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Discussion Starter · #1 ·
How do i know if the bearings(rod and Main) are oversized in an engine?
I measured the rod bearings yesterday after removing the pistons from a 302 and they measured around .05 or slightly above-perhaps .054 thickness.


Also, what is the best way to clean the tops of pistons out of the block. I have them sitting in my cleaning tank right now and i plan to let them sit there for a few days and then scrub them off. Any other ideas on how to get them nice and clean??
Thanks!
 

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Junior Charter Member
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If the bearings are oversized it will state the size on the back side of the bearings, .010 ect.
I cleaned everything with carb cleaner. It cleaned everything like new. I used a broken ring to clean out the ring lands that worked great.
Tim
 

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Discussion Starter · #4 ·
The block only had 2300 miles on it. The crank looks great, but the bearings did have some wear. The ring lands are perfectly clean, but the pistons did have some carbon build up-probably from when the mass air meter was partially fried and the car was running rough.
 

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And if you use and old broken ring to clean the groves, wear gloves. They are sharp, and will cut your fingers up...been there. The type of rings you will need depends on the pistons you have. Consult the piston manufacturer for specs.
 

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FFCobra Fanatic
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Most times bearings will be stamped on the outside. STD for standard +10 ect. You can also use plasti gauge to check bearing clearence on the old bearings same as with new. You'll need the red and green plasti gauge for the two ranges of tolerance's needed to be measured during assembly.
Crank needs to be measured with a micrometer to know it's size to determine if still within limits or needs machineing. Same goes for cylinder bores. Bore gauge,snap gauges or inside mic's must be used to determine amount of wear and roundness,along with taper.
Piston rings will be metric or sae depending on year and if forged or not. I ran into a problem with the last 302 I did with ring package. You need to measure the old rings thickness. Certain rings are very hard to find,even tru Ford. I Recieved help from gordon here. Very helpfull in finding the correct ring package. seems some ford forged piston were made by TRW. later forged were'nt.
I've used ring groove cleaners and old broken ring to clean grooves. Old rings worked best. Make sure ring groove is spotless. Any carbon here has big effect on final ring fit. don't alter the size of the grooves.
Tops of piston can be clean starting with a putty nkife to remove any heavy carbon. Scotch brite pads,wire brush,and oven cleaner will also work. Depends on how much cleaning is needed. Oven cleaner does good to soften carbon and can help in removeing heavy deposits.
Carefull measurements,and correct tolerance's make for a long lasting engine with good oil psi. and proper ring seal. ;)
 

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I raised a post a couple of months ago on this, by far the best piston cleaning chemical was "Gasket Remover" - blue can, ~$5.00, think it was made by Pematex. It dissolved the crud and varnish very quickly, is safe for aluminum.
 

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And the first time you fire up the car, those nice shiny piston tops won't be so shiny. Not that you'll see them anyway.


I just hit mine with steel wool to knock of the loose carbon, and called it done. I didn't see the point of wasting calories on something that was just going to get buggered up again.

-Greg
 

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FFCobra Craftsman
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On the outside surface of the bearing insert there will be several numbers/logos.Mine had
010US
on one line which means .010inches undersize
 
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