Carburetor pick-up relocation, help needed

Eastep

Eastep

True Classic
Hello all. Im needing help or possibly pointed to a tutorial on adding/relocating the fuel pick-up, in the carburetor. Several years ago while attending an autocross in Hershey, Steve H. suggested I do this mod, as a fuel starvation occurred in a long & tight sweeper; which absolutely killed what would have been, my best run of the day. I was emailed an outline of this mod, but it has since been lost. My V1.0 search skills are next to null, so any help is appreciated. Thanks.
 
If you have/can find a copy of the PBS "Project X1/9" race prep book, this mod is mentioned on pages 31-32. I'd scan the few paragraphs from my book for you, but my scanner is currently non-op. :(
 
Thanks, Jeff. I have an original PBS manual, but unfortunately, it is packed away in storage. Maybe Ill try to find it later today?? Thanks again.
 
I just read the PBS book online. It describes cutting the bottom of the float to prevent sloshed fuel from forcing the needle closed. The info on modifying the super-jet pickup port is on the Mirafiori web page under PBS Fiat X1/9-128 racing modifications. I need to do both of these for my Yugo as it completely dies coming out of the corner.
 
fyremanbill said:
I just read the PBS book online. It describes cutting the bottom of the float to prevent sloshed fuel from forcing the needle closed. The info on modifying the super-jet pickup port is on the Mirafiori web page under PBS Fiat X1/9-128 racing modifications. I need to do both of these for my Yugo as it completely dies coming out of the corner.
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Thanks for pointing me, that way.I will check Mirafiori. My PBS manual is burried in the depths of storage, and Im not too keen on looking for it, a.t.m.
 
I had the same problem at autocross and found I had too much fuel due to sloshing.
I lowered the float level some and that fixed the problem.
Before that, I looked at the PBS mods and tried to do the little snorkel, but found it too difficult to do with normal tools.
But this was 20 years ago...
 
Ulix said:
I had the same problem at autocross and found I had too much fuel due to sloshing.
I lowered the float level some and that fixed the problem.
Before that, I looked at the PBS mods and tried to do the little snorkel, but found it too difficult to do with normal tools.
But this was 20 years ago...
Click to expand...
Im still having issues, finding said PBS mod, info. I looked on Mirafiori, but its only the second time Ive visited the site, and no luck.
 
Eastep said:
Im still having issues, finding said PBS mod, info. I looked on Mirafiori, but its only the second time Ive visited the site, and no luck.
Click to expand...

This is from a short pamphlet published by PBS on the Mira site.

"Either the stock 32mm carburetor or the 34 DMTR can have the venturis bored to improve high speed breathing. The Project X1/9 book, written by PBS for Fiat, details these modifications for production class racing. One design problem which these carburetors have is that the super-jet, high-speed-enrichment-circuit, pickup port is located high enough in the float bowl that the fuel level drops below it during hard left-hand corners. This causes the carburetor to go lean when the secondary is open. One way to solve this problem is to install a pickup tube, into this port, which extends down to the bottom of the float bowl. This tube can be bent up from 1/8" O.D. copper tubing and filed down to fit snugly in the pickup port. The copper tube can be epoxied in place with a filled, slow curing epoxy such as Devcon plastic aluminum."

https://www.mirafiori.com/pbs/pbssohc.html

Source for the complete PBS book: https://www.scribd.com/doc/194781504/Project-x19-Pbs
 
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And the related segment from the "Project X1/9" book (PBS) reads:

"To minimize fuel starvation problems during cornering, the floats should be cut off at an angle on the outboard lower corners. Cut them off from the mold parting line, on the outboard surface, to about 5/16" from the inboard lower corner."

It also states the "super jet" problem only applies to the 32DMTR carb; "The 34DMTR comes with a blank (undrilled) air bleed jet and a large fuel jet. This enrichens the mixture at the top end when the superjet comes in."

For me, without having the carbs to examine directly, some of this is a little vague. The book isn't the best documentation I've seen, but has lots of great info.
 
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Thanks fellas. I just so happen to have all the materials, leftover from a model airplane I scratch built
 
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