 using clevite P77 bearings what should the clearance be rod and mains. Thanks for any information in advance. KB9GIB
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Per 69 Plymouth service manual:

.0005" - .0015"
 
I have always run .0025 - .003 on main and rods an high volume pump. What is everyone else running?
 
MoparMike1974 said:
I have always run .0025 - .003 on main and rods an high volume pump. What is everyone else running?
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I also run this clearance range. I'll typically target 0.0025 but up to 0.0030 shouldn't be a problem. 10W-30 oil with a high volume oil pump. 65'
 
Plymouth 65 said:
You need to use 0.020 under crankshaft and rod bearings. The clearance should be the same as listed in the FSM. use some plastigauge to confirm. 65'
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20 thousandths? That's why you shouldn't believe everything you red on the internet. .002 yes .020 no.
 
Jeasus H Christ
depends on you load and rpm range
depends on your oil weight
stock is for grocery getters with stock cam and rpm ranges
remember oil flow through the bearings helps cool
that tight does not work well with marine or HD trucks, HD towing, motorhomes, etc
That tight with high rpm? sure with 15 weight oil for a head's up dragster that's going to get torn down every week
and if you do decide 50 weight or 70 weight is more better then you had better preheat it
IMHO appreciate feedback
 
Magnum Valiant said:
OP's crankshaft is "20 under," which I assume means .020" undersize, so. 20 thousandths would be correct.
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Those measurements are only used by the manufacturers. If your crankshaft is turned .020 it is 20 thousandths of an inch undersize. The OP was asking about bearing clearance. (oil clearance). That is .002 regardless of how far the crank has been turned.
 
Ok guys this is what the green plastic gauge shows. Is this within range? my son and I are just trying to make sure on his motor that it’s right. I appreciate all your help. Thanks kB9GIB

101E93A1-B6D6-4394-BFC8-E7943EA86560.jpeg
 
KB9GIB said:
Ok guys this is what the green plastic gauge shows. Is this within range? my son and I are just trying to make sure on his motor that it’s right. I appreciate all your help. Thanks kB9GIB

View attachment 1715571868
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Good to go. .002 is not too tight or too loose. Great for a street rebuild.
 
What is the intended use of the engine? Grocery getter Or low rpm use you can run tighter clearances (such as 0.001 or 0.0015, high Revving or racing you want more clearance (such as 0.002 or 0.0025).
 
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