Engine shakes excessively at idle

[Donewright]

UPDATE:

I reset the Volume Screw and the Bypass screw on the carb.

I also adjust the Bypass screw and got the rpm's set to 1000.

The SHAKE disappeared!

I am also now getting readings with my Timing Light, but they alarm me;

Idle - 28 degrees
3000 rpms - 42 degrees

I think my next step is to rotate the distributor to bring the 3000 rpm value down to 32 degrees

UPDATE #2: I was able to slightly turn the distributor and the 3000 rpm value dropped down to a steady 32 and at idle is was down to 16-18

I had to adjust the Bypass screw just a little after that and it's idling at 1000 rpms with just a tiny shake, so tiny I think it's normal!!!

It idled smoothly for over 15 minutes without dying!

[Dusty1]

There are too many variables here to simply point at the carb and the distributor. I see no mention of a compression test. You bet it's gonna run rough if you have something like 125 (psi), 125, 85 and whatever. Or good compression on one side of the engine, loose heads on the other.

It's worth a visual inspection to verify that case savers have been installed during the long, long life of that "H" case.

I'd pop the valve covers off and see what I had for heads. 040 or 043 prefix... maybe cause for celebration. 111 or 113... they may have as many laps around the block as the case.


I'd be tempted to tear that thing all the way down. I like taking things apart. Doesn't everyone?!


Looking at the engine specs, 88mm P&Cs, 76mm crank it's a good bet it has a hi- po cam as well.

You may be able to keep your 009, add a set of Kadrons and achieve the "magical" combination someone thought this would be.

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[Donewright]

chrisflstf, thanks, I did give the transaxle mounts a visual inspection, they do not appear to be torn up, separated or damaged.

[chrisflstf]

You may have bad trans mounts also

[Donewright]

awesome, I'll add that to my todo list

ToDo:

Reset and adjust the idle mixture and idle speed screws on the carburetor
Increase idle RPM to 1000
Increase full advance from 28 to 30-32 degrees
Check for play in the distributer shaft

[EVfun]

With no heat riser for the intake manifold I would bump the idle up to a full 1000 rpm. It is going to have a tendency to be a bit of a cranky pants at low rpm with low throttle opening.

You might have better luck in a open (and generally cold running) buggy to bump the full advance timing up to around 30-32 degrees.

One last thought is to do a quick test of the distributor. Pull off the cap and rotor and try to wiggle the shaft side to side. A loose distributor shaft can cause timing scatter. You mentioned it was jumping around at idle. That can worsen idle quality.
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[Donewright]

greetings oprn,

Thanks for the reply!

Unfortunately I am the third owner. The man I purchased it from was unable to elaborate on the exact build of the engine. So I'm trying to figure it all out.

The buggy has a lot going for it and the rough Idle with a slight hesitation entering each gear are the only obvious symptoms.

The hesitation seems to be overcome by giving it more gas. Samba Members have indicated that this is a result of the 009 mechanical advance distributor and the 34PIC T-3 Carburetor being mostly incompatible.

As for the rough idle, you can see I'm still troubleshooting that one.

Would you mind sharing what you would change? I am open to any and all ideas and comments. I don't have a machine shop, but if it is just changing out parts, I can do that.

The next step I will try after work will be adjusting the carb.

[oprn]

I have never been able to get a consistent carb tune on an engine with a stock intake with no heat riser. They run ok... sort of... but not really... one day and worse the next.

Any idea What cam is in that engine? The dual cannon exhaust is not helping the idle and low end either. I suspect it's a combination of cam, exhaust, distributor, and lack of intake heat that is adding up to prevent it from running right and all 4 need to be addressed.

What you have there is another one of thousands of old VWs that the owners/builders have made poor choices on. There are at least 4 other things that I would change on that Buggy too based on that one photo.
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Our cars get old, we get old but driving an old VW never gets old!

[Donewright]

Thank you for the replies.

I already saw 28 degrees of advance when using my timing light and increasing the throttle by hand.

I'll skip the step to set/verify the idle advance.

Next, I'll walk through the steps to set the idle mixture and idle speed screws on the carburetor (Making note of currently how many turns out they are) .

[scrivyscriv]

just a casual observation but it doesn't really matter what your timing is reading at idle with a mechanical advance distributor. You could be describing timing scatter, carburetor not tuned or dirty, ignition misfires... could be anything causing the shaking.

Ignition is electronic so nothing to adjust there, but do make sure your + and - wires are on the correct coil posts. John @ AC.net advises that most "carburetor problems" people have are actually ignition related.

Set timing to 28ish degrees total advance, disregard the idle reading
It sounds like you may have some FOD in an idle circuit. I'd highly recommend tearing the carburetor down and doing a good ultrasonic cleaning. To my understanding, all the fuel going into the idle circuit first passes through the main jet. You need to make sure there is no sediment in the bowl and that the main jet is clean/not varnished. At a minimum, set the idle mixture and speed to spec - IIRC 950 rpm.

While you're in there, check for intake and exhaust leaks.
And, worst case, maybe you have some sloppy internal engine clearances or balancing problems.
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Robert in Memphis
Dünkelgrügen 1967 Java Green bug thread
Engine rebuild thread
If you're ever in the Memphis area, you are welcome to stop by for advice and help.

[mukluk]

So the engine idles fine with the choke on, then idles unevenly and will eventually die with the choke off. Seems pretty clear to me the problem is your idle mixture is too lean. You're looking at either incorrect carb adjustment/setup, dirty passages/jets, or a vacuum leak.
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1960 Ragtop w/Semaphores "Inga"

[SBD]

I know this seems stupid, but just to be absolutely sure... check that your plug wires are on in the correct order. Sometimes it's the simple stuff. A couple of switched wires could maybe cause your problem?
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"Just $99 down and $64 a month for 36 months buys you a brand new Volkswagen Beetle!"

[my3bugs]

myself i like back up plans , when i replaced my 09 with the 034 i undid the distributor clamp nut n removed it as 1 unit clamp n all , now its already perfectly timed n ready to drop back in - in minutes , just find TDC and drop it in n tighten it . ok you gota push in the plug wires takes another minute .

i have it marked as an 09 # 1 isnt in the same place as 034 #1 .

another thing i do is when ya finally get it running right i put a small dot of model paint between the distributor and the clamp so if it ever moves i can see where it belongs that easy .

i have the 09 in my daily bug tool box as a back up . my trunk tool box is kinda big these days .....

[my3bugs]

myself id prolly put the points back in n see how it runs . i think its just points n a rotor needed to go back to stock .

i think you said when you gas it the timing looks to be 28 degrees ? should be closer to 30 with this dizzy fully advanced . but i dont think thats your problem , just scratchin my head .

when ever running the modern electronics you/i want a set of points n a rotor in the trunk just for in case . if thats not it you can put your electrinics back in .

i had one of those at a time , dont know exactly what i did but i touched the wire to the coil wrong side and it was toast that fast , points wont do that so i stay with points .

it was like a 100 dollar goof !!!

[Donewright]

my3bugs,

It seems to be a rubber cap. covering a tube that goes into the intake manifold

Funny that it says remove.

I have no contact with the man that built the engine, so I'm trying to figure this all out

The distributor module was already installed when I got it. I do know that the idle did not get better or worse after the work I have performed.

If going back to points would solve my idle issue, I have no problem with that either.

What brand of distributor does everyone recommend ?

[my3bugs]

did it work before distributor module ? i like my points you cant look at that module n see if its opening or anything , its now a mystery electronic part in your distributor ..........i like to keep it simple .

[DesertSasquatchXploration]

https://www.jbugs.com/vw-distributor-svda-style-va...OIQAvD_BwE

I bet my left nut those have a sloppy bushing so the point gap is all over the place wont run worth $hit. J bugs is just off-loading JUNK. Everything they sell is JUNK.

[Donewright]

yeah, I'm stuck on setting the timing at idle. With the timing light on the marks, the marks are literally jumping all over the place at idle. When I hit the throttle, the marks stabilize at 28 degrees.

So, I'm back to trying to determine why the engine has such a shake at idle and the timing marks are jumping all around at idle.

[my3bugs]

in your second pic what is the rod thing sticking out between your pump n carb , that doesnt look stock to me ??? looks to have some lettering ???


looks like it says REMOVE ???

[my3bugs]

you clearly have tune up issues , we cant see what it is .......you can prolly make it work with what you have , set your points , timing , and adjust your carb . when it runs can you get a timing light on it to see where its set ? cant adjust the carb till the electronics are SET !!!


you have some electronic module so maybe the points are good , check timing , then adjust carb .