Aby bottom end rebuild, plastigauge?

[cquattropower]

Ok guys need some help here. I have a Aby bottom end I have bought new rods from Aron or is Aran, anyway, forged rods, new genuine piston rings, new dual layer sump gasket with new bolts a set of better condition pistons and now I am trying to put it all back together, but a friend of mine said , STOP!! have you used plastigauge. My answer, what??? now I know what is is, does everyone on here use this to rebuild their engines? I have seen that you put the putty stuff on the crank and then screw the end cap of the rod back on torqued properly (anyone know what the proper setting is?) then you remove and see the space compared to a card that you get with it. This tells you what space you have between the rod and the crank, i.e is there enough space for oil to flow properly. If anyone has any advice on this it would be great, as I would like to finish rebuilding this engine before the end of the year. A quick 1 year project is turning into a 3 year project and even that is being hopefull.

[mcandmar]

Unless you had the crank repaired/remachined there is no real reason to do this. Assuming your crank is second hand it will have worn and therefore increase the oil clearance between the bearings. Not a lot you can do about that, and not worth correcting unless the bearing surfaces are badly scored or pitted. Having said that i measured mine out of curiosity, and as i expected each one had a small amount of wear but well within the weat limits listed in the workshop manual.

It IS worth doing for rods if your fitting after market components, just for peace of mind more than anything else. I measured my SPM rods just incase they were too tight.

[cquattropower]

Pink

So what exactly am I measuring? Is it the width of what is left on the crank? Does it come off or do you just leave it on there? Do you put just a little on?

[mcandmar]

Instructions come with it

In short you get lube and strings of the red plastigauge stuff. Put a layer of the lube on the crank and bearing to prevent the plastigauge from sticking to it, then carefully lay a piece of the plastigauge across the crank, fit the bearing cap and torque it up.

Remove the bearing cap again and the plastiguage will be spread out flat as per the pics, then you measure the width of the plastigauge against the card provided to work out what the clearance is.

Couple of things to note, i dont know if the stock crank bolts can be reused, i'm using the ARP stud kit so that wasnt a concern. And you have to be very careful not to rotate the crank during the process.

[JP]

Don't ever use plastigauge with lube as it will give incorrect tolerances. The plastigauge dissolves in oil so it is very easy to clean of the crank journals and it doesn't tend to stick to a fresh set of bearings anyway.

When using plastigauge you are checking for three things.

1) That the journal of the crank hasn't worn so far that the oil tolerance is too great. Ideal 3-4thou not ideal 7thou+
2) that the journals are worn evenly i.e. same clearance across the width
3) that the journals are round. if not they'll need repolishing.

hth

[cquattropower]

Wow thanks for that guys. Lots to watch out for then. Will hopefully get some next week and try it next weekend. Does anyone know what torque setting I should go to on my torque wrench?