Timing (groan)

[Mags]

OK, so a complete can of worms topic I know but I've got to ask the question.
I have a '72 bus fitted with a Beetle Type 1 Twinport 1600 (I don't have the engine code to hand, I think it's AD?)
Bone stock Solex 34 Pict 3, oil bath filter and everything, even points in the dizzy! but the SVDA dizzy is a new one from VWH so presumably not German.

How do I determine the correct timing? I have read the German VW manuals and they tell you the timing based on the engine code so does the cam determine this? Does the dizzy model affect the timing or the engine code? Should I be trying to source a correct German dizzy?
According to the german manual (for Beetle Type 1 engine's) depending on the exact engine model it's either 0deg at idle with Vacuum hoses disconnected or 5deg after TDC with vacuum hoses connected. I will check exactly the engine code but I guess the question is do I need to worry about the specific model of the dizzy as it's aftermarket?


It run's OK but I'm trying to get rid of the dreaded flatspot at part throttle. I've done everything else and I think this might be the last little piece to improve it further, going to a refurbed Solex appears to have helped.
My timing light seems to cut-out before I get to max mechanical advance as I know this is critical so maybe I need a new timing light first!

 

[vinvan]

Watch this on youtube
https://www.youtube.com/watch?v=787INwvir24

 

[Mags]

Watch this on youtube
https://www.youtube.com/watch?v=787INwvir24

Thanks but how does this answer my question?

Sent from my SM-G900F using Tapatalk

 

[vinvan]

I have the same engine 1600 twin port with a Solex 34 pic 3 and a SVDA dizzy
dont think it matters what engine code it is
the timing is set at 7 degrees before TDS with the rotor arm pointing at number one cylinder
first static time the engine as shown in the youtube video
i had the same problem with a flat spot, re timed the engine, check the valve clearances, found out the carb needed to be tuned
there are plenty of video's on youtube showing how to retune
if that dont work may be worth getting hold of an original Bosch dizzy, think i saw one on ebay the other day

 

[atafonso]

With an aftermarket Chinese ditributor the curve can vary by many degrees, afecting greatly the driveability and even risking damaging the engine due to pinging/overheating.
Using a timing light with advance feature, get the engine to about 3-3.5k rpm's and set the timing with the vaccum hose connected to 30deg. Let it idle and check how many deg you have at idle. It should be between 5 and 10. If you have more than 10, say 12, back up the max timing to 28. If you have less than 5, get another distributor. Do not go over 30 deg max advance or you risk running too hot and pinging is a certainty.
Abel

 

[Mags]

Thanks. I've ordered a new timing light, mine just cuts out at about 2k rpm so I can't tell the max advance. I'll go this route first, everything else is good and generally German, I had it timed up to 0deg TDC running with vacuum connected and it was the best it's run. I'm not sure if the extreme cold weather is making the problem worse as I recall it always ran better in the summer.

 

[subheatadey]

If it ran better in summer as well as the timing, I would look at things like the pre-heat tube on the manifold is not blocked too.

 

[thejinx]

I like the fisher buggies U Tube timing videos really easy to follow

 

[redgaz54]

With an aftermarket Chinese ditributor the curve can vary by many degrees, afecting greatly the driveability and even risking damaging the engine due to pinging/overheating.
Using a timing light with advance feature, get the engine to about 3-3.5k rpm's and set the timing with the vaccum hose connected to 30deg. Let it idle and check how many deg you have at idle. It should be between 5 and 10. If you have more than 10, say 12, back up the max timing to 28. If you have less than 5, get another distributor. Do not go over 30 deg max advance or you risk running too hot and pinging is a certainty.
Abel

Shouldn't the vacuum hose be disconnected from the dizzy and blocked?

 

[atafonso]

If you are checking the timing at idle and with a gen VW dist yes, but with the aftermarket dist you want to make sure of total advance as this is the most important.
Abel

 

[Mags]

So to follow up with where I got to. My points let me down on the way home from Volks World and as I have had enough of chinese copies I decided to go all out and buy a 123 dizzy knowing it replaces the chinese dizzy, points and will serve me in the future if I get around to an updated engine.
Straight out of the box it has made a huge difference, rock solid idle and almost zero hesitation at small throttle just running on the default one size fits all curve. The bus has never driven better so I'm pleased I made the investment.
Next I'll try the correct curve for would have been the correct Bosch dizzy but as it runs so well now I'm tempted to leave well alone.
I've timed it to max advance of 30 deg BTDC which seems to be around 7.5 deg at idle so all good.