Timing question...

[qwik914]

Got some timing question for my 914. This car has 1.8 liter engine with Elgin cam, 10.5 to 1 compression, and Weber carburetors. I normally race the car with 110 octane leaded fuel, and I am not sure what the timing need to be set at. I have ran the car with timing set to 35 degree as mentioned in: http://www.pelicanparts.com/techarticles/914_timing_carbs/914_timing_carbs.htm
Now, my questions are:
1) What do I need to set my timing to be using 110 octane gas?
2) What the spark plug gap should be for using 110 octane gas?
3) Will everything stay the same if I add MSD ignition?

Thanks,
Kyan.

[John Rogers]

I would stop using the leaded gas, it'll ruin the engine. About the only people that use it anymore are some of the off road racers. I have 10.5 to one compression and run 36 degrees total advance with 101 octane unleaded gas. With the MSD they will tell you to open the plugs up some (I have .055 gap) and timming should not have to change (mine didn't) as you just get a better, more consistant spark. Good luck.

[KWales]

To quote my professor in college "you want to run at the hairy edge of knock for maximum power". And "a car with high comprssion and retarded timing has more power than a low compression engine with fully advanced timing". Since octane can be roughly interpeted as a knock rating, you can advance the timing more (and get more power) when you use higher octane gas.


Based on this, I would first FULLY warm up the engine until at operating temperature (1/2 hour or so minimum) by spirited driving. Next, floor it and listen for knock. Advance the igniton timing slightly and floor it again while listening for knock. Continue advancing the timing in small steps/flooring the pedal until it knocks under wide open throttle (WOT). Once you find the knock point, retard the timing slightly. Might want to do this up a small hill or rise to properly find the knock point under worst case full load condition. That's how we used to set up my Karmann Ghia for autocross. It was a pretty strong contender in it's day.

"he who controls knock....."

Ken