My (hopefully) last MFI question. -timing high butterflies
 

Hello,

yesterday I worked on my engine and I was wondering if due to the high butterflies and the higher mounting of the injection nozzles the MFI pump needs an earlier advanced... The nozzles is about 10 cm higher than stock, but still under the butterfly itself.
How do you guys do this?

many thanks, regards Malte

Hi Malte,

I would set timing to stock and see what you have. You can then play with it if you think there is an issue. Considering that the timing of the pump was the same on all the MFI engines regardless of cams would indicate that it is not very critical.

Hello Aron,

thank you very much for your answer! I will set it to stock! I also haven´t found anything different about SC RS or RSR engines which as far as I know have high butterflies original.

Thank you, regards Malte

The RSR engines were note timed as the others .... They were 54 deg earlier
Some say it's better, some say not ...
A guy I made a MFI pump for said 5hp more ...
Philippe

RSR pump timing is 14 degrees BTDC compared to the stock pump timing of 40 degrees after TDC.

good maths Mark :)

40°+14°

I have seen cars come in that were timed 180 out that ran with very few issues. Something was wrong but they could not quite figure it out.

The RSR that I worked on was timed both ways. I could not feel a difference nor did my mixture require altering. But I would not be surprised at a HP difference.

I would imagine that around 8000 RPM on a dyno you might see a difference in performance with the pump timing.

Thanks for all these informations!!!