TR2/3/3A TR2/3 Judson F/S

[cheseroo]

I have no idea who this is and have zero financial interest. Insert anything else applicable to show that I am running away from any involvement more than passing along what I have found on the local craigslist.

Judson supercharger for 2800 scoots

 

[TR4]

Not so much as an undersized image included in the listing?

OK, all I really want to do is window shop............Say supercharger and I snap my head in that general direction, and at $2800 large, they have us thinking it's in close to new condition?

 

[TR3driver]

Probably is in fairly good condition; most of them weren't used for long!

There were at least four substantial flaws in the design:

1) The ignition timing needs to be retarded while under boost, because the boost makes the mixture burn faster. The Judson setup had no provisions for this.

2) The vane-type blower used has pretty bad efficiency, which means that it both takes more power to produce the same amount of boost, and that extra power goes into heat, which winds up in the intake fuel/air.

3) The blower also requires that lubricating oil be mixed with the incoming fuel/air mixture. Oil decreases octane substantially.

4) The simple 1-bbl downdraft carb used had no power valve, and a tendency to go lean at high flow rates.

The quadruple whammy of too much timing, too much heat, not enough mixture and not enough octane leads to detonation, which can destroy the pistons in a matter of seconds. The setup can be made to work, but controlling detonation is paramount and many people didn't. Once the motor blew up (sometimes on the very first outing), the blower tended to get relegated to the shed.

Here's a little eye candy, though

 

[TR4]

Wow Randall, that sure is PERTY.

 

[glemon]

I remember reading about these in my early days of British cars and thinking it would be soooooo verrryyyy cooooool to have one. This was the late 70s early 80s, they were no longer available new, and there was no internet to help find them, or to share information like this about them either. I think one of the classic sports car mags tested one of these recently, maybe on a Sprite, the period ads said somthing like a 45% power increase, as I recall they did not get near that, maybe 20-30% don't remember exactly, but I do remember not as advertised, but nothing to sneeze at.

I have also read the the vanes were basically an oiled paper or cardboard type thing, and didn't last long. I still think it would be cool to have one, neat period accessory, the seemed to be popular for Spridgets and TRs, but they made them for a lot of other imports as well.

 

[TR3driver]

I have also read the the vanes were basically an oiled paper or cardboard type thing, and didn't last long.

I believe they were originally layers of fiberglass cloth impregnated with phenolic resin and pressed together (rather similar to a printed circuit board). From what I've heard, they hold up reasonably well as long as they are kept oiled. But the oiler needs to be refilled basically with every tank of gas, and wear is much more rapid if someone forgets to fill it.

Plus, when they get worn, they tend to disintegrate and wind up inside the engine ...

 

[newmexTR3]

I still have a Judson that my dad handed down to me. It was installed briefly on my 3 in the early 90's, but I lost a vane, and at that point it got relegated to storage. At that time it was hard to find someone knowledgeable about these units, much less find replacement parts.

With the good ol' internet though, I was able to find out about George Folchi ( Folchi Judson link ), who seems to be one, if not THE preeminent font of knowledge on Judsons.

I've been following prices on these units, and 2-3k is a fair price for them at this point, because of their rarity. 2k for a unit in okay shape up to 3+ for a rebuilt/refinished one.

Prices on the original Marvel Mystery oilers have gone up like crazy too. You can still buy new ones though, I"m pretty sure.

My Judson is sitting next my desk right now. I'd love to install it, but I hesitate because I'm afraid the car wouldn't be as reliable with it.

Randall- have you ever run one for an extended period of time? How about long haul road trips? How did it hold up?

 

[TR3driver]

Randall- have you ever run one for an extended period of time?

Nope, never run one at all. I've had one for quite a few years, but it is still in a box in the shed. My feeling, after all that I've read and heard, is that I would have to build a motor for the purpose (no oversize liners or higher compression ratio) and make some modifications to have a reliable setup (eg water injection and boost retard).

Still on my "bucket list", but probably not until at least after I retire.

If I were really just looking for more power instead of pursuing a neat period accessory, I would use a more modern blower, either a turbocharger or a Roots type with a priority valve. Moss should be announcing their TR3-4 blower kit soon, as they were showing it at TRfest a few weeks ago:

 

[6969ronin6969]

How did the Moss setup look/sound and most importantly, does it seem to be an add on that actually performs as intended and doesn't hurt reliability? Just looking for opinions because this is very tempting (albiet after I've saved up quite a few pennies).

 

[TR3driver]

How did the Moss setup look/sound and most importantly, does it seem to be an add on that actually performs as intended and doesn't hurt reliability?

It looked very professional, but that's all I know about it. I didn't hear or see the car run.

But their other blower kits seem to work out well. I helped a buddy install one on his Miata some 10 years ago, and it's still going. Maybe not quite as strong as it was, but with over 100,000 miles with the blower (and some 40,000 before that), it's not surprising that it's getting a little tired. I think he's adding one quart of oil between changes, which ain't bad at all.

ISTR someone mentioned that they were pretty happy with the Moss TR6 blower as well.