Need help with idle!

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g49bridges

g49bridges

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Just got a 74 duster slant 6 225 car. This is the first slant six I've ever messed with, so I'm still on a learning curve. My problem is, after adjusting timing, rebuilding carb, and countless hours of adjusting, it still seems very rough. On first inspection it had 3 bent pushrods. I'm assuming when the previous owner got it running after 9 years of sitting, the lifters had sagged and rods fell out of the cradle. Anyway, that is fixed now. It runs smooth and fires on all 6 like a champ. Even had it up around 75mph this afternoon. The issue now is that when you put it in gear it drags the motor down and kills it. I've got the idle bumped up around 1500 rpm, and it will still die when you put it in gear. At this point I'm completely out of ideas. Any help would be great. As far as I know, it's all factory except the 2bbl carb. I know this car ran great in the past, then sat for 9 years, and now it just been revived. No parts have been changed since it last ran back in 2005.
 
Telltale sign of a mis-tuned carb. If under load it dies, or is a dog, you are asking it to perform with a bad a/f ratio. In park you may be able to get it to rev, bc with no load, itll run on fumes...or even a way too rich mixture, which is more likely the case. An engine should idle below 1000....i have a 13.1 drag engine with a .700 lift cam thatll idle at 700. Telling me u have it idled that high to make it run says u are out of tune. Check the butterflies at idle, and the float levels...and needles n seats.
 
Thanks johnnymac. FYI, it will idle just fine at 700-800 rpm, I just had the idle up that far to try to keep it running when I put it in gear. Only other thing I can think of is a vacuum leak, which it does have....somewhere. I'm guessing that could be part of the problem too? It also seems to me like it's running pretty rich, but when I try to lean it out, it won't run. Is that a carb issue, or could the vacuum leak be causing that as well?
 
Vacuum leak for sure will do that as well as above posts , I use W-D 40 to find any vacuum leaks, start it up idle it down to say... 650 to 700 rpm and spray the side of your carb, ... then base plate ....and intake and if it raises in rpm you found one of many vacuum leaks. where do you have the trimming set at ? Oops for got to say block off your Vacuum advance and any port leaving your carb, remember your vacuum advance at the distributor could be leaking in the diaphram as well
 
Timing is around 8 above at the moment. It was set with vacuum advance hooked up. Does it need to be unhooked and plugged when setting the timing?
 
Pull the vacuum advance and plug the vacuum line and set it to about 10 to 12 and see
how it does... But 67Dart273 is most likely right ( good tech here) along with many here.
 
Ok so here's what I've found. After trying to retime the motor (i was wrong earlier when i said +8, it was acually at - 17) I'm at -15 now. Anything closer to tdc and the motor won't run. After that I've checked for vacuum leaks and found its sucking air at the intake on the back 3 cylinders. So yeah, there's my big problem, lol. Just wondering though...if I get all the vacuum leaks taken care of, is that going to let me bump up the timing, or does that sound like another issue?
 
May be a tooth off but I would fix the leaks ( which may require re-surfacing the manifolds ) and go from there.

Ive been having lots of practice with similar issued lately so Im becoming an expert at all of this real quick :)
 
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