356/912 74mm counter weight crank in a 36hp case

[bialzi]

Hi has anyone used an AA performance counter weight 356/911 crank in a 36hp engine? Does the case need extra clearance for the counter weights? Has anyone got any pics? Thanks in advance Neil

[gimmesomeshelter]

You're biggest challenge is dealing with the 55mm mains used on the C/SC/912 cranks. Pre-A, A and B cranks used 50mm mains, so they can be run using 36HP bearings. If you go the C/SC/912 route, you have to install Porsche bearings ($$$).

Additionally, you'll need to do the following:

1) Align bore your case 1 over. All std 356 bearings have an outer diameter that's 1 over the size of a VW bearing.

2) Mill oil groove into case. The Porsche 55mm bearings are too thin to contain the oil groove, so it has to be milled into the case.

3) Mill bearing slots into the case. The bearing are held in place by little tabs instead of pins. You'll need to mill little slots into your case to accommodate the tabs.

If you go to a shop that does a lot of 356 work, they'll know what to do.

Cheers,

Paul
_________________
"I would rather have questions that can't be answered than answers that can't be questioned."

Richard Feynman

[bialzi]

Hi, Thanks for the reply. I have my case in the US now awaiting the bearing work etc and i already have the Porsche bearings but i am a bit worried about which crank to get as most of the engine builds use non the counter weighted cranks and once i buy a crank i'm stuck with my choice. The Scat crank in your picture is very nice but i'm going to get the cheaper AA crank. Are they any good? Thanks Neil

[Alstrup]

With the crank.
There is also the option of having DPR or Demello welding up a stock crank to 74 or even 76 mm stroke. I have had made a couple of those. Full circle, 76 mm stroke, Porsche rod journals. BUT on the 76 stroke I had to use H beam rods or I would not have had enough room for the cam and i would also need to clear the case more than I liked. The next stroker I will build will be with Yamaha or Honda motorcycle rod journals and rods, as they are much slimmer and requires less clearance inside the case.
I have recently begun building a 83 x 76 engine right now. (With Porsche biral cylinders.) The case is going out to Joe for chemical treatment when I have finished modding the case. Because this time I want to build an engine that both works well and looks as nice as Joe´s engines does.

T

[bialzi]

Hi, How do you fit the porsche birals? I have some og cast porsche 82.5mm barrels and pistons, the end that slips into the case is 90mm but that is right on the limit of the head stud thread. I was going to open the case up to 88mm and turn the barrel down to suit. Im also thinking about using case savers to offset the stud thread a mm at each corner. The studs are very tight on the barrels. I may have to machine some of the barrel away to allow the stud to pass. Which way do you prefer? Thanks Neil

[DHVW]

Great question, I'd like to know as well. Also, is there an advantage to using the Porsche p+cs rather than the 40hp big bore p+cs?

[gimmesomeshelter]

"How do you fit the porsche birals? I have some og cast porsche 82.5mm barrels and pistons, the end that slips into the case is 90mm but that is right on the limit of the head stud thread. I was going to open the case up to 88mm and turn the barrel down to suit. Im also thinking about using case savers to offset the stud thread a mm at each corner. The studs are very tight on the barrels. I may have to machine some of the barrel away to allow the stud to pass."

Porsche, like VW, changed the stud spacing over the years. When I had my Nickies made up, had Charles take a set of Pre-A 80mm barrels and modify them to take 82.5mm pistons and fit a VW head.

Other people have done what you're doing, but it takes some machine work to make everything fit.

BTW, where did you send your case for machine work?

Cheers,

Paul
_________________
"I would rather have questions that can't be answered than answers that can't be questioned."

Richard Feynman

[Mr. Okrasa]

Hi Paul.
Here's a photo that I posted on theSamba over 9 years ago about using 912 liners and modifying them to fit the 36hp block.
The bore is: 83.50mm and the stud pattern was moved over so they would slide through the headstuds.
It was too cost prohibitive for making them to sell so I shelved the idea. Cheers! Mr. Okrasa

_________________


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[DHVW]

Are the Porsche cylinders better than the 83mm VW cylinders?

[Mr. Okrasa]

[Alstrup]

I basically do as Joe refers to further up. - I move the studs 2 mm out in a "star" pattern. Then I use 8 mm head studs. This way I get no clearance issues at the cylinderhead side. The relocation of the studs is not the bad boy cost wise, the new 8 mm studs are.
T

[DHVW]

Are custom studs necessary (e.g. Raceware?)

[Mr. Okrasa]

[Alstrup]

I used custom studs, and they were expensive. I might try and see if I can make it work with type 1 stuff nex time. I have not looked into it at all yet. So no idea if it is possible.

t