I have fuel flowing, I have spark, I got everything timed in at TDC, my starter is cranking up fast and strong.

When I try at full throttle the engine kicks in, but when I take my foot off the gas and let it idle, it either dies immediately, or if it idles, it idles VERY sloppy, lopey, and cluttered, and when I hope out and try to adjust the dizzy with it running, it dies.

It likes to be retarded more than advanced no matter where it starts, but I've tried dropping it in at the next notch, and that's not it.

When I open up the choke, it dies.

This engine with this carb set exactly how it is ran BEAUTIFULLY last week at idle, throtle, everything. The only difference between then and now is I swapped intakes.

What do you guys think is going on? Throw anything out there, I'll cross it off the list if I can. I've been battling this truck for almost 2 years, I'm getting closer and closer to that point.....

 

Sounds like a vacuum leak.

 

Sounds like a vacum leak to me too. Have you tried slowly spraying carb cleaner around the gaskets? Thats the easiest way to find a leak. You may have to turn the idle up to keep it running while you do it to keep it running. When your leak is found the engine will speed up due to running on the carb cleaner. You have to be slow and methodical while spraying it though to find the leak.

 

I second vacuum leak. Unless your missing any shop rags.........

 

looks like I actually thirded. I type sloooow!!!

 

Really? I swapped intakes to correctttt a vacuum leak, I was incredibly careful when installing the new one, and dry fitted everything over and ooooover again.

 

maybe the timing is off if not a vacume leak

 

maybe the timing is off

 

Didn't forget to hook up the pcv or anything like that that would be a larg vacum leak? I just did this on my shortbed got carb all done & reinstalled & no idle started to cuss then saw the pcv sitting there.
john

 

Well I popped out a plug and got the cylinder to the top and mached up the rotor with that, so I think my timing is good, but I'm going to check again before I take the intake off.

 

Well the PCV is actually just hanging there, but I've been running that way for a while, on my old engine, and on this engine. I will check all other vac sources though.

 

10x on a vacuum leak or timing issue. For the former, grab some carb cleaner and spray it around the mating surfaces of the new intake manifold and the carb base. If the idle improves or idle speed increases then you've located the vacuum leak. For the latter, loosen the dizzy and work it around until it can maybe idle.

 

You should have at least 15 inches at an idle,steady ,Timing chain jump? incorrectly installed a tooth off? Scott

 

15 inches at an idle? Not understanding you there, sorry. The timing set is fine though, this engine ran fine last week, all that has been changed is the intake.

HIO, will use your and PEB's advice on the carb cleaner check tomorrow. I've been twisting the dizzy though, to no avail. That's what's got me really wondering, and not thinking timing issue. The couple times I've gotten it to hold an idle, I've jumped out and twisted it, and it seems to like being retarded more than advanced, but both ways kill it, really any change kills it. Retarding the timing also helps a little no matter where in the adjustment range I am, which is obviously weird.

Will keep you guys posted I guess, but this truck is just starting to hammer me more than I would like.

 

What kind of intake and carb are you running? Performer Intake and Holley carb by chance? If so you might need an adapter plate to mate a Holley carb on that intake. Otherwise try plugging the PCV into an intake port not the port on the carb base. My fresh 400 wouldn't idle and when I moved the PCV to an intake port my problem went away.