Measuring the little end with wax. How?
 

Hi Guys

I have my 993 engine sitting there awaiting refurbed heads and a set of low mile pistons and cylinders to be fitted. I want to measure the conrod little ends, but do not have a suitable tool. I was told secondhand that the journal can be filled with wax and once extracted the wax measured to giva an accurate reading.

I can imagine how this might work, but has anyone actually done this and can tell me the correct wax and procedure.

Actually my existing P&C's do not look bad, but the replacements have done only 36k rather than my 186k so worth going with.

Many thanks... Berni

The wax procedure isn't the best method in my opinion, as the wax can distort when removing it from the bushing. Should just go buy a bore gauge for that size and use it with an appropriately sized mic to get your dimensions. The telescopic type probes are cheap, like these:

Amazon.com: Anytime Tools 6 pc 5/16" - 6" PRECISION TELESCOPIC T BORE GAUGE SET: Home Improvement

Would love to hear how you use plastigauge in a wrist pin bushing.

Hi

Excellent idea, they sell those sets in the UK as well. I did not know they existed. Will order one now.

Many tks

Berni

Not plastigauge, "candle" wax. The theory behind it is you tape off one end of the bushing, pour hot wax into the rod to fill the bushing up, then extract/measure the wax after it cools and solidifies to determine bushing ID. Highly unorthodox, and easy to see why.

Yes, thanks Adam-- I was responding to a post that apparently the writer suddenly realized he needed to delete! :)

Or you could get some good spring calipers and measure them with
a standard mic.

andy

The wax would contract upon cooling, so it doesn't sound like a very accurate method to me.

A telescoping bore gauge set is your best bet.

I have always made my own go/nogo guages for small holes.
I find it easier and faster to lathe a piece of brass with a "step" in it to see if the hole is the right size.
For Harleys...I use one that has 6 steps...each one is .001" bigger as it goes down the shaft.
Of course...the bike engines are assembled using yardsticks anyway....LOL.
Bob

Hi There

I have in my possession a set of bore gauges that look like the letter "T" and two micrometers. A very old imperial traditional one, and a modern vernier digital type.

I have been measuring my little ends and have found it difficult to get consistent readings with the bore gauge. Is there a best place to measure? I have been placing the gauge in the same plane as the body of the rod, ie to measure the up and down wear. I might have measured opposite the oil hole, would that have made a difference?

With some practice I ended up with a set of readings of between 23.02 and 23.03mm on the digital and 90.06/07 on the imperial micrometer. I say 06/07 because it fell between those marks on the scale.

Can anyone tell me what the tolerances / measurements on the little ends should be please? I saw a post on 964"s that said 23.02 +0.13mm I quickly measured one of my old cylinder bores while putting stuff away and it came out as 99.99mm. What should those measure as?

Many tks

Berni

Use a plug gage. The bore gage works better on big openings e.g. the cylinders.

A pair of plug gages set up as a go/no-go will work fine and won't cost you very much at all.