tuning help

[bronx23]

ok, first off i start the truck up idles fine, rev it up a little and there is miss all the way from idle to 3500 dont wanna rev it higher than that since the motor is rebuilt. if i hold it anywhere from 1500 to 3500 for about 3 seconds and let come back to idle it will idle fine for about 2 seconds than slowly start to drop rpm's and die. is this a fuel problem or a ignition prob? also after ive ran it each header is hot so i know i dont have a dead cylinder, ive advanced the timing and it still misses and dies. this is gonna sound stupid but could it be that i have open headers? please help me

[ChevyKiD_69]

all you could do is pull a plug wire off at a time and then you could find it that way.

[bjcrazyz]

have you checked for a va* leak?? what carb are you using? and have you adjusted it??

[bratass]

When I had a miss and couldnt find the cylinder I spray painted spots on header tubes near flange with cheap enamel then ran it making sure to keep in rpm of miss bad cylinder showed up quick http://www.s10v8.com/images/smilies/icon_cool.gif You also need to make sure of no vac leaks good luck

[bronx23]

ill check for vacuum leaks right now, thanks

[bronx23]

well, once again s10v8's members have helped me solve another problem, one of the vacuum lines on the carb was off, that solves the mystery of it dying but it still misses

[jackfast]

Almost sounds like it is Cross Wired one or two wires makes a huge difference....

[coppergmc]

Could be related to the carb or timing. Could be a lobe going south. There are so many different things that it could be.



It could be that you just aren't used to the way the engine sounds with open headers and a big cam. Some of the engines I've built in the past with larger cams sound wild from off idle to 3500 or so and level out when you rev a little higher off of the cam.