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DRR Trophy
posted
A friend has a 1/8 mile drag car. Nova, 555 inches,.700 roller, 10.5 compression, 4.10 gear, 32 tire, 1.8 straight cut glide, 8" ATI. 1000 gas carb. I talked him into going to alcohol and he purchased a new 950 Holley HP carb and it slowed by .1 any help? No other changes made. It slowed across the board, 60' through MPH. tried on 2 different tracks 3 weeks apart. Last outing removed power valve, dropped jetting 6 down on all 4 corners and slowedf by app. .02
 
Posts: 42 | Location: East Coast | Registered: February 25, 2010Reply With QuoteReport This Post
DRR Sportsman
posted Hide Post
Fuel starvation. In my estimation that 950 is way to small for that size engine. Did you use the same fuel system set up as the gas car? What size fuel pump? mechanical or electric? Line size from pump to regulator? to many unknowns to answer this question and correctly address the issue.
 
Posts: 700 | Location: At the beach | Registered: August 05, 2003Reply With QuoteReport This Post
DRR Top Comp
posted Hide Post
Move the tank to the front, or don't.
 
Posts: 9398 | Location: Madeira Beach Fl. | Registered: June 12, 2018Reply With QuoteReport This Post
DRR Pro
Picture of Brktracer
posted Hide Post
The 950 Holley has a 750 diameter Venturi. Compare the Venturi size.
Also, if the regulator is between the pump and carb, that’s another possibility- low fuel volume.


Matt Ward



 
Posts: 1394 | Location: South Carolina | Registered: March 20, 2004Reply With QuoteReport This Post
DRR Sportsman
posted Hide Post
I've run this same carburetor to 4.90s in the 1/8'

What kind of fuel pump (electric or belt drive)?
What fuel pressure regulator and how many?
Are you still using the stock bowls and .150 NS?
Do you have jet extensions on the back?
 
Posts: 477 | Location: here | Registered: February 12, 2006Reply With QuoteReport This Post
DRR Sportsman
posted Hide Post
Why did you install smaller jets especially after removing the power valve.
It's been said here hundreds of times, but:

Did it gain temperature during a run?
How much fuel did you use per pass?
Is it responsive off idle?
Are you milking the oil?
What water temp are you staging at?
What fuel pump? Electric or belt?
Cell location?
And on and on and on...

Just trying to help



Cool
 
Posts: 621 | Location: Atco, NJ | Registered: March 14, 2002Reply With QuoteReport This Post
DRR Top Comp
Picture of Curly1
posted Hide Post
quote:
Originally posted by M120:
Why did you install smaller jets especially after removing the power valve.
It's been said here hundreds of times, but:

Did it gain temperature during a run?
How much fuel did you use per pass?
Is it responsive off idle?
Are you milking the oil?
What water temp are you staging at?
What fuel pump? Electric or belt?
Cell location?
And on and on and on...

Just trying to help


All good questions there. It should pick up on alcohol. My guess is carb is too small. I would try a known good larger carb.


https://postimg.cc/gallery/np3zpruo/
"Dunning-Kruger Effect"
-a type of Cognitive bias where people with little expertise or ability assume they have superior expertise or ability. This overestimation occurs as a result of the fact that they do not have enough knowledge to know they don't have enough knowledge.

Before you argue with someone ask yourself, "Is this person mentally mature enough to grasp the concept of a different perspective?" If not there is no point to argue.

4X NE2 CHAMPION. 2020 TDRA NE2 Champion
 
Posts: 4069 | Location: United States of Texas | Registered: April 02, 2011Reply With QuoteReport This Post



DRR Trophy
posted Hide Post
quote:
Originally posted by maliciousintent:
Fuel starvation. In my estimation that 950 is way to small for that size engine. Did you use the same fuel system set up as the gas car? What size fuel pump? mechanical or electric? Line size from pump to regulator? to many unknowns to answer this question and correctly address the issue.


Ok, carb is small all will agree but this is a comparison from 1000 cfm gas to 950 carb on methanol. Fuel system is a new Holley compatible pump with a nice Aeromotive regulator, -8 line. This is not what is on mine but I have seen a SBC run 6.20"s with no problem and was quicker than when on gas.
 
Posts: 42 | Location: East Coast | Registered: February 25, 2010Reply With QuoteReport This Post
DRR Trophy
posted Hide Post
quote:
Originally posted by Mike Rietow:
Move the tank to the front, or don't.


Yes tank is in the rear..
 
Posts: 42 | Location: East Coast | Registered: February 25, 2010Reply With QuoteReport This Post
DRR Trophy
posted Hide Post
quote:
Originally posted by team:
I've run this same carburetor to 4.90s in the 1/8'

What kind of fuel pump (electric or belt drive)?
What fuel pressure regulator and how many?
Are you still using the stock bowls and .150 NS?
Do you have jet extensions on the back?


Yes, stock bowls and seats and jet extensions on back jets. All previous questions answered in above post.
 
Posts: 42 | Location: East Coast | Registered: February 25, 2010Reply With QuoteReport This Post
DRR Trophy
posted Hide Post
quote:
Originally posted by M120:
Why did you install smaller jets especially after removing the power valve.
It's been said here hundreds of times, but:

Did it gain temperature during a run?
How much fuel did you use per pass?
Is it responsive off idle?
Are you milking the oil?
..

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Smaller jets because he thought is was getting too much fuel.
It a noticeable amount more than my car which runs 5.7-5.8
Does not appear to gain much temp, only 160 when done but has a large radiator.
Responsive yes, milking oil no, electric new holley compatable pump, electric, cell in front.
What water temp are you staging at?
What fuel pump? Electric or belt?
Cell location?
And on and on and on...

Just trying to help
 
Posts: 42 | Location: East Coast | Registered: February 25, 2010Reply With QuoteReport This Post
DRR Trophy
posted Hide Post
I was thinking on the line of converter. Maybe not right with the 32 tire and 4.1 gear. The only reason I did not look at the pump/ furl system was because i know of a SBC running 6.2 with this same set up.
I was also wondering if the carb was junk!
 
Posts: 42 | Location: East Coast | Registered: February 25, 2010Reply With QuoteReport This Post
DRR Trophy
posted Hide Post
quote:
Originally posted by Curly1:
quote:
Originally posted by M120:
Why did you install smaller jets especially after removing the power valve.
It's been said here hundreds of times, but:

Did it gain temperature during a run?
How much fuel did you use per pass?
Is it responsive off idle?
Are you milking the oil?
What water temp are you staging at?
What fuel pump? Electric or belt?
Cell location?
And on and on and on...

Just trying to help


All good questions there. It should pick up on alcohol. My guess is carb is too small. I would try a known good larger carb.



160 temp but large radiator, A noticeable amount of furl difference compared to mine which runs 5.7-5.8, Yes responsive, no milking of oil, 140 / 150 stage, electric pump rear cell...
 
Posts: 42 | Location: East Coast | Registered: February 25, 2010Reply With QuoteReport This Post
DRR S/Pro
Picture of banjo
posted Hide Post
What is a holley compatiable fuel pump? What is that actually flow rate?

To what Matt said, i always like the regulator at the end of the system and let it bleed off pressure. The regulator is a restriction. With that said does it run though clean, or does it pop at all.


Bill Simpkins
74 Nova
SBC 406
3240 pounds
Speierracing heads

60 1.27 (10/16)
1/8 6.03@111 (10/16)
Best 9.87@131 on the rev limitor 1 Feb 2013


nova

quarterpanelview

wheelie

FTI Converter
www.speierracingheads.com

 
Posts: 1830 | Location: San Angelo | Registered: March 07, 2005Reply With QuoteReport This Post



DRR Sportsman
posted Hide Post
One of my cars has a 498 with a 850 holley on alky, bg 280 fuel pump (which IMO is undersized, but works). 7 psi of fuel pressure, and everything runs fine.

My good car has a 468 with a 950 holley, Magnafuel 500 pump, 7 psi of fuel pressure.

468 has 148 jets, 498 has 155 jets.
 
Posts: 664 | Location: UTD | Registered: September 25, 2019Reply With QuoteReport This Post
DRR Trophy
posted Hide Post
quote:
Originally posted by banjo:
What is a holley compatiable fuel pump? What is that actually flow rate?

To what Matt said, i always like the regulator at the end of the system and let it bleed off pressure. The regulator is a restriction. With that said does it run though clean, or does it pop at all.


140 GPA i think, runs clean and smooth, sounds good
 
Posts: 42 | Location: East Coast | Registered: February 25, 2010Reply With QuoteReport This Post
DRR Top Comp
Picture of Curly1
posted Hide Post
When I ran a carb I ran TWO Mallory Comp 250 pumps. Did it need that much? No, but I never starved it for fuel. My other car ran the large Aerospace Components pump.

Having the fuel cell up front is always better as gravity and G forces help feed the pump. Not an absolute requirement but having the pump in the rear and a relatively small pump may be part of the problem.


https://postimg.cc/gallery/np3zpruo/
"Dunning-Kruger Effect"
-a type of Cognitive bias where people with little expertise or ability assume they have superior expertise or ability. This overestimation occurs as a result of the fact that they do not have enough knowledge to know they don't have enough knowledge.

Before you argue with someone ask yourself, "Is this person mentally mature enough to grasp the concept of a different perspective?" If not there is no point to argue.

4X NE2 CHAMPION. 2020 TDRA NE2 Champion
 
Posts: 4069 | Location: United States of Texas | Registered: April 02, 2011Reply With QuoteReport This Post
DRR Top Comp
Picture of Curly1
posted Hide Post
I would add that with the Comp 140 pump it is marginal as is and if you have a deadhead regulator even worse. If your fuel lines are too small could be another problem.

I think he needs to look closely over his whole system. Alcohol uses much more fuel and if the fuel system was marginal on gas he is going to have problems on alcohol.

If you removed the power valve you should have went up on the jetting. I like to have the power valve in the front and only remove it from the rear because it can uncover on the launch.

From my experience if you have enough gear and stall converter you can not get too big a carb with in reason. Certainly think 950 is too small for a 555 even if the pump can feed the fuel.


https://postimg.cc/gallery/np3zpruo/
"Dunning-Kruger Effect"
-a type of Cognitive bias where people with little expertise or ability assume they have superior expertise or ability. This overestimation occurs as a result of the fact that they do not have enough knowledge to know they don't have enough knowledge.

Before you argue with someone ask yourself, "Is this person mentally mature enough to grasp the concept of a different perspective?" If not there is no point to argue.

4X NE2 CHAMPION. 2020 TDRA NE2 Champion
 
Posts: 4069 | Location: United States of Texas | Registered: April 02, 2011Reply With QuoteReport This Post
DRR S/Pro
Picture of Lenny5160
posted Hide Post
quote:
Originally posted by Curly1:
If you removed the power valve you should have went up on the jetting. I like to have the power valve in the front and only remove it from the rear because it can uncover on the launch.


There is removing the power valve, and there is plugging/blocking the power valve. I’ve owned alcohol carbs with both configurations.

If just removing, you can go a lot smaller on the jets.


Tony Leonard
 
Posts: 3173 | Location: Inver Grove Heights, MN | Registered: March 18, 2004Reply With QuoteReport This Post
DRR Elite
Picture of adv ET 266
posted Hide Post
Wide Band O2 data removes the guess work when results like this show up. Also, methanol fuel needs/like less trimming than gas.



2005 2000lb 4 link dragster
home brew 582 BBC Dart 355
1.058
2.98
4.629@149
6.094
7.310@185

 
Posts: 12173 | Location: 33463 | Registered: February 04, 2004Reply With QuoteReport This Post
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