I have been trying to solve a cold start issue on my car forever. Last night for ***** I set the T RPM setting at 500 rpms to 15 instead 10 and got a much quicker start. Is 15 too much for idle? What would be the limit of advance at idle?

Thanks

 

15 degrees is about where I start for idle advance. Generally I find engines are a lot happier from 15 to 18 degrees at idle then where most people place them.

The limit depends on your engine and setup. You can advance idle timing and adjust fuel accordingly (generally pulling it) until the idle becomes unstable or you have to start adding fuel to keep EGTs from heating up (or the engine from running lean AFRs).

Ports with more overlap like bridges like a lot more timing with a lot of split at low loads.

 

Yeah, I definetly had to remove some fuel at idle after uping the timing. When cranking I get a healthier start then before, I havent tried it completely cold yet but I definetly liked the way it responded to the change. I will experiment a little more today with more timing, take it up to 18 and see the results. I will monitor the EGTs as I make the adjustments.

My idle EGTs are around 900 and cruise around 12. Idle AFRs are mid 13's cruise are 14's I belive I can go leaner. EGT bung is at the rear about 2" from the port.

Thanks for the input!

 

i am running 20* of advance at idle, that's where my engine seems to be happy. i have tried lower but it just idles crappier, i am wondering when is it too much?

 

Too much is when it starts to become crappier again, you need to add fuel, or you burn out plugs.

 

I tried 20 last night, it smoothed out the idle a little bit more. The switch from 18-20 kept the switch from 15 to 10 HG at idle from being so lumpy. Something I couldn't tune out with the fuel.

 

mine is set at 22* at idle

 

15 degrees is fine. on my heavily ported street port engines i run 5 btdc otherwise you get a lumpy idle.

 

How about half bridge motor, I'm running 20*? What do you recommend?

 

I am wondering the same thing,right now i have my HB at 1500 rpms and 15* and is a little rough,I will like it to make it idle well brap a little better.m

 

With a half bridge, try around 18 degrees and 15 degrees of split. Of course the Microtech's crappy timing setup might not allow you to run 18 degrees at idle without effecting other areas of the map...Shoot for an AFR in the low to mid 13s.

 

half bridge around 20 degrees is good.