302 crankshaft clearance q?
 

I'm using a red plastigage to measure up the crank and main bearings. what are the correct or specific numbers?

so far i have this to show:

main #1 .003+
main #2 .002=
main #3 .003=
main #4 .003=
main #5 .003=

I bought this long block from someone. and the plans are to go carb with some iron windsor jr heads.


thanks

ttt

That's way too much. Your range is .0005" - .002" for the Mains, and .0008" - .002" for the rods.

Take care,
-Chris

why is too much if it falls in between those numbers you mentioned?


thanks

you should run .0025 on both rods and mains. .003 is a bit loose but will work. anything tighter than .002 is not good and will speed up bearing wear and heat. since you have different clearances between all the mains i would suggest you have the crank cut .010 under so all the clearances are the same.

Which one is between the specs I gave you? Your lowest was .002" in one journal. Your max should not exceed .002" on any journal. Actually, the "hot rodders' say no more than .0015, but I like .002".

Take care,
-Chris

I appologize for my dumbness...

my chart here can read .002 to .006 inches. and my numbers above seem not so accurate or correct according to what I've read in the forums here.

the higher the number, the tighter it is, based on the red plastigage and it's chart. wouldnt .0015 inch be too loose?

.002 inch should be really tight.

So I'm still confused.
maybe I'm using the wrong method here.

Are you saying it's okay to be above .004 and no more than .0015?

if so then that answers my question

no its not ok to be above .004, thats 4 thousandths of an inch, chris said the tolerance is between .0005" and .002" (1/2 of a thousandth and 2 thousandths of an inch)

i had my crank polished a while back just to get some small scratches out and the machine shop told me to use stock size bearings, so i did and the clearance was about .0025-.003" this is too much and because of it my oil pressure is pretty low at idle (about 29psi)

my advice is to get your crank ground .010" under and get .010" under bearings to get it closer

perfecto

Now I understand.

thank you very much
:)

Just so I'll feel better;

0.0000 = No clearance

0.0010 = A little on the tight side

0.0015 = Preferred

0.0020 = Your Max limit

0.0025 = Loose

0.0030 = Way too much clearance

Take care,
-Chris

now im convinced that my method of checking the clearance its way off.

I'm going to go ask for another type of plastigage
:D

You should be using green plastigage.

Take care,
-Chris

thank you very much