[WurlitzBurg]

I have spent many hours trying to get my Edelbrock #1411 750cfm carb to transition from cruise to part throttle accelerate. It hesitates all the way to around 3,000 rpm in all gears. I know it was set up as an economy tune by Edelbrock. I think I would be better off with the normal tune 800 cfm. I have changed primary jets, rods, and power mode springs until I can't see any more because of the smoke rolling out of my head. Engine is a mild 402 BB.
I recently installed an Innovate wideband A/F gauge but the numbers are changing wildly during the transition. I would like to now disable the secondary to take it out of the equation. Can I just tie the secondary throttle shaft in place where it exits the passenger side of the carb?

 

[Andy's Auto Repair]

The secondaries are air valve controlled so yes, the only way to disable them is with a tie wrap. Your A/F def sound off.

 

[Geo71]

Did you check the floats and do you have your fuel pressure around 6psi?

 

[WurlitzBurg]

Yes, I have set the floats and am using the correct Edelbrock pump. It does not lack for fuel when I go WOT.
Thanks.

 

[1966_L78]

How's your ignition? What kind of curve do you have? Where's the initial set at? How much mechanical advance? Vacuum advance?

I have been running the Edelbrocks for a few years now, and only one had stumbling problems... It turned out to NOT be carb-related at all, but a failing distributor... Idle was fine and WOT was fine, but it had a bad stumble... Then it had hard-start problems, then failed all together... Once I realized it was the distributor, I swapped in a new one, and the "carb" issue was gone...

 

[WurlitzBurg]

Tony, I have an HEI dist from Jegs. I think it is working fine.
I have adjusted the vac can to 17* max. Initial advance is 18*. Mech advance is another 18* and ends up at 36* at 3,000. I think this is in line with most street big blocks per the forum. It starts, idles, and cruises fine.
I just found out that the Edelbrock carb uses both vac and mechanical linkage for the secondary. I disconnected the actuator rod and it has a spring that keeps it closed. My guess is that it is still being operated at some point by vacuum. What do you think?
Edelbrock tech says the secondary does not affect my part throttle accel (PTA) problem. But, this is what happened after the disconnect:
The PTA problem was much reduced in all gears. The A/F gauge was what I expected originally. The numbers did not change wildly and generally produced logical values. It seemed the secondary was still operating to some extent because the A/F ends up in the 11s before I let off the throttle and it sounded and felt like it.

 

[Tom Mobley]

I've had several Eddie carbs that acted like that and refused to be tuned out. I don't run or recommend them for exactly that reason. A bigger Eddy is not going to be the answer.

The throttle plates are controlled by the mechanical linkage, the air valve is controlled by vacuum/air velocity. It's actually similar to a Q-jet in the basic design, but there's issues with the implementation somehow. I've had poor results with this Eddiebog deal despite spending a lot of time parts on fixing them.

 

[WurlitzBurg]

Tom, my comment about the 800 cfm vs the 750 was because the #1411 750 is "calibrated for economy" (ie. lean) by Edelbrock and the 800 for performance.
Your thoughts are appreciated.

 

[Geo71]

Yes, I have set the floats and am using the correct Edelbrock pump. It does not lack for fuel when I go WOT.
Thanks.

That is good. I found out with mine that they dont like too much fuel pressure.

You should be able to tune it for performance regardless how it is out of the box. My 1406 is similar but I was able to get it tuned by going richer on the rods, using the heavy spring and jetting up the secondaries. Still needs a 750.

Did you try the different holes on the accel pump rod? Not sure if it would affect that though.

 

[woody31]

I never had any luck with either edelbrock carb i own ,,,even after a rebuild and using there suggested set ups,,,,,,the hot set up for power and economy is a stage 2 -- 750 cfm Sean Murphy Quadrajet,,,he is out in California,,,i run one on my 362 cubic inch small block,,with a comp 280 roller and 10-1 comp,,mild port work ,,auto trans 2500 stall and 2,73 gears for street 3,73 for the track,,no bogs or hesitation,,and get 17-18 mpg,,,cheers,,,the number for S.M.I. is

1-714-843-9169 ask for Sean,,,,tell him woody sent you,,,

 

[novaderrik]

do you have the manual that Edelbrock sends with every new carb? the one that came with my 1910 Quadrajet is very thorough and covers every aspect of the engine- fuel, ignition, cam...

 

[WurlitzBurg]

Yes, I have tried those things.
I have a manual that I have studied at length. I have spoken with Edel tech. They tell me things like: you need to run ported vacuum, you have way too much initial timing, secondaries don't affect PTA. I have compared the 750 jet/rod combos to those in the 800. I may try one of the 800 setups. I am currently running the #12 setup for the 750, which gives max rich power mode on their chart, with the stiffest springs.
The hesitation that I am experiencing lasts about 5 seconds while it approaches 3,000 rpm.

 

[LevonH]

HI Tom. Glad you posted this up.
I found this and it may be of help????:

"The edelbrock AFB carb has a crude non adjustable secondary air door ( velocity valve) that is regulated by a pair of counterweights on each end of the air door shaft. The counter weights control how fast and when the air door opens. There are also small fuel orifices right at the leading edge of the air doors that as the door begins to open a small amount of fuel is sucked into the air stream Simular to a secondary accelerator pump. As far as i know there is only 1 air door/counterweight available from Edelbrock The old carter AFB carbs had many different ones.
You may need to play withe the weight and shape of the counter weight to dial inthe secondary door transition.
I've found my Edelbrock is fine at launch from a stop but sometimes there is a momentary bog as you go WOT from part throttle. The air door counterweights may need to be lighter or it may need weight added.
if you remove the aoor door/counter weight assembley and look at it you'll see that the shape of the counter weight has a lot to do with it not just the amount of weight but the position of the weight relitive to the air doors ( offset). It look "crude" but is actually complicated and infanatly adjustable by changing the weight and offset of that weight on the shaft. Remember that particular counte wight is a universal one size fits all thingy. its up to you and your imagination and a lot of trial and error to dial it in for best secondary response. too bad edelbrock does not have a bunch of them available."

FWIW we just did my buddies car last night. Similar problem but with a Holley.... and we had to go 1 heat range hotter in the plugs to overcome his stumble (plugs fouling slightly). Timing was the same as yours as well.

I'll keep looking for info as well but there has to be a solution to this as they sell lots of these carb's and they can't ALL be bad .

 

[WurlitzBurg]

Thanks for the additional info, Levon. Wow, you mentioned plugs. One more variable that I did not consider. I am running the stock plug. I will research that later.
The air valve info jives with the Edel manual. Also, according to the manual, the air valve does not start to open until the scondary throttle plate moves enough to allow some air flow. After studying this and how the linkage operates on my car, I believe neither mechanism moves until the accelerator linkage gets to the 65% position. I think that is where my A/F gauge starts to go crazy. The car definitely runs better with the secondary disabled. It even has very good acceleration. So I don't need the secondary until I want to go WOT. Instead of hacking on the air valve, I think I will grind on the part on the secondary linkage that determines when it starts to open. I can do that a little at a time.


http://s1220.photobucket.com/user/t...pg.html?&_suid=137789588395309211190660261896

 

[1966_L78]

The hesitation that I am experiencing lasts about 5 seconds while it approaches 3,000 rpm.

Mine had the issue about 2400-3000 rpm, IIRC. Mine was mainly at light throttle, the car would bog and buck... At WOT and other RPM ranges, I don't recall a problem.

Tony, I have an HEI dist from Jegs. I think it is working fine.

I was running a new Summit HEI ( maybe the same supplier?)... Ran great for a few years, even raced it several times... I think similar curves...

Mine ended up having two of the pressed/welded pins (that hold the advance weights/springs) actually pull out of the top of the shaft plate... This screwed with the advance curve...

Finally had trouble starting, had fuel, so I pulled the cap and rotor, and thats when I saw the problem. A 10 minute swap to another distributor, and everything was cured...

BUT, my spare distributor was another Summit part, so I am now trying to decide what i want to get... I run a CD box, eliminating the module, so maybe I'll try to find a nice GM HEI, but I worry that I'll also find a cheap, import POS...

 

[1966_L78]

HI Tom. Glad you posted this up.
I found this and it may be of help????:

"The edelbrock Performer AFB carb has a crude non adjustable secondary air door ( velocity valve) that is regulated by a pair of counterweights on each end of the air door shaft. The counter weights control how fast and when the air door opens. There are also small fuel orifices right at the leading edge of the air doors that as the door begins to open a small amount of fuel is sucked into the air stream Simular to a secondary accelerator pump. As far as i know there is only 1 air door/counterweight available from Edelbrock The old carter AFB carbs had many different ones.
You may need to play withe the weight and shape of the counter weight to dial inthe secondary door transition.
.

If this is the case, then stepping up to the "AVS" version might be worth looking at...

The Edelbrock AVS "Thunder" carbs have an adjustible air door, using spring tension, rather than swapping/grinding counterweights.


I wonder if the issue Levon noted with the regular "Performer", is the same issue Tom was experiencing...

 

[lg1969]

Edlebrock design the Thunder series for that reason. They use adjustable secondary air valve. Very similar to secondary of a Q-jet.

 

[383ram]

And just to add, on the Thunder series I have played with, I have had to slow the air door opening down to get rid of bogs from cruise to WOT. So don't just think you need to grind on the weights to make it open faster, it could be just the opposite. And it may truely seem that way if it is better as you say with the secondaries disconnected.

That one feature of the adjustable secondary door makes these carbs a joy to play with. I have played with the regular ones and sometimes they can be a real bear to get right if at all because once you mess with that weight, sometimes you can not go back to stock.

 

[Tom Mobley]

your A/F meter goes crazy because the crude design of the carb exposes the sec discharge nozzles to manifold vacuum when you floor the throttle or just use heavy throttle. It goes pig rich, then leans out as the air door flops open and floods the manifold with fresh air. There's no air velocity through the carb until the RPM builds up so the metering circuits don't meter. Check out the design of the Q-jet for a decent implementation of the air valve concept. It works and works right until some magazine reader starts screwing with it.

Levon, I've worked with those AFBs till blue in the face, grinding down the counterweights, making slots in the flaps, installing lead shot to the weights and/or the flaps, blocking the flap partially open, etc, etc, etc till wanting to vomit at the sight of the things. AFAIC, it's cruddy cheap design. They saved money by not including a sec fuel flow control mechanism like the Q-jet sec metering rods. And that's exactly what it acts like. IMO, a POS. Of course, I'm entitled to my opinion just like everybody else.

 

[LevonH]

HI Tom.
We're all trying to help Tom, the O.P. with his issue. He will decide what he thinks is best. It's not like Edelbrock carbs are the only ones with issues. Try a Holley 850VS if you want to entertain yourself.