Could use some help diagnosing a problem
- Thread starter dan juhasz
- Start date
If anything pressure would flood the bowls. Just something to eliminate. I don't think it is the root cause here. A regulator should do it. If the worked before it should still be fine. I run 9.0@150 on 6 psi with AFB carbs.
Doug
Doug
I ordered a Holley regulator with gauge will hook it up this weekend. Is it ok on dual quads to just use one regulator for both carbs?
tonysrt
Well-Known Member
Yes it is because that is the setup I'm using right now. 1 regulator for the dual Quads on my Hemi. I run about 6 psi from the regulator because I have an electric pump in the tank for the Fitech I was running before it quit on me and left me stranded. Trouble shooting after market F.I. is a major problem now.
lewtot184
Well-Known Member
not if your using one of those cheapo $25 holley type regulators. those small cheapos only have a .210" flow orifice.
lewtot184
Well-Known Member
the cheapo are supposed to be one for each carb. they're really designed for small stuff but can be used in multi carb by using multiples. if your looking for stock appearing the factory vapor separater with return line looks correct and does work. i'm not a "regulator" guy for things that are driven using a pulse pump. if the engine is stock or near stock a carter 6903 pump is an easy way out.
Another thought my heat riser valve is balky, not smooth in its operation. Question is in what position is it open , I’m just wondering if it could be related to the issue I’m having. Is it open clockwise or counter clockwise?
Dragon Slayer
Well-Known Member
I do not think it is fuel pressure either. It runs fine at lower RPM right? Lower RPM is when too much pressure might causes issues.
The Hemi spec is 7 to 81/2 psi and it is measured at the inlet of the carb, so the vapor separator is in the circuit. So any pressure drop is already accounted for. It also should be measured with a 6" max rise above carb inlet. Frankly it may be the fuel pump. How long did it sit. May be a volume issue. You should be getting a quart a minute at 500 rpm.
When you shut the motor down, how fast does the pressure drop off. When needle is closed the pump pressure should drop slowly or the check valve is leaking excessively in the pump and your not getting your volume out.
The Hemi spec is 7 to 81/2 psi and it is measured at the inlet of the carb, so the vapor separator is in the circuit. So any pressure drop is already accounted for. It also should be measured with a 6" max rise above carb inlet. Frankly it may be the fuel pump. How long did it sit. May be a volume issue. You should be getting a quart a minute at 500 rpm.
When you shut the motor down, how fast does the pressure drop off. When needle is closed the pump pressure should drop slowly or the check valve is leaking excessively in the pump and your not getting your volume out.
I ordered a pump , I'll see what happens.
Found my problem today with the help of it breaking down on a test run. Turns out the coil had a crack in the ceramic area by the negative terminal post, it was leaking a little oil also . I guess it was failing and causing erratic ignition first at high rpm until today when it conked out and stayed that way long enough to do a quick roadside diagnosis. I wiggled the terminal a little it started back up so I could limp it home. I would have bet it was fuel related but I was wrong. I'm just happy it happened close to the house, had an old coil at home popped it in went for another road test and now it runs as I always remember. That car gets your blood flowing 
Dragon Slayer
Well-Known Member
Glad you got it. I was going to ask about the electronic set up as I have seen the box fail at higher rpm, but I assume it was the same set up used as before other than distributor.
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