today i checked my timing marks balancer is at 0 and my number 1 plug is lined up with the rotor . all wires are on the cap right . its starts right up when cold revs up fine no misses take down the street its still fine i pull out to the main road and its boging ,missing has no more ideal let it cool down for some time start it back up and its fine. what heck could it be. please any info at all will help

I had a similar problem which I cured by changing the fuel pump. Cold start it works fine (with the choke on its more rich). After the carb warmed up the old fuel pump was marginal so the carb would run out of fuel and cause sputtering and popping around sharp turns.

Long shot but it could be something like trash in fuel that takes a little while to get in the needle and seat then you let it sit and trash settles starts and runs fine for a little while again i have had this happen to me it would run great for 1-5 miles then flood and shut off or just start running like s--t. How about ign module could it be getting hot and messing up?
One time i had a Tach that was bad somehow and it would idle fine when i reved it up it would just start poping and missing i unplugged it and ran good reconnected and ran bad? I did have a fuel pump that was some how sucking air through the side you couldn't hear it but when i drove it it idled great and if i was light on the throttle ran great but if i tried to take off remotely fast it would buck,spudder, pop,backfire ran horrible? All shots in the dark, What did you originaly change or do to the car when it started or did it just happen all by itself?

Might check the coil. What kind of ignition?------------------
A little is good, More is better, too much is just right.



[This message has been edited by 70 Z UC (edited January 19, 2005).]

In addition to above, plugged cat or maybe a bad gascap not venting making fuel pump suck vacuum.

yep


http://www.supermotors.org/getfile/163584/thumbnail/lawnmower.jpg

[This message has been edited by Mwilson (edited January 19, 2005).]

its new mallory dis. (hei). i put a new cam in it and now it will not run right at all thanks for the input i will check into all the listed above tonight thanks guys

Dist. 180 off on the comp. stroke?

I'd try making sure the #1 piston is at TDC by watching the piston in the cylinder bore. There is a chance that you do not have the right timing tab on your engine especially if somebody had an aftermarket timing cover on there before you got it. Chevy used about 3 different positions for their timing tabs so it's easy to get them mixed up. Also if your harmonic balancer is pretty old then there is a chance that the outer metal ring spun causing the timing mark to be off.

Change the fuel filter too.

Check fuel pressure when hot.

If it happened as a result of cam change i wouldn't think it was a fuel problem, is the timing chain of the marks a little? You didn't get one of those 3 way timing chains and set it up on two different marks did you?

Vacuum leak? They are always worse when the motor warms up -

<font face="Arial,Verdana" size="2">Originally posted by El Guapo:
Vacuum leak? They are always worse when the motor warms up -</font>

I had one ounder my old Q-jet years ago that made my car act just like that