Am I crazy or what???

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Dcudaboy

Dcudaboy

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scottsdale Az
O.K. Been working on my 65' cuda for--ever. On the road, runs great, fixing the last little things, and now I've got an idle surge I can't figure out how to fix. 300-400 rpm surge at running temp, not rhythmic, vacuum fluxes from 12-15 inhg. Otherwise the engine runs great on the road. Been thru the carb, checked the vacuum advance, timing, checked the vacuum lines (all three of them). I suspect it's a hidden leak may be in the intake manifold gaskets or something like that. Or could it be the pcv valve? Whatever it is, it's driving me nuts. Any ideas?
 
First off, welcome to the family. As for your idle issues, if you suspect a hidden leak, have you tried hunting it down with a can of carb cleaner? While engine idling, squirt a spot at the time everywhere you suspect. Lines, gaskets, carb base gasket, etc. If it IS a vacuum leak, you notice the difference in the idle immediately when you find it.

There are a LOT of very knowledgeable folks here. I'm sure someone else will be along shortly with more/better advice. In the meantime, how about some more details and pics of you ride.
 
Yeah, I ain't surprised, that is next after I check the float settings (again). I've had a 65 cuda with a 66 318 in it since 1978. drove it every day til I parked it to restore it in 90. Took all the hot rod stuff off and replaced it all with as much mopar as I could find, even down to the low profie cast iron spreadbore manifold. I'm at 90% now and am just knocking out the bugs, the poor idle issue, and I still have a "soft shift" and no passing gear even though the linkage is correct and functioning. 904 push button in the dash with a shift kit and a stall speed converter in it. runs great manually, but I'm a nut about thigns working right and will beat on it til it's fixed. thx got to get the wife to take some new pics and will post them shortly.
 
Not enough initial timing. What are your cam specs and how much initial timing are you running?
 
10 degrees btdc. It's a Crane cam that's just slightly over stock no overlap, I'll get the book out for the specs. Funny thing is that I haven't had this problem earlier, when I first got it running all was good no idle issues, just a little lower idle vacuum which I attributed to the slightly larger cam. All you know what broke loose when I started tweaking the carb, put a kit in it re-adjusted all the linkage and so on and so on. I got it running pretty good, good vacuum and steady idle, even went out and ate a vette just for fun. :thumblef: This just sort of popped up, changed the pcv valve which help a bit but still having a slight surge and the running temp is up 10-15 degrees.
 
Dcudaboy said:
10 degrees btdc. It's a Crane cam that's just slightly over stock no overlap, I'll get the book out for the specs. Funny thing is that I haven't had this problem earlier, when I first got it running all was good no idle issues, just a little lower idle vacuum which I attributed to the slightly larger cam. All you know what broke loose when I started tweaking the carb, put a kit in it re-adjusted all the linkage and so on and so on. I got it running pretty good, good vacuum and steady idle, even went out and ate a vette just for fun. :thumblef: This just sort of popped up, changed the pcv valve which help a bit but still having a slight surge and the running temp is up 10-15 degrees.
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I'd bump up the timing just 2 degrees at a time and see if the surge goes away. Unless you have the ability to limit total timing, I wouldn't drive it but give it a couple bump ups and adjust the idle fuel mixture and idle speed at every bump. It could well be a vacuum leak too.

Dcudaboy said:
F.Y.I. I got 10 acres outside of Cripple Creek, the wife was raised in the Springs.
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Nice area up there around Victor and Cripple Creek. I used to take Gold Camp Road to Phantom Canyon Road and end up in Canon city. :thumblef:
 
Think I got it, timing up to 12 degrees btdc helped the low idle in gear vacuum, but the culprit was a stuck or sticking primary throttle valve. It went into its surge issue after running 10 minutes or so, took off the air cleaner and tapped on the valve body covers and zoom, the left one was periodically sticking closed. So far so good, got the idle in gear vacuum up to 12 in hg and the mixture screws back down to 2 1/4 turns. Thx for the advice, be up in yer neck of the woods over the 4th of July.
 
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