I'm not a mechanic.....

Running issues. I'll try to be quick.
Car ran fine under power, or any time above idle. but when it comes back down to idle, runs rough, kinda like it's loading up, never did this before, but happened all of a sudden one day.
Changed- cap, rotor, plugs, wires, magnetic pick-up, rebuilt carbonator, good gas...
When running (at operating temp) vac gauge fluctuates between 0 and 10 at idle, stays steady with throttle open(2000 or so rpm). while giving it gas, I slightly hear a sound similar to that of bad exhaust gaskets thru the carb.
My thought is bad head gasket between cylinders. PLEASE correct me if I'm wrong.

Any thoughts????

Also...today I drove it around to get temps up, ran good, but I got back home, and while checking vac, and timing the r's came up a little then it died. didn't want to restart...not squirting from the primaries, bowl is dry.

I'm not a mechanic, and I don't have too much more hair to pull out.

 

Sounds like a fuel issue. Did anything change from when it ran good till before you made the changes. Possible float issue or maybe clogged filter not allowing fuel to pass to the filter

 

crack in vac line...

 

Agreed... Assuming carb is OK(assembled correctly, float free, etc), no fuel from squirters is either a restriction in fuel line, filter or maybe a bad pump... On rare occasions can be a leak before the pump that's allowing it to pull air instead of fuel...

 

The first time I had running issues, it was an all-of-a-sudden type thing, on my way to a show, ran fine but when I got to the town the show was in, in car show traffic, started to idle rough. On the way home, started fine, ran fine...took a scenic route through a small lake town, did it again. Clears up when over 1300-1500 rpm.
As far as vac lines go, there isn't any, just rubber plugs on the ports on the carb. Also, I squirted starting fluid around the intake, with no change to idle.
The second issue, with it not running now, just happened, nothing changed. Fuel pump is a Holley mechanical(Carter I suppose), I have another pump, that I plan on swapping today, depending on time.

Thanks for any and all thoughts on this.
Chris

 

im thinking you have a valve problem.
do a compression test. that should tell you if you have a valve problem and where it is.

 

Not sure if it could be vapor locking due to under hood engine heat because it clears up after it hits a certain RPM - We towed a camper to upstate New York once, with an IH Scout, and got into a situation such as this - the car would loose power and stubble until it stalled, them ran like crap at idle - we had to pull off the side of the Interstate and wrap the steel fuel line with aluminum foil to deflect the heat and it ran fine the rest of the way up and back home

 

Thanks all for the responses.
I haven't been able to get back to it this week, Yellowcar takes a backseat to other life things too often.

 

Compression test.....Number 5 cylinder, would pump up to 150, then do nothing else, clear the gauge, and would be zero all other cylinders were between 180-190. Long story short..two broken valve springs,#5 and #6. A friend came over with his scope, and saw no damage on the piston.

 

Thanks for the follow up. All too often these kind of threads are just left opened with no indication of the final fix...

 

I was going to say check valves. I had the same problem coming home from a car show on the freeway. All of a sudden started to run like crap. Pulled valve covers noticed valve spring broken. Replaced & ran fine... Glad you found it.

 

"while checking vac, and timing the r's came up a little then it died. didn't want to restart...not squirting from the primaries, bowl is dry"

You seem to have two separate issues going on here as broken/weak valve springs will not cause this fueling issue. Check flow and time the fuel pumps output into an empty container and roughly calculate the gph. Also look for aeration that Tom already eluded to as well. Pumps diaphragm/check valve may have gone bad from the ethanol content in today's gas. These pumps are cheap and damage is cumulative.

 

Yes, I agree on the two separate issues, I have an extra fuel pump, that wasn't the issue I was worried about, it was just part of the story.
......and thanks all for the responses