Invader Sandstone

I own a 74 with a rebuilt 350. It has an edelbrock carb and performer intake.

When I bought the car it always gave me a problem starting when hot. I put a spacer under the carb and that made it about %50 better. The mechanical tach broke last year and I had a new distributor installed with a tach drive key. Previous distributor was also a hei.

This year, when the car sits in idle after driving about 20 minutes, it will stall randomly. It will start back up immediately with no smoke or problem. Sometimes the car will stutter a little before stalling, but sometimes it just dies while idling perfectly.

This gets complicated.

I have a wideband meter. And I turned the carb to get a 13.6 reading at idle. My timing is 12* advanced and my fuel pressure is 8 pounds. Yesterday I replaced the fuel line and filter and moved the line away from the engine towards the side of the car, in an attempt to solve my stalling issue. Once the work was done I was getting a 15.5 afr reading. I had to back the idle screws out 5 more turns each to get it to 14.1. It didn't get any lower but the car idles smoothly. I took it for a 20 minute drive and when I got home it stalled in the driveway. It started back up immediately but stalled a few minutes later. If I blip the throttle I see fuel dumping into the chamber. That leads me to think it's not vapor lock.

I read that the carb I have can't take any more that 5.5 psi from the pump. Could all of this be because too much fuel pressure? Also today when I started it, the idle rpms jumped from 800 in neutral to 950. I haven't touched it yet, I'm pretty much at my wits end.

Im selling the car so I'm trying not to spend hundreds on this car, but I'd like to get this issue resolved before selling it.

I can't really check the spark because it always starts right back up, so I can't see if it drops the spark for a few seconds. But one time a few weeks ago it stalled 4 times in a row. I didn't have my told with me so that day I couldn't confirm anything.

The temperature is around 180 when these problems start, might be a coincidence, but I thought I might mention it.

Help.....

Invader Sandstone

I've spent weeks doing searches and trying to find the resolution. Lots of sleepless nights looking for answers.

hugie82

If the car idles perfect and then dies out of nowhere, I would be thinking ignition or maybe your timing isn't what you think it is? Hormonic balancers like to slip over 30+ years.
You also might be one of those guys that like a real low idle. If you are and you have it @650 rpm the carb can loss the vacuum signal and stall.

mvftw

Ignition Module cause interment problems when hot...

CaseyJones

That sounds reasonable to me.

silver74vette

The only thing that sounded odd to me was how many turns if the idle mixture screws it took. Sounds to me like there may be a vacuum leak Exacerbating the problem. The ignition module is a cheap check. You can take them in and have it tested.

Jbster

I would put a fuel pressure regulator on it, get the fuel pressure down where it should be, and then see how it runs.

Amorget

Seems to me that normally when the Ignition Module is failing the car won't restart right away, it takes a few minutes for it to cool off and start working correctly again. Taking it in to be tested also can be misleading as a module that it failing intermittently can test as good.

That said, it's a cheap place to start.

Haggisbash

I have a wideband meter. And I turned the carb to get a 13.6 reading at idle. My timing is 12* advanced and my fuel pressure is 8 pounds. Yesterday I replaced the fuel line and filter and moved the line away from the engine towards the side of the car, in an attempt to solve my stalling issue. Once the work was done I was getting a 15.5 afr reading. I had to back the idle screws out 5 more turns each to get it to 14.1. It didn't get any lower but the car idles smoothly.

Okay, so why did the AFR change just because you moved the fuel line? Does the AFR stay the same when measured with a cold engine compared to hot? Have you tried blocking off all vac lines and see what AFR is.

Avette4me

A pickup coil will do that sometimes.

diehrd

For a carb your way to lean ... You should be 13.5 WOT not idle and about 14 cruse , idle should be somewhere around 12.5 to 13.2 .. To lean will cause a stall ..

Also check the ignition as others have suggested

Shark Racer

Does the stalling feel like it's slowly shutting off, stumbling off, or just turned off as is you turned the key to the off position?

ssenay72

Had a distributor do the same thing to me, car would just die, wait a few and it would fire again. It was an accel distributor go figure. Module or pickup whichever was more than likely it. I swapped the entire unit out.

carriljc

it would fail when it got hot; so of course, as soon as I opened the hood it would cool down enough so everything worked ok and it would start right up........ took me forever to figure it out.

It's a cheap easy thing to check by changing out the coil and seeing what happens.

Invader Sandstone

I installed a fuel pressure regulator and it had no effect. I picked up a new ignition coil today and will install it tomorrow. My distributor has no model number on it anywhere so I had to do some guesstimating.

It would just die like someone turned the key off, but before that it would stumble a little every ten to twenty seconds.

Also, the harmonic balancer is fine. I checked my TDC. A few weeks ago.

Invader Sandstone

And my idle rpms are 800 neutral and about 6-650 in gear.

zigvs

try new fuel filter.I struggled for a long time and it was a broken new filter

Shark Racer

I suspect it's the module or coil, then.

donyue

I too was having problems with stalling at high temperatures. I realize that it most likely has to do with the fact that I have an aftermarket fuel pump with no fuel return line.

I've recently installed a pressure regulator with return port to connect to the stock fuel return line to the tank.

Do you have an stock fuel pump with a return line or an aftermarket fuel pump with no return line on your engine?

If you have no operating fuel return line that very well maybe your problem. If you have an aftermarket pump, I would replace it with a stock pump with a return fuel line/port. That will rule out any fuel vapor lock issues.

Do a search on this forum and pay particular attention to information provided by Lars... He is one of the great mechanical gurus on this forum. Good luck!

Duane4238

Have you replaced the rubber S hose at the fuel pump? My '72 started stalling when hot. If it sat for a minute it would restart and off I'd go, until a little while later it would stall, again. The warm rubber hose was collapsing, and then would refill after sitting for a minute. Check your hose! (On your car, that is.) Good luck.
Duane