Timing and misses...
05-15-2012, 10:00 PM
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St. Jude Donor '07
Timing and misses...
Noticed after increasing the timing, I developed a miss or rough spot at 2000 to 2400 rpm. Above and below that everything was fine. Retarded the timing while I was holding the motor at 2000 and it went away. What causes the rough patch in the power band. Vacuum advance, spring size, etc????
05-15-2012, 11:44 PM
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It likely got lean at that spot. You could probably set it at 2000 with high timing and play with idle screws to see if it smoothed it to see. They might still be active at the RPM with no load.
Same thing happens with too much vacuum advance. Starts skipping/missing and surging when driving iff too much.
JIM
Same thing happens with too much vacuum advance. Starts skipping/missing and surging when driving iff too much.
JIM
05-16-2012, 10:35 AM
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05-16-2012, 11:02 AM
#7
what is the total mechanical advance at about 3,000, assuming you dont have factory springs? how much additional is the vacuum advance adding?
05-16-2012, 12:56 PM
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Will need to check that out. A buddy have my snap on light, so that will have to wait. I think my total all in was 35 to 38. Springs are not factory(using the lite springs) and yes 24 was without vacuum.
This motor revs very fast, so timing needs to come in quick.
This motor revs very fast, so timing needs to come in quick.
05-16-2012, 01:35 PM
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I agree with 427 - timing won't make it miss, but a lean-out issue exaggerated by timing can cause a miss.
24 initial is a good setup on an engine with a bit of a cam - I run 24 initial with a short and quick curve on mine, and it's right where it wants to be.
Lars
24 initial is a good setup on an engine with a bit of a cam - I run 24 initial with a short and quick curve on mine, and it's right where it wants to be.
Lars
05-16-2012, 02:52 PM
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A guess I could always increase the size of the squirter cam to add more fuel at a lower throttle position. Guess I need to just play with it little more.
On a funny note, as I was adjusting the timing you could hear the unburn fuel exploding in the pipes. Thought I blew out a gasket. lol.
On a funny note, as I was adjusting the timing you could hear the unburn fuel exploding in the pipes. Thought I blew out a gasket. lol.
