🚀 go-pugleaf

In article <LARRY.93Jan5132642@rock.psl.nmsu.edu> larry@rock.psl.nmsu.edu (Evil Engineer doin' it the Cowboy Way) writes:
>>>>>> On Tue, 5 Jan 1993 13:06:38 GMT, wwebster@bnr.ca (Bill Webster)
>Bill> said: Okay. I'll bite.  What is a "stuffer" backplate and
>Bill> where do you purchase them?  I expect it's a new backplate
>Bill> to decrease crankcase volume, thus increase crankcase
>Bill> pressure.

I've heard that this was one of the secrets to running a Fox Stunt. It
was partly crankcase volume but the other problem was that the conrod 
had a lot of forward-backward play. I forget the person who came up with
the fix but it was a nylon face on the backplate. I suppose Teflon would
work better.

I had a Brat .28 that had an inordinate amount of this play, and it 
vibrated like crazy. It also blew its rod after a half dozen runs. Qua-
lity control was a problem with this brand of motors, as was frequent 
parts spec changes - comparing it with other Brat parts the piston webs
were thinner and the head of the rod was narrower and this led to a lot
of fore-aft play. If I knew what I were doing I could have put a piece 
of nylon sheet on the front of the backplate and made a "stuffer back-
plate".

>As far as I understand, that is precisely what it is. My information came
>from _Round & Round_, the Tulsa Glue Dobber's newsletter. Apparently there
>is also a special hemi-head version of the venerable Fox .35 available now
>too. (It must be custom machined..)

>I personally like the OS FP needle valves, with the spring and knob
>removed. They are fairly cheap ($5 - $6), available, and consistent
>quality. I had bad luck on the KK assembly on a Dixon-modified OS-40FPS 
>once and have never messed with one since, although they appear to be of
>fine quality. (They also require drilling the case, which ruins it for
>smaller diameter NVs..)

One thing I've gone to exclusively is the remote needle. This is easy to 
make: use an OS FP R/C NVA - fuel comes in off the side and comes out at
the end. I use it with bladder pressure but I'm sure it'll work with suc-
tion - OS used to sell a remote needle bracket for its engines that at-
tached to the backplate. You also got a replacement jet for the carb. In
either case you need to make sure there are no leaks - use a piece of
small fuel tubing over the needle. 

At the engine end you can drill and tap for a fuel nipple (eg. Du Bro's)
if you are using pressure or just use an old NVA with a broken needle in
it (or a needle opened wide, or seal off the needle end with solder).



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Iskandar Taib                          | The only thing worse than Peach ala
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