Jetting suggestions for 34 PICT on 1776

First thing, set your timing at 30-32 BTDC with the vacuum line disconnected and the RPM up past the point of maximum mechanical advance, say around 3000. Max advance should run up over 40 with the line back on and when you bring up the RPM slowly. That extra

If your 34PICT carb is old, consider buying a new one. By the time you get one of these rebushed, rebuilt, new solenoids, choke, etc, it will cost close to what a new one runs and it will likely still have some issues. If you can't get the neccessary 1.4-1.8CC/stroke on the accel pump due to internal check-ball seat corrosion inside the hidden passages, you will never solve hesitation problems. And the choke may still get you issues even if you buy a new element. If you do buy a new carb, get it from a supplier who will stand behind the sale such as

Jetting isn't rocket science. 55 idle at sea level should work even on a 1776. If the idle RPM peaks at 2-3 1/2 turns out, you're OK. If it takes 4 1/2 to 6 turns to peak, go up a size or (1/2 size if you can find them - rare!). Main jet should be around the 130-135 area to start at sea level. Air correction 75 to 125 and these are changed only to richen up or lean out the engine at a certain RPM range when you're running on the main. Check out the articles at this excellent website for more detailed information;

Here are results from yesterday. Valves were fine, I then checked for any intake leaks. None were detected, even around throttle shaft. So, I let it warm up, and set the timing to 32 degrees full advance. I have a 52.5 idle jet in it, so it took about 4 1/2 turns to get max rpm ( thru a tach on my timing light).

Maybe someone can help me understand this volume control screw/idle jet. I believe the volume control screw lets in more air into idle circuit as it is opened. Now, my question is, why is my car so rich at cold idle? I have a 52.5 idle jet, and my header pipe points to the ground, so i can see a sooty spot on the ground. The car does not speed up when cold and choke engaged. It seems if i go up on idle jet, it will get more fuel and be more sooty? But then i look at my 1600 and it runs a 55 idle jet and operates as it should.

Any advice is greatly appreciated.

vg> I am diving into it today. I will start by verifying timing, and jet > size.

Volume control screw allows air to bypass the throttle plate. The position of the throttle plate is critical to the progression ports and the vacuum signal to the distributor. And since all engines wind up being slightly different, by using an adjustable bypass circuit, you don't have to disturb the position of this plate to get an engine to idle properly.

Change out the idle to 55. A 34PICT carb usually doesn't like leaner-than-stock idle jets in my experience. 4 1/2 turns out confirms this. Verify your fuel pressure with a gauge that reads accurately at low pressures, say 0-15psi. 2 1/2 lbs of pressure for a stock carb is a good target. Toss in a rebuild kit that has a new needle valve if you suspect your fuel level is too high in the bowl. Cause your symptoms sure point in this direction. To cause soot on the ground, your getting wayyy too much fuel and it isn't the idle jet.

Don't rule out a vacuum leak if your engine lumps along on 3 cylinders for a while when cold. I chased a demon in my engine for longer than I care to admit and it turned out to be an intake leak. I kept suspecting that but even ether didn't bring any change to the idle speed. Turns out the leak was where the end casting bolted to the head at a spot where pressurized air from the cooling fan squirted out from the cylinder tin. In retrospect, maybe I should have used one of those little red extension tubes to get the spray concentrated right down into the crevice.

RT

Raymond,

Thanks for the info. I read this post AFTER I had tinkered for a while, and here is what i discovered I swapped idle jet to 55 at first, and there was no change. Then I went to a 45, and 2 to 2 1/2 was max idle. I drove it around the block, and performance seems identical to the 52.5 jet. Odd, ain't it? It is pretty peppy, mind you. Definately not a beater running on 3 for sure.

I think that you are dead on about maybe the needle/seat being worn. Once the choke goes out, and i blip the throttle (at the engine) I see a black waft of smoke and smell fuel. It is not dripping anywhere, so it is being wasted out the exhaust. I thought, maybe too rich of main jet, but that would not explain the soot hitting the ground at idle.

I think i will attempt a rebuild of this beast tomorrow. I will pick up a carb kit and see what happens.

Raym> > Here are results from yesterday. Valves were fine, I then checked for

That's a good start but I would stress strongly that a fuel gauge is a must-have. Maybe an industrial supplier or decent parts store that carries Wika gauges. They're good quality and fairly cheap.

RT

My friend at the VW shop has a pressure gauge...I will test tomorrow when i buy the kit.

Too much fuel pressure could for sure cause what i am experienc> vg> > Raymond,

I think a 34 pict is too small for a 1776. I have a 1641 (groan) and it can barely cope with it at higher revs. I'm running 55 idle and 132.5 main jet.

--Steve

vg> I am diving into it today. I will start by verifying timing, and jet > size.

It seems the carb will be maxed out on the 1776 for sure. But I also have one on a 1641 and can go over 90 mph if i want to, so something may be amiss with your car.

If the car was runn> I think a 34 pict is too small for a 1776. I have a 1641 (groan) and it

I have a 1600DP and I'm have 34pict3 with idle 60 main jet 132.5 Corrector air 80

I don't think it is rich, but I haven't the tools to check that. I have to buy a lambda first. It runs strong from idle and I don't see any black smoke. If you have the stock air filter try to clean it hard to improve the air flow.

Jo=E3o

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