Q-jet experts , couple questions

Greg Hill · 12-01-2009, 09:36 AM

If you are changing from a Holley to a q-jet you will need a better fuel system. The mallory 140 pump probably will not do the job. The 250 with a 1/2 inch line is the minimum.

Redlight · 12-01-2009, 11:21 AM

Greg, I am going from a (single)Holley to 2 Qjets.

Do 2 Qjets hold similar volume of fuel as 1 dominator with standard bowls (no extensions)?

Do you think the 250 is still needed?

I am kinda type "A" with fuel and wiring.

Here is the present system:

8 Gallon cell with dual #8 outlets from the sump,(2) #8 mesh filters to a Y with #8 inlets to a #10 out direct to the pump, #8 line to the front mounted paper filter,#8 fitting dirct to the regulator, dual #8 outlet lines to the carb, the return is also #8.

There is only 1 90 degree fitting (full flow) and it is on the high side before the regulator.

The cell and pump are mounted in the trunk,high. If I remove the lines up front at the carb, fuel will gravity feed!

tj310 · 12-01-2009, 05:22 PM

You only need more fuel if you are going faster
Thanx Trevor

Greg Hill · 12-02-2009, 07:39 AM

I don't know. I've never heard anyone try to run 2 q-jets.

Alan Roehrich · 12-02-2009, 08:51 AM

Two Q-Jets do not hold as much fuel as a single 4150 or 4160 Holley, never mind a Dominator.

To run Q-Jets, you need serious volume, without high pressure. Often you'll find you can't even run 7 psi with the 0.130" needle and seat.

Redlight · 12-02-2009, 09:37 AM

tj310, faster would be nice but if can stay where I am (10 flat @131mph) I would be happy. Maybe be dreaming but unless you try.........

Greg, this manifold and carb combo has worked on a 12 second car with great results. The intake has "some work" to even out distribution so the plugs are very uniform in color after a run.

Alan, do you like the Mallory 250 vs the 140 with the system listed above or do I have 40 feet of #10 line in my future?

Greg Hill · 12-02-2009, 06:11 PM

Q-jets are the most finicky and sensitive carbs I've ever fooled with. They can be made to run extremely fast but the can also get screwed up for no apparent reason. I would definitely go with the bigger pump. Personally I have had nothing but trouble from Mallory fuel pumps and regulators, but I do have a couple of friends who run the 250 pump and it seems to be okay.

12-01-2009, 11:21 AM	#2
Redlight Junior Member Join Date: Aug 2009 Posts: 23 Likes: 0 Liked 0 Times in 0 Posts	Re: Q-jet experts , couple questions Greg, I am going from a (single)Holley to 2 Qjets. Do 2 Qjets hold similar volume of fuel as 1 dominator with standard bowls (no extensions)? Do you think the 250 is still needed? I am kinda type "A" with fuel and wiring. Here is the present system: 8 Gallon cell with dual #8 outlets from the sump,(2) #8 mesh filters to a Y with #8 inlets to a #10 out direct to the pump, #8 line to the front mounted paper filter,#8 fitting dirct to the regulator, dual #8 outlet lines to the carb, the return is also #8. There is only 1 90 degree fitting (full flow) and it is on the high side before the regulator. The cell and pump are mounted in the trunk,high. If I remove the lines up front at the carb, fuel will gravity feed! Last edited by Redlight; 12-02-2009 at 12:30 PM.

12-01-2009, 05:22 PM	#3
tj310 Member Join Date: Sep 2009 Location: Dresden On. Canada Posts: 460 Likes: 0 Liked 0 Times in 0 Posts	Re: Q-jet experts , couple questions You only need more fuel if you are going faster Thanx Trevor

12-02-2009, 07:39 AM	#4
Greg Hill VIP Member Join Date: May 2006 Location: Louisville , KY Posts: 1,995 Likes: 69 Liked 279 Times in 68 Posts	Re: Q-jet experts , couple questions I don't know. I've never heard anyone try to run 2 q-jets. __________________ Greg Hill 4171 STK

12-02-2009, 08:51 AM	#5
Alan Roehrich Veteran Member Join Date: May 2006 Location: Murfreesboro TN Posts: 5,132 Likes: 1,600 Liked 1,912 Times in 429 Posts	Re: Q-jet experts , couple questions Two Q-Jets do not hold as much fuel as a single 4150 or 4160 Holley, never mind a Dominator. To run Q-Jets, you need serious volume, without high pressure. Often you'll find you can't even run 7 psi with the 0.130" needle and seat. __________________ Alan Roehrich 212A G/S

12-02-2009, 09:37 AM	#6
Redlight Junior Member Join Date: Aug 2009 Posts: 23 Likes: 0 Liked 0 Times in 0 Posts	Re: Q-jet experts , couple questions tj310, faster would be nice but if can stay where I am (10 flat @131mph) I would be happy. Maybe be dreaming but unless you try......... Greg, this manifold and carb combo has worked on a 12 second car with great results. The intake has "some work" to even out distribution so the plugs are very uniform in color after a run. Alan, do you like the Mallory 250 vs the 140 with the system listed above or do I have 40 feet of #10 line in my future? Last edited by Redlight; 12-02-2009 at 06:22 PM.

12-01-2009, 09:36 AM	#1
Greg Hill VIP Member Join Date: May 2006 Location: Louisville , KY Posts: 1,995 Likes: 69 Liked 279 Times in 68 Posts	Re: Q-jet experts , couple questions If you are changing from a Holley to a q-jet you will need a better fuel system. The mallory 140 pump probably will not do the job. The 250 with a 1/2 inch line is the minimum. __________________ Greg Hill 4171 STK

12-02-2009, 06:11 PM	#7
Greg Hill VIP Member Join Date: May 2006 Location: Louisville , KY Posts: 1,995 Likes: 69 Liked 279 Times in 68 Posts	Re: Q-jet experts , couple questions Q-jets are the most finicky and sensitive carbs I've ever fooled with. They can be made to run extremely fast but the can also get screwed up for no apparent reason. I would definitely go with the bigger pump. Personally I have had nothing but trouble from Mallory fuel pumps and regulators, but I do have a couple of friends who run the 250 pump and it seems to be okay. __________________ Greg Hill 4171 STK

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