14 apache

iTrader: (1)

I see what you are doing now with the 180* Think you are good with what you got for measurement I didn't know you where using plastigage.

mike tkach

iTrader: (3)

you cannot get very acurate measurements with plastigage.also an endurance bbc needs more than .002.

Camalot

Yes it does I agree with that .002 is to tight, and I have now found out your right plastigage ain't to accurate!!

Camalot

So today I've done some more measuring
measured crank journals:
#1=2.7476
#2=2.7480
#3=2.7478
#4=2.7478
#5=2.7475

Assemble journals with bearing:
#1=2.7516 clearance= .0041
#2=2.7519 clearance =.0039
#3=2.7520 clearance=.0042
#4=2.7518 clearance=.0040
#5=2.7520 clearance=.0045




I then installed bearings 1 and 5 and used a better DTI checked my run out on journals 2,3 and 4.
#2=.00025
#3=.00005
#4=.00035
I have no way of checking the concentricity of the block journal which I'm now thinking is my problem?

BillK

Not sure if I understand exactly what you think the problem is ?

Camalot

Yeah penny just dropped......................... it's the Plastigage whats giving me odd reading

14 apache

iTrader: (1)

Assemble journals with bearing:
#1=2.7516 clearance= .0041
#2=2.7519 clearance =.0039
#3=2.7520 clearance=.0042
#4=2.7518 clearance=.0040
#5=2.7520 clearance=.0045

That's more than I would want make sure your not making a mistake with something I doubt the plastigage is that far out.

BillK

Try this. Get everything good and clean and oil free. Sit the crank in the block. Put the front main cap on but do not torque it yet. Take a .003" feeler gauge and measure it to make sure it is actually .003 and make sure there are no burrs on the edges for the first inch or so. Shove the feeler gauge in between the front main journal and the bearing in the cap and snug it down by hand. Then torque it to specs. Now if you can pull the feeler gauge out you have at least .003" clearance. You can then try a .004 and see what happens.

I am not sure who told me about this method but I tell some of my DIY customers about it as a good way to double check what the plastigage is telling you. Of course you can only use it on the front main.

I prefer using my Sunnen bore gauge.

Camalot

I thought I would give this thread a conclusion!!

I took the block and crank to the local engine machine shop for them to check, they checked the block journals for straightness and all was good . They then did the same checks as I did and got readings .0005 smaller with there bore gauge than I did but the same diameter readings of the crank journals. So I'm happy with the results around .0035 clearance. I believe temperature played a part in my first plastigage reads.
To save on heating costs I let the workshop drop down to 5*c at night, I checked it first thing in the morning the first time and the block and crank was "cold", I've have the heating set to 20*c since and I get consistent readings with the plastigage showing .003/0035.

Thanks for the pointers everyone