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Posted by: finchmunoz Jul 31 2022, 07:23 PM

Any engine builder might help me with an advice…

I’m building my 78x96 engine and found an issue with the piston pin… my liner kit came with 24mm pins and the rods are 22mm.

Can I have the rods opened up to 24mm? Will it be safe? (I’m using a c55 cam - 7k rpm maximum). The machinist will end up reaming the rods taking out 1mm to allow the pins to fit

Your opinions will really help.

TIA
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Posted by: Montreal914 Jul 31 2022, 08:11 PM

You will actually need to bore out the connecting rod larger than 24mm since you should have a bushing in there. At this point, your rod will have been weaken a lot at the small end.

I would get the right pistons with 22mm wrist pin, such as the Keith Black for stroker.

Posted by: finchmunoz Jul 31 2022, 10:08 PM

QUOTE(Montreal914 @ Jul 31 2022, 06:11 PM)

You will actually need to bore out the connecting rod larger than 24mm since you should have a bushing in there. At this point, your rod will have been weaken a lot at the small end.

I would get the right pistons with 22mm wrist pin, such as the Keith Black for stroker.

Posted by: cgnj Aug 1 2022, 01:48 AM

I have a few questions before I toss my opinion.

Have you test fit your crank, cam & rods in the case?
What size are the rod journals?
How long are the rods?
What is the chamber volume?

Assuming that you have no clearance issues, I would use either KB stroker pistons, or JE pistons.
There is a big difference in the weight of 22mm pins compared to 24mm. I don't recall the difference, but I weighed both types on an analytical scale. Less rotating = free power.

Good Luck with the build.
http://www.europeanmotorworks.com/vw/type-4-pistons-cylinders.html

Posted by: ChrisFoley Aug 1 2022, 04:53 AM

Didn't the machinist tell you altering the rods that way was a bad idea?

Posted by: 930cabman Aug 1 2022, 05:40 AM

Find the correct pistons. I would not alter the rod's