Idle Setup Problem

[JK73Super]

After spending a gread deal of time (have learned a lot) and replaced most fuel and iginiton components, the engine still does not idle properly.
What am I doing wrong?

Background: Purchased used engine, ran but would not Idle well. (summer 2010) details below:

1. Dual port 1600cc, AHxxxx built 1973
2. Generator with new Regulator (all wiring repaired and checked out)
3. Distributor - Dual Vacuum Dual Advance, new points set 0.016”, new condenser, new dual advance vacuum canister (old one leaked).
4. Original Ignition coil.
5. New Spark Plugs 0.025"
6. New Spark Plug Cables
7. Carburetor – Solex 34 PICT-3, Main Jet 1.325 mm (rebuilt, throttle shaft slightly worn, temporarily sealed with Silicon RTV)
8. Intake manifold gaskets all new – no leaks
7. Fuel Pump – New (style that allows mounting of an Alternator)
9. Valves set at 0.006” (Intake and Exhaust)
10. Fuel filter new clear in-line. Fuel pressure – don’t know yet.
11. Compression – don’t know yet

Engine would start, run at high idle, warm up and eventually stall on idle.

Phase 2 – Spring of 2011 - Installed new:

1. New Pertronix Vacuum Advance (SVDA) Distributor – Complete with Ignitor Ignition module installed – from CIP1
2. New Pertronix Flame Thrower Chrome Coil – from CIP1
3. New Euromax 34 PICT-3 Carburetor- from CIP1.

Still having difficulty with setup and Idling.

Started out by setting engine TDC for No.1 cylinder, installed new distributor and new coil. Set old carb Bypass Air screw (large) and Idle mixture screw (small) 2 ½ turns out from fully seated. Plugged off both vacuum lines. Engine started and ran but at fairly high idle. Adjusting the carb would bring the idle down, but it would not idle for long before stalling.

Installed new Euromax carb (can’t tell main jet size – very poorly marked – generally this carb appears to be poor quality). Set the bypass and idle mixture screws 2 ½ turns out. Plugged off both vacuum lines. Distributor set at TDC for No.1 cylinder. Started engine and it ran at a high RPM. Again attempted to adjust carb and distributor to bring down rpm to the 800 – 900 RPM idle. It would idle for a short time but then stall.

Noticed that the fuel level in the clear fuel filter was very low, close to the bottom inlet line. Added a few more gallons of fuel and tried running again, but the level in the fuel filter was still very low. Is this normal? Shouldn’t the filter be at least half full or more? Could the engine have such low vacuum at idle that it could run out of fuel and stall? I understand that the fuel pressure should be between 1.5 and 2 PSI. I will be looking for meter to mount just before the carb.

Perhaps I’m not following proper procedure for set up. I thought that I should be able to set the RPMs around 800-900 with the distributor set at TDC for No.1 cylinder, attach the timing light and set the timing at 7.5 degrees BTDC, re-adjust my RPMs with teh carb, attach the single vacuum hose, plug the other vacuum hose on the front of the 34 PICT-3 and be done. Any recommendations?

[Piledriver]

A "low level" in a filter generally means it's CLEAN.

It also tells us you have a clear filter in the engine compartment, I HOPE it's on the inlet side of the fuel pump, and not headed up to the carb...
(See many threads on ways to kill your VW)

Sounds like you probably have a vacuum leak.

You can usually find these with an UNLIT propane torch, but the fan thing makes it a bit difficult.
Brake cleaner will choke the motor (and you if you get a lungful of it out of the exhaust) but works sometimes when the propane etc will not. Only use the brake cleaner trick outside in a strong wind--- The combustion byproducts are probably very bad for you if you "find" a vacuum leak. If the leak is big enough s a shot of brake cleaner will put out the engine, IOW stall it at idle.

[Steve Arndt]

Carb cleaner spray works better than brake clean spray for finding vacuum leaks.

[Piledriver]

Carb cleaner spray works better than brake clean spray for finding vacuum leaks.

Carb cleaner is also highly flammable.

[Steve Arndt]

Yep, but it is better for you to breath in the byproducts of it than brake cleaner. Neither will add any longevity though :p

[JK73Super]

Well I'm still not able to bring the idle down to around 900 rpm, but now the fuel filter sight is full when the engine runs on high idle. BTW, when it stalls out as I try to a bring down the rpm, it always starts back up immediatelly as soon as starter starts cranking. Could I have a main jet issue? Someone I met last year at the June Jitterbug had installed the Euromax carb, but he file the main jet to a larger opening for proper operation. Any thought on jet size?

Before I go any further with the carb and distributer, I decided to check the compression, unfortunately the compression gauge access to the cylinder is very tight. So, I'm in the process of using an old spark plug and welding a pipe to it so that I can make the necessary solid connection to the gauge.

[JK73Super]

Well finally I have completed the compression test and it looks bad, according to John Muir's 'How to keep your vw alive'.

After warm up, here are the results:

Cyl. 1 - 80 PSI
Cyl. 2 - 80 PSI
Cyl. 3 - 90 PSI
Cyl. 4 - 90 PSI
I understand that at this point the engine needs a rebuild.

After adding a few squirts of oil throught the spark plug hole:

Cyl. 1 - 80 PSI - Leaky valve
Cyl. 2 - 90 PSI - Worn piston ring
Cyl. 3 - 100 PSI - Worn piston ring
Cyl. 4 - 100 PSI - Worn piston ring

One more thing. By the time I wanted to do the oil drop test, the engine cooled down. So, I put the plugs back in and warmed it up on high idle. Then I observed something abnormal.
Cyl. 1 & 2 intake manifold was very hot while intake mainfold 3 & 4 was barely warm. Also Cyl. 1 & 2 sprak plugs were hot, while cylinder 3 & 4 sprak plug were cool.
The engine seemed to have been firing normal and appeared to run fine on high idle. Why would cyl. 3 & 4 spark plugs be cool after warm up???

[Piledriver]

It could be that since 3/4 have somewhat better compression, it's running more on 3/4.
(That or your tinware is horked)

If you have access to one of those IR temperature guns hit the ex pipe stubs, that will tell the tale as or more clearly.
(I primarily use mine to play with the cats with the laser )

[astglenn]

80 PSI is not great, but it is plenty to support reasonable combustion and useful vacuum. Like Piledriver said. This really sounds like a vacuum leak. I would be looking at the intake manifold to head intersection. Good old water, through a SPRAY BOTTLE will also tell you the tale. It does not take much. WD-40 is a partial combustible that also works good. Many times a weak cylinder will pick up a bit of RPM with misted water. The expansion of the steam fixes that low cylinder pressure with a quickness.

[69vw1915]

Do you have access to a Bentley's manual? There is a 10 step procedure for setting the idle on a 34PICT-3 that distills down to the setting of the bypass screw (large slotted) that is "up and forward" with the carb on the car from the volume control screw.

Even with the volume screw set to 2 1/2 to 3 turns out from being gently closed, the bypass screw determines if the engine will idle at all. Been There-Had To Do That...

[Clonebug]

I put 25,000 miles on my engine while it had only 90 lbs. compression.

I also ran it with a turbo for 3000 miles until I found the case had a crack in it.

It always ran nicely........Most problems I had were carb related.

I would run it till it blows if I were you.

My guess would be you have a severe vacuum leak on the throttle shaft even with the silicone. Spray some carb cleaner at the throttle shaft when at an idle. It will tell no lies.....

Pull the carb apart and put orings on the shaft or get the bushings redone by a well known carb rebuilder.

[Twystd1]

Adjust your valves before you do anything more.

Then set timing. See if this effects your cold cylinders.

Then retest your compression with a hot engine. report back.

That is where i would start.

C

[Marktt]

Reviewing this post for research on the idle issue; noticed in opening post the following was represented:


Started out by setting engine TDC for No.1 cylinder, installed new distributor and new coil. Set old carb Bypass Air screw (large) and Idle mixture screw (small) 2 ½ turns out from fully seated.

Maybe someone caught it and commented on the problem with opening up the bypass in the responses, didn't read all, but if in fact he set the bypass air screws 2 1/2 turns out that equates to a huge vaccum leak/lean affect (at least on Webers it would).

[Piledriver]

That procedure was for the original Solex carb, paraphrased from the service manual.
It was also from 2012....