Idle problem with 34-3 carb

[bncjr8]

Hopefully this photo will shed light on what I have done. I have about run out of things to try on this rail project. It was running rough and would not idle when I bought it. Here is what I have done so far...

New Empi 34-3 carb
New Pertronix svda distributor
New intake boots and gaskets
New NGK plugs
New plug wires
New Beru coil
New generator and Bosch regulator
New fuel lines and filter

It runs better but what concerns me is I had to back idle adjustment screw almost all the way out to get it to idle. I also had to back out the mixture screw about 4 or 5 turns. I have not gave this rail a road test yet because I don't want to buy a tag until its road worthy but just reving it still seems a bit of a flat spot still with the svda and at about 1/4 throttle a bit skippy. I have played with the timing and advanced it way more than I thought it should be just to get it to idle and run better. I am doing this all by ear and old school but I have ordered a timing light to get it in that 32 range. I feel I have advanced this dist past the 32 in my trials and still not perfect but I will see when I get my light where we are. I have also heard stories of worn out low compression engines needing timing at 44 degress.

I need suggestions from VW pros that have experienced similar hair loss problems

[wythac]

http://www.thesamba.com/vw/forum/search.php?search_keywords=34-3&search_forum=12

Search is your friend.

[64glitterbug]

I have a very similar problem. I've raced and built race engines for years, so I'm not a novice at engine tuning, just air cooled VWs. My buggy runs flat with the timing set in the ball park of what my manual says it should be, but advance the timing and it runs , drives, accelerates very smoothly. But then I can't back the idle screw out enough to slow the idle down where I want it. The valve lash, dwell, plug gap etc.... are all within specs. It just runs sluggishly at 7 degrees idle and 35 degrees advance. Generating too much heat would be my concern right now but after riding this summer I think I'll leave it for the winter. I'm interested in what you find.............

[Q-Dog]

I have not heard one single good thing about empi carbs ... not one. You would be better off with a professionally rebuilt original german carb.

If you are going to run the 34pict3 you need manifold heat. And Until you get the timing correct you can't really get the carb set correctly. If it were me I would use a vacuum gauge to see how much vacuum is at the carb advance port and how much is needed to move the distributor advance. Since both your carb and distributor are aftermarket parts, they may not be compatible with each other.

While you are fixing things, your generator is installed 90° off. Unbolt it from the shroud and rotate it.
_________________
Brian

'69 Dune Buggy
'69 Beetle Convertible
'70 Beetle

[clonebug]

Proper setup of the carb is critical.
Follow these directions and see if it helps.

http://www.vw-resource.com/34pict3.html
_________________

[jspbtown]

Check for vacuum leaks.

[andygere]

I'm running an Empi 34-3 carb and find it well made, clean and a good runner when set up. Be sure valves are adjusted, and let the motor warm up thoroughly before tuning. Without manifold heat, this can take quite a while. As others have suggested, try advancing the timing. You can check to see if the vac advance is working by pulling vacuum on the hose by mouth. Are you timing with a strobe type timing light?

[bncjr8]

Thanks andygere. I have adjusted valves. I get everyone keeps saying heat risers but with carb adjustment screws according to factory this thing will barely crank so heat will not help at that point cause there is none. I hate to spend money on new exhaust and intake and still have same problem.

As I said I was able to get it to run and idle with volume screw out about 7 turns and mixture screw almost all the way out. That tells me something is missing.

I have advanced timing just by ear but I had to order a light and have not got it yet. I did see a video of a guy that said he ran into a bus with low compression and had to advance timing to 44 to get it to run smooth.

[andygere]

Don't be freaked out by how far out the screws are, the "factory settings" are a starting point, and based on the Solex carb, and the Empi carb is slightly different. Have you verified that carb internals are clean? Remove the idle jet, and blow out with compressed air and make sure it's clean. Don't ream out with wire or other material. Also, pull the "secret small idle jet" out and be sure it's clean. It's the one that's hidden under a small brass plug on the right side of the carb. If either are dirty, idle will be difficult to get right. Perhaps most important is verifying timing is correct. Have you checked compression, or just worried that it might be low?

[jspbtown]

Seems like all that extra fuel is being dumped in to compensate for a vacuum leak....

[scooter trash]

I had a similar problem that was caused by the intake manifold icing. A single carb set-up must have a heated manifold. If your exhaust has provisions for the manifold heat tubes, buy a stock (uncut) intake manifold and hook it back up as it was originally. I the exhaust does not have provisions for heat tubes, you will need to replace it or go to dual carbs. IMO

[bncjr8]

I finally got my timing light and I had to advance timing to around 30BTDC at idle and near 55BTDC at high rpm just to get it to run smooth and idle. I think this motor is worn out.

[Meco]

Are you disconnecting the vacuum hose from the carb or distributor (and plugging the carb vacuum port) when you time the engine? I am pretty sure thats what you need to do to set timing when you use a vacuum advance distributor. Let me know if I am wrong, please.