Holly stumble question

[76bonanza]

At idle in park if I stab the throttle really fast it will stumble how do you get rid of this?

[76bonanza]

I found most of the problem the cam for the acelerater pump needed adjusting.

Anyone know what size the discharge nozzle is stock in the holley?

[Cole's 87]

Here is a link to a really good info on holley's

http://holley.com/HiOctn/TechServ/TechInfo/FMCTech.html

[1FaastC10]

sell the Holly and buy an Eldebock!

[1972C10]

Sounds like the acel pump needs adjustment the way i set mine is make the clearence 25 thousands at WOT and then fine tune as needed

No edelbrock can compare to the response of my holley i built But they are testy things if you dont know how to tune one up .

[1972C10]

O yeah the stock nozz is somewhere around 25

[TIMSPEED]

Originally Posted by 1972C10

Sounds like the acel pump needs adjustment the way i set mine is make the clearence 25 thousands at WOT and then fine tune as needed

How would I go about doing this??

[1FaastC10]

Originally Posted by 1972C10

No edelbrock can compare to the response of my holley i built But they are testy things if you dont know how to tune one up .

the "Eldebock" thing was meant as a joke. its spelled wrong.

i will agree, the Holley will give you better response, but you'll have to retune it with every tank of gas. they dont hold a tune for $h!t.

[1972C10]

Originally Posted by TIMSPEED

How would I go about doing this??

On the front of the carb there is the acel pump with the engine off ..

Take a 0.25 feeler gauge then open the carb to WOT adjust the bolt on the acel pump untill there is 25 thousanths of clearence between the bolt and the acel pump lever

then what i do is just test it by hitting the throttle lever quickly and see how it responds


.. Now about having to tune a holley per every tank of gas And they dont hold a tune/ thats a new one on me

I built my 750 DP and put it on my 72C10 about half a year ago still on there and i have only retuned it once due to rejetting ,

The Holley carbs are great If you know how to tune one alot of people arent patient or dont have any Info on how to do so i really like holleys external float adjustment as well as the acel pump adjustment

Maybe your past expeirence with one not holding a tune had been monkeyed with by an enexpierenced person or had the cork metering screw gaskets wornout.

Edelbrocks are good carbs dont get me wrong but IMO holleys are hard to beat As far as Response .

[1FaastC10]

Originally Posted by 1972C10

Maybe your past expeirence with one not holding a tune had been monkeyed with by an enexpierenced person or had the cork metering screw gaskets wornout.

actually, the only experiences i have had with Holleys were when i put one on my TA. i have helped a friend of mine with his drag cars, and street machines, some of which are Holleys, most of which run Quadrajets. on the street cars, the Holleys will NEVER stay tuned. but, as you said, he probably doesnt know what he's doing, he's only been running them on the race cars since the 60s.

[TIMSPEED]

Originally Posted by 1972C10

Take a 0.25 feeler gauge then open the carb to WOT adjust the bolt on the acel pump untill there is 25 thousanths of clearence between the bolt and the acel pump lever

This is what you're talking about right? There has to be .25 between the bottom of the bolt, and the arm right?

[1972C10]

Yeah that is what im talkin about That is the general start off clearence I always tweak from there for best accelration.

I just find it very odd that i have run holleys on the street without any problems

And besides this guys post wasnt Lets see who can bicker over whats a better carb And what does and doesnt hold a tune. edelbrock or holley,

He was asking a simple questions about how to Stop The Stumble From Off Idle

So I tryed to Explain How To set up the acelerator pump on his holley carb.

[DCRANER]

Originally Posted by TIMSPEED

This is what you're talking about right? There has to be .25 between the bottom of the bolt, and the arm right?

Good points 1972C10, although I would add for those unsure that the clearence is not a gap, but resistence that allows the feeler gauge to slide in & out.

Also, I would suggest making sure choke is not hanging up, this is very common, and start with the orange plastic cam in position # 1. And, Holleys are lean from the factory, so around a low 30's number shooter is a good starting point.

Thanks.

[76bonanza]

I guess I am not understanding if the bolt presses the lever down they are touching so at WOT they will still be touching so there will be no clearence? I know I am missing something here just not sure what it is.

One more thing does making the spring longer give more fuel or less or is that only to adjust when it engages the lever?

[76bonanza]

I think I get it now does this seems right. At WOT I should be able to move the pump lever down an additional .025 away from the bolt?

[DCRANER]

Originally Posted by 76bonanza

I think I get it now does this seems right. At WOT I should be able to move the pump lever down an additional .025 away from the bolt?

Well, yes, but that is what I meant by being able to slide the feeler gauge in & out, not soo tight that you could not do that. And, .025 would be kind of loose, .015 is what I have seen over the years.

Expanding the spring will contact the pump arm, so at idle you want the arm contacting so when you just move the throttle the pump arm compresses. If loose and arm does not contact immediately you will get a stumble. If all is correct the pump arm (at idle) should be in contact, but if spring is over expanded it will be like you have speeded up the idle,then you have to loosen the spring. I like to have it idling and move the throttle by hand and just see / hear a crisp response, and fine tune pump arm pressure up or dowm from there. If still a stumble then check your shooter, most performance small blocks need a #32 to #36 to get a good response. Factory Holley shooter is probably a #25, too small & will stumble even if pump arm setting is correct.

[76bonanza]

One more stupid question the shooter they have straight type and tube type what is the dif.?

[DCRANER]

Originally Posted by 76bonanza

One more stupid question the shooter they have straight type and tube type what is the dif.?

I do not recall exactly, but the straight type should be your choice. I think the tube type is used to get the discharge into the center of the carb bore, mixes better with the air in very high performance applications, tunnel ram setup etc., O/k, now I will have to go to my books / info for a better answer.

[76bonanza]

Looks like mine has the tube type on it now have not pulled it yet but it has gold tubes sticking out of it.

[76bonanza]

Another one more question if I change cams will I have to readjust the lever arm.
Or does the cam just change how fast the pump compresses and not the total amount compressed?

Many thanks guys.

[76bonanza]

Last one I swear I have never checked my floats and I am sure PO did not either should I I dont seem to be having any problems with them. What problems would incorect float level cause?

[76bonanza]

I just pulled my shooter it is tube type number 31 If I still think I can get better throttle response should I try a larger shooter or different cam? Or just leave it and be happy?

Also how can you test the choke lever to see if it is hanging?

[DCRANER]

Originally Posted by 76bonanza

I just pulled my shooter it is tube type number 31 If I still think I can get better throttle response should I try a larger shooter or different cam? Or just leave it and be happy?

Also how can you test the choke lever to see if it is hanging?

Well, at this point I think you should start from "Ground Zero" so to speak. I suggest going to the Holley web site and downloading the carb tuning section. It is very to the point and is probably the best way.

If the float level is off and / or choke wrong you can go crazy trying to find a problem. Start with the float levels at the bottom of the site holes, set the choke at the center index mark, and make sure there are no vaccum leaks. That should give you a good starting point. If you use a plastic cam with a radical ramp / curve you will have to reset the pump arm, but this all gets back to starting from scratch.

If you start from scratch you will most likely resolve or locate any problems. And once you start to make changes, do one thing at a time and see the result. If you think 3 or 4 things need to be done and you do all 3 or 4 at once then you will never know what made it better or worse, then you will be pulling your hair out.

Good Luck.