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Wed May 07, 2025 7:02 pm

Is there an acceptable cylinder Height variance ? Relating to the Head being able to still make a good seal across both cylinders. When dialing in my deck height I put a level across the tops of the cylinders and noticed about a .002 variance with a feeler gauge till the level had no rocking. So I measured the cylinders at 4 points around each base that touches the case and most had some variance of up to .002 . I had already surface plated the tops of the cylinders so I am assuming the variance is in the bases.

Do I take them to a machine shop and try and true the bases up?
It’s a stock motor build 1300cc
The case was decked at the machine shop when it was line bored.

Wed May 07, 2025 7:24 pm

Looks like you're checking the wrong ledge, should be 0 difference, never seen them very more then .002

Wed May 07, 2025 7:28 pm

Check your case decks first, if they are ok then move to cyl. finally head seats for cyl., all should be parallel.

Thu May 08, 2025 2:33 am

It is acceptable for the case surface to be .001 or .002" high in the middle when assembled with bearings. This is because the center bearing has a heavy interference fit.

I don't really know why people bolt down cylinders to measure them, I don't.
Sometimes you have to put a small 45 degree chamfer on the case bore to get them to sit flat. Maybe this is why?

Those look like 10mm studs, consider changing to 8mm

I don't panic, but look at this
https://www.thesamba.com/vw/forum/viewtopic.php?t=781058

Thu May 08, 2025 5:59 am

Thanks Modok, it does have 10mm studs with Case savers. I consider changing them to 8mm with case savers. But was concerned with the case all ready being decked that I may cause more issues removing and replacing the case savers and possibly not get the new ones to sit flush. With it being a pretty much stock 1300cc I thought the 10mm with savers would be ok?

Thu May 08, 2025 1:17 pm

This feels like the time for a stupid idea...

Could you take a couple pieces of thin-gauge solder placed 180* apart from each other on each cylinder top, torque it all together, pull the heads back off, and then mike the crushed solder pieces to see if the .002" variance remains?

The solder will reach a minimum crush thickness somewhere above zero, but it's the variance we're trying to solve. This would indicate if the variance goes away with full torque-down.

Or would that damage the head sealing surface?

Any other things I'm missing?

Thu May 08, 2025 5:57 pm

So it appears there is about a .004 difference across the deck of the case.

Thu May 08, 2025 10:24 pm

How straight is your level?

Fri May 09, 2025 6:05 am

jason wrote: How straight is your level?

Jason it’s not certified, but I ran it across my 4” thick marble surface plate with sandpaper all the way up to 2000 grit. So it bottom surface is a good straight edge.

Fri May 09, 2025 5:08 pm

Has the case ever been decked?

Fri May 09, 2025 5:14 pm

RWK wrote: Has the case ever been decked?

Yes, it was decked by the machine shop when they did the line bore. So I am guessing it was decked to the parting line and not the crankshaft bore.

Thanks

Fri May 09, 2025 7:32 pm

I'd suspect the milling machine that decked that case has a sad table.

Fri May 09, 2025 7:35 pm

modok wrote: I'd suspect the milling machine that decked that case has a sad table.

Yeah, probably have to get it redecked to correct the issue. To much time and money in to the project to not have it done correctly. Been a great learning experience. Just have to find someone that actually knows what there doing. Can’t trust everyone’s recommendations.

Fri May 09, 2025 7:41 pm

https://www.amazon.com/dp/B017CFWP58?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_3

Sat May 10, 2025 9:17 am

Maybe use a paper gasket under the barrel to make up for the difference?