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64 ghia Samba Member
Joined: January 29, 2008 Posts: 29 Location: Greenwood, AR
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Posted: Tue Apr 04, 2023 3:19 pm Post subject: Judson problem |
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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?
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Bub Samba Member
Joined: June 10, 2004 Posts: 1151 Location: Central Washington
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Posted: Tue Apr 04, 2023 5:21 pm Post subject: Re: Judson problem |
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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. _________________
hitest wrote: |
Had a girlfriend once who shall we say, nearly arrived at the mere sight of a semaphore in action- easy to please she was... |
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Ojai63dbl Samba Member
Joined: March 12, 2007 Posts: 452
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Posted: Tue Apr 04, 2023 7:38 pm Post subject: Re: Judson problem |
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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 |
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64 ghia Samba Member
Joined: January 29, 2008 Posts: 29 Location: Greenwood, AR
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Posted: Wed Apr 05, 2023 5:45 am Post subject: Re: Judson problem |
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I'll get a larger main jet to try.
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64 ghia Samba Member
Joined: January 29, 2008 Posts: 29 Location: Greenwood, AR
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Posted: Wed Apr 05, 2023 5:47 am Post subject: Re: Judson problem |
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I'll try backing that timing off a little bit. I do have the original Jetson pulleys on. Thanks |
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[email protected] Samba Member
Joined: June 24, 2015 Posts: 718 Location: Rialto. CA
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Posted: Wed Apr 05, 2023 7:50 am Post subject: Re: Judson problem |
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Don't you guys also have to eliminate the choke for judsons superchargers remember reading this some where .... |
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RolandD Samba Member
Joined: January 15, 2017 Posts: 247 Location: Menomonee Falls, Wis
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Posted: Wed Apr 05, 2023 7:40 pm Post subject: Re: Judson problem |
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What does your boost gauge tell you?
Roland |
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steven wardlaw Samba Member
Joined: January 13, 2012 Posts: 142
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Posted: Mon Apr 10, 2023 7:08 pm Post subject: Re: Judson problem |
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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. |
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64 ghia Samba Member
Joined: January 29, 2008 Posts: 29 Location: Greenwood, AR
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Posted: Thu Apr 13, 2023 4:26 pm Post subject: Re: Judson problem |
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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. |
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64 ghia Samba Member
Joined: January 29, 2008 Posts: 29 Location: Greenwood, AR
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Posted: Thu Apr 13, 2023 4:45 pm Post subject: Re: Judson problem |
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Sorry but I left the "h" out of Mr Folchi's last name. |
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