Which timing method is better?

[autonewbie]

Ok lets talk timing.......
When I bought an SVDA distributor for my Squareback, they recommended that I time the engine at 2500 rpm, using a timing light with a dial on it. The idea being that at 2500 rpm or so, with the vacuum line still connected, the dizzy weight were at full advance, and the vacuum advance was at max also. I set my dial on the timing light to 39 degrees and timed it with the zero mark aligned with the case half. This method resulted in the car never advancing more than 39 degrees max.
My Karmann Ghia has the dual vacuum dizzy and it has been suggested that I remove the retard hose, cap the port and time it at 7.5* btdc.
Would it be better to time that way or the 2500rpm method with the dial on the timing light? I suspect the end result is very similiar, but i don't really know for sure. The 2500rpm method seems to insure that one has the engine set to avoid over advancing, but I more often see the "remove the advance hose and set at 7.5*" method.
Is this all a moot point or is one better than another?

[Bookwus]

Hiya auto,

......When I bought an SVDA distributor for my Squareback, they recommended that I time the engine at 2500 rpm......

Who is "they"?  Having bought a few SVDA distributors (from John Connely at Aircooled.net) I found that the instructions with all of them indicated 7.5 degrees BTDC at idle.  I even went so far as to check with John himself.  He added that it would make no difference if the vacuum advance hose were hooked up or not.  Nowhere in the available literature can I find VW's recommendation to time any of their OEM distributors in the manner you outlined above at 2500 RPM.

However, that particular timing procedure is pretty darn close to the usual timing procedure for a centrifical only, mechanical advance distributor such as a 009.  Inasmuch as the 009 was not designed as an automotive-use distributor, I would be disinclined to use the timing procedure for that unit on another OEM style unit.

My Karmann Ghia has the dual vacuum dizzy and it has been suggested that I remove the retard hose, cap the port and time it at 7.5* btdc.
Would it be better to time that way or the 2500rpm method with the dial on the timing light? I suspect the end result is very similiar, but i don't really know for sure. The 2500rpm method seems to insure that one has the engine set to avoid over advancing, but I more often see the "remove the advance hose and set at 7.5*" method.
Is this all a moot point or is one better than another?

I have found that whenever I'm in a quandry about parts or procedures that the best advice comes from VW themselves.  In this particular case I'd definitely follow their advice for timing a DVDA.

[autonewbie]

Now this is getting interesting....
I bought my SVDA from John at Aircooled and as I recall I was directed to download instructions from their website. I have those instructions in front of me now as I type this. I was off a bit on the rpm but the instructions clearly say:

"To verify the corrct operation of the SVDA, the timing should be
A) 28-30 Total Advance (hose disconneced) @3500 RPM.
B) 38-45 Total Advance (hose connected) @3500 RPM."

I was off a bit on the rpm but that is a quote from the instructions.
They then state in their instructions:

"Let it idle and re-check the timing, you can now use this timing setting to set the timing at idle, though we do recommend you check the full advance settings to make sure the SVDA is working properly at both idle and full advance."

I bought my SVDA about a year or so ago and was very very happy with it. I am not trying to make this into a big discussion, I just wondered if the 3500rpm max advance timing method was the better way to go.

Yes they initially say to time at 7.5*btdc at idle, then they recommend the above procedure to verify timing.

[Bookwus]

Hiya auto,

Way interesting!

When I purchased my SVDAs from Aircooled.net some years ago I got printed instructions for installation and timing.  Did you receive those also?  These instructions outlined the time at idle, 7.5 BTDC approach.

As it turned out, in the meantime, I had forgotten exactly what the written instructions specified as the timing degrees.  I wrote to John and told him that I recalled it being 7.5 degrees BTDC.  He replied that I should be timing the SVDAs at 8 degrees BTDC (I'm assuming here that he's just doing some convenient rounding off) at idle.  And that it would not matter if the vacuum hose was connected or not.

While I can understand and appreciate the reason for timing at full advance at 2500 RPMs, I'd still be inclined to go with the more accepted method.  Especially in light of John's advice.

Thought about running it out to 2500 RPM and checking the timing/weights and then popping it down to idle and setting the timing conventionally?

[autonewbie]

Well first let me make sure we are on the same page.
It was my mistake to first type 2500rpm
The instructions actually state 3500rpm.
And yes I believe the best procedure is to time it traditionally at 7.5*, but then do a final check at 3500rpm to make sure the mechanical and vacuum advance don't advance too far.
Lastly, I seem to recall reading somewhere that timing at the higher rpm, takes into account some of the slop (wear) that might be in some of the components. No idea if this is valid or not.
Here in hot Florida, I guess making sure the engine is not advanced too far might be a cautious way to go.

[Bookwus]

Hiya auto,

........time it traditionally at 7.5*, but then do a final check at 3500rpm to make sure the mechanical and vacuum advance don't advance too far......

I'm thinking you'll be good going this way.

[bowlingbrad]

Well, I'm going on a slight tangent here...
I just bought a dwell/tach meter and a timing light.  I have no real idea how to use them, but I am going to time my Ghia on Saturday morning.  I did the static timing of my new SVDA.  But that was the easy part.  The engine wasn't even running!  Since I've watched the Bug Me video, I consider myself sufficiently tainted.  I've also read the aircooled.net stuff several times.  I don't know what I'm reading but, I guess I'll make it work.  Any suggestions on what to do?  I never found out what to do if the timing is not correct.  28-32 BTDC at 3500 rpm ..... WHATEVER THAT MEANS ..... I just know it means the TDC mark should be somewhere close to where the belt and flywheel separate.  I haven't found anything telling me how to adjust the timing.  Do I adjust it while the engine is running?  Oh yeah, and that DWELL word.  Point gap 'verification' using a dwell meter.  So, do you check the dwell setting, turn off the car, remove the dist, open/close the gap, replace the dist, start the car and test the dwell again?  Do I need to worry about the battery connection when I'm fiddling with the dist?  Should I disconnect the battery every time I touch the dist?

As you all can see from my comments, I am a certified amateur VW mechanic with no real clue how to do this.  Any help (PICTURES!) would be much appreciated!  Maybe a list with simple words instead of a very detailed explanation from aircooled.net?

[volkenstein]

Brad,
      Go here : http://www.vw-resource.com/tune-up.html#timing and read up.

Setting dwell accurately does indeed mean stopping the motor (ign completely OFF), fiddle with the point gap and re-test until it is within spec. No need to remove the distributor, just cap and rotor. Be sure to run a clean piece of cloth or paper through the points after everytime you've stuck a set of filthy feeler guages in there.

BTDC? Before Top Dead Centre. The 28-32* BTDC setting is with the vacuum hose disconnected and plugged on an SVDA. When you get the light going (and pulley marked as per Rob 'n' Dave) you'll see that when you rev the donk, the pulley mark at 28-32 BTDC will try and "move" right to left to line up with the crankcase half. The TDC mark will "move" from right to left at the same time. What you are interested in is that at say 3/4 throttle the 28-32* mark does NOT keep going to the left past the crankcase half mark.

Now...to adjust the the distributor you'll see the clamp bolt under the distributor near the fuel pump. Loosen it off until you can twist the distributor left or right (not spinning like a top!). With your donk running and timing gun strobing madly, just a little twist left or right will change where the timing mark is in relation to the case half (do it at idle, easier...). Slightly tighten that clamp bolt, tools (I use a long 1/4 inch drive extension on the 10mm nut..) and fingers out the way then try strobing it at 3/4 throttle watching for that max advance mark. All good? Stop everything and tighten the clamp bolt. Re-check to be sure to be sure.

Oh...to make things really visible, mark the fat (rear, rear of car) pulley part with a hacksaw blade (just need a tiny "slot") and put some white paint or correctette in it. Make sure your bod blocks out the sun too.
Or go mega-bling and fit up a Berg Equalizer Degree Pulley .


A lot easier to "show" than explain if you get my drift..

P.S. Is your timing gun a one lead inductive or does it have 3 (+, - and sprak plug)?

HTH
Volkenstein

[bowlingbrad]

Silly me.  I did read all of the info on vw-resource.com too!  All of that reading just blends together after a while.  I am at work right now, so I can't check my timing light.  Is one better than the other?  I can take it back if I have to (it is still in the packaging).

And thanks for my new favorite word; DONK.  I am assuming it means car.

[Bookwus]

Hiya Brad,

I'm thinking that donk can be translated from Australian as engine or motor in American.  God only knows what it is in English.

[bowlingbrad]

It's slang for a woman's big butt.
Look it up! I'm not lying!

[volkenstein]

Brad,
     Not in my part of the world . Donk = engine.
Both types are OK, they hook up differently, although the cheap 'n' nasty tend to use bad (red) bulbs.
Xenon (white) is better. An inductive light has the spark lead only and may run off a "D" cell battery. The other uses car supplied battery power.

Regards
Sean

[bowlingbrad]

OK!

I replaced the fan belt.
I adjusted the valves to .016 edited: .006
I checked the static timing at 7.5 BTDC
I adjusted the points to .016
I hit a solid 50.6 on the dwell meter.
I used a strobe for the final timing.  I don't really know if I did it right.  This 'ACTRON' strobe light didn't come with the best instructions.  I think my RPM at idle was 700.  The advance at idle as a little above 7.5.... More like 12.  I revved the engine and the TDC mark went right to the point at which the belt touches the large pully.  Am I good to go?

[volkenstein]

Brad,
     No. Have you adjusted your carb to spec? Then disconnect and plug the vac line and you should be shooting for about 900 rpm idle. Once your carb idle speed is set then set timing @ idle to 7.5* BTDC.

Hopefully you have marked your pulley 41mm to the right of your TDC mark/dimple?

So with vac line still disconnected, when you rev it @ 3/4 throttle the mark at 41mm is the one that lines up with the case. The 7.5 mark moves left until it is almost hidden by the belt.

Then, you can re-connect your vacuum hose.

PS. If you have to take the choice of two evils pick setting your advance and let idle fall wherever. Just be sure that re-connecting the vac hose at idle changes nothing.


HTH
Volkenstein

[singlecab61]

I adjusted the valves to .016

I only hope this measurement is in MM not inches!