Carburetor and high idle ... (Problem Solved)

[FarmerDave1321]

Let's talk carbs!

First some general information about my setup:

Blueprint 347ci Crate Motor
Edelbrock 1406 600cfm Carb single pumper
MSD Ignition and Blaster Coil
Mechanical Fuel Pump

The problem:

Starting off, the first 4k miles have been great. Engine runs fantastic, plenty of power, nice and snappy ... until this weekend. I plucked the car out of storage since we had some nice weather over the weekend. Did all the basic checks, oil, tires, checked for leaks, etc. Car fired right up and settled into a somewhat high idle, about 1200RPM - normally it sits around 850/900 or so and is nice and lumpy.

After putting some miles on the car, the idle started acting erratic. It would vary from 850/900 to 1200 at stops and eventually wouldn't settle under 2000. Fortunately, I have basic rebuilt kit for the carb (all gaskets) and decided that maybe it just needed a good clean and new gaskets. Off came the carb, cleaned it up, put in all new gaskets and the car still won't drop until a 2000rpm idle.

Looking for advice on a few things ...

Firstly, troubleshooting. I'm wondering if maybe there''s a vacuum leak somewhere that could be causing it? I thought perhaps it was timing, but the car runs brilliantly at speed so I'm not so sure that could be the problem.

Secondly, carburetor upgrade. After consulting the goggle I thought perhaps replacing the whole carb and doing an upgrade would be beneficial while I'm dealing with the problem. I'm considering a Holley Brawler 650cfm double-pumper as an overall upgrade.

Thoughts? Need more details?

PROBLEM SOLVED

Learning moment for sure, laughably dumb ... also for sure. Problem was two fold.


The electronic choke wasn't set correctly so it was never fully releasing the choke.
Throttle cable was too tight and it wasn't allowing the carb to retun to idle (even after the choe was reset).


At least I learned a few things. How to rebuild a carb, how to troubleshoot vacuum leaks and how to set the idle on a carb.

[Mike.Bray]

Okay disclaimer, I hate carbs. They're so 1800's. And I've messed with most of them so speak from experience.

Two thoughts on your situation. Edelbrock carbs are the bottom of the barrel so that's one strike.

Second thought, carbs don't like todays gasoline with ethanol. The gas evaporates and leaves a residue from the ethanol. It's why you can buy ethanol-free gas at Home Depot for your weedwhacker. When you mentioned storage this is the first thing I thought about. Same as getting a lawn mower out for spring with ethanol residue in the carb.

I'm betting a good cleaning will get you back running decent, as decent as you can with a carburetor.

[FarmerDave1321]

Okay disclaimer, I hate carbs. They're so 1800's. And I've messed with most of them so speak from experience.

Two thoughts on your situation. Edelbrock carbs are the bottom of the barrel so that's one strike.

Second thought, carbs don't like todays gasoline with ethanol. The gas evaporates and leaves a residue from the ethanol. It's why you can buy ethanol-free gas at Home Depot for your weedwhacker. When you mentioned storage this is the first thing I thought about. Same as getting a lawn mower out for spring with ethanol residue in the carb.

I'm betting a good cleaning will get you back running decent, as decent as you can with a carburetor.

I fully disassembled, cleaned and replaced all the gaskets in the carb - still the same problem. That's why I'm thinking it's possibly a vacuum issue, either in a vacuum line or the carb itself has a leak somehow.

[rich grsc]

OK, then start looking for the vacuum leak if thats what you think. Sure could be a cause

[Mike.Bray]

Does it keep running when you put your hand over the carb? Do you have a smoke machine?

[Norm B]

I suggest you run the engine and get to normal operating temperature. Shut it down, remove the air cleaner and re start the engine. This will allow you to eliminate two things. Air cleaner interference with the high idle/electric choke linkage and check that the throttle plates are closing to the idle position.
If the throttle plates are closed and the rpm’s are high, you have a vacuum leak.

HTH

Norm

[Cobraman]

It sounds diffently like a vacuum leak somewhere. I'm sure you're not using that ethanol tainted fuel for your ride. I buy ethanol free and use and octane booster. I also can get 100 octane fuel at an distributor close buy.

[GoDadGo]

Steve's Stupid Questions:

Have you tried spraying Starter Fluid or WD-40 around the base plate and various hoses and connection points?

The Starter Fluid will tend to make the idle go increase if you hit the source where the WD-40 tends to do the opposite.
I like using WD-40 to look for vacuum leaks because it is easy to wipe things off after I find the culprit.

On the same note, are you 100% sure that you cleaned all the ports and orifices?

Are all of the ports on the carburetor hooked up or properly plugged if not being used?

Have you checked your PVC valve, assuming you are running one, to make sure it isn't stuck in the open position?

I think you may have some suborn crap some place in the carb or possibly an issue by the throttle plate setting.
Hope this helps and sorry if it doesn't.

Good Luck!

[FarmerDave1321]

Problem solved .. updated my first post.

Thank you all for the input. All the troubleshooting steps helped me zero in on the problem.

[Mike.Bray]

https://www.imagecoast.com/images/MichaelBray1/fbimg1718707686265.jpg

[FarmerDave1321]

Hahahaha! That's about how I felt.

[RoadRacer]

Btw, that 650dp brawler is exactly what I have and love.

[CraigS]

Glad you got it fixed. A bit embarrassing maybe but it's fun to learn new stuff isn't it? And everyone who reads this thread has been there, done that.