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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.

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:
>
> 
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

.



...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...



...Grab that file and store it on your hard drive...



Now, just a minute. This is from a guy who worked on his own carbs for a decade, trying to chase out the demons, fruitlessly applying logic and procedure, and finally gave in, sending them off to the High Shaman of carburetor Voodoo in his mountaintop Himalayan monastery.

Don't believe what these so-called experts are telling you. Unless you possess the right spiritual connections, no amount of logic and procedure will get your carbs running the way you imagine they should. You will get close, but the carburetor will always hold something back, just to taunt you. They can be so cruel that way.

There are only a handful of mortals left on the planet who have 'the touch'. Save yourself years of mental anguish and deliver your carbs to one of them. Take a vacation, or just get drunk for a week, and when you get the carbs back you can move on to joust with life's other dragons.

Once the Shaman has worked his magic, maintaining carbs is relatively simple. The dance of the mixture screws is easily mastered and takes just a few minutes to restore proper tune. And once or twice a year, a tweak of the idle stops will get you back in synch.

Life is too short to waste any of it setting up carbs. You'll need the time to work out which oil to buy.

.

Last edited by Sacto Mitch

Okay Have followed everyone’s suggestions. Now starts and idles beautifully. If i start off easy and light throttle thru the gears no popping. As soon as I get a little aggressive on the throttle I get carb popping. Timing at 3K rpms approximately.28 to 30 after tdc.

any thoughts?

I feel I am close to getting it right.

Thank you

@Phisaac posted:

Okay Have followed everyone’s suggestions. Now starts and idles beautifully. If i start off easy and light throttle thru the gears no popping. As soon as I get a little aggressive on the throttle I get carb popping. Timing at 3K rpms approximately.28 to 30 after tdc.

any thoughts?

I feel I am close to getting it right.

Thank you

It's BTDC, BEFORE not after. The spark happens before, it takes time for the flame to burn across the top of the piston before it creates the pressure that slams the piston down.

Try a few more degrees, no more than 5, up to 32 or 33 degrees just to see if the popping goes away. If it does, pull it back to 32 degrees or 31. You don't want pinging, which sounds like marbles shaking around in a tin can. This can happen with too much timing.

What distributor do you have? If it's vacuum advance, disconnect the vacuum line from the distributor and plug it. Then rev up to 3k and reset your timing. With high vacuum, your timing can reach 38-40 degrees. But, under load, the vacuum advance will be zero. The vacuum advance only functions at light throttle.

The throttle is involved. I am by no means an expert but my understanding is that things like springs and weights inside the distributor determine at which RPM it reaches maximum advance.

The distributor mechanism will have some amount of advance, say 22 and then you add more, say 8, by rotating the distributor to reach 30 max.

The last time I set it, which was several years ago, I think I just reved the engine until it reached max. advance, whatever the RPMs were, and rotated the distributor until I had the total advance I wanted.

Maybe someone else can enlighten us. I probably should put a timing light on my engine to confirm what I have.

There are two advances the initial advance and the centrifugal advance.     The initial advance is set at idle say 10 degree BTDC.  The centrifugal advance is from the springs with lets say allow 20 degree of addition advance when spun by the engine.  When you add the two advances together, you get the total advance 10 + 20 = 30.

The weaker springs get to the 20 degrees faster than harder springs.  You probable don't need to change your springs.

Don't overthink this, Paul.  It's not that involved but it's different for vacuum advance and centrifugal advance distributors.  

The vacuum advance style has a small rubber vacuum hose going from one or both intake manifolds (or a port at the base of the carbs) over to the advance diaphragm on the side of the distributor - it looks like a small flying saucer attached to the disti side.  THAT is a vacuum advance system.  To set the advance on that you need to consult a stock VW service manual like Bentley's or Haynes for the proper base advance, but it is set at idle and is most often 6º - 8º advance at idle, set by loosening the hold-down clamp at the base of the disti, rotating the disti body until you get to that range and then re-tightening the clamp to keep it there.

For centrifugal advance:

For centrifugal advance we don't really care what the advance is at idle.  All we care about is advance at 3,000 rpm.

Slightly loosen the disti hold down clamp just enough to allow stiff movement.  Attach your timing light to #1 plug wire.  That is usually at around 4 o'clock when looking down onto the top of the disti cap and it runs to the front (towards the cockpit) passenger side spark plug.  

Have someone sit in the driver's seat, start the (previously warmed) engine and have your assistant run the engine up to 3,000 rpm and hold it there as best they can (yes, it makes a lot of noise).  Avoid the spinning fan belt and deftly rotate the disti while watching the timing with a timing light to get the advance up to 30º BTDC.

Turn off the engine and tighten the disti clamp without moving the disti body.  Re-start and do a check to make sure nothing moved and you're done.

Last edited by Gordon Nichols

Guys, you're confusing things a bit. Paul, yes, rev it up to 3000 rpms and hold it there. It really helps to have another person do this for you. Then set the timing by loosening and turning the distributor until you get the advance you want. I hope you have a degree wheel pulley, it makes it easier. Check what you have now, before you change it, I'd like to know what it's set to.

I know the engine builder said 28-30 degrees, and I agree with that. I'm just curious if you give it 32-33 degrees HOW IT RUNS. If you give it full throttle after you advance it a little and it stops spitting and sputtering that's good, it didn't have enough timing advance.

If it still spits and sputters, report back what you find.

Lots of good advice here. We want to help. Almost impossible to fix anything via email.

One last thing.

If you don't know how a properly set up and adjusted engine will run you definitely have a disadvantage. If the carburetors are correctly adjusted at idle. the engine will be running very smoothly. No shaking at all. When you reconnect the linkage nothing should change.

Check your accelerator pump linkage. There should be 1/8 to 3/16" of the threaded rod unless you have 150hp or something like. Weber gives a specification for the volume the pumps are to deliver, it's a starting place not an absolute. This was a major problem for me. I have gone thru the same problem and after everything else this was the fix.

Back off the adjustment nut. Both carbs should be the same.

Last edited by Jim Gilbert - Madison, Mississippi

Difficult or not you better have a look. Very likely you have 1/2" sticking out. It will flood every time you get on the gas.

At 2 1/2 turns on the idle jet screws will have you wasting more gas than you can afford to buy.

I have a 911 shroud on my engine and turned the carbs around to have access to the adjustment screws. If you have the VW shroud you may not be able to do that. As much time as I spent working on the carbs it was worth the effort.

Last edited by Jim Gilbert - Madison, Mississippi

Jim, good advice, except that very last one. First, they're actually VOLUME screws, not mixture. The mixture(ratio of fuel to air) is set by the jets, and we merely adjust how much of that mixture the idle circuit receives. Think about it, the fuel and air ratio is determined by the jets, not the screws.

I've found the correct range is somewhere between 1 and 1.5 turns out from(very carefully and softly) closed. If you end up with peak idle speed at less than 1 turn, the jets are too rich. More than 1.5 turns, the jets are too lean.

2.5 turns is the STARTING POINT for Dellortos, they have a finer thread screw.

1.5 turns out is the STARTING POINT for Webers and clones.

From there, you screw them in until idle speed drops off, then turn them out to peak speed, and maybe 1/8 turn more(NO MORE THAN THAT). I have good luck with exactly at peak speed.

Follow my procedure.

Jim is right though, that the acceleration pump circuit can be problematic and make you think it's the idles or mains. If steady state cruise is OK(no pops, no gas smell, and smooth running) and WOT(wide open throttle) is good(except for initial throttle application) you're probably looking at the accelerator circuit.

But remember, 90% of carburetor problems are ignition.

@Phisaac posted:

Okay Have followed everyone’s suggestions. Now starts and idles beautifully. If i start off easy and light throttle thru the gears no popping. As soon as I get a little aggressive on the throttle I get carb popping.



Phisaac,

I don't know if it is possible on Weber/Empi, but on Dellorto one can install the auxiliary venturi upside down.  Perhaps on re-assembly?  On the 1-2 side?

I know (don't ask how) that when the aux vent is upside down, you can have perfect balance and idle, and it runs well with gentle acceleration up to about 2000.  But if you tromp it or try to accelerate past 2000ish you will be rewarded with truly attention-getting snarly backfiring.

It is not the kind of thing one would normally look for, but it is east to spot if you do.

Like I said, that may not even be possible; just a thought - - - -

Last edited by RS-60 mark

I've been reluctant to weigh in on this because my experience is all Dellorto. While Dells and Webers are very, very similar, there are some minor differences in adjustment ranges, etc. However, the carbs are very similar. The possibility of a torn/blown out intake manifold gasket has been talked about and skipped over to some extent. I've never had any success (like 0/100) finding an intake leak with carb cleaner, WD40, ether, or anything else-- because the leaks are very, very often in the web between the intake ports, where they get super-close. The only way you can eliminate that as a possibility is to take the intake manifolds off, and if you take them off, you'll need new gaskets anyhow. Forewarned is forearmed.

Regarding the difficulty of access to the accelerator pump adjustment:

Pan-based cars don't afford very much room outboard of the carbs in the engine compartment. You might have better luck accessing all of the stuff by just removing the carbs from the intake manifolds (one at a time). Sometimes, just going ahead with the "harder" thing is easier in the long run.

Also, I've always wondered about cutting access holes in the panel that separates the engine bay from the wheelwell. Nice looking cover-plates could be fabricated easily enough, and while you'd need to jack the back of the car up and remove the wheels to get to the carbs through these panels, it's also make changing the number 1 and (especially) the number 3 plugs much easier as well. I've got more room, so it's nowhere near as big a deal for me, but every time I see a CMC/JPS/VS or early IM engine bay, I think that I'd do it for sure if it were me. I'm a fat-fingered primate though-- you may have the limber dexterity I lack.

Either way, it seems like both Jim and Danny have good answers for you. The take-away is that if you need more than 2 turns out to keep the car from popping, there's probably another issue.

Bobby thanks for checking. Per the engine builder I adjusted the accelerator pumps.Then Realized the distributor cap and rotor were both in bad shape. Filed and sanded best possible and popping stopped. I order CB Performance replacements as not available locally. Sooooo,
Hope all will be well🤞.
Thanks to all who helped.
Paul ISAAC
@Bobby D posted:

What type of coil do you have now?  As long as you don't have the Magna spark dry coil pack you are probably fine.  I just had a bad experience with the them.

I had a "Bosch Blue"* coil and had issues with it. Until I used an analogue multimeter to check it and found it out of spec. After I'd chased "carburetor problems" for a month.

Stan knows whereof he speaks.



* Probably the Chinese crap that they sell as Bosch Blue coils these days.

@Phisaac posted:
Maybe I should replace the coil as well? I had several issues going on. Carbs dirty and gunked up along with a sticking float. Plus accelerator pumps not pushing enough fuel. Once the parts arrive I will know if all good.
Paul

Paul ISAAC

Do you have a multimeter?



"Use an Ohmmeter to test the coil.


Remove all the wires taken off the terminals of the coil attach the positive and negative, red and black, wires of the meter to first the terminal 15 (positive) and 1 (negative) that are stamped on the coil.


A reading of at least 3 - 4.5 ohms, indicates a good coil.
A bad coil will show a higher reading then 3 - 4.5 ohms.


Place the red or black lead from the meter to the center of the coil (secondary post), and to either one of the terminals, 1 or 15 on the coil.


A reading of 9,500 - 10,000 Ohms, sometimes less, indicates a good coil.
A reading of 11,000 Ohms or more, or a reading of zero indicates a bad coil."

Last edited by dlearl476

I’m curios as to where you folks have your coil mounted?  If it is attached to the fan shroud or with a bracket holding it above the engine case next to the distributor, it is subject to “heat sink” when the engine is turned off, especially in hot weather.  All the residual heat in the engine case saturates anything mounted above the case.  Particular attention must be given to electronic stuff like Pertronix ignition modules and some types of coils.  Heat is not their friend.  The reason some coils are oil filled is to dissipate heat to let them survive in their environment.

Regardless whether you have a so-called “oil filled” coil (wet pack) or a “dry-pack” that is usually smaller and surrounded by epoxy, it helps their longevity to mount it on the driver’s inner wheel well  and away from the case heat.  

I ran a MagnaSpark I dry pack for 30,000 miles with no issue, then replaced it with a Mark II version (all I wanted was the newer MagnaSpark II disti, and the new coil came in the box, too) still no problems.  Both were mounted off to the side on the wheel well panel.

Just food for thought.

.

A few random thoughts.

I’ve been running a Magnaspark II for a few years now. I put it in to fix some serious spark scatter I had with a Pertronix-branded 009 knockoff. It did the trick. The mechanical spark advance bits in the MS seem to be much better quality than the corresponding stuff in today’s Chinese 009 repops.

So, this was another example of ignition problems masquerading as ‘carb’ problems. The symptoms had been a slight miss in the ‘transition’ range between idle and about 2000 rpm. This is where many people have the most trouble getting their carbs sorted out, but if spark isn’t solid and consistent there, no amount of carb tweaking will do any good. And, since it’s a fairly simple thing to check the spark consistency with a timing light, it just makes sense to do that before messing with some ornery carburetors.

Also, the Magnaspark is perfectly happy (on a VW engine, at least) with an old-school Bosch coil. The MS folks will tell you this (in the fine print) but they’d much rather you buy one of their fancy-Dan gluten-free designer dry coils. I’ve been using the same old coil I did with my old dizzy and it’s been just swell. Do check yours out to make sure it’s OK, though. And yes, as Gordon suggests, my coil is mounted on the side panel of the engine compartment, as far from heat sources as possible.

Coaxing these engines into tune is a process that should follow some clearly defined steps. The carbs are complicated, finicky devices. Our basic ignition systems are simple. Do the simple part first just to eliminate that as a source of trouble. Then, move on to the carbs.

If you’re really lucky, you may not have to.

.

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