280zwitha383 Posted November 23, 2008 Share Posted November 23, 2008 So the Z hasn't been on the road for about a year because I spun some bearings in the 383 right about the time I got divorced and up until a few months ago I haven't hardly touched a car... I know, sad story... haha:violin: Anyway, life goes on and I rebuilt the 383 and put a comp 282 hyd. roller in it and had some bowl work done to the heads, other than that nothing has changed. I just can't seem to get the thing to idle right. It will idle steadily for a second and then stumble and die if it's not warmed up yet (under load, while in drive). If it's cool outside it will idle so so in neutral but as soon as you put a load on it it will usually die (again, when it warms up it's better). The thing has a 3000 stall too so it's not like I'm really putting much of a load on it at idle in gear so.. I don't know. I've checked my power valve (it's a 4.5 and doesn't leak) and I've readjusted the valves, my timing is between 10-12.. for some reason it jumps around about 2 degrees even though I put a new bronze gear on the distributor. Could that be from too much end play on the shaft? I haven't ever been able to set my idle mixture screws on my holley 670 street avenger with a vacuum gauge because it doesn't ever change when you back the needles out but I've tried them anywhere from 1/2 turn to 1 1/2 turns with pretty much no noticeable change. I'm pulling right at 10hg of vacuum at idle but it goes down to 5 when it starts idling poorly. I just don't know what to point my finger at. The carb has the stock jets in it (I don't remember what they are off the top of my head), the floats are set right.. I've checked everything I can think of really and it still runs the same. Once it's going it runs right but it's just the idle that I can't get down. I haven't ever had a cam this big but surely you should still be able to get the thing to idle right.. The cam with the 1.6:1 rockers is a little under .550 lift intake and exhaust. I'm not running a vacuum cannister and I don't usually but would running one help me out any? I appreciate any ideas. Quote Link to comment Share on other sites More sharing options...
jt1 Posted November 23, 2008 Share Posted November 23, 2008 Try running a lot more initial timing, like 18-20 degrees, and see if it helps. If so, check your total timing and limit it to 35-36 deg. This will clean up the idle a lot. Then set idle speed and try to adjust the mixture screws. Hopefully they will be responsive now; if not, you will need to open the secondaries a little to get the primaries off the transition circuit. jt Quote Link to comment Share on other sites More sharing options...
Bowtiez Posted November 24, 2008 Share Posted November 24, 2008 You said it has not been run in a year. If you used the gas in the tank, it is probably rotten by now. Varnish in the carb will give you all kinds of problems. Change your filters and go through the carb, drain the tank, pump fresh gas through the lines. Quote Link to comment Share on other sites More sharing options...
Pyro Posted November 24, 2008 Share Posted November 24, 2008 Yes, use much more timing and adjust mixture screws for best idle (highest vacuum) 20 initial then plug the vacuum advance into the manifold vacuum source. should be idling at 30 to 35 degrees at idle with the vacuum advance. that cam needs a 1000 rpm idle speed and should have around 12 inhg of vacuum at that rpm. Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted November 25, 2008 Author Share Posted November 25, 2008 Ah, I wouldn't have thought to advance the timing that much. I did drain the tank before I even set the engine in there again but I have thought to take the carb off and double check everything. I'll give the timing a shot asap. Quote Link to comment Share on other sites More sharing options...
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