Air_Adam

Hey guys, I'm kinda baffled by this one. The typical fixes didn't seem to do anything for my problem.

I have a Holley 3310 on my 350, and it has a WOT hesitation problem. Under normal driving conditions, it seems ok, no hesitation, stumbling, etc, during part throttle driving. But when you nail the gas, it hesitates before it goes. It also only happens below about 2200 rpm. Above that, theres a very little bit, but not much.

The carb has primary and secondary jets (not metering plates) and they are 69 and 76. The accelerator pump cam is the Holley white cam. Well, its white plastic, so I assume thats how they are identified? By color?

Anyway, its also been rebuilt a few months ago, with new gaskets, jets, etc, and nothing leaks. Float level is set just below the edge of the sight hole. If it makes a difference, the distributor base timing is also set at 8*.

I've tried a few things to help this, but nothing has really helped much. I've played with the accelerator pump tuning, jetting, ign timing, and none have helped.

five7kid

iTrader: (14)

What squirter size is installed? What secondary spring? Is the secondary check ball in place?

Air_Adam

I'm actually not sure about the squirter size. It would be the same as what it originally had, since it had never been rebuilt before I did it, and I didnt change it. The secondary spring is also the stock one, but again, I'm not sure. I didn't take the secondary diaphagm and all that apart. The carb is an early one, so I don't think it came with a secondary check ball.

five7kid

iTrader: (14)

I was under the impression that all VS had the check ball. But, I could be wrong.

What's the dash# of the 3310?

Air_Adam

I think only in the '80s did the check ball come around. Mine, I think, was first built in the '60s. There is no dash number, its just '3310'. Its one of the very early ones that had secondary jets as well, instead of a metering plate.

five7kid

iTrader: (14)

http://www.holley.com/HiOctn/ProdLine/CarbList.pdf

Note -1 is the first one listed. Had .025 "discharge nozzles" (squirters) until -4's started coming with .031's. I put .035's in mine, didn't really notice any difference (didn't have your apparent problem, though).

As for the check ball, are you sure you're not thinking of the power valve protection check valve? http://www.holley.com/HiOctn/TechSer...o/4150-60.html #68 is what I'm talking about.

F-BIRD'88

http://www.holley.com/HiOctn/TechSer...o/4150-60.html

Further on this same exploded parts view check to see that
#'s 72 to 76 are in your carb 106,107 and 108 also. Tend to get lost during rebuilds. Check the accel pump linkage arm ( that rubs on the colored plastic cam to see that it isn't bent. Would cause
you to not receive a full shot of accel fuel shot when you floor the gas. Bend it back if nessessary.

Air_Adam

Ok, I checked out what you guys are asking about:

A) Discharge Nozzles - My carb is the one before the 3310-1. I can't find anything for this one, but its probably .025 like the 3310-1.

B) Secondary Check Ball - Yes, I know the part you are describing. I haven't taken apart the secondary diaphagm, so if it does have one, it should still be there. The manual I used to rebuild the carb (Haynes Holley carb manual) says that I shouldn't have one, because my carb was built before they started using them.

C) Accelerator Pump - All the parts are there. I remember installing them again when I rebuilt the carb, and all the parts are within spec. I dont remember what that is now, but I measured everything when I did it, and it all checked out.

I haven't thought to look at the acc pump arm, but it does appear to work fine. When I pull the throttle open by hand, it does push down on the acc pump arm and you can hear it getting a shot of fuel.

five7kid

iTrader: (14)

But is it getting a shot long enough? That's where the lever/cam adjustment and squirter come in. If the pump is sitting at mid-stroke at idle, it's going to run out of squirt mid-throttle. Similarly, if the squirter is too big, it will let the squirt through while the throttle is still opening (that's why there's a spring on the pump lever pushing on the pump arm). The squirter size is marked on the piece, by the way.

How do you know it's never been apart before? Since this is a used carb, it behooves you to verify all details of the unit.

Air_Adam

I never actually thought of looking at it like that... I'll have to check that out after work tomorrow and see where/how it actually sits on the cam.

todd200

According to a buddy of mine that works at Holley, they stopped using secondary check ***** in the VS carbs a couple years ago. I guess they didn't have them, then had them, and now don't have them again. Unfortunatly Adam, I don't have any advice as I'm having a similar problem. My friend (from Holley) is going to take a look at it with me Saturday evening. If we get anywhere and your problem is still unresolved I'll let you know what we did. Good luck.

Air_Adam

That would be a HUGE help! Thanks man!

-----------------

I just had a thought, and I thought I'd post it, just because...
Under my Holley, I have an Edelbrock Torker intake. Now, before you guys go telling me to get rid of it, I already know its not the best out there, but I like it.

Anyway, back to my thought... This intake is a single plane, and Edelbrock claims its powerband to be 2500-6500 rpm. If you notice in my first post, I said this problem really only happens below 2200 or so. Could this be part of my problem?

five7kid

iTrader: (14)

Back in the 70's, I had a 302-clone (283 crank in a 327 block, .060" over), LT-1 angle plug 2.02/1.60 heads, LT-1 solid cam, Torker intake, and 3310 780 CFM carb. With a stock '65 Impala aluminum Powerglide 1200 stall behind it. All this in a 3800 lb car with 3.31 gears. "Hesitation" is hardly the word for what happened below 2500 RPMs. "No guts" is more like it. It wouldn't "bog" per se, it didn't backfire, it just didn't do any more at WOT as it did at 1/3 throttle. After getting above 2500 RPMs, regardless of where the throttle was, it would scream on demand.

Any of that sound familiar? Or, is it really a "hesitation" when you nail it?

Chickenman35

Have you tried changing pump cams? Pump cams are critical in Holley tuning. They control the Volume of total pump shot ( Nozzle size has nothing to do with total volume ). Together the Nozzle size and the profile of the Pump Cam control the timing of the pump shot. Very few books give the pump cam lift per degrees of throttle opening...that is critical. One book that does is Dave Emanuel's book ...ISBN 0-931472-08-3. Might be a new revision out so check it.

When you have the proper info, you can look at the different cam profiles. A white cam is pretty wimpy. Very slow profile. SBC' seem to like a short, fat shot...especially single plane manifolds.

Going from Emanuel's chart you can see that either a Blue Cam in the #2 hole and a #31 or #35 shooter should do the trick. If you need more pump volume, try a Green cam in the #1 hole.

The cams also have numbers on them. A White Cam is #218. Blue is #427 and Green is #290. An old Pink cam loses it's color over time and looks almost white....so it pays to check the numbers.

Always use the minimum pump shot required.

Chickenman35

A) There is no model before the 3310-1. That is the earliest model of the 3310 that Holley made...at least according to Holley's Technical manuals that I have. Probably the -1 didn't get stamped well. And yes a .025" shooter is standard and it is wayyyy to small for a Single Plane manifold and any type of camshaft other than stock.

B) The Haynes Manual is wrong ( Not your fault...Haynes is notorious for having incorrect information ). All 3310-1 series had a check ball in the Secondary diaphram housing. In fact I believe that all 3310-X series with the metal Secondary housings and covers had the check ball. New ( made in Mexico ) versions with Plastic Secondary housings may not.


C) Make sure that the pump lever to pump cam clearance is set correctly. Some people misinterpret the .015" clearance figure specified by Holley. There must be a minimum of .015" extra travel at WOT available to the pump daiphram.

At idle there should be Zero clearance between the pump cam and the pump accelerator linkage arm. Any freeplay at this point can cause a hesitation....even with the correct cam and shooter installed. I always add 1\2 to 1 turn preload to the pump spring after adjsuting to zero clearance. Seems to help sharpen the pump shot. Pump shot should be immediate and sharp with the slightest movement of the throttle. Dribbling is an indication of a problem.

todd200

I have a #35 shooter and a orange cam in the #2 hole. We are going to be playing with shooters and pump cams to see whats up. Also I think I'm a little fat in the main system so we are going to lean it out some.

Air_Adam

There is a 3310-nothing. I do have one. It isn't like the 3310-1, because it has a secondary metering block, like a double pumper, and not a metering plate like the -1 to -6 (or whatever is the current number). Its also got a few other differences as well. Holley doesn't list it with the rest of the 3310s though, and I don't know why. I'll take pics of the carb if you guys want to see.

Also... yes I have a single plane, but its got the stock cam in it as well. The only reason I have this manifold is because I had to get the computer out of the car to make it run right, and this manifold is what I had at the time. It will probably be replaced this summer with something a little more modern.

Quote:

At idle there should be Zero clearance between the pump cam and the pump accelerator linkage arm. Any freeplay at this point can cause a hesitation....

Ok.... I think that may be the problem. The Haynes manual only said ".010 clearance on accelerator pump" but they didn't say where. So I think I 'clearanced' the wrong part! I'll check that today and let you know what I find.

Chickenman35

The 3310-1 DOES have a metering block. The 3310-1 is the earliest model listed by Holley....at least in the THREE Holley Parts and Technical Manuals, with full listing specs, that I have. And I have two of them. And a 3310-3, which has a plate.

Buy yourself some good Holley books, Haynes are garbage. The one I mentioned by Dave Emanuel is excellant.

And trust me on this....if getting rid of the freeplay doesn't solve all of the problem (which I doubt it will ), buy a cam assortment. Put the Blue cam in the #2 hole and start off with a #31 shooter ( tube type preferred. Part #121-31 ).

five7kid

iTrader: (14)

The first link I posted indicates -2's started getting metering plates (look at the p/n's in the "Secondary Main Jet or Metering Plate" column).

I have also heard (don't recall where, probably this forum) that a dash-nothing is the same as a -1. They don't start stamping the dash number on the carbs until the -2's come out.

I have absolutely no idea what dash # the 3310 I bought new in 1977 was.

Air_Adam

Ok, I took your advice Chickenman, and I think I did fix it!

I checked out the lever for the accelerator pump, and it was.. uhh... loose? I tried adjusting the looseness out of it, but got nothing. I took it off, bent the cam-end of the lever down just a little bit, and reinstalled it. Theres no play at all in it now that its been adjusted right.

After that, I started it up and let it warm up so I could take it out for a spin. I took it to the cleanest road I could find (lots of snow here still) since the motor has to have a good load on it, like having the tires hook, to properly test this, right?

So anyway, I got it out on the highway, and punched it in 1st from about 1200 rpm and it was just a little lazy, but the bog was gone! So I took it to a side road, and richened the idle mixture about 1/8 of a turn, and that completely fixed it!

I took it back on the highway going the other way, did the same as before, punched it from about 1200rpm in first, and went through the gears to the top of 3rd, and there was no hesitation at all... I hit the gas, and the car just hiked up and took off!

Thanks for all your help guys, I owe you one
I never would have thought to check the play in the accelerator pump lever on my own, although now it seems fairly obvious, lol.

Air_Adam

Heres a pic of the numbers on the carb. The pic didn't come out at all, but its still somewhat readable, but you can see there is no dash number after "3310"

Chickenman35

I think you may be on to something there. Would explain why Air Adam's carb is stamped as 3310, but Holley Parts manual's list starts with 3310-1. I'll have to have a closer look at my two 3310-1's and see if they actually have the "-1" stamped on them or not.

Chickenman35

Glad you got it fixed. Richening the idle mixture will cover a slightly lean transition.

You may find that your idle is too rich though and you might start fouling plugs. If the idle mix was correct to begin with, then richening it to cover the lean transition ( too weak of a pump shot ) is a kind of Band-Aid cure.

To correctly set idle, warm up car thoroughly. Hook up a vacuum guage to manifold vacuum. With car in neutral, slowly turn idle screws in ( 1\8th turn at a time ) till vacuum guage just starts to waver or drop. Stop at this point. Back out and in, 1\8th turn at a time, to make sure that you find the EXACT spot that the vacuum guage starts to waver.

This is what is called " Best idle". 1\4 to 1\2 turn in ( Leaner ) from this is called " Lean Best idle " ( usually used for passing emissions test ). 1\4 to 1\2 turn out ( Richer ) from this point is called " Rich Best Idle".

Cars with stock cams such as your's should be adjusted to " Best idle" or even " Lean Best idle". Cars with mild to moderate cams will respond best to " Rich Best idle".

If you've adjusted the idle more than 1\4 turn Richer from " Best idle" then I'd say that you're covering up a weak pump shot with excess idle mixture and you should look at some accelerator pump tuning as suggested. If you're within a 1\4 turn Richer from " Best Idle" then I wouldn't worry about it.

Air_Adam

Actually, I think its all around a good thing I richened up the idle a little bit. The plugs were reading somewhat lean anyway, even with the slightly rich jetting I have on this engine, so we'll see what happens.

I'd like to adjust the idle mixture with a vacuum guage, but I have to find one first!

Jamaicajohn

Hi Guys
I am new to this and may be posting in the wrong place but I need help.
I have a Suzuki Samurai in which I have installed a Camaro drivetrain. +.040 305 sbc, turbo 350.
High rise airgap single plane intake, 202 valves, mild cam, headers. 3" pipes with cherrybombs.
I live in Jamaica and built it up out of what was available.
I have a Rebuilt Holley 1850S
This works Ok but bogges on initial acceleration.
If I give it a second pump it gets up and goes.
I changed the Pump cam to a blue one in number 2 hole and the squirter to a 35. Now it accelerates great on initial acceleration but hesitates badly after a second of acceleration and a second pump will pick it up and it goes great. I know little about carbs so would appreciate any suggestions.