Pump nozzles? Guys that race ? Help please.

[Fathead Racing]

For the guys that race? What size pump nozzles are you running on your dual quads? I haven't checked to see what size I have but they are not big enough. I can either buy Edelbrock in size, .024 ,.033 , .043 or all three. Hate to buy the smallest size only to find that they are already in the carb! I tried the top and bottom holes on the accelerator pump lever with no luck. I haven't bent the pump rod to the full 1/2" stroke yet but I don't think that's going to do it. Help please

 

[bluescreamer]

Pump Nozzles?

Ray

The 750 Edelbrock come equipped with .035 nozzles. The number is stamped
on top of the cluster.
I have found if my motor stumples I change them to .028 and place the rod in the upper hole. This give a leaner shot for a longer time span. I got the .028 out of a 3361 and 3362 set up. I believe what is happening is the motor can not take all that fuel and air on the initial call for acceleration.
This has done on many different dual four combination I have run over many years. (Stock 3361-3362, 600, and 750 edelbrocks.)
Allen

 

[Fathead Racing]

Thanks Allen. I have 600 cfm Carter Comp series carbs. Engine dies and front carb is on fire when I poke it in the ***. I would say this is a lean condition. I think the size may be stamped on the cluster but I am not sure.

 

[bluescreamer]

pump nozzles

Ray
That's a back fire, I believe partly because there is to much fuel in manifold.
also check timing start with 34 degrees total, than increase if needed
up to 38 or 39. Make sure you have enough heat in motor doesn't like
a cold block.
and make sure that oil is hot before you try going all out.

In the process of changing the upper control arm mounting point,
on the bluescreamer.
Allen

 

[Ronnie Russell]

Ray, I have had the same results as Allen. Took a bucketfull of nozzles to the strip one day, carbs had .028 , every increase caused poorer performance. Ended up right back at the beginning. .028. With the converter and rear gear you have, Im real surprised about the stumble. Dont grind any metal off secondary air valves, that will cause a big stumble. Keep poking around on it, I bet we can all put our heads together in Ky. and make it good.

 

[Fathead Racing]

Good to hear from you guys, I had the pin vise and .035" drill all ready to go. I have a couple of spare 600 cfm Carters and will drill pump nozzles as needed. I will bring a couple of drilled .035" nozzeles to Clay city just in case. Allen engine has 36 total right now at 2500. It was pretty brisk here at 45 dgs. engine was at 180+ oil was hot. I can brake stall to 2500 must flash higher. I have the rod in the center hole on the pump lever. I have been fooling around quite a bit so I need to check timing again. Clusters are stamped .028" on the carbs I am running now. I have two spare carbs one with a .035" nozzle and another with a .028" I am going to drill the .028" to .035" and bring them with me to CC.

 

[dq409]

Hummmmmm,,,

It does sound like a timing thing though. We`ll see after Ray checks it.
And it doesn`t sound like a pumper problem from what Allen has posted.
I also agree that you have too much fuel under the carbs.

Ray if it still does it , pops and back fires after you check the timing , pull the caps off the front carb metering rods and check to see if the rod is stuck.
Sounds weird but I had this happen to me once and caused the same problem you have.

Don`t know what caused it and I reused the same rod without it happening again.

,,dq