Plastigage for rod bearing checkup

[cranetruck]

I have had a discussion with Robert (Rdixiemiller) about checking my rod bearings to determine where the engine "knock" comes from.
What range of Plastigage thicknesses should I look for and does age matter (oldies on ebay)?
I need to get my deuce road ready again and if I don't get started on the 8x8 when the weather turns nice again, the deuce may have a chance to get fixed....

 

[clinto]

I don't know if age matters, but I suspect the shipping will kill any discount you get from buying on eBay. Most any decent parts house will be able to get plastigage. Many of the major engine parts manufacturers offer plastigage, like Michigan 77 (formerly Clevite 77), sealed power, etc.

I would try to get some thing like .001 to .010, but I don't think they are sold in ranges like that.

Mopar Performance sells a nice kit that is typically about $8 and any dealer can order under part # 4286819. It goes from .001 to .009.

 

[Blake]

Bjorn,

I think I have some at work. Ill look tonight. If so, Ill mail you some.

 

[poppop]

The last I used I got at NAPA and it was very cheap.

 

[doghead]

 

[wdbtchr]

I had some old stuff, probably 15 to 20 years old, that broke up into small pieces and settled to the bottom of the sleeve. It still worked, just harder to use.

 

[ida34]

It is cheaper buying it locally than to send it. Find out what your oil clearance should be for the bearings and get the plastigage that fits that size. Look for the serviceable limit. I looked over the manuals and found a main bearing oil clearance of .0062 but could not find a clearance for the rod bearings. If sounded like having two or less over that figure is ok but the manual was written before plastigage as it has the bearings being measured by expandable gauges and the journal being measured by caliper. You could go through and find a difference between the two figures to see what the difference is but the manual handles it as two different operations. One to measure the journal and one to measure the bearing inside diameter as installed. Plastigage was made to combine these operations but it is obvious that the manual was written before plastigage as it does not have a plastigage procedure or measurement I would do the math from the engine -34 based on your crankshaft size right now.

 

[Jones]

Plastigage is good for checking clearances but a look at the shell surfaces and crank throw surfaces is wise too, in order to spot scoring which can be the reason for low oil pressure and increased bearing wear; or copper showing through, but only in certain areas. The visual is necessary 'cause Plastigage won't spot egg-shaped bearings.
Scoring is often a result of unclean assembly practices or too long between oil filter changes and contaminants getting past the filter and back into the oiling system.
Before using Plastigage, wipe the oil off the shell's bearing surface and the crank journal. An oil film is actually measurable and will throw off your readings.

 

[cranetruck]

Thanks for your inputs fellows, I'm getting closer to doing something about it (engine knock), for sure.