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plastic gage specs on rod journals
Sick68VW - June 15th, 2007 at 07:12 PM

hey all just mocking up the bottom end and checked the rod clearence with a plastic gage but cant find the spec anywhere in my book i want to know if they are in spec here they are
num1 .038mm
num2 .051mm
num3 .076mm
num4 .0.76mm

im not jst a bit suss about number 1 as it seems very different to the others. anyone know thanks

dangerous - June 16th, 2007 at 06:52 AM

Hi Stephen,
Those sizes are within spec and wear limit.
My books say .03mm to .09mm.....BUT!

Generally you would want to have less than .075 and at least .05 for a performance application.

Numbers 2 to 4 will be fine, but number 1 is a little tight.

Plastigage is a good check, but try it again because you may have squeezed out the plastigage a bit when removing the cap.(thus indicating less than actual clearance)

If in doubt,the number 1 rod journal or rod tunnel in case it is in error.

Good man for checking clearances, most people don't and think 'she'll be right'.

Sick68VW - June 16th, 2007 at 01:02 PM

Thanks dave for the info i rechecked the clearence on number 1 and found it to be .076 so i am know happy and i can start to put the bottom end together .I would rather spend the extra hour of rechecking things then more money and time if something go's wrong. Do it once do it propley thats what i belive.:thumb

StephenM - June 17th, 2007 at 06:35 PM

Where did you learn about building engines. I'm thinking about doing a tafe course. What do you think?

Sick68VW - June 17th, 2007 at 10:59 PM

I use to work in a vw workshop in sydney and learnt a lot in my time and now i try and do eventhing myself. yeah it would be worth doing a course at tafe its always good to learn new things i learn somthing new eveyday.

dangerous - June 18th, 2007 at 05:21 AM

I also learn something new every day, and I got into volksies in 1983.

Wish i could learn how to understand chicks, somethings cant be learnt.

vw54 - June 18th, 2007 at 07:09 AM

Quote:

Wish i could learn how to understand chicks, somethings cant be learnt.



yep that 4 sure

fullnoise - June 18th, 2007 at 09:05 AM

I tried the plasti-gauge but I couldn't do it without moving the rod and smearing the Plasti-gauge. Some tips on how to do a successful measurement would be appreciated. Thanks

CT

66deluxe - June 18th, 2007 at 12:14 PM

Quote:
Originally posted by fullnoise
I tried the plasti-gauge but I couldn't do it without moving the rod and smearing the Plasti-gauge. Some tips on how to do a successful measurement would be appreciated. Thanks

CT



Ct, i just lay the crank on the bench and lay the plastigage across the journal then very carefully mate the rod cap to the rod, then slowly torque the rods first to 15 ft lbs then in increments of 5 ftlbs till i get to 25 to 30 ft lbs depends on which rods you are using. while i torque the rods i have one hand on the crank and rod holding both still, and torque with the other hand. It takes me about 10 minutes per rod. then once both bolts are torqued, i dissasemble slowly, and with a soft tap with a soft face hammer i pop the cap off. It takes time but worth it. i got three sizes of plastigage from repco @ $2 a pack. Damo.

dangerous - June 18th, 2007 at 05:06 PM

You have to be careful with anny tapping of the caps that it does not squash the plastigage
and give a wider reading (and therefore less clearance reading) .

When doing the check, the journal and beaing must be dry,
and the plastigage in the centre of the bearing semi-circle.
Most bearings actually have more clearance built into them as you get near the parting edge.
It is designed into the bearing as an oil wedge
to hold the bearing away from the journal in dynamic operation.

What ever method you use, try it twice to see if you can get repeatable results.

fullnoise - June 18th, 2007 at 06:42 PM

Thanks for the tips guys.

I think this will take a bit of practice. At least now I know it can be done.

A weak excuse to build another engine none the less.

Regards