Cams and FI

RD Rick rickydik at ix.netcom.com
Tue Sep 3 22:07:38 GMT 1996


I wrote:
>>My '73 914 just happens to have a high lift cam with a lot of 
overlap.  >>It won't idle decent below about 2000 rpm.  To pass a smog 
check, I set >>the lifters out to .030", and then it idles fine.  
Clatters like hell.  >>I've never had backfires with it.
>>
>>An additional problem is the low vacuum, about 12", below 2000 with 
>>that engine.  The Djet responds to low vacuum by squirting more fuel, 
>>which makes it richer until it dies.  I have found a fix for the ECU 
to >>alter the fuel curve, but haven't tried it in the car yet.

Talltom replied:
>Don't know if it's relevent, but we've run more radical cams than that 
regularly>and get good idle at 1200-1300 rpm with a pissing in the wind 
system.(k) The >accepted mythology is this can't be done, but being as 
we do it I have a tough >time believing it. Our theory sez that as long 
as the pulsation isn't large >enough to pressurize clear out to the 
barn door(cone) it don't matter what >kind of cam you have...

>  Don't know if 914 ever used pissing in wind with barn door systems.

Yes, the 1.8 is Ljet, but my 2.0 with big cam is a 2.0 Djet.  I am 
thinking of converting it to Ljet just to fix the idle.  Last week I 
even put a barn door airbox in place of the aircleaner on my stock 2.0, 
and it created only one inch of vacc at WOT/5800, which is about 3% 
power loss per my charts.

Is your 1200 idle with a 4 holer, or a V8?

RD




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