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Re: [T3] FI timing change for '72+?

On 19 Mar 2006 at 10:28, Toby Erkson wrote:

> Volkswagen Fuel Injection Technical Manual by Henry Elfrink
> Page 16:
> "Modified injection timing for type 3 engines
> Starting with the 1972 model year, fuel injection timing has been changed for
> type 3 engines.  A modified trigger contact unit changes the injection timing is
> such a way that fuel is injected behind the closed intake valves for all four
> cylinders."
> Thus, fuel is NOT injected into an open valve, only a closed one.  Is this true?
> Is there a way to identify if a FI car has this?  I didn't find any such info in
> my Bentley.

The late distributors have the FI timing cam slightly rotated on the shaft. 
It's not much of a change and I've never been able to tell for sure if it 
actually made any difference at all. The last 4 distributors listed in the 
Bentley (MT & AT for '72 & '73) have this "feature."

You can see the difference if you take 2 distributors apart. You could probably 
also tell a difference if you turned the engine over by hand with the ignition 
on but the coil disconnected. You should be able to hear when the FI valves 
click and compare this between cars, but I've never done it.  

Jim Adney
Madison, WI 53711-3054

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