high comp pistons with stroker crank for 36hp

[esde]

I have a set of NOS Kolbenschmidt domed high compression 77mm pistons, and was wondering if they were feasible to run with a stroker crank. It feels like I should shelve them for another build, but I already own them..
I have a 69mm 36hp. crank from DPR, and some nice heads that are getting done with the Okrasa valves, and cut down 2mm. I know I could get 80mm, but I already own these..
My rough calculations say it would be 8.8:1, IF there wasn't any valve to piston interference.
Thoughts?

*edited for spelling
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modok wrote:
Bent cranks are silent but gather no moss. I mean, ah, something like that.

[Bub]

Why not build it? Sounds perfect to me.
Single port heads w/ Okrasa valves? Awesome. I'm running 8.5:1 w/ 40 hp big bore and it runs amazing, HOT but amazing.
Dual carbs with Some tall manifolds, light flywheel, the right cam and that is the perfect vintage speed build.
Not too technical or crazy, other than the p/c's that's the next build I'd like to do if I get to it.
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[esde]

[esde]

It's on!
parts are arriving, and I'm eager to mock it up.
One thing I am eager to see, is the piston to head clearance. I have to order the cam, but I should probably give them piston to head clearance, to lessen the chances of interference, right? It's tough to know what step to take first. I have a domed piston, protruding into a chamber that I intend to make smaller, and an (undecided) cam sticking the valves into this hypothetical space. In a perfect world, what order do I go about this? The cam will either come from Isky or Schneider
SD
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modok wrote:
Bent cranks are silent but gather no moss. I mean, ah, something like that.

[Alstrup]

Hang on. If you have not dived into the heads yet. Stop and re evaluate. - The sgl port heads do not need more exhaust valve. It flows well as it is. In fact the I/E ratio can be quite nice with the 33 mm intake, giving you a significantly better overall powerband..
Next. while the shimming of the cylinders etc is normal in this type of biulds you can minimize it by mirror machining the pistons. You can easily take away 1 mm on the outer diameter so that the piston protrudes into the chamber. This will reduce the need for shims.
8,8 CR with the stock cam is pushing it. I would stay below 8,5.
As for running hot. - Not necessarily. Swopping the fan to a 40 hp one will give you more cooling air at lower rpms. Another option is speeding up the factory fan with a 356 generator pulley. (I prefer the 40 hp fan swop)
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https://www.thesamba.com/vw/forum/viewtopic.php?t=435993

[esde]

[Alstrup]

OK. With more cam duration it is of course a different matter.
To be honest I have mainly done it when I needed more compression, like 9-1 or so. - Don´t think there is a lot of difference at the end of the day except that you will need less shims under the cylinders.

Isky & Schneider are of course also an option. I like the Elgin better.
With sgl port intakes you will be interested in conservative duratio and higher valve lift. The right thing to do was to have a split dur cam made for it. But I have only little experience in doing that with the 36 hp base.
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https://www.thesamba.com/vw/forum/viewtopic.php?t=435993

[esde]

Thanks Alstrup. Your advice is greatly appreciated
I'll update this as things come together
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modok wrote:
Bent cranks are silent but gather no moss. I mean, ah, something like that.

[Bub]

[Alstrup]

Personally I do not like copper shimming except when using Nikasil cylinders. There it can be beneficial. When using cast iron or biral barrels it is almost always the copper shims that give in and result in premature cylinder to head leakage. For this very reason I never use them, Porsche or VW.
Taking 1 to 1,5 mm out of the cylinder base and then use a copper shim between cylinder and head is counter productive. You get exactly the same result as if you kept a larger deck height in the cylinder because the copper shim will just release its heat where it can get rid of it which is mainly the cylinder since it is the coolest of the 2 surfaces.
If you want to improve it you can zero deck the cylinders and then step cut the heads so you have a perfect 40 to 43 thousands tolerance. Then you get the heads to work their best and the least temperature in the cylinders.
The next thing is oil. By using splashers or squirters to spray oil on the underside of the pistons as well as cylinder walls to keep them wet and oiled at all times will also contribute to removing heat and keep the piston well tempered.
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https://www.thesamba.com/vw/forum/viewtopic.php?t=435993