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Having reall problems. Seems to be running rich. But carb popping during load accelerating editing 2nd gear. Black exhaust pipe stains. Very bad exhaust fumes. So much carb popping on one carb inside black stains.

timing is correct. New plugs. Old ones dry but Black.any thoughts? Carb rebuild?

only 2000 miles on car. Although has sat up a good bit before I purchased.

Thank you

Paul

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@Phisaac posted:

Having reall problems. Seems to be running rich. But carb popping during load accelerating editing 2nd gear. Black exhaust pipe stains. Very bad exhaust fumes. So much carb popping on one carb inside black stains.

timing is correct. New plugs. Old ones dry but Black.any thoughts? Carb rebuild?

only 2000 miles on car. Although has sat up a good bit before I purchased.

Thank you

Paul

My smoke is sooty black

Rust/dirt/crud/shmutz in the tank from sitting could have clogged the idle jets and possible other passages in the carbs.  I'd try cleaning the idle jets first.  That would at least tell you if that's the problem.  The cure might involve cleaning out the fuel system.  At the very least I'd expect new fuel filters.

Sitting is bad.  I had a similar problem with mine when it sat while I tried to get it first registered with our lovely SC DMV.

It was running when I parked it! They were pretty much all were. It don't mean they'll run now.

Redlineweber.com has a lot of free information. Download the IDF stuff. Read it and re-read it and read it again when you are working on the carburetors. Just like spaghetti sauce...it's in there.

EMPI carburetors are a copy of Weber 44's. If your car has setup for a while you'll need to rebuild the carburetors. Get new carb kits and be sure that the float needles have viton tips.

Check for air leaks at the intake manifolds below the carb bodies and at the connection to the heads. Check for air leaks in the exhaust headers at the heads and any other exhaust connections.

If you have a heavy smell of gas fumes in your garage you likely have a float that is not closing. You may also have gas in the oil. If you smell gas in the oil; change the oil immediately before running the engine. Be sure all oil is drained from the system if you have a remote filter and oil cooler.

Idle jets are a fairly constant issue. Remove the jets and blow air thru the orifice. You have to be able to see thru the jet. Be sure to replace the o-rings on the jet holders. Be sure that the old o-rings are not in the carb body. Also blow back thru the carb body where the jets were. If you don't have an air compressor you can buy canned air at Office Depot.

Install Jet Doctors. They do wonders, but you'll still have occasional idle jet blocking.

The float bowl is open to the atmosphere within the air filter. Nothing you can do about that.

The idle stop screws are never more than 1/2 turn in from contact with the arm. You will never get the carbs set right if they are set more than 1/2 turn.

Balance of the carbs is critical. They either work together or work against each other. They cannot be balanced with the carb linkage attached.

There have been volumes written about this issue here. Search the archives.

Rust/dirt/crud/shmutz in the tank from sitting could have clogged the idle jets and possible other passages in the carbs.  I'd try cleaning the idle jets first.  That would at least tell you if that's the problem.  The cure might involve cleaning out the fuel system.  At the very least I'd expect new fuel filters.

Sitting is bad.  I had a similar problem with mine when it sat while I tried to get it first registered with our lovely SC DMV.

After sitting who knows how long in FL, then being "restored," then sitting outside through 2 NY winters after I bought it, I probably soaked and swished close to a pound of rust flakes out of my tank over the first two years I really started driving it.

After leaving it sit with a coating of Gibbs Brand over two winters while I had the car apart for modifications, then replacing the fuel pump and filters, I think I've finally got it cured.

I'd say new filters and a carb rebuild would be a good start.



Check for air leaks at the intake manifolds below the carb bodies and at the connection to the heads. Check for air leaks in the exhaust headers at the heads and any other exhaust connections.

I've posted this tip before, but barring having an expensive smoke generator to do this, a stick of incense makes a great leak detection tool for checking this out.

Bonus: it smells good, too.

Exactly what Jim Gilbert said.

I'll only add to remove the idle mixture screws, and blow carb cleaner through them. It will come out the idle jet holes. Then blast it through the other direction. A lot of times the idle circuit is full of junk, and cleaning the jet only gets the one chunk of gunk. There's usually plenty more where that came from.

In fact, remove the carbs, and take the tops off. My money is on white goo in the bowls, and everywhere else in the carbs. Clean them REALLY well. Rebuild and assemble.

Make sure you retain track of all washers, o-rings, and springs.

Did you get the Weber tuning guide?

How have you determined it's 1 & 2?

Does the popping start when you let off the gas?

Is the popping back thru the carburetor? Check for exhaust leaks.

Are the air by-pass needles  closed?

Did you check for air leaks at all gaskets with spray carb cleaner? Spray anything that has an o-ring or gasket.

Proper tightening of the carb body screws does not mean trying to wring them off. Sequentially tighten the screws in a cross pattern, just snug and one more grunt.

All adjustment screws are lightly seated when screwed in. Not tite. There is no repairing a damaged carb body from over tightening the adjustment screws...as far as I know.

Idle jet blocking should not be a factor above 3,000 rpm.

Check the ignition timing.

Have you adjusted the valves?

Chasing the popping can be really annoying. The engine will run fine until you want to take it to a show. They never give any problems when you have no plans.

I'm one of those guys who wants to fix it NOW. Sometimes I find that if I just put it down for a few hours and then go back the problem gets resolved...what ever it is. Sometimes it doesn't.

Don't know what your abilities are, hopefully they trend toward mechanical. It's not rocket science, but can be tedious.

All things work together.

Careful, step by step will get it right.

"I am Still getting some popping from the #1-2 carb under load."

Spray some carb cleaner around where the carb mates to the manifold and again where the manifold mates to the head.  I'm betting on a gasket leak.  If it leaks, the idle speed should change when you spray it around the gasket intersection, but not always.

Did you use new gaskets on both ends of the intake manifold on that side?

Last edited by Gordon Nichols

You will get this. I synched and set mine after installing jet doctors and had the same problem you have: mid-load popping. Synched them and set the idles again.

No good.

Third time was the charm.

Now of course I will have to pull them apart again in the spring after I get air-fuel readings from the wideband O2 reader. They are rich AF.

It gets easier with each iteration.

@edsnova posted:

You will get this. I synched and set mine after installing jet doctors and had the same problem you have: mid-load popping. Synched them and set the idles again.

No good.

Third time was the charm.

Now of course I will have to pull them apart again in the spring after I get air-fuel readings from the wideband O2 reader. They are rich AF.

It gets easier with each iteration.

I am going to disconnect the linkage again. While on engine reset to bench settings and try again. Everything I read said to adjust low speed by ear which I did. This time I will use a tach.

.

The 'donut' connectors that came on a lot of our exhaust systems are notorious for leaking and causing popping. If that's the case, you can have NASA clean and adjust your carbs, and you will still have popping.

I was going to ask if you have any black, sooty stains on the exhaust system around those donut joints near the muffler, and then I read in your initial post 'black, sooty exhaust stains', so hmmm... maybe have a closer look at that.

Better systems use welded-on real flange joints instead of the donuts.

Just a thought.

.

Good point, Mitch. Leaks, both intake and exhaust, and both rich and lean can cause pops and backfires. As well as normal warm-up, mine pops and burps a little until it's been driven a good 5 minutes and actually starts to warm up. I drive gently until it does so, and don't get those burps and pops.

And don't adjust your carbs unless the engine is HOT. Very important tip to follow here.

Exhaust flanges? Old school. V-clamps are the way to go for no leaks and no gaskets needed either.

Any recommendations for bench settings that work best? I have read and heard several.

Paul Isaac
Sent from my iPad

> On Dec 23, 2020, at 8:23 AM, PAUL <phisaac@comcast.net> wrote:
>
> Thank you everyone for your input. Mine are welded on so I can eliminate that one. My initial adjustment was not done with a warm engine. So I am going to run to warm then disconnect linkage and set back to bench settings and start over.
>
> Paul Isaac
> Sent from my iPad
>
>>> On Dec 22, 2020, at 10:18 PM, SpeedsterOwners.com <alerts@.com> wrote:
>>>
>> 

I thought the article was so good, I saved it on my computer.  As you guys know I battled with my HPMX carb this year.  I had two main issues that cause problems.   The first was a vacuum leak at the manifold.  The second was a bad Magna Spark Coil.  These two issues made me think the carb were the problem.  I chased these around for two months.  Removed and cleaned the carbs three times.  The HPMX carbs are a good product.

Hole-drilling @ALB wrote about Danny P's Carb article:

"A little wordy, don't you think? "

Not at all.  Just thorough.

There's a bunch of people on here who have never had to tinker with a carburetor other than on a lawn mower or weed wacker.  To many people (my son, included), working on a carburetor is akin to lighting incense and tossing dried chicken bones onto a tanned alligator skin to unlock their celestial meaning.  There must be some sort of VooDoo involved with making a carburetor work right.

They're sure of that shortly after their first "rebuild".  

They're totally convinced after the third (and possibly successful) "rebuild" when they didn't do anything different from the first two, but now the "Carburetor Druids" are appeased and, Behold!    The damn thing runs.

Grab that file and store it on your hard drive.  Better yet, because you'll probably lose it in the unstructured clutter of your computer, incorporate it into a custom digital  Service Manual for your car so that in a year or two or four when you have troubles and you've forgotten most of that stuff, it will still be there waiting to help you out.

Doctor Dan to the rescue!

@ALB posted:

@DannyP- I just read your carb adjustment/synchronization article, Danny, and all I can say is wow, it took forever!  A little wordy, don't you think? 

Compared to my usual spare style, maybe?

Your car finished yet, Al? Methinks no room to talk, Yoda?

It's two pages, Al. It's not a novel. Are we airing grievances? It is Festivus today. Grumpy are we?

Gordon, Paul, and Bobby, thank you.

And Paul, set the mixture at the hot idle speed you want, not barely running. Every time you change the throttle plate position you need to set the mixture screw again. Empi is wrong.

Last edited by DannyP

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