Judson problem

[64 ghia]

Installed a rebuilt Judson on a rebuilt 40 horse engine. Ran engine for about three hours total on test stand before installing the Judson. Ran great. 110 +/- 4lbs compression. Everything was rebuilt to spec on engine and the Judson rebuilt with new seals, bearings, and vanes. After installing the Judson it ran as expected at idle up to about half throttle but past that it runs like it has a governor. The engine is all stock except for 010 distributor (rebuilt), header, and the Judson mag/coil. The carb main jet is 122.5. Set static timing at 7.5 advance. Tried adding advance in small increments since I couldn't get rpm high enough to properly set for the 010. The added timing had little to no effect. This is my first Judson build. Am I missing something? Any suggestions?
Thanks

[Bub]

Actually TOO MUCH advance can cause that problem. When you start firing the plug too far ahead of TDC you will feel an effect like a governor.
Not saying that's your issue, but start from scratch with timing.

Do you have the correct size pulleys for the Judson? It's tuned for certain boost per specific RPM, and I'd think wouldn't take much of s discrepancy to throw it all out of wack.
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[Ojai63dbl]

I thought judson needed a 135 main jet on a PICT28 for 40hp application to get enough fuel. Ill try to find it in the archives, but someone will be along shortly Im sure to correct me

here is one reference to 135, but I think people run up to 140
https://www.thesamba.com/vw/forum/viewtopic.php?t=512713&highlight=judson+jet

[64 ghia]

I'll get a larger main jet to try.
Thanks

[64 ghia]

I'll try backing that timing off a little bit. I do have the original Jetson pulleys on. Thanks

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Don't you guys also have to eliminate the choke for judsons superchargers remember reading this some where ....

[RolandD]

What does your boost gauge tell you?

Roland

[steven wardlaw]

Were the slots in the rotor in good shape? When I first installed my Judson it ran about like yours because it didn't produce any true boost pressure. I ended up having to replace the rotor and that made all the difference. You will have to adjust the main jet to allow more fuel and that can be judged by checking the spark plug color and it runs.

[64 ghia]

Thanks everyone for your suggestions. Turns out the problem was the vane hub was not properly oriented to the housing. Thanks to George Folci for sharing his knowledge.

[64 ghia]

Sorry but I left the "h" out of Mr Folchi's last name.