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Discussion Starter · #1 ·
383 sbc using a mech.fuel pump,with Mallory regulator (set @ 7 1/2)I have the lines under the hood covered with heat tubing.It seems that ONLY when the temps on the street get to around 190,( and this is on real hot days) and I stop for a traffic light, then start again,the psi starts to rise upwards to 10 -11 sometimes 12 psi and does not come down only when I shut down the car does it drop,and that takes awhile also.

What could be the problem,and how can I fix it? Thanx for any help
 

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Is the regulator atmospheric reference port blocked off ?


383 sbc using a mech.fuel pump,with Mallory regulator (set @ 7 1/2)I have the lines under the hood covered with heat tubing.It seems that ONLY when the temps on the street get to around 190,( and this is on real hot days) and I stop for a traffic light, then start again,the psi starts to rise upwards to 10 -11 sometimes 12 psi and does not come down only when I shut down the car does it drop,and that takes awhile also.

What could be the problem,and how can I fix it? Thanx for any help
 

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It has to have some sort of vacume/reference port or it would be alttitude incapable. Maybe that is the problem. The port is blocked or missing.

This particular reg does note have one. It is just a 2 outlet 1 inlet Mallory.
 

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Discussion Starter · #5 ·
The unit I have is a Mallory 4207.It DOES not have a vacume port as do some of the efi units have.It has a 1/4' npt that is being used for the fuel psi gauge that runs to a isolator then into the car
 

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oh its a dead head style. Thats the whole problem. The only option you have is to put in a bleed or change to a return style regulator.
 

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Discussion Starter · #7 ·
Now we're getting somewhere.When you refer to a "bleed" are you refering to the small brass nipple on some regulators? if so,were does this connect to? Thank you for the help
 

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Well you use a -3 fitting the AN end cut down to fit a Nitrous jet and put a return line on the -3 fitting with the jet in it and run it back to the tank or pump inlet line. This will get the excess pressure off the regulator. You put it between the Output of the regulator and the carburator.

There are tons of tutorials on this availbe. I would think something as small as 0.015 would be plenty big enough to get the extra pressure off. the pump will like you more to.

The other option is to take that POS regulator put it on Ebay and get a return style 3 port regulator and fix it the right way.
 

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Discussion Starter · #9 ·
Thanx much.I have a stock tank with a nipple the same size I think as the type you are describing.Think it's a quick fix untill I get one with a return outlet.............
 
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