Holley Carb Problems

[bigmac73]

since you are in NM , i would wire the choke open fully, you should not need it either way in your climate,

[storm9c1]

14" of vacuum at idle seems low for a stock or mild setup. Does this have a lopey cam or does it idle smooth?

Also factory timing specs are terrible (designed for emissions and 60s/70s fuel). A SBC likes 8-12 degrees initial at idle. Yes, this will bump up your idle speed. So once you solve the idle speed problem, I'd put the timing back in that range.

I agree that the next step is to disconnect all vacuum lines and plug them at the carb. Any difference?

I'm wondering about the choke setup too. Something doesn't sound right there either.

[cool68]

so, post a couple of picks of carb - maybe someone will see something that is not right.

[landy]

AFAIk, the motor is original and stock. I think the idle vacuum reading will be lower as elevation increases. I'm a mile high above sea level, so 14 in. is probably ok.

[familyfast64]

Are you holding the throttle linkage open when turning the electric choke housing? That's how you have to do it in order to watch the choke blade move to 90

[familyfast64]

What carb do you have? I know you said street performer but I've only heard of the street avenger. I'm not trying to be a smart ass and correct you just making sure you don't have some old carb I've never heard of. Which is possible. If you do have the street avenger I can personally tell you mine doesn't work that way and someone prolly rebuilt it and didn't put it together right.

[familyfast64]

A stock motor should also have close to 20in hg. I don't think elevation has anything to do with vacuum bud. Just your air fuel ratio is all.

[familyfast64]

I would pull her off and rebuild it yourself so you know it's right. There's a few good videos and articles that will dumb everything down. You'll be thanking yourself later because tunning is a regular must do with carbs. Especially as weather changes. Once you learn all 4 circuits and how to diagnose issues with each you'll be balling. Lol

[landy]

FamilyFast64, you're wrong on the vacuum. A vacuum gauge reads the difference between a reference pressure (atmospheric) and a negative pressure (vacuum) inside your engine. Pressure varies with elevation, so the higher the elevation, the lower the reference pressure.

Here's a link that describes basic vacuum gauge theory. Refer to the note section under performing a vacuum gauge test.

http://www.gregsengine.com/using-a-vacuum-gauge.html

Anyway, back to the choke issue. I've looked at some Holley Carb youtube clips and they show the choke blade when fully opened as in the same position as mine, i.e., less than 90 degrees from horizontal. So I guess that must be the way Holley designed it.

Well, back to figuring out the idle issue.

[familyfast64]

Yup that makes sense. But still your only a thousand feet above sea level right? Would it effect it that much? And how do you know your spring in the choke isn't wound once two many times? Just adjust it to where it'll work. Then set your carb to the base starting point and tune.

[Captainfab]

The OP said he is a mile above sea level....that is 5280 feet which will affect his engine's vacuum considerably

Originally Posted by familyfast64

Yup that makes sense. But still your only a thousand feet above sea level right? Would it effect it that much? And how do you know your spring in the choke isn't wound once two many times? Just adjust it to where it'll work. Then set your carb to the base starting point and tune.

[landy]

FamilyFast 64, the electric choke works great, just as it should. Truck starts easily and runs good when cold, and good when fully warmed up. What I'm confused about, besides the idle issue, is that the choke linkage appears to be designed in such a way as to not allow the choke blade to open 90 degrees from the horizontal, i.e., more like 65 to 75 degrees. I guess if it runs good that way, I shouldn't sweat it and just focus on the high idle issue...

[familyfast64]

Ok but could you shave the blade? Sry for being wrong about the vacuums and ft above sea level. Thanks for clearing that up. I remember filing off the edges of the choke blade. would you be able to do something like this? Even if this doesn't effect your idle speed it should open to ninety correct? I was just trying to give a guy some help. Il opt out of this one.

[homemade87]

Landy, I have something like this happen before. Just put a little pressure on the choke blade to move it open and open the throttle a little and see if it opens all the way while holding pressuse on the blade. If it does realease the throttle while still holding pressuse on the choke blade and see if it stays open. If it does then the choke needs adjusting some how to correct. You could start it at this point but dont touch the gas peddle or it will go back.You could also do this while running. And check idle and see if it helps. The blade should always be at a 90* when fully warmed. This was from my experience. Hope this helps.

[landy]

Yeah, I'll get some pics this weekend and post. I've looked at some Holly Carb clips on youtube, and the choke blade position looks similar to mine. May be the intended design position.

The choke works great, truck starts easily when cold, choke blade opens as truck warms up, and truck runs great when warm. Just puzzling that the choke blade can't by design open completely to 90 degrees from horizontal.

[landy]

I'll take some pics of the choke linkage this weekend. A pic is worth a thousand words... Hopefully, the pics will better illustrate my the problem or my confusion.

Thanks!

[GASoline71]

Double thread. You got one in the engine section too.

Maybe a moderator can merge the 2 for you.

Gary

[cool68]

attached some pics of same carb, I guess, that you have on my '68 getting ready to sell/trade - using Edelbrock Performer manifold.. shows at start up, then warm up. recently moved return spring pulling toward rear, will move back to pulling from bracket at front - seems to idle down better.

[landy]

So is the choke blade vertical, i.e., 90 degrees from horizontal when the engine is warmed up?

[cool68]

Originally Posted by landy

So is the choke blade vertical, i.e., 90 degrees from horizontal when the engine is warmed up?

** No - look at pic - top shot (not too good) at warm up - bottom at initial start up.

[msgdsrf]

Your return spring doesn't have enough tention to give good return as set up in your pic. You may adjust the choke to open more by removing the rod (remove the three bolts holding the choke timing spring) and giving it a little more bend, but this will also open it more when in a closed position.

[msgdsrf]

The closed position may not actually be as effected on that model, I'm not sure about that. But adjust for more open by giving the rod to the butterfly a little more bend in it at the bigger mid point bend.

[cableguy0]

Your return spring isn't tight enough. Second disconnect the throttle linkage and make sure it isn't holding the throttle open. It should be free. Im gonna bet between that linkage and the springs not being tight enough its causing your high idle. The choke definitely should be open a bit farther.

[burnin oil]

I had to bend the linkage rod on my 4160 carb to keep it from doing the same thing. Mine is a manual choke so it effects all of them.

[landy]

Took some pics of the choke blade position and linkage. Choke blade position is identical to Cool68's choke position, and it looks similar to other Holleys that I've seen pics of. Maybe that's the factory setting, but it sure seems like it should be opened completely or 90 degrees from horizontal.

First pic shows choke closed at start-up. Second pic shows choke rod on top of fast idle cam- idle adjustment screw has been completely backed out. Third pic shows choke blade at engine fully warm and choke completely opened. Last pics shows choke linkage at fully warmed up position.

I can push the throttle linkage slightly forward to bring the idle down slightly, but it still is idling too high, and idle adjustment screw is completely backed out. Guess I need an even stronger return spring, or the linkage is binding at the carb.

Vacuum secondaries don't seem to be opening under acceleration. I saw that one can confirm that the vacuum actuator rod is moving by tying a bread wire tie around the rod, doing a drive, and seeing if it was pushed/moved down the rod.