late 40hp model dual relief case?

[Chickensoup]

hello, i have heard of people that have a late model 1200cc case with dual relief. are these the reproduction cases or did they actually come in vw's?

thanks

[Albertoprop17]

I've rebuilt a customer's 40hp engine and installed a 1400cc big bore kit on it, the case was a replacement one with dual relief.

That is the only one I saw
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[Slow 1200]

yes, they came from the factory during the 70s, they also had same cylinder register as 1300/1500/1600 cases, so basically they are exactly the same as any other dual relief case but with a "D" engine number

[Albertoprop17]

[PEPPE]

they are for the countries where 1200 have been sold after 1970. in italy they continue to sell them until 1986. there are in 87mm and 90mm register. most of them are with 10mm headstuds. some very late are also in 8mm

[Slow 1200]

I think the german cases changed to 90mm but the mexican ones went back to 87mm, or was it the other way around?

[Alex Juszczyk]

Hi all, a bit of technical advice would be greatly appreciated.

I have one of these dual relief cases on a project I’m restoring. It’s got a piston diameter of 77mm and a stroke of 64mm making it a 1200. Iv been looking to increase the cc as the gearbox it’s running is from a 1600gt with a very low final drive.

My real issue lies that the crank casing hole is 90mm+ and all the piston and sleeve sets Iv found are for a crank case hole of 87mm....

Any advice would be appreciated.

[grvwsic]

Here is a site with a 90mm casing diameter and 77mm piston.

https://aapistons.com/collections/piston-liner-kit...late-model


Also, I found this newer dual relief case at a swap meet a few years ago. It was originally 1200 with the 87mm case hole but I had machine work done to it
It's aside at the moment for a future 1679cc project

[Alex Juszczyk]

Hi grvwsic, thanks for the website listing.
Sadly that’s not what I’m looking for I wanted to increase the piston size from the 77mm that I already have (and was in that link) closer to the 1600cc mark to work better with the gearbox I have from a GT.
It says in that listing they will work with all 1600 late model cases, so surly I need to find some 1600 late model piston and cylinders where the case hole is 90mm? :s

[grvwsic]

Ok. All 1600, 1641, 1679, piston and liner set should work for you. They are all 90mm

[grvwsic]

Unless you are looking for the big bore set -83mm piston /90mm case hole. I don't have any info on that.

[brass gears]

I went through this on my ‘64. There is a difference between the wrist pin diameters. For the 77mm pistons, it’s 20mm and for the 85.5 mm pistons it’s 22mm. So, that wouldn’t work with the connecting rods.
40 hp connecting rods are wider than those of the 1600. They can be machined down to fit a 69mm crankshaft.
If I were to do it again, I might have gone with changing the crank
The Tom Wilson book on rebuilding VW engines explains that.

-Rob
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‘ 64 beetle

[grvwsic]

Yeah, I guess I didn't clearly understand the question. Is the request to get an upgrade in the size of the piston/cylinder bore that will also fit the 90mm case casing hole. If that's the question I have no info on that upgrade.

We do have that in the US with an 83mm 40hp big bore kit. But that works with the 87mm case casing hole.

For my own 1679cc project with the newer 40hp case, I completely agree with using a 69mm crankshaft.

[Alex Juszczyk]

Grvwsic; yeh increase from 1200 in that 90mm case

Rob; thanks there are some interesting points that you have brought to light!! Am I silly to think that the simplest way would be to machine the con rod to accept a 22mm pin and then it being thicker would surly be a bonus...? You wouldn’t happen to know if the gudgeon pins on the 83mm bore piston are 20/22mm I would much prefer to go at least 85.5

[Albertoprop17]

[brass gears]

[Albertoprop17]

[Alex Juszczyk]

Albertoprop17; I think you have hit the nail on the head!!!! Please have a look at the listing below, I haven’t seen any reference to this fitting on the 90mm case. I will contact to find out. But hopefully you have cracked it.

Brass gears; this idea of spacers or spigot rings has come up a couple of times. It couldn’t just be left to float but I think we are getting closer to an idea that might work for a while

[Albertoprop17]

https://aapistons.com/collections/piston-liner-kit...l-european

Here you have it, I think you can find them on your local aircooled shop
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[Alex Juszczyk]

Albertoprop17; you are an absolute gent!!!!

Thank you so much. Iv contacted loads of uk dealerships and it’s not a common product over here but I think Iv found one AA dealership so fingers crossed at the moment but it’s looking promising.

I’m assuming this is the simplest way to give the engine some extra “geegeez” to handle that gt box?