Hesitation when accelerating

[BudW]

I wouldn’t change the choke pulloff without testing to verify its failed, first.
If it does need replacing, there is a couple of adjustments it needs before it will work correctly.

 

[Justwondering]

BudW -
Here's a really novice question.
How do I tell what type of carb I have?

I see all these comments about holley and edelbrock, 2 and 4 bbl... It just looks foreign to me.

I'll be rerouting my hoses on Wednesday (spent too much time sewing and tractoring today) so I can take pictures and look at things.

 

[BudW]

You have a Holley 6280 2-bbl with Lean Burn (computer controlled carburetor).

My ’86 also had the same carburetor, but it is now taking up space in garage, while a Carter BBD 2-bbl (non-computer controlled – but computer doesn’t know it yet) sits in its place.

 

[Jack Meoff]

You have a Holley 6280 2-bbl with Lean Burn (computer controlled carburetor).

My ’86 also had the same carburetor, but it is now taking up space in garage, while a Carter BBD 2-bbl (non-computer controlled – but computer doesn’t know it yet) sits in its place.

Just to note......
My 87 Fifth has a Holley 2280. (non-computer controlled)

Not sure if that's a Canadian only thing.

 

[Justwondering]

Do you know this because they all came that way?
Is there something I see that I could identify it?
Just wondering about stuff tonight.

 

[Jack Meoff]

Do you know this because they all came that way?
Is there something I see that I could identify it?
Just wondering about stuff tonight.

The 6280 has two solenoids

The 2280 doesn't.

As far as I know that's the only real difference.

 

[Justwondering]

what does a solenoid do?

 

[Jack Meoff]

The experts can answer that one.
I know one is for the idle. The bowl vent one I'm not that sure.

THIS is why I classify myself as a driveway mechanic.

 

[rcmaniac791]

I believe the solenoid near the throttle kicks the idle up ever so slightly when the A/C is turned on. Don't quote me on it, but that's what I think. The bowl vent solenoid opens up to allow fumes out of the bowl to go to the charcoal canister, or somehow back to the engine to get burned. Anyway, I know that it's emissions related. Now, under what conditions that solenoid opens, not too sure.

The carb I put on is originally off a '77 cordoba, so it doesn't have any plugs or solenoids. It also doesn't have those stupid concealment plugs for the mixture screws.

 

[BudW]

Justwondering, you have shown me what’s under your hood, so I already know (you shown me yours, now I need to get out of town before your hubby finds out).


In ’87, there were two different 2-bbl carburetors used (plus 4-bbl for police, but that is not the case here). The two different 2-bbls were both Holley, version 6280 and 2280. The later one is not computer controlled.

Captain is partially correct, he said:

The 6280 has two solenoids

The 6280 actually has three solenoids.

The red arrow points to the third solenoid, which is the fuel mixture control solenoid, which is what the Lean Burn computer uses to adjust the fuel mixture while driving.

This is a US emissions thing. All other countries get the normal carburetor (unless special ordered with the US emissions package).

This solenoid has roughly a capacity to adjust the air fuel mixture about 10% (or so).
This is just another reason why gasoline with 10% (or 15%) ethanol mixed in, causes problems for our cars – because vehicles running ethanol requires 10% (roughly) more fuel compared to 100% gasoline – which is more than carburetor can compensate for – or is close to max limitations.


The Fast Idle solenoid is either used for A/C (bumps idle speed up a smudge) and/or is used for after-run condition (when vehicle is turned off but engine has a piston hot spot and car keeps running from hot spot igniting the fuel). By opening the throttle a bit, it generally will keep the after-run gremlins away.
I consider this to be a good solenoid.


The bowl vent solenoid does keep gasoline vapor of the atmosphere and does keep gasoline in carburetor (evaporates out, especially after hot engine shutdown), which makes startup easier and fuel mileage a bit better.
If system is working, I recommend keeping it in place.
If I’m missing parts, I doubt I would go the distance to find parts to reattach it (unless visiting California with the car).

BudW

 

[Justwondering]

BudW
You are too cute... I forget about all the pictures I've loaded out there for reasons other than carb identification.

Besides, the house rule from day 1 "Lookie no touchie".

 

[BudW]

Do you know this because they all came that way?
Is there something I see that I could identify it?

There is a number engraved or stamped on all carburetors, that identifies what brand, model number and usually a date code.
Generally, it takes some cleaner and some scrubbing to read it – once you know where to look.

 

[Jack Meoff]

Justwondering, you have shown me what’s under your hood, so I already know (you shown me yours, now I need to get out of town before your hubby finds out).


In ’87, there were two different 2-bbl carburetors used (plus 4-bbl for police, but that is not the case here). The two different 2-bbls were both Holley, version 6280 and 2280. The later one is not computer controlled.

Captain is partially correct, he said:
The 6280 actually has three solenoids.

The red arrow points to the third solenoid, which is the fuel mixture control solenoid, which is what the Lean Burn computer uses to adjust the fuel mixture while driving.
View attachment 17152 View attachment 17153
This is a US emissions thing. All other countries get the normal carburetor (unless special ordered with the US emissions package).

This solenoid has roughly a capacity to adjust the air fuel mixture about 10% (or so).
This is just another reason why gasoline with 10% (or 15%) ethanol mixed in, causes problems for our cars – because vehicles running ethanol requires 10% (roughly) more fuel compared to 100% gasoline – which is more than carburetor can compensate for – or is close to max limitations.


The Fast Idle solenoid is either used for A/C (bumps idle speed up a smudge) and/or is used for after-run condition (when vehicle is turned off but engine has a piston hot spot and car keeps running from hot spot igniting the fuel). By opening the throttle a bit, it generally will keep the after-run gremlins away.
I consider this to be a good solenoid.


The bowl vent solenoid does keep gasoline vapor of the atmosphere and does keep gasoline in carburetor (evaporates out, especially after hot engine shutdown), which makes startup easier and fuel mileage a bit better.
If system is working, I recommend keeping it in place.
If I’m missing parts, I doubt I would go the distance to find parts to reattach it (unless visiting California with the car).

BudW

Thank you for the clarification Sir.
THIS is why I said that somebody with more knowledge would clear this up.

 

[bremereric]

I would dump the lean burn and go back to a Mopar ECU unit and distributor. You can get the whole unit at Mancini Racing or Summit Racing.
Then look for a rebuilt plain Jane carburetor.

 

[Justwondering]

Oh my. That seems somewhat drastic. I'll certainly keep your recommendation in my car book in case I can't resolve this hesitation problem.

 

[Jack Meoff]

Oh my. That seems somewhat drastic. I'll certainly keep your recommendation in my car book in case I can't resolve this hesitation problem.

I've found that the lean burn setup works fine. Till it doesn't. THAT'S when I'd do the swap.

 

[bremereric]

I've found that the lean burn setup works fine. Till it doesn't. THAT'S when I'd do the swap.

I dumped it on the Gran fury I had. I used a MSD ready to run distributor that totally replaced it. And it was an easy swap.

 

[BudW]

If Lean Burn is working, I’d recommend leaving it alone.
I’d also say that one needs to rule out all of the non-Lean Burn problem areas first – which if I was to guess would be more likely anyway.

The choke thermostat is (in my opinion) the more likely suspect.

I also think with that, and a good carburetor cleaning/adjustment, new plugs and wires (which I think, has been done) will fix most hesitation/drivability concerns on a ’87 vehicle.



Justwondering, you mentioned before about the silver flex hose that runs between the air cleaner and exhaust manifold heat stove, not staying in place.
That part really only has a function when engine is cold and outside temp is cold. Otherwise it is not doing a thing. If temps do not get that cold (think southern CA, NV, FL, southern TX, etc.), then one could toss it altogether and not miss it.

If you do get temperatures at the freezing mark or thereabouts, then it might be a good thing to keep in place. I don’t have any recommendations on how to keep it in place, but if it is not fitting on the heater stove 100% - then that might not be a big issue.

The black hose (black or silver, same hose, but black is part paper, silver is all metal) on my car just disintegrated – so I need to find a replacement, in the next couple of months.

 

[Cordoba1]

Justwondering, you mentioned before about the silver flex hose that runs between the air cleaner and exhaust manifold heat stove, not staying in place.
That part really only has a function when engine is cold and outside temp is cold. Otherwise it is not doing a thing. If temps do not get that cold (think southern CA, NV, FL, southern TX, etc.), then one could toss it altogether and not miss it.

If you do get temperatures at the freezing mark or thereabouts, then it might be a good thing to keep in place. I don’t have any recommendations on how to keep it in place, but if it is not fitting on the heater stove 100% - then that might not be a big issue.

The black hose (black or silver, same hose, but black is part paper, silver is all metal) on my car just disintegrated – so I need to find a replacement, in the next couple of months.

I'd like to expand on this. There is more going on here than just helping when the temperature is cold. If you follow the vacuum lines, you will note that the line from the actuator on the air cleaner goes to another sensor on the air-cleaner. If you follow the next hose, it goes to a vacuum source. The sensor/controller on the air cleaner is called a thermactor. It is measuring the air temperature in the air cleaner. It's function is to control the air temperature entering the carburetor to 90 degrees Fahrenheit. Keeping the air temperature at a particular set-point allows for finer control over A/F. It's a $25 part, and very hard to find. I can tell you that my Slant 6 runs so much better after finding out that my thermactor was ... not working. It took a Slant-6 guru to track down both the problem and the part. I understand it is not as critical on the V8 cars, but it is a pretty important system.

 

[Cordoba1]

Helps control carburetor icing, too!