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Engine basics => Engine set up tips => Topic started by: Dennis Toth on August 07, 2023, 01:23:17 PM
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Since SSW is no more and Len doesn't seem to be here, I was wondering if anyone knew the mods he did to the FP 35's that gave them the power he seemed to get from them?
Best, DennisT
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I picked this up from SSW years ago.
I always thought Leonard was very generous to provide so much detail.
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Id thought his blurb on the comercial site ( Stuka Stunt ) mentioned a ' Hemi Head ' . ? ( as well as the blocked bypass ) anyone got one ? .
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I believe that the hemi-head for FPs was a Bob Zambelli initiative.
Certainly, Matt, the head that I use on the FP 40 on the Cardinal and the one I sent you — but was lost by Australia Post — was to Bob's specification.
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They managed to loose a Gardner ABC FP 40 piston / liner set too . Tho I now believe it was taken off their hands by persons from north of the border / State Line . Some seem to be on the giggle juice , or been in the sun to long .If not both .
https://www.worthpoint.com/worthopedia/os-35-fp-len-neumann-stuka-stunt-l-1952906423
Theres one there with semi obliterated text / instructions .
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From reading that file, he completely blocked the boost port, decked the top of the case .010" to lower the exhaust port, cut the side transfers up .010", made a head with no squish band and the right compression ratio and ran a rather large venturi. Oh, and I recall something about aftermarket con rods? Did I miss anything? Not much of that can be done by the average Joe.
MM 8)
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Maybe the head was like this?
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Or maybe more like this?
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Dave, the heads I had modded here in Australia used the early spec.
I bought six Tower 40 heads and had them all modified to the early drawing about 16 years ago.
I installed one on a late (ABN) FP40 which runs as sweet as with the standard FP (3.5mm dia) NVA and the standard FP 20/25 (6.55mm dia) venturi.
I still have four more ready to install — with a NIB Tower 40 among the engines destined to see s new head.
I gave one to Matt (Air Ministry) and posted it to him in a little padded bag from Australia Post. It never turned up at his address about 100 miles from me. :-(
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The SSW aftermarket conrods were for the OS .35S (and .30S by default). I have no idea where they were made, but maybe Matt Newman would know who made them, and how many were made? I guess it's possible Henry did them?
I assume that Brian Gardner has his crew make rods that are similar, if not copies, of the SSW .35S conrod. I have a conversion kit, but haven't installed it yet. I think there's a rod in there, somewhere. D>K Steve
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Dave - the first generation (PDF) was my starting point. It worked well but something else needed to be done.
The hand sketch that incorporates the 5 degree upward angle of the squish band and breaking the sharp edge made a very noticeable difference. The break from fast four cycle to two cycle was more pronounced and seemed to be a bit more powerful. At least, that's how I perceived it.
Give it a try. I did this mod for a number of people and all feedback was positive.
I've done this on a quite a few engines including the Brodak 25, the FP 35 and 40, the LA 40 and 46, the Super Tiger stunt 35 (bushed case and baffle piston) and the K&B 40
Bob Z.
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Thanks for the clarifying information, Bob!
Dave