67' 352 hesitates, stumbles, & hard starting - solution Holley 500?

[Chopperman]

Background
Recently picked up an original owner 67' 2wd f250 352. With the exception of the last few years, the truck has been very well cared for and all services records documented. I think the owner just got to a point in life where he just couldn't keep up with it anymore and let a lot of things go.

Anyway, due to lack of recent maintenance, I've done the basics plugs, wires, fresh fuel, charging system, belts etc. Engine was rebuilt in mid 80's and again in 2007. I guessing the last rebuilt has no more than 20,000 miles on it (speedo broke) It runs VERY well and no smoke or other signs of wear.

Symptoms
When cold, truck fires right up without touching pedal. Has major hesitation/ stumble when cold off idle. Once warm runs like a champ but still stumble a bit off idle. If I turn the truck off and restart immediately no problem on firing. If I wait 10 min, it takes 10 seconds or so of cranking to fire almost like it's flooded. So I have a couple issues.

What I've checked
-Verified fuel is squirting into carb by working throttle and looking onto the carb.
-Pulled air filter after shutting down to verify fuel isn't spilling into intake.
- pulled vac advance and found no leaks and its working properly
- highly unlikely to be a vapor lock situation as it's hard to restart after just getting warm and letting sit

I've read numerous possibilities and just as many solutions. Again, PO kept exceptional records and I can tell from the number of rebuilds on the carb he logged, this carb has always needed attention. I'm heavily leaning towards buying a Holley 2300 500cfm and wanted to get some final thoughts before I pull the trigger.

Sorry for the long winded post, and Thanks for the feedback

[MadJoe]

This is exactly the same symptoms I had with my '71 360. Everything except firing when cold, anyway. It would start, but I needed to pump the peddle to get it to fire and keep it running.

Anyway, all I did was squirt some carb cleaner in it while it was running, let it stumble but didn't stall it. Did that 2 or 3 times and the hard starting and hesitation off idle improved DRASTICALLY.

Another immediate benefit included my idle dropping, and quieting significantly. Prior to this I thought I had an exhaust leak on the passenger side because whenever someone opened the passenger door while the truck was idling, the exhaust noise was almost unbearable. Now it is, if I had to guess, at least 10-15dB quieter at idle. It was literally such a drastic change that it feels like a whole different truck.

After that I went one step further and put maybe 2oz of Seafoam in the crankcase. I thought the idle was smooth as I was doing it, but it smoothed out even more as I was pouring! It was amazing. Then I put some in the fuel and tried to do the "hot soak" but did it wrong and ended up stalling it too fast. But after those simple steps, this truck is running so much better that I'm not going to bother with the hot soak.

I'd try that first, unless you really want a new carb and need a reason to justify it. Can't blame you for that, I was leaning in that direction as well but I couldn't source a reasonably priced 4V intake (people around here seem to think old iron intakes, that look like they tried cleaning them up by leaving them outside for 5 years, are worth as much as brand new Edelbrock aluminum intakes).

Best of luck!
Joe

[Lee]

Hi,

Is the choke set up correctly?

On a cold start you should put the pedal to the floor 1 time to set the choke and then start the engine.

Ensure that when warm, the choke is open all of the way.

Lee

[Chopperman]

Choke is manual and set up correctly and open.

Should have mentioned that the 500 carb I'm looking at is the large Holley 2300 2bbl.

[Ren]

I also have a '67 with a 352. Once upon a time, I had the exact same problems you describe. And more. A knowledgeable friend and I rebuilt the carb that came with the truck. Some problems went away, some remained. I bought a rebuilt, replacement carb. What I actually bought were more problems.

I considered the Holley 350 and 500. After some research, I bought the smaller 350. All of my problems magically went away. Problems I didn't even know I had went away.

From what I've read, the stock 352 truck engine can't take advantage of a larger carb without expensive and time consuming changes.

[MadJoe]

Ok, my hard cold-starting doesn't appear to be as completely cured as I thought yesterday. This morning when I went out to see how it would start from a complete freeze, it started to catch a little easier than usual, but actually seemed harder to keep running until it got warm, but the rough idle returned (however it is still much quieter than it was previously). But, when warmed up it no longer has off-idle hesitation (when cold it still threatens to stall if I don't rapidly pump the throttle, but that used to happen even when warm).

And my "warm" starting issue is seems resolved as well (the same as you, when it was warmed up if I shut it off and then tried to start it again after a few minutes it would be almost as difficult as when cold, but it would stay running once fired). So I'm guessing my issues were a handful of things working together to mess with me.

Now to diagnose what I believe to be a faulty or maladjusted choke since cold starting is still an issue. Lee: the choke is fully open when warm, but I didn't think to check it while cold. In an hour or 2, once the truck cools off again, I'll go check it to see if the choke is working correctly when I "set" it and report back.

-Joe

[Chopperman]

I'm going to rebuild, adjust, and check timing before committing to a new carb.

Will report back later today

[ThinLizzy13]

I have a '67 F250 as well with the 352. My truck always hesitates when cold off idle; no issues once warmed up. Same thing even when I got rid of points.
I'd get your timing set and ensure everything else is in spec. Get a dwell meter and a vac gauge if you don't have those yet and tune it in. A vac gauge can give you a lot of insight into what's going on in an engine
Good luck!

[Chopperman]

Carb rebuild did the trick. Pretty nasty inside.

Saved 300 bones too!

[cep62]

The FE intake is a big heavy piece of cast iron , it take awhile to warm it up for proper fuel atomization.
Sometimes the heat passage that runs through the intake from head to head can get plugged up and keep it from warming up properly also.

[iwhodat]

Have you replaced all of your rubber fuel lines? My 360 did the same thing when I got it. I tried all kinds of stuff, but no luck. The old rubber fuel hose going to the fuel pump wasn't leaking gas, but it was sucking air, causing a hesitation on acceleration. My issues went away after replacing that piece of hose. Make sure you don't have any vacuum leaks, also. Good luck!

[MadJoe]

Hi,

Is the choke set up correctly?

On a cold start you should put the pedal to the floor 1 time to set the choke and then start the engine.

Ensure that when warm, the choke is open all of the way.

Lee

I was able to wade through the snow yesterday and un-bury the truck enough to see that the choke is, in fact, not working at all. It just sits partially open all the time, pressing the peddle to the floor, and when trying to manipulate it locally something is physically stopping it from fully closing. Manually choking it with my hand while it idles cold seems to improve it, but as soon as I move my hand away it goes back to a rough idle and threatening to stall.

I'm also pretty sure my failed attempt to hot soak with Seafoam might have fouled a plug or something, so new plugs, plug wires, oil (high zinc), air filter, oil filter, and fuel filter are all on their way. Once i get this choke working it better purr like a kitten, or my wife is going to kill me.

-Joe

[Chopperman]

So I finally solved the hard start issue.

I accidentally broke the terminal on the coil off and had to replace the whole coil. Problem solved. Truck even runs stronger and idles smoother.

If you have a hard start issue when warm, might not be getting enough fire to light off a warm motor. Try a coil. Easy fix and under 20.00.

[Diveboss]

A common problem with the 352 is the carb heat. They come from the factory with an aluminum carb spacer that on some versions was actually connected to the engine coolant. The theory was that it would keep the carb cool from sitting on the hot manifold, but would actually heat up the carb after turning off the hot engine. Also, the spacer was made of aluminum furthering the heat transfer. The heat would actually boil the fuel in the carb bowl, and make it flow into the intake after turning off the engine creating a flooded condition. So, engine would start fine cold, but would be flooded when hot.
Solution is to swap out the carb spacer to a phenolic resin spacer which will keep carb cool, and also put a fuel line insulator on the fuel line running to the carb.
The holly carb will help as the fuel bowl is slightly higher than on the Autolite carb, but you may still have the same problem.

[tsherry]

A half hour ago I installed an Edelbrock 600CFM on my '67 with a mild 390. Pulled a Carter 650CFM Comp Series. Night and day difference. Could not start it without starting fluid, despite a full rebuild and through cleaning. Immediate starts, far more power, stunning difference. And, they included an air cleaner and a fender cover for free.

Thank you Jegs. You rock. Best $340 I've spent in a looooong time.