Carburetor adjustment

The vacuum nipple to be connected with retarding diaphragm actuator is now closed, because double diaphragm actuator doesn't appear in the market and the retarding concept had been quitted soon, only for 1 to 2 years interval production of air cooled VW.

But, this closed nipple with often closed hose is so useful to adjust the 34PICT3 carburetor, because the air inlet from this nipple while idling shows the condition so apparently as to know the moment A/F mixture, rich or lean.

Gradual inlet from the nipple would gain or loose rpm, increasing the idle speed means too rich and decreasing does too lean. In short the inlet of air from this nipple can increase only the air volume without any screws rotation adjustment.
This useful method is not reported by anyone in the Web site?

The experience on WEBER 40 DCOM side draft carburetor for over 10 years equipped in PEUGEOT Talbot 205 Rallye, passing the Legal inspection by myself in the government line made me possible to know the mixture ratio and a motor condition.

According to my career, most of carburetor setting scenery the mixture is too rich and the fact caused ill-understandable strange phenomena giving up the precise adjustment for most of the engineers.

The sweetest point exists very narrow and small area on the adjustment screw, so the key to success is to know the condition now is rich or lean exactly! Positioning very near to lean points.

In addition the ill-mixture adjustment affects not a little on the transition to middle speed sometimes even to high speed because of moistened spark plugs.
Anyway the adjustment of idle speed and obtaining stability in combination with transient characteristics to middle and hi speed was in my capability.

Performance changed

I feel some change of air-fuel mixture in 34PICT3 carburetor this morning, because the carburetor assembly was replaced into Mexican Bocar from original German Solex. Acceleration became vigorous and my VW 1302 Super Beetle runs about so quickly like a different automobile compared with the past moment of carburetor pre-replacement.

The pressure leak was found on the portion of the arm holding nut inner surface, finding out while cleaning air gun nozzle was applied in the throttle valve center shaft. It means the air leak can be caused when the valve was closed and the reason why the bypass screw had been tightened to the closest point.
In order to prevent this kind of invisible error, much more precise checking is necessary, silicon coking material would be applied to seal there.

Automatic choke module's angular position is going to be set adequately, several trials are necessary.
Warming up time interval and the mixture control are up to the position.

Overhaul determined

Any making detour are not allowed if I would continue fully mechanical controlled old VW 1302 Super Beetle.
I cannot avoid the problem happened on the mechanical carburetor, Solex 34PICT3. No way to pretend that I do not know about it in spite of self clear recognition on the carburetor problem.
Replacing the important parts to solve the problem, acceleration hesitation and stumbling already, for the next, I must proceed to the carburetor however much I may run away about from the problem, the time come just in front of me.

Consequently I must do that, full over haul of a prepared carburetor, Bocar(Mexican) 34PICT3 would be disassembled and replaced on my Beetle today.
I'm making effort to know what part the check ball exist and how many are there?
The reports about the carburetor later:

Successfully the carburetor on VW 1302 Super Beetle was replaced, obtaining completely different responses, eye-opening result was at hand.
Bocar Mexican carburetor prepared was from the YaHoo auction as a junk but like new one without any failures, the pressure leak on throttle butterfly center shaft was not observed.
Carburetor adjusting was performed by actual running test driving 200km today to Northern Kyoto along Route 9.

Acceleration transition was far improved and the rotation from low speed to moderate one was so smooth as to satisfy myself on the 1600cc VW Air-cooled AD type motor.
The reaction and response were linear and apparent according to the adjustment screw's rotations.
Anyway my Super Beetle transformed into completely different automobile from a dull and slow turtle. Now quick and light action it has like a young fish released into clean, clear and fresh water.

After disassembling original Solex 34PICT3 carburetor, I found out a critical error on the power jet, that was completely closed with some hard material. This is the main reason of strange acceleration phenomena, hesitating and stumbling.
Periodical replacement overhaul kit is sold at Flat4 in Tokyo at 4,200 yen.
Do I do that or just replace the power jet with 0,60mm diameter hole?

How to set up Solex 34PICT3 carburetor

I just studied and bare in my mind followings:

The motor must be warm up enough conditioned and choke must be fully opened.

Throttle position screw must be set so precisely as to attain the point to 1/4 turn screwed in and the screw would not appear later adjustment, firmly fixed untouched later, never!
Because the idle speed would be adjusted only by bypass screw, but for this screw no way to adjust the idle speed 800-850 rpm.

While adjusting air volume control screw with closing in, the sweetest point must be within 1/2 turn(mostly out) gaining idle speed.

The rate of initial turning out of both bypass screw and air volume control screw are 2 plus 1/2 turn from the closed positions.

The air volume control screw would not be turned exceeding 1/2 turn, so adjusted position exists between 2-3 turns out position.

Always try to keep the idle speed at 800-850 rpm by adjusting only bypass screw.

Finally volume control screw must be closes in until rotation looses 25 rpm(slightly leaner).

Transition in acceleration

The time is come to study and to understand the fundamental function of Solex 34PICT3 carburetor on VW AD motor in 1302 Beetle model, because some unnatural rotation transition is apparent when acceleration at middle speed.

Deeper inspection would recover this inconvenience, disassembling thoroughly, full understanding on the mechanism and it's functions and precise adjustment on acceleration pump and it's transition, of course the combination with the ignition timing and mechanical centrifugal & vacuum advances are in more importance.

The adjustments of transitions on accelerating seen low to middle and middle to high are very difficult and require professional keen skill, experiences reinforced by scientific technology and background.

Bocar 34PICT3(same as Solex but Mexico made) is already obtained for my own experiments on upper described matters.

Imagine I the accelerating fuel pump adjustment would be the most effective for stumbling and hesitating phenomena, because the centrifugal and vacuum advance systems are already adjusted after replacing from 009 to original German made distributor with vacuum advance actuator.

Distributor

Indispensable replacement parts, the original distributor assembly was disassembled and serviced well to keep it in VW Beetle as a emergency compensating parts.
The contact point surfaces were flattened with diamond fine grain flat file.

The moving parts for ignition timing advance were adhered and partially destroyed, vanish and sticky material inside were cleaned in a organic solvent tray and after drying moving parts were lubricated in combination with Microflon, micro grain Teflon powder, for good performance in the point arm hinge micro movement portion.

Centrifugal mechanical ignition timing advancing system and replaced vacuum solenoid control valve both attained smooth movement after maintenance.
The mechanical system requires periodical maintenance to re-gain ultimate performance.

Here we find a fundamental difference in Air-cooled VW Beetle from nowadays automobile.
This is why I chose Beetle as a partner of automobile life from now.

Servicing all day long

PC does not start up this morning, how come?
I forgot to write down about the critical error on Beetle's driver side seat, the right side lumber support spring welding was broken. So, the driver was forced to sit with hip right side twisting, this is why I felt some fatigue only on the right side.

As a compensation, 3mm iron bolt and nut were applied on the metal spring flame work with making hole, it went well after mending without descriptions.
Replacing seat cover and seat pad carried out remarkable change of driving feel like a different automobile is driven.

Cooling fan drive belt was replaced yesterday on VW 1302 Super Beetle at last, originally Bando was equipped but this time is Continental one.

Increased hip and back support by replacing parts brought a completely stable driving driver's position, fantastic!

Working in the hottest weather condition consumes body energy unusually.