TheSamba.com :: View topic

Wed May 02, 2012 8:43 pm

I have struggled a bit with finding TDC on my Type 4 engine. I have gone the infamous "pencil" rout, but then questioned my findings and accuracy when seeing the "twiddling Cylinder 3 Finger" method. So I have been scratching my head a bit.

What I am going to try next is a tool from IPA tools that seems to be similar to the pencil method, only it has a scale on the "pencil" to help get it precise. Has anyone else tried using one of these? It seems like it would be perfect.

http://www.ipatools.com/7880.html

Wed May 02, 2012 8:48 pm

can't do it on a T4 engine. Here is why - plugs are almost perpendicular to the pistons.

Wed May 02, 2012 8:49 pm

Exactly what is your objective here? finding firing TDC for a valve adjust or some sort of uber acurate timing adjustments?

Wed May 02, 2012 8:50 pm

SGKent wrote: can't do it on a T4 engine. Here is why - plugs are almost perpendicular to the pistons.
Some red thing pooed all over your engine there Steve :P

Wed May 02, 2012 8:52 pm

you can use a plastic drinking straw with the crinkly bendy bit. But why?

Wed May 02, 2012 8:53 pm

Damn - sounds like I have a return to Amazon in my future.

I simply want to time and do a valve adjustment. However, the two methods listed above left me with about a 15 degree difference, so I'm not quite sure which mark I made I should go with. Is "close enough" sufficient? I will admit that with the feeler gauge, there was nominal difference.

Wed May 02, 2012 9:00 pm

Don't you have a mark on your pulley and a timing scale installed? There's only one stroke that #1 cylinder makes compression and you can feel it with your finger as you turn.

Wed May 02, 2012 9:05 pm

Hope this helps.

Wed May 02, 2012 9:10 pm

Bus Daddy - that is RTV that holds down the wire for the cyl head sender along a fin so it doesn't sit 1/2 across between the fins.

Also - have you ever considered reading minds for a living?

Wed May 02, 2012 9:24 pm

they also make a whistle that plugs into the spark plug hole, but I just used a bore scope. have you seen this http://www.ratwell.com/technical/FindTimingMark.html

Wed May 02, 2012 9:27 pm

I have a timing scale, but unfortunately I do not have a mark at all on my pulley. I have gone through this quite a bit, but cant find any mark even similar to Ratwell's post. So I have felt a puff of air, but it seems pretty inprecise (+/- 15 degrees or so?). How "perfect" should it be?

Wed May 02, 2012 9:46 pm

I haven't worked on one but I think some 914 and type 4 (like 411 etc) have a timing mark that is viewed from above thru a hole. On most of our T4 bus pulleys there is a notch on the belt part - just a little V. You need to find someway to mark it because you need to be able to time it.

You can bend a thick wire or piece of flat bar stock and stick it in so that as the piston comes up it rocks the wire or bar stock - kind of a bent straw approach. Then use a dial indicator to measure movement - let it drop say .020 in each direction and go 1/2 way in between. TAKE THE BATTERY CABLE OFF while you do this so if the darn phone rings you don't get distracted and forget the bar is in there and turn the key destroying the engine.

Thu May 03, 2012 6:12 am

The way I find TDC on a T4 engine is remove the spark plug, insert largest screwdriver that fits down in the cylinder, carefully and slowly rotate the engine till it stops, mark the pulley, carefully and slowly rotate the engine in the opposite direction until it stops, mark the pulley. TDC will be in the middle of the two marks.