fuel pressure question - Page 3

kfickler · 10-06-2020, 07:15 PM

In my experience, the PE dead head regulators like a "bleed" to minimize the droop when you go from low demand (idle/2-step) to high demand (launch, etc.). Too low of input pressure from the pump will cause regulated pressure to creep. You want to maintain at least double your intended regulator pressure at the regulator inlet during high demand. Have you been able to check the pump pressure?

The PE bleed is a jetted orifice that allows the dead head regulator to always bypass fuel but still creates a system with higher pump pressure than regulated carb pressure. A simpler version of this used to be common: https://product-engr.net/collections...ulator-systems

True bypass systems such as many engineered by Aeromotive operate at the regulated carburetor pressure throughout the system.

Dissident · 10-06-2020, 08:03 PM

By definition, a regulator is not a dead head device as that would be a bubble tight valve. The regulator must be flowing some amount in order to be set correctly (see below).

By definition, a droop curve for a regulator is a plot of pressure vs flow. The weep system that you described is for A) controlling the creep of the regulator and B) has the regulator already regulating so it has a much more rapid response in applications such as N2O or other.

If I knew how to attach a plot of a series of various regulator droop curves I would do so, but I am at a loss on how to accomplish doing that with a big file.

Sufficient to say that some have drastically different curves.

Also to a previous post: Holley carbs with two needles and seats of 0.110" diameter have a working bowl volume of 0.066gal and a QJ has a working bowl volume of 0.022gal. The N&S of the QJ would have to be about 0.155" diameter to flow the same as the Holley as listed above......Not practical. 0.150" is common, but larger is pretty iffy.

Regards to All that like this kind of stuff,
HB2

Dissident

GTX JOHN · 10-06-2020, 11:50 PM

I think to bowl volume of my beloved Thermoquads is close to the Holley Dualfeeds?

rboyle · 10-07-2020, 10:23 AM

I used Aeromotive pump and Magnafuel regulator -10an return and vent and feed to regulator

jamie2370 · 10-07-2020, 10:33 AM

So far looks like it was the N/S in the carb, took it apart and cleaned everything. Tried the reg off our other stocker and it went right to 6.5. Put my Product Eng reg back on that was set as low as I could get it to 6. It was then at 3. So I was able to screw it in to get 6.5. Much better. No more trying to crank like the timing is too high lol. It cranks from outside the car now. Now to change the oil and hope my brand new total seal rings didn't get washed down....oh and fixed my cracked 200 that lost second gear and cost me a round win. Get you a Stocker....it'll be fun they said

10-06-2020, 07:15 PM	#21
kfickler Junior Member Join Date: Aug 2007 Posts: 29 Likes: 1 Liked 10 Times in 2 Posts	Re: fuel pressure question In my experience, the PE dead head regulators like a "bleed" to minimize the droop when you go from low demand (idle/2-step) to high demand (launch, etc.). Too low of input pressure from the pump will cause regulated pressure to creep. You want to maintain at least double your intended regulator pressure at the regulator inlet during high demand. Have you been able to check the pump pressure? The PE bleed is a jetted orifice that allows the dead head regulator to always bypass fuel but still creates a system with higher pump pressure than regulated carb pressure. A simpler version of this used to be common: https://product-engr.net/collections...ulator-systems True bypass systems such as many engineered by Aeromotive operate at the regulated carburetor pressure throughout the system. Last edited by kfickler; 10-06-2020 at 07:22 PM.

10-06-2020, 08:03 PM	#22
Dissident Member Join Date: Jan 2016 Location: Colorado hills Posts: 123 Likes: 11 Liked 73 Times in 36 Posts	Re: fuel pressure question By definition, a regulator is not a dead head device as that would be a bubble tight valve. The regulator must be flowing some amount in order to be set correctly (see below). By definition, a droop curve for a regulator is a plot of pressure vs flow. The weep system that you described is for A) controlling the creep of the regulator and B) has the regulator already regulating so it has a much more rapid response in applications such as N2O or other. If I knew how to attach a plot of a series of various regulator droop curves I would do so, but I am at a loss on how to accomplish doing that with a big file. Sufficient to say that some have drastically different curves. Also to a previous post: Holley carbs with two needles and seats of 0.110" diameter have a working bowl volume of 0.066gal and a QJ has a working bowl volume of 0.022gal. The N&S of the QJ would have to be about 0.155" diameter to flow the same as the Holley as listed above......Not practical. 0.150" is common, but larger is pretty iffy. Regards to All that like this kind of stuff, HB2 Dissident Last edited by Dissident; 10-06-2020 at 08:03 PM. Reason: spacing

10-06-2020, 11:50 PM	#23
GTX JOHN VIP Member Join Date: Jun 2009 Location: Boulder City, Nevada 89005 Posts: 2,528 Likes: 2,220 Liked 1,792 Times in 571 Posts	Re: fuel pressure question I think to bowl volume of my beloved Thermoquads is close to the Holley Dualfeeds? __________________ John Irving 741 Stock 741 Super Stock

10-07-2020, 10:23 AM	#24
rboyle Senior Member Join Date: Jan 2015 Posts: 582 Likes: 1,416 Liked 554 Times in 156 Posts	Re: fuel pressure question I used Aeromotive pump and Magnafuel regulator -10an return and vent and feed to regulator

10-07-2020, 10:33 AM	#25
jamie2370 Member Join Date: Dec 2014 Location: Perry, GA Posts: 329 Likes: 11 Liked 236 Times in 89 Posts	Re: fuel pressure question So far looks like it was the N/S in the carb, took it apart and cleaned everything. Tried the reg off our other stocker and it went right to 6.5. Put my Product Eng reg back on that was set as low as I could get it to 6. It was then at 3. So I was able to screw it in to get 6.5. Much better. No more trying to crank like the timing is too high lol. It cranks from outside the car now. Now to change the oil and hope my brand new total seal rings didn't get washed down....oh and fixed my cracked 200 that lost second gear and cost me a round win. Get you a Stocker....it'll be fun they said