Fuel pressure/needle size?
#2598867
12/30/18 05:15 PM
12/30/18 05:15 PM
|
Joined: Jan 2003
Posts: 20,179
Park Forest, IL
slantzilla
OP
Too Many Posts
|
OP
Too Many Posts
Joined: Jan 2003
Posts: 20,179
Park Forest, IL
|
I am intersted in the idea of lowering fuel pressure and putting in bigger needle/seat assemblies. Question is, how big should I go? I have a 600 DP and am at 6 psi now with .110 needles. I want to drop it to 4 psi. Thanks! 
"Everybody funny, now you funny too."
|
|
|
Re: Fuel pressure/needle size?
[Re: slantzilla]
#2598914
12/30/18 07:25 PM
12/30/18 07:25 PM
|
Joined: Feb 2005
Posts: 4,313
Prospect, PA
BSB67
master
|
master
Joined: Feb 2005
Posts: 4,313
Prospect, PA
|
I am intersted in the idea of lowering fuel pressure and putting in bigger needle/seat assemblies. Question is, how big should I go? I have a 600 DP and am at 6 psi now with .110 needles. I want to drop it to 4 psi. Thanks! In theory your flow rate will stay the same with inversely proportional changes between pressure and cross sectional area. Assuming my phone math is correct, that would be a theoretical 0.127" N&S, or a 0.130" Holley N&S.
|
|
|
Re: Fuel pressure/needle size?
[Re: slantzilla]
#2598935
12/30/18 08:13 PM
12/30/18 08:13 PM
|
Joined: Jan 2003
Posts: 20,179
Park Forest, IL
slantzilla
OP
Too Many Posts
|
OP
Too Many Posts
Joined: Jan 2003
Posts: 20,179
Park Forest, IL
|
I suspected I would probably be fine with .110" needles, but figured I would ask. I'm lucky if I'm making 300 at the crank. Thanks!
"Everybody funny, now you funny too."
|
|
|
Re: Fuel pressure/needle size?
[Re: slantzilla]
#2598991
12/30/18 11:16 PM
12/30/18 11:16 PM
|
Joined: Sep 2014
Posts: 4,457
Washington
madscientist
master
|
master
Joined: Sep 2014
Posts: 4,457
Washington
|
You need to call BLP and ask about their bottom feed needle and seats.
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
|
|
|
Re: Fuel pressure/needle size?
[Re: slantzilla]
#2599015
12/31/18 12:02 AM
12/31/18 12:02 AM
|
Joined: Aug 2003
Posts: 43,180
Bend,OR USA
Cab_Burge
I Win
|
I Win
Joined: Aug 2003
Posts: 43,180
Bend,OR USA
|
I am intersted in the idea of lowering fuel pressure and putting in bigger needle/seat assemblies. Question is, how big should I go? I have a 600 DP and am at 6 psi now with .110 needles. I want to drop it to 4 psi. Thanks! Please explain to me why you want to lower the pressure with those size needles and seats? I use to turn the pressure up until it would force the needles and seats open with the motor running and then back it down around a 1/2 Lb. on all my old race cars on gasoline  That was around 9.5 to 11.0 lbs. depending on the carb, fuel pressure gauge and regulator  On my current E85 Dominator carb. with .130 stainless needles and seats I didn't see any performance loss or gain going from 7.0 lbs. down to 5.5 lbs.  Volume and pressure are two different measurements but I'm a firm believer in pushing the fuel into the carb. with enough volume and pressure to keep the jets submerge in enough fuel to not run the motor lean in the 1/4 mile
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
|
|
|
Re: Fuel pressure/needle size?
[Re: BSB67]
#2599041
12/31/18 01:29 AM
12/31/18 01:29 AM
|
Joined: Sep 2014
Posts: 4,457
Washington
madscientist
master
|
master
Joined: Sep 2014
Posts: 4,457
Washington
|
I am intersted in the idea of lowering fuel pressure and putting in bigger needle/seat assemblies. Question is, how big should I go? I have a 600 DP and am at 6 psi now with .110 needles. I want to drop it to 4 psi. Thanks! In theory your flow rate will stay the same with inversely proportional changes between pressure and cross sectional area. Assuming my phone math is correct, that would be a theoretical 0.127" N&S, or a 0.130" Holley N&S. It's not a flow gain per se. It's a flow quality gain. And it's fairly big.
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
|
|
|
Re: Fuel pressure/needle size?
[Re: Cab_Burge]
#2599042
12/31/18 01:32 AM
12/31/18 01:32 AM
|
Joined: Sep 2014
Posts: 4,457
Washington
madscientist
master
|
master
Joined: Sep 2014
Posts: 4,457
Washington
|
I am intersted in the idea of lowering fuel pressure and putting in bigger needle/seat assemblies. Question is, how big should I go? I have a 600 DP and am at 6 psi now with .110 needles. I want to drop it to 4 psi. Thanks! Please explain to me why you want to lower the pressure with those size needles and seats? I use to turn the pressure up until it would force the needles and seats open with the motor running and then back it down around a 1/2 Lb. on all my old race cars on gasoline That was around 9.5 to 11.0 lbs. depending on the carb, fuel pressure gauge and regulator On my current E85 Dominator carb. with .130 stainless needles and seats I didn't see any performance loss or gain going from 7.0 lbs. down to 5.5 lbs. Volume and pressure are two different measurements but I'm a firm believer in pushing the fuel into the carb. with enough volume and pressure to keep the jets submerge in enough fuel to not run the motor lean in the 1/4 mile You can force fuel into the bowls and foam the [censored] out of it. Foam is bad. We are in the 21st century. There are new designs for things. Needles and seats are one of them. I agree with the OP. Bigger, better needles and seats with lower pressure is a win win deal every day. The bottom feed needle and seats are a simple upgrade, but you need to let the carb guy pick the size and not guess.
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
|
|
|
Re: Fuel pressure/needle size?
[Re: slantzilla]
#2599059
12/31/18 02:18 AM
12/31/18 02:18 AM
|
Joined: Jan 2003
Posts: 20,179
Park Forest, IL
slantzilla
OP
Too Many Posts
|
OP
Too Many Posts
Joined: Jan 2003
Posts: 20,179
Park Forest, IL
|
Correct, I am wanting to avoid fuel aeration. It may or may not be happening now, but I figure lowering pressure will make life easier on the pump and such.
"Everybody funny, now you funny too."
|
|
|
Re: Fuel pressure/needle size?
[Re: slantzilla]
#2599182
12/31/18 01:28 PM
12/31/18 01:28 PM
|
Joined: Jan 2003
Posts: 20,179
Park Forest, IL
slantzilla
OP
Too Many Posts
|
OP
Too Many Posts
Joined: Jan 2003
Posts: 20,179
Park Forest, IL
|
No, but I have the carb off and home now. Was just going to do this while it's apart anyway.
"Everybody funny, now you funny too."
|
|
|
Re: Fuel pressure/needle size?
[Re: slantzilla]
#2599360
12/31/18 06:55 PM
12/31/18 06:55 PM
|
Joined: Jan 2003
Posts: 20,179
Park Forest, IL
slantzilla
OP
Too Many Posts
|
OP
Too Many Posts
Joined: Jan 2003
Posts: 20,179
Park Forest, IL
|
Thanks all! Got some .120" BLP's on the way. It may be overkill on my turd, but they can't hurt anything either. Dennis
"Everybody funny, now you funny too."
|
|
|
|
|
: you're good to swap the standard .110" for .120" bottom feeders and run them at 5.5-6 psi. I don't think there's a huge fuel flow increase w/ the bottom feeders, but you can get the advantage of reduced foaming from that design, in addition to not having to run high pressure.