Idle jet circuit help (Webers)
 

Hi,

I think that the problem with my 2 cylinders showing no activity at idle is finally coming from the carb on 1-2-3. 2-3 are not doing anything at idle but they pick up when the accelerator is pressed.

Took the carburator off again. Took the top part off and removed the floats.

Inspected idle jets, mains, emusion tube. Everything is clean and nothing is cloged.

Took the air compressor and started blowing in every passage. Nothing seems cloged.

Friend of mine put fuel back into the bowls and started blowing air where the mixture screws while cloging the hole in the barrel.

On number 1 fuel spits right out of the carb via the air correctors (like 3 feet hight).

On number 2 fuel barely goes out of the air corrector.

Seems like the passage is clogged in the idle circuit and i'm trying to identify the path that the fuel takes from the bowls to the mixture screws.

Anyone have an idea on the actual path or a reference to a picture or shematic?

TIA

Marc-Andre Morin
70 914-6 conversion 3.0 Webers



On number 3 nothing goes out of the air corrector.

update
 

Just got back from the flaps with 3 cans of carb cleaner...

Not sure about the path but i do know that they seem to be blocked between the idle jet and from where they take gas from the bowls.

Again number 1 spits out carb cleaner out the emulsion tube hole while number 2 and 3 seem pretty much blocked (nothing coming out of the hole in the bowls over the main jets or coming out of the emulsion tube hole.

It will be almost 2 months now that i'm not enjoying my Porsche as summer is pretty short in my part of the woods.

Please help!!!

Marc-André Morin
70 914-6 conversion 3.0L webers

Marc,

I would take a small piece of wire and gently probe the ports. Try going the same direction on one carb, and then do the same on the other carb. If any of the passages or ports seems blocked, then investigate.

I would hesitate to start poking very hard but if the same port/passage on three sides of the carbs are clear, and you find what might be an obstruction on the other one, then one could assume that something is not right and needs to be corrected.

I have never seen a schematic of the circuts internal to the carb but there should be one somewhere...

Joe

Marc..I'm curious..it seems like a lean condition could toast a valve..do your spark plugs look HOT???........Ron

Concerning the plugs.

These 2 cylinders kick in when i press on the gas pedal. For sure, i'm squirting gas from the accel pump.

So after this short trip on the highway, or gunning it just before i hit the driveway and shut the engine they look pretty much white (lean).

I did the test again installing new plugs and letting it idle for 10 minutes last week. Plugs show no activity on these 2 and come back out almost like new. Others are tan.

Seems i'm not even lean on these 2. It's sparking with only air at idle.

I'm now pretty much sure of where the passages that are blocked on 2 and 3.

It's definatly located between the idle jet port and to where it takes it's gas from the bowl.

Drill in hand, with a really small drill bit (way smaller than the lead plugs), i'm taking a chance and drilling out 2 lead plugs as i'm about sure where the blockage is.

Be back in a while.

Marc-André Morin
70 914-6 conversion 3.0L Webers.

Marc,

I would be careful about drilling out until you are positive that it should be clear... some passageways are plugged on purpose after they make the carbs.

You are braver than I am here but if needed guess you could plug it back up if needed with epoxy.

Joe

Marc..thanks for the reply...sounds like your repair is a done deal...makes me think that an EGT probe in each exhaust tube could read the lean situation...If only one cyl. was lean it could burn a valve before the problem was noticed and repaired..does that sound logical??...........Ron

I had a bad plug, straight out from the box. It came along with the revs, but did not work when idling. It might give you spark when in free air but when the sparkplug is "compressed" it might not work.

I've tested with several (4) different sets of plugs. Let's say that i have spares in my toolbox for a while. Compression test was done again showing no differences between the 3 barrels.

Synchrometer shows nice vacuum activity and equal on all 3. I'm hoping i don't have a burnt valve.


Concerning the passage. Found the offending one.

Gas feeds by a passage located at the bottom of the emulsion tube holes. Fuel then goes in the same direction as the main jets in a passage.

90 degree bend to go straight up A lead plug is located here

Once at the top of the carb, another 90 bend to align with the idle jet port. Another lead plug here.

Both barrels were clogged between the 2 lead plugs (the passage going straight up).

No it's clean and 3 cans of carb cleaner are now empty.

Now to race around town to try to find some lead plugs!!!

I really hope to find some this morning and drive the car this afternoon.

Marc-Andre Morin
70 914-6 conversion 3.0L, Webers

Lead plugs
 

I had a lead plug fall out. Potential consequence is an engine fire. Two people recommended lead shot to fit, about 00 or 04 size, just bang it in. That's the low-tech solution. I drilled out the hole, tapped it, and put in a bolt with threadlocker. It doesn't look as slick, but I sleep better at night.