Volkszone Forum banner
1 - 9 of 9 Posts

·
Registered
Joined
·
91 Posts
Discussion Starter · #1 ·
Sorry, looked allover but we are still not really sure now how to time our 2l type 4 engine.
We adjusted the valves and found a sticker on the engine which states "7.5 BTDC"..now we are not really sure what to do with this information. since we dont have a fancy dwell meter and a timing strobe gun, can we just time it staticly? so when the light comes on our TDC mark on the pully has to hit the 7.5 on the scale?
Are we having to do anything with our vacuum advaced distributor (apart of turning to adjust it), like take off the vacuum hose or something like that?

some help would be lovely!
Tobe n Ash
:)
 

·
Registered
Joined
·
4,904 Posts
You can time it statically with a dummy light which is a light bulb with two crocodile clips on it. It is not so good as using a strobe gun which can be bought quite cheaply.

basically you need to move the engine to no 1 piston firing top dead centre usually you can get this from the dizzy lead. you need to know where 7.5 degrees is on your pulley and set the engine so that this mark lines up with the crack on the crankcase. Clip the crock clip on the wire that runs from the dizzy to the coil and the other to ground.turn on ignition Release the collar on the distributor so that you can rotate the distributor you need to turn it so that the dummy light just goes off. be precise move the distributor back and forward to ensure you have this exactly right . If you listen very carefully you will hear the points arc too. lock of the distributor and your done. remove your light.
 

·
Registered
Joined
·
5,684 Posts
The ignition timing depends on you Bay's engine setup. If it has got it's original (single) vacuum distributor or a Bosch SVDA distributor then the ignition timing will be as follows (assuming manual transmission):-

Vacuum hose: Disconnected and plugged/capped at the distributor vacuum can end.
Ignition timing: 7 1/2˚ BTDC
Engine idle speed: 850 ± 50 RPM
 

·
Registered
Joined
·
91 Posts
Discussion Starter · #4 ·
brilliant thanks alot, just went out and bought some crocodile clips...now fingers crossed that I am not getting my hand shot off by an electric shock ;-)
And jep, it is a manual tansmission.

cheers guys
 

·
Registered
Joined
·
5,684 Posts
brilliant thanks alot, just went out and bought some crocodile clips...now fingers crossed that I am not getting my hand shot off by an electric shock ;-)
And jep, it is a manual tansmission.

cheers guys
Ah misread the first part of your first post. 2 litre type 4 aircooled engine (twin carburetters) ? If that is the case, then it should have a DVDA distributor, where it's ignition timing should be set to 5˚ ATDC with both vacuum hoses connected.
 

·
Registered
Joined
·
5,684 Posts
PMed you back. I think you need to post some pics of your bay's engine bay on here so that we can see what engine setup your bay has actually got.
 

·
Registered
Joined
·
91 Posts
Discussion Starter · #8 ·
Thanks for your PMs!
sorry didnt know there is such a variaty, hoped 2.0l type 4 would be clear enough.
But anyway I am quite happy showing my engine of at the moment after cleaning and painting!


but I think all is good now! thanks for the 7.5 degree confirmation...he really sounds good as well...although I still wanne get him on a strobe timed.
cheers for everything, was very helpful!
 

·
Registered
Joined
·
523 Posts
Got a timing light and a tachometer? Basically you want to make sure that when you're actually driving your heavy bus, you don't over advance your ignition. In a normal car you can hear when your advance is set too far but in a bus the engine is a long way back and theres a lot of noise ;) That can cause your engine to run hot, and will burn up your valves. Equally, having your timing too retarded can also give you a lot of heat.

The distributor may be DVDA (dual vacuum dual advance) which was an emissions thing - basically it slowed the engine quickly by retarding the ignition. Often the retard side doesn't work and to be honest that's not a problem - the advance side MUST function though.

Setting the timing at idle is a good starting point but you don't drive at idle and you also don't know whether your distributor is working as it should. The VW type 4 engine expects between 28 and 32 degrees of mechanical advance at 3500 rpm regardless of the distributor in it. I set mine to 30. To set it up a tachometer is useful but not essential because at some point all of the mechanical advance will be "in" (the exact RPM depends on the distributor you have). You should get hold of a timing light as part of your basic tookit though and do the following:

* Disconnect all hoses to the distributor. That will stop the vacuum from interfering with the reading.
* Increase revs to 3500. Noisy but necessary.
* Adjust your distributor so the timing light falls between 28 and 30 degrees on the timing scale. That's your maximium mechanical advance.
* Let it fall back to idle - note where the timing falls - it should ideally be around 7.5 degrees but don't adjust it if not, the bus will still run fine. Just make a note. That way you can check it quickly with your static timing light in future.
* Tighten the distributor down and reconnect the hoses.
* Rev it to 3500rpm again. You should see the vacuum advance kick in and advance it up to around 40 degrees. If it doesn't, either your carb isn't sending any vacuum (check by feeling for suction on the end of the hose) or your distributor isn't picking it up (often because the vacuum can on the side of it is broken, check by sucking the hose connected to the distributor and seeing if the plate inside it moves). Either way your ignition will be retarded when you're driving and your engine will run hot (and poorly).

You can get a cheap Gunsons timing light for less than £20 that will do the job.

Hope that helps.
 
1 - 9 of 9 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top