What timing is everyone runnin on there street strip motors?

ok maybe you guys can help,i am running 18*initial and 36*total,but i am experiencing run on when i`ve been running the car for about a half hour or so,and its not the MSD run on,would it help if i lower my initial?it wont do it if i throw some race fuel in there,i tried some octane booster when i cannot get some race fuel but it doesnt do anything,a friend of mine told me to increase my initial timing even more and it`ll cure it but i always thought if you lower it it`ll stop,any suggestions are greatly appreciated.

Thanks

 

I also wanted to add that i am running cold running plugs,it does this run on for about 2 sec. after i shut the engine off,it coughs through the carb,then when i try to fire her up she cranks alittle more than usual then turns over.


Thanks

 

In neutral since its a manual car,i am idling at about 800-900 rpms,i can shut it off in gear but its just freakin annoying,do you think if i lower my initial it may stop?i never had this problem before its been doing it on and off since i`ve installed the aluminum heads?

Thanks

 

Maybe more initial and then you can close down carb blades some to get idle back down. Mine runs on a bit if idle is set to high. Tom

 

More timing?i`m at 18* initial now where should i put it to?

Thanks

 

Left my timing alone at 18*initial 36*total and just lowered my idle from 900 to 700-800 and it stopped doing it,had the car out all day today just to see if it would do it and it didnt,i guess my idle was just alittle too high,i wanna thank everyone for there input.

Thanks:TU:

 

As stated above, it doesn't matter what your timing is once the key is off! Setting the timing will not cure a run-on situation.

Instead, look for hot spots in the combustion chamber, too much air at idle, some extra fuel getting into the motor somehow, or some other mechanical problem.

-Bob Cunningham

 

Hi, what I meant was to give it a little more timing at idle which would raise your idle speed a little more then you can close down the carb some to get idle back down. I didn't realize you had a 4 speed car, I am so used to working with the auto trans in my car. I am glad just slowing idle down fixed it. I know mine will run on at the races sometimes if idle is set to high and right after a run when everything is really warmed up. Tom W

 

So far so good Tom,i thank you for the suggesions,why do they run on if idle is alitte bit higher though?

Thanks

 

I really don't know the reason that engines do that. I do know that some different engines have a solinoid on the throttle that when you turn the key off the solinoid goes in and closes the carb all the way so they don't run on. I think it has to do with things running hot enough that the motor is kinda like detonating, meaning things are hot enough to ignite the gas/air mixture without spark. I could be way off base but that is my understanding of what is happening. The cam I have idles about 1100 in park and after a trip down the drag strip when things are warmed up real good sometimes the idle will climb to almost 1300 and it will pop some when shutting it off, if I turn idle back down to 1100 when things are warmed up good then it won't, I am wondering if the octane in the gas needs to be a little higher, I run on 93 but I don't know of any stations around me here in Wisconsin with 94 octane without alcohol mixed in. I don't really want to go through the expence and time to mix racing gas but maybe I should, at least when I race it. I don't know how to properly read the plugs so maybe it is a little lean or something but I don't think so, I have a old 1050 holley that came with 84 jets front and back with power valves. I had 86 in the front and 96 in the back without a power valve and with jet extentions. I have 2 blue holley pumps with nice big lines and a return so I assume it is getting plenty of gas to carb and carb has the bigger inlet needles than what comes in the cheap rebuild kits. I have carb jetted up to 88 and 98s right now but have not raced it that way yet because I am in the middle of putting in the roll bar so racing is put on hold for a little while and with back acting up right now I just don't feel like working on it lately. Sorry for long post. Tom W

 

I had similar problems after installing aluminium heads. you should be able to cirrect it by going to lighter springs (more initial advance) or as i did i fixed the mechanical advace and set the timing to 35 degrees all of the time. probelm solved. starts very quickly hot or cold, idles at 800, rarely does it run on (seems to do this only when i rev it a couple of times then shut it off) and runs like a ..... a buick!

ta

 

yea i heard that more initial will cure run on but i always thought more timing= more cylinder pressure therefore = run on?

Thanks

 

I guess I don't understand how ignition timing can affect run-on, if there is no power to the coil (and therefore no spark and therefore no timing)...

-Bob Cunningham

 

I think it has to do with more timing means the carb throttle blades are closed down more to get the same idle speed as with stock timing and carb opened up a little more to get the idle speed. A example of what I mean is if you have stock timing and engine idleing and you advance the distributer the idle speed will come up also, so to get the idle back down you back out the idle speed screw on the carb. I still don't totally understand why more carb opening makes run on worse but I know on my car it does, maybe if the idle is on the lean side it increases the temp in the chambers enough to make it keep trying to run without spark. Maybe the plug ground strap is glowing red or something like that to make the fuel keep burning. I have run into the same thing in snowmobile engines if they are running to hot they want to run on also. I once had a old 793cc 3 cylinder Hirth freeair cooled snowmobile engine that was so lean and so hot that killing the igntion would hardly slow it down, it ran without spark till it melted the pistons and seized up tight, we tried to pack snow on the heads to cool it down to get it to stop running but was to late. We probably should have just pulled the chokes on the carbs to flood it with fuel to get it to stop but we didn't have much time to think when it was happening. Sorry to wonder off topic some but my point is if motor is running warm it seems to make run on worse also. I don't know if I helped anyone with this, but it is what I have noticed over the years. Tom