Fuelly Forums - Retarding Timing?

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Quote:

Originally Posted by ShadowWorks (Post 105341)

I've a question, my engine is suppose to be at 16 BTC from the factory, its a turbo car so it has a vacuum advance on the distributor, I adjusted the timing to 18 BTC as I was told I could run more turbo boost, now I don't care about performance, would having my engine at 18 BTC hurt FE?

If I set my timing to 14 BTC would this help FE?

I don't know much about turbos, but for NA engines, I have heard that a little spark knock from a hot engine at low rpms when you open up the throttle is a pretty good timing setting.

IMHO, more advance is usually better- unless you are getting a lot of spark knock (sounds like a rattle under the hood), lots of spark knock can shorten the life of the engine. Some engines have a knock sensor so the ECU automatically retards timing or richens the mixture if it senses too much spark knock- this would decrease FE.

Ford was getting sophisticated in 87. The distributor (if its old tech) will have centrifugal and vacuum advance (ported not vacuum). When the turbo kicks in the vacuum is gone and can actually be positive pressure, which will retard the timing whenever boost is applied. The distributor will have either one or two vacuum lines attached to it.

Hook up a timing light and pull the vac line off the dist, see if the timing is reduced. At idle the engine will run rough without the vac advance working.

Another thing about Ford ignitions of that era, don't underestimate them. My dads 84 had a bad ignition switch and wouldn't shut off. I pulled the coil wire off with insulated pliers and the spark jumped 6 inches to the engine block!

The first Porsche 924 (dog 1.7 liter) had a warning under the hood about the fact that if you pulled the wires off the plugs the spark could kill you.

I wouldn't retard the timing, it shouldn't help your mileage unless its too far advanced already. If you want to fiddle with it advance it 2 degrees at a time and see if it knocks. If so retard it immediately. Personally I would fix the knock sensor.

regards
gary

Quote:

Originally Posted by ShadowWorks (Post 105341)

first of all, someone gave you bad advice , 18 BTC is 2 degrees advanced, which will not allow you to run more boost. 18 BTC will give you better gas mileage if it isn't pinging. what mpg are you getting?

There is a knock sensor on the engine which is plugged into the ECU, it cuts out the fuel injectors or spark, I have installed a red LED from the ECU next to the boost gauge so I can see the engine knock as a flashing light beam.

I do get some knock when I boost to hard, I think I need to by a timing strobe and adjust the timing back to 16 BTC as my FE is really bad, I am lucky if I get 20mpg.