Project Aircooled Efficiency-(57 beetle)

[Dawie]

The accelerator jets were injecting way too much fuel. With every move of the accelerator pedal, the exhaust gas meter would go to the rich end and stay there a few seconds.(Hooked up while driving). So i modified the arms on the throttle body that operates the acc pumps. Stroke is reduced by half. Also changed the adjustment on the shafts.

Vacuum port for distributor advance normally only comes from one carb.Wanted to use both,for better signal. Carefully drilled the other carb for a similar port. Then used a T junction to combine the two.

Here is a picture of the most recent aircleaners with the longer pipe that passes through the element to the extended top for longer velocity stack. This richens the mixture at full load,when the intake pulses are strong. Makes a HUGE difference.
The engine is now 1423 cc's. Bore 77mm, stroke 76.4mm.
Used an Oettinger/OKRASA crankshaft that was made for the wasserboxer. Actually found an 82mm one long ago for R1000, when a standard crank with counterweights welded on would cost R1500. (Early nineties). Then exchanged it for the 76.4mm one at that wbx place in Kemton Park. Made from chrome-moly i think, the bearing surfaces are very hard. McDonald engineering polished and fitted it to my AS21-casing.
Dont know what difference the harder bearing surface makes to friction,but even if it is half of a percent,everything adds up.
Assembled the engine myself. Was the first engine i opened.Had a special camshaft made, with less overlap.

[calooker]

Nice work man, you must be a very patient dude, as you need to be when toying with carbs.
Instead of the longer filter throats have you ever considered Velocity stacks or flared ram tubes they help smooth things out under load, I have not realy messed with them but I have a David Vizard book that covers this kind of thing and it's amazing how ramming the air affects jetting, fueling and perfomance. I need to dig it out again.

[Dawie]

Specifications at the moment:

Late seventies AS21 engine case.

77mm bore, (Mahle)
Total seal rings.
76.4mm crank,hard chrome moly type, with counterweights,made by Oettinger.
1423cc's.
8.6:1 compression ratio.
1mm deck height.
Special camshaft with different lobe centres,reduced valve overlap.
Ratio rockers 1.25:1,with needle bearings,
Distributor: modified centrifugal and vacuum advance curves.
32/34PDSIT 2/3 twin carbs, smaller 24mm venturies from type3/ SPcarbs, rejetted,reduced accellerator pump stroke.
Tall aircleaners, for ram effect that causes enrichment at full throttle.
CDI ignition system,homemade.
Oil filter adapter from type 4. Homemade full flow oil filter system.
Cyl heads: late 043 type with 9mm exhaust valve stems.Did minor exhaust porting.
3 Angle valve seats,
Modified for cylinder head temp sending units.
Removed minor flashing between cooling fins, (left over from casting process).
Thermostat-refitted standard factory system.
4 into 1 exhaust system, (early Cowley type)
Diff ratio: 3.875, (Late 1600 type)
4th gear: 0.82: 1

Currently working on a twin spark ignition system.
Also have to get a proper wideband exhaust analyser.
Old one i have actually measures exhaust gas temperature.

Torque is good, full power is usable from 1000 rpm,no hesitations and stumbles.
Easily cruises at 130 km/h, quieter and more comfortable because of taller gearing.
Top speed about 150.(Speedo corrected).

Will post more on fuel consumpion a bit later.