TheSamba.com :: View topic

Sun May 17, 2015 5:05 pm

Hi guys ,
My other 912E has finally arrived to Europe. It has stock engine , 91k , no rebuilds switched to Webers idf 40 long time ago. The engine was running very rough so I have made some basic tuning.
I have rebuilt the Webers ( new gaskets , o-rings , needle valves , new diaphragms , cleaning , set float , etc...). No dripping . I have tried to tune them by the book ( mixture screws and idle screws procedure ) but not sure about the results .
I have found following jets on them : air 200 , main 135 , idle 50 , emulsion is F14 or 11 ( cant read it well ) . Venturis are 28.
I have also put new cables , new distributor cap , new rotor , clean spark plugs , fresh oil and filter , checked timing and have set valve clearance.
I have some problems :
- Unloaded it idles ok , no backfire , popping or miss . But when I open the throttle fully and rev the engine I get smoke , not black , whitish I would say . Or bluish ?
- When I drive the car modestly is ok but when I open the throttle it starts to popping . Or it is misfire I am not sure .
So I am running lean or reach ?
- that smoking at high revs concerns me more , do I need an top end rebuilding ? Also valve train noise is still present inspite of the fact I have checked the valve clearance .

The engine seams strong , no oil leaks , I havent made a compression test yet.

Please watch my video if it helps anyhow . The sound is not so realistic I know.

http://www.youtube.com/watch?v=qNSj4...ature=youtu.be

Thanks for your suggestions :)

Mon May 18, 2015 3:25 am

I have played with the carbs again . It sounds and goes much better now. No popping and the smoke at high revs is 80% gone.
Valve train a bit noisy but I reckon all type 4 engines are built that way.

Mon May 18, 2015 4:35 am

The venturies are on the small side and probably do not help the engine at higher revs.

try 30 or 32mm venturies.

28mm work well with a type 1 1600cc.

30 or 32mm will not seriously compromise the torque at lower revs, but the engine will breath happy at higher revs.

What distributor is set up on your engine? Best is a 050. But often a 009 is fitted. Timing varies between the two and of course this affects also the overall settings and performances.

Mon May 18, 2015 3:16 pm

Thanks ,
I know I need biger venturis and smaller main and air , it runs lets say ok for now till I get them.
I cant read the numbers on the distributor but it has no vacuum canister so I reckon is 009.

Sat May 23, 2015 3:00 am

Following since I have a 356 that I am tuning at the moment with the webber set up.

Sat May 23, 2015 3:25 pm

The engine runs ok now after couple of miles driving around a block and some more adjustment but it cant be compared with the original L-jetronic since there is no cold start mechanism on these carbs so engine runs on very low rpm till it warms up a bit.

Sat May 23, 2015 8:11 pm

Years ago I put a big bore kit on a Porsche T4 914 - added Webers at same time. Never did get it to run as smooth as the stock fuel injection. Suspect part was due to fact that I kept the old FI cam.

Fri Jul 10, 2015 11:50 am

Is there a reason you went Webers rather than keep the L-Jet setup on it?

Sun Aug 23, 2015 11:44 am

Dual Webers just look cool and it cleans up all those hoses on top of the engine. Tuning them is a near full time hobby though. I finally discovered that you could solder the brass jets closed and redrill them for different mixtures rather than having to buy different sized jets.