timing jumping = impossible to set (type 4)

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sean
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Re: timing jumping = impossible to set (type 4)

Post by sean »

I don't believe those gears are your problem. I think you are too focused here on the mechanical side. As retrovan has suggested, I think it may still be external electrical issues causing this. I cant say this for the "strange" noise you are hearing though.


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Re: timing jumping = impossible to set (type 4)

Post by marcw »

Well it is all back together again this morning. Battery charged fully last night so will start with no alternator connected and see what happens. Earth is good with two extra points attached to the engine and the coil is runing straight from the battery. This removes all the possible electrical interference I can think of.
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Re: timing jumping = impossible to set (type 4)

Post by marcw »

Hello again

I have dobe everything I can now think of without pulling the engine.

- Direct negative to the engine (jump lead from battery to engine)
- Direct wire from + to coil
- Checked everything from the distributor drive shim up to the plugs. New plugs, New wires, New cap, New rotor, New points, New condenser, all springs free in dizzy, the dog has nice square edges, the dizzy drive is turning nicely with 1mm play all round 360 degrees.
-Put in entirely different electronic points dizzy which has its own coil.

https://youtu.be/ZXyjZ23mgTU

Same issue with timing wandering 10 to 15 degrees at 3000rpm. At idle its arround 5 degrees wandering.

I am at a complete loss on this one and have no idea what to do next. Even if I take the engine out what do I look for?
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Re: timing jumping = impossible to set (type 4)

Post by retrovan »

It would seem the Goest spicks are gone, but you now have a 5 deg wonder.

this could now be the vacuum, and if you have twin carbs, you may be trying to run the vacuum off one carb only.

Do you have a 10 mm plus pipe between manifolds, and have you got the two carb's vacuum tubes joined to a "T" section before going to distributor. ???

Please note the timing will self adjust with the difference in vacuum, so this is not always a problem.

Have a look at all caskets and joints for leaks.

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2020 MeFusco Beetle Truck 2Lt type 4
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Re: timing jumping = impossible to set (type 4)

Post by Dawie »

Are both distributors electronic- aftermarket or wbx type?
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Re: timing jumping = impossible to set (type 4)

Post by Dawie »

From a different post i thought that you went back to points. Set to 0.4mm?
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Re: timing jumping = impossible to set (type 4)

Post by Dawie »

It may be wandering at 3000rpm because centrifugal advance is not all in and engine slightly wandering in speed. If you go for max centrifugal advance, then use 4000rpm minimum because the centrifugal advance only reaches its endstop around 3600rpm. (Aftermarket "009" distributor ends at lower rpm, that may be where the "3000rpm" thing comes from).

As a test, see how stable timing is at a slow idle, (800rpm max). As a test, adjust idle down or retard distributor to make it run slower. The aim is to test stability when advance is against end stop. Theory of setting timing is to have it either against the lower or upper endstop of centrifugal advance, not somewhere inbetween.

Distributors do have some wander. The type 4 has a big diameter pully compared to others, so this wander will appear as a bigger distance in mm.

If engine speed is wandering/unstable because of a mixture issue, semi-fouled plug, wrong valve clearance or leaking valve, then obviously timing will wander as well if operating somewhere inside the centrifugal advance curve... it is supposed to that.

What happens when you drive the car?
Last edited by Dawie on Thu Jul 20, 2017 7:28 pm, edited 1 time in total.
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Re: timing jumping = impossible to set (type 4)

Post by marcw »

I can't drive the car, she is missing very badly. On each jump of the timing it misfired. Otherwise in would drive to Pierre.

It's not vacume since that is disabled whilst setting. Plugged as well. Whilst running I have pipes from both carbs with a t piece.

Points dizzy is a vw other is electronic. Same issue with both. Points dizzy worked fine for the first 1000 kms.

The carbs were set and working fine for 500kms nothing changed there.

At idle, 900rpm, it wanders from 2 degrees to 8 degrees
At 4000 rpm she is missing and suttering and I can't even see the mark anymore its so all over the place. Occasionally I can see it at 40 degrees and at 20 degrees.(No vacume)
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Re: timing jumping = impossible to set (type 4)

Post by Dawie »

Unstable timing would not cause misfiring. Must be misfiring because of something else.
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Re: timing jumping = impossible to set (type 4)

Post by marcw »

So its a compression check in the morning then.
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Re: timing jumping = impossible to set (type 4)

Post by marcw »

I can just see myself spending another R15k in Primrose.
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Re: timing jumping = impossible to set (type 4)

Post by Dawie »

Misfiring will cause unstable speed which will cause centrifugal advance to operate/change as it should.
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Re: timing jumping = impossible to set (type 4)

Post by Dawie »

Do you have the points distr in at the moment, or did you do the change a while ago.
Think from an earlier post you had a faulty/troublesome aftermarket electronic distributor at some time, if so i would not use that one as a test.
Also not impossible to have issues with both distributors, like a fauty condenser or burnt points... weird things have happened before.
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Re: timing jumping = impossible to set (type 4)

Post by Terry Phillips »

Why not do a dry and wet compression test then use that as your starting point.
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Re: timing jumping = impossible to set (type 4)

Post by sean »

marcw wrote: Thu Jul 20, 2017 7:22 pm
The carbs were set and working fine for 500kms nothing changed there.
:hanged:

Don't assume, you could be running on only one carb. Those dual carbs on type 4 motors can really have some hidden mysteries...... Things suspiciously change over night on them. Quite possibly the most frustrating component ever installed on a VW.

This would however cause spluttering and struggling, not a misfire. If it is definitely a misfire and you can here it and see the timing jump at the same time, it has to be ignition. Again, don't assume trying another distributor that it is in working order, as Dawie mentioned, it can have the same problem.

This issue is not engine mechanical.
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