Micro-switch

[ian cox]

Hi
Just one more thing.
I am sure that you are all aware that there a 2 adjustment screws on the pump itself. One is for slow running and the other is for high rpm running.
The best way to set these up is on a rolling road and using a gas analyzer.
As ian_uk said they run them very rich in race cars to aid cooling but many people run them too rich on the road.
So after the pump has been recalibarted etc it is off to a rolling road.
I went to JZ Machtech and achived 219. Steve Mchale asked if the compression ratio had been raised but it had not been.
these engines to make over power if set up correctly.
Ian

 

[jamescharnley]

What possible damage could be caused by running an over rich setup at higher rpm's?

 

[38F3E1]

ORIGINAL: ian cox

Hi Ian,
IMHO the MFI systems is better as it compensates for altitude as well as being a fully sequential fuel system.
It was very advanced in its day and Porsche used on the 1983 SCRS cars to get the power as well as the turbo Le Mans cars.
Its major down fall in the end was when fuel economy satrted to be introduced in motor racing.
It is the best fuelling system bar none.
People tend to put PMO carbs on later SC and 3.2 Carrera engines to get the horse power they need as the standard fuel injection systems are built to meet the then world emsiision standards.
MFI was introduced to get power and any other considerarion was forgotten.
Ian

Good information to know. My MFI has always run beautifully so no intention to ditch it. Fuel economy certainly suffers if you drive in a spirited manner though.

Funny you mention PMO on later cars as I am thinking of converting my 964 to run on a PMO setup to get rid of all the electronics which I feel dulls the responsiveness and power of the engine.

Ian.

 

[38F3E1]

ORIGINAL: jamescharnley

What possible damage could be caused by running an over rich setup at higher rpm's?

The eyes of following drivers :-D

I would imagine you'll have problems with spark plugs fouling and possible accelerated wear on your bores due to the excess fuel washing the oil from the surface.

Ian.

 

[jamescharnley]

it was the bore washing I was worried about

 

[pmjt]

I can attest to the incredible ability of James' car to damage your eyes while following him!

Also, surely running overrich would give a risk of damage to the piston surface itself through overdetonation? I've seen race car pistons with holes in, I'm sure caused by incorrect / overoptimistic fueling adjustment.

Philip

 

[jamescharnley]

as long as the timing etc is fine you won't hole a piston through over -rich. If its running lean it could ( bunson burner effect ) or of course the timing etc is out which might cause it to 'fire' on teh upwards stroke of teh piston

 

[ian cox]

Hi
Bore washing is a problem that will eventually ruin your piston rings. It is these that are expendable as the nikosil lining is bullet proof.
You have to be really unlucky to damage these beyond repair.
So perhaps a leak down test would be in order.
If you do anyting less the 5% on each cylinder is good. Race engines are between 2/3% on each cylinder.
After a top end rebuild mine were around 3 % on each cylinder.
Ian

 

[jamescharnley]

my car has only been running rich for the last 200 miles ( it only does 2000 a year [] ) , prior to that it was perfect. I'm confident any 'damage' is a long way off and if new injectors don't solve the problem I'm going to pay a visit down south to Bob Watson

 

[Bertroex]

ORIGINAL: BLD

I would really like to re-establish a loving relationship with this car as it is the only vehicle I have ever owned which seems to have permanent menopause.

I am a psychologist if that's any help [][]

Bert