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Deeper investigation about the combustion firing timing of '71 Super Beetle in the Website obliged me to try more experimental searches on my own vehicle. Deserting double diaphragm vacuum advancer, single diaphragm was invited---changing the original condition is a new condition. Complicated anti-pollution system was introduced in '71 models. This is why it makes is complicated and confused to set the adequate combustion timing. To know the best firing timing in every phase and smooth transition by driving by myself actually.

Old VW movie appeared in the Website illustrated centrifugal advance and vacuum one were drawn together but not shown actual advancing firing timing respectively in combination both advancing effect together. The width of the angle of BTDC drawn in the scheme is too broad to specify. Though some discretion might be required, both narration and scheme did not explain enough to understand the phenomena of combustion timing. I have been overcame by anxiety for long time about this problem. The fact that no improvement did not done by time passing, I tried to prove it by myself. Comparison of the centrifugal transient characteristics between 009 and ordinary distributor with no vacuum advancer should be known actually. This kind of unknown trial makes me enthusiastic.

New part ordered few years ago and left untouched 009 with fully mechanical centrifugal vacuum advancer, with no vacuum diaphragm device might be one of a choice. This kind of research and development is great fun for me and purpose to live. Coming long holidays in the beginning of May would be killed by this procedure.

Cataract surgery done on my right side eye is going favourably in about one month. After replacing from innate crystal tissue into artificial one has far improved my eyesight as to capable in driving vehicle.
Artifucial one has the focus poing at 5 m distance, so just a bit brule at infinity scienry but abalable.
Removing curtain from my right side eye as if covered with gauz , I feel great at all. To be more specific, the aspherical construction caused ring shaped blure and ghost in the hi-light, but they are acceptable for me. And the color is too better, white is so transparent, no complaint if different from innate lef side. God would give me some punishment if I declare something.
My quality of life has far improved, I appreciate my eye doctor and sophisticated technology in the field.

It's a great fun for my life to compensate the gap between overlooking and under looking. Basically, I gathered necessary information by consulting papers and articles written by former researchers in specific field. It was so difficult to do that wasting time. Articles I wanted were floating in the Ocean of them. But, now, in the period of Internet, Web is scattered in every direction and very easy to do that in very short period of time.

In spite of golden condition, I have been in misunderstanding thought about combustion firing timing of VW Super Beetle for over tens of years. I knew about the double diaphragm vacuum advancer specifically equipped in '71 production and the fact that advancing and delaying functions performed done at the same time. Recognizing such a function with watching the scheme actually, I still believed in the necessity of vacuum advancing effect for smooth acceleration. The shape of mechanical distributor was that of equipped diaphragm(single) chamber aside, so printed in my Cortex. This is why I fed vacuum signal to distributer without doubt for long time until few days ago. I had some suspicion on the function of accelerator fuel pomp in the carburetor body, because of ill function while departing phase.

Watching up the graphic drawn the relation between vacuum advance and delay also mechanical centrifugal advance, I come to the conclusion that vacuum advancing is not always necessary for replacing distributor from double diaphragm to single or less chamber distributor! After adjusting the timing at zero degree under no vacuum condition, I was so surprised to feel completely different attitude of 1600 cc AD motor as if released from heavy burdens. In addition to lubrication on the steering gear box, these improvements changed it's character like different vehicles. Also, first idle phase with stall tendency was far improved without thermostat function.

Most of the case, we didn't discuss about the existence of Thermostat at all even in the foreign air-cooled category. Though old Beetle's motor is so designed that cooling system is not liquid cooling but air-cooled, the parts, thermostat is equipped is equipped on the #2 cylinder fin. This mechanical construction controls air amount at first idle stage from closed to fully opened. As a matter for regret, this air controlling doors are kept fully opened because of thermostat failure leading to over cooled condition at first idle stage. This is why make it difficult to keep idle motor control. Most of air-cooled have some failed thermostat that is relatively fail, in addition, this parts never appear in the market, so grasp it without hesitation if you come across wherever and whenever it might be.
Consequently, idle speed control is not always depended only on the construction of choke controlling system installed in the carburetor body, this mechanism is controlled by coiled bi-metal heating electrically. I make it a rule to cut the circuitry at the beginning of first idle while cold season to extend warming up stage.
What I wanna say here is next stage to know the relation with idling stop tendency between BTDC 5 degree and TDC zero. As for my fortune telling, first idle will turn worse because choke control is done under advanced combustion condition. More investigation would be required on this point. This marvelous mechanical controlling system was invented by the German engineers over 50 years ago, interesting don't you think?

Once the steering feel was far improved by lubrication, too sensitive accel feel was appeared up. I have been in the thought that distributor should be equipped both vacuum advancer and centrifugal one and they work well in harmony. Vacuum advancer react more quickly than mechanical centrifugal advancer, so the former one is indispensable to obtain smooth and sensitive accel feel. Consequently, BTDC 5 degree was applied as a common sense. Remembering past, I applied TDC 0 degree on the way back home from Kobe Transport Bureau, acceleration became better. The bad habit to have a tendency to cough and stall if accel pedal was pushed down too much. Consequently, I determined to think it over combustion timing consulting VW manual for '72 Super Beetle manual.

The diaphragm vacuum advancer equipped on 34PICT3 carburetor was so strange as to have double diaphragm, they are for advance and delay construction respectively! Also, dash-pod was set at idle stopper point to prevent sudden low down of rotation. Double diaphragm construction is aimed at keep ATDC 5 degree idle rotation. All of these measures are purposed for Anti Pollution exhaust gas controlling.

Judging from the vacuum control performance appeared in the manual, they always act antagonistically leading to no advance nor delay as a matter of fact.

According to the information from manual description, no vacuum control and centrifugal advance controlling only is done!

Then I close vacuum hose for advance only diaphragm activation with 5mm dia. brass material and the combustion timing was set at zero degree TDC. It means that only centrifugal advancer is alive from TDC 0 degree.

The impression of AD motor I have been in my mind for long time has completely revolved---now no complain at all! Bingo!!

No hesitation to push down accel pedal, no coughing nor stall down. Probably most of my elder brothers might know that 009 distributor has no vacuum advancer, this is why this one is so popular in US. A 10-year mystery has solved!

This description is done under happiest emotional condition.