Holley issues

[iamtherealJayy]

I’ll be the first to admit, I don’t know anything about a holley. I’ve never used one. I recently traded my 1986 K10 pos for a 1982 GMC C30 High Sierra(my first gmc aswell) truck was originally a diesel supposedly and swapped to a 350. It’s got a holley carb and that’s about all I know about the engine. It will start and it idles very high in my opinion, I looked at the carb and the choke takes forever to open and a blip of the throttle will stall it. I’m assuming accelerator pump is shot but I don’t know how they work on a holley I see an arm coming from the throttle linkage going under the front of the carb, there’s a bolt/stud with a spring. The spring compresses when you give throttle but the arm under the carb doesn’t move. It’s smoking on the drivers side if you give it throttle so I’m going with rich because I reek of fuel now. The carb has an electric choke but I traced the positive and it’s not connected to anything(I did a lot of wire tracing truck was previously a fire department water truck so the spaghetti under the dash had to go) I also noticed if you have the truck running and shut it off and then try to start it, it won’t start unless you hold the pedal to the floor and when it starts it’s a smoke show. I believe the truck was originally a manual but it now has a freshly rebuilt th400 in it.

 

[fast 99]

Choke thermostat needs power and ground otherwise rich. After fixing that, choke plate should close completely but not much more. Turn the T housing until plate just closes. That's a good place to start.

Engine off, choke open, look down the front venturis, move the accelerator pump arm. There should be fuel squirting out near the center.

Sounds like the passage is plugged somewhere. Really if that's the case carb should be rebuilt. It's very likely the power valve diaphragm is leaking too. Most are if the carb has any age.

 

[iamtherealJayy]

So if I find a ignition power source and connect positive to it that’ll help some, I’ll start with that the choke closes after you press the throttle but I had the truck running for probably 15-20 minutes and the choke still hadn’t opened on its own. I did find out the choke not fully opening was causing the really high idle. I need to find the vent tube on the trans PO claimed it was clogged causing atf to spill over the dipstick tube. I really don’t know what I plan on doing with this truck yet honestly but I hope to do something to give it new life

 

[fast 99]

Choke will take hours to come off from ambient under hood heat. Yes, need 12 v to it and suitable ground. Trans vents are usually on top of case. Will also spit out fluid if very hot or overfull.

 

[Matt69olds]

The solution is obvious, GET A Q-Jet!!!

It’s a Holley, of course you will need to fool with it.

Noe that is out of the way, let’s see if we can solve your problem.

Start with the basics. The choke needs an ignition hot power source. Find the pink wire that supplies power to the distributor, or most likely there will be a few empty fuse taps in the fuse box. Some people turn their noses up at getting choke power from the ignition feed to the distributor, but the choke coil doesn’t pull much current. The choke grounds thru the carb body, or there might be a separate ground wire.

Next, with a completely cold engine, push the throttle open, then release it. The choke flap should close. If not, loosen the screws that hold the choke thermostat to the housing, rotate the housing until the choke just barely closes, then snug the screws.

Next, find the fast idle screw. It will be under the choke linkage. Don’t mess with it for now.

Start the engine. Watch the choke blade, as the engine warms the choke should slowly open. Adjust the fast idle screw to about 1100-1200 rpm. Keep in mind, whatever you set it at cold will probably be a couple hundred rpm higher once the engine fully warms.

Once the engine is warmed, hit the throttle once, the engine should come down to base idle.

As far as the accelerator pump, if the plunger is moving, most likely the diaphragm or check valve is defective. One of the few advantages of a Holley is its simplicity, but that can also be a curse. Because they are easy to work on, lots of people screw around with things without having any idea of what they are doing.

If the carb needs to be rebuilt, get a good rebuild kit. Look on holleys tech page, it gives the factory jet, accelerator cam color and mounting position, etc for each carb part number. Compare that to what’s in the carb now. If things have been changed, put it back to as factory delivered calibration. Once the truck is running, THEN start fine tuning.

 

[iamtherealJayy]

I added the ignition power wire it was ran inside and I found a spot on the fuse box that had ignition power and stuck it there. The truck seems to still be running rich, it doesn’t have reverse lights and I was backing up in the dark so I was going slow and the truck stalled and it sputtered while cranking then I held pedal to the floor and it fired instantly. I own probably 12 holleys but I’ve never used one. I’ve got a tbi truck, edelbrock, and a quadrajet, So this is my first time messing with a holley. Is the fast idle screw underneath the choke thermostat? I didn’t visibly notice it earlier but I wasn’t necessarily looking for it either. This truck doesn’t need a whole lot to get it drivable, just a bunch of small things.

 

[Matt69olds]

It’s been a while since I messed with a Holley equipped with a choke, but the fast idle cam and screw is on the front throttle shaft, under the choke heater.

If the float set correctly? Leaky needle/seat? Missing check valve under the accelerator pump nozzle?

 

[SirRobyn0]

I think the most important thing to keep in mind here is that they are all doing the same thing. Whether it's a Q-jet, a Holley or an Edelbrock they are all accomplishing the same thing. All 4 barrel carbs will have two idle mixture screws, one fast idle screw, one curb idle screw and if it's equipped with a choke, will have something to control it if it's an electric choke it needs 12V, and ground and adjusted via loosening up the choke thermostat and turning it.

The specific parts between manufactures look a little different but similar. So Jacob I'm just saying if you remember how your Edelbrock, or Q-jet works on one of your other trucks, then the Holley won't be a big deal to adjust.

Now if you decide to rebuild one of these carbs they are all quite different internally.

Since @Matt69olds brought it up, I agree GET A Q-Jet!!! I'm not really a Holley fan personally but it should be capable of running your truck.

 

[Ricko1966]

I haven't messed with a holley in 30 years or so all I remember about them is how to set the float,which I'm sure you already know. But what I remember that may be relevant to you,was if they backfired they destroyed the power valve and ran rich until you replaced it. I do not remember the exact procedure on picking a power valve. Try searching internet about holley power valve selection. All I remember is you check Vacuum and pick a power valve that takes less Vacuum to open.

 

[idahovette]

I thought Mike, @Paladin would be chime in to set us all straight??!!!!!!!........lol

 

[Paladin]

I thought Mike, @Paladin would be chime in to set us all straight??!!!!!!!........lol

Yes Perry, I seen the thread and was sorely tempted but refrained because once again this seems to be a case of someone who may be use to a piece of S=HIT Q-Jet instead of a good carb like the HOLLEY which they currently have. Once the OP gets used to having a REAL carb as he does now, he'll be spending more time driving it and less time f=ucking with it.

 

[Craig Nedrow]

Holly is my fav carb, but I have a q-jet and AFB as well. Brian, Matt and Rob are giving good advice. If is runs rich, FIRST!!! adj the float level, super easy. With the weep plug on the side of the bowl out, the fuel should be right at the bottom of the hole, and should "weep" when you shake the truck. the adjuster is on the top of the float bowl has a lock nut. The carb number is on the front of the air horn, use it to order a rebuild kit ...IF IT NEEDS IT! they are about 60 buck, so do the float thing, and the electric choke thing. In central WA in winter, I press the peddle once, this shoots fuel into the venturi sets the choke, (key on,) and starts right up. I have some threads on the holly I will point you to. I installed a AEM air/fuel ratio gauge in my truck, WHAT AN AWESOME TUNING DEVICE!! go here:

https://www.gmsquarebody.com/threads/1973-k20-350-to-454-swap.29840/page-8

 

[Craig Nedrow]

Here's the results,

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[iamtherealJayy]

I’ll have to look into float height, I noticed it was wet under the throttle linkage, on an edelbrock that’s sign of float too high. I think half of the running issue is the accelerator pump. I verified now that it doesn’t move. At all. The spring just compresses.

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Here’s some photos of the carb

 

[iamtherealJayy]

Update, I drove the truck around the yard a little today it fires right up idles fine doesn’t like taking off(accelerator pump?) and it seems to flood out in lower rpm times like I was backing up to the shed and it flooded out and stalled it started back up but stumbled and was smoking I put it in drive took off and it cleared up and ran fine. Could idle mix be the issue with the low rpm flooding? You can tell when it’s starting the issue because it acts like it’s got a cam with huge valve overlap and the accelerator pump issue worsens.