Hard Starts, When Cold and Hot

Hey Guys,

I'm new here, this is my first post and my truck is a 1975 Ford F100 shortbed 4x4 which I've only had for a few months. I've been having a cold start and hot starting issue lately.

Here is what I know about the truck and engine. This is either from what I can tell or what the previous owner told me, so bear with me.

The engine build is approx 7 years old. I haven't seen any receipts, so who knows...The previous owner was claiming some big HP numbers, but I think its probably around 400hp or the trans is slipping really bad. LOL

1968 429ci block, which has been re-worked to a 472
Seems to have a mild cam, nothing too exciting
CV9E Dove Heads, roller valve train
Edelbrock Air-Gap Intake
Speed Demon 750cfm (Vacuum Secondaries)
MSD Pro Billet Distributor (Vacuum Adv)
Headers and Flowmasters
MSD Blaster Coil
GM Single Wire Alternator
C6 Auto Trans.

Originally, when the truck would be driven around for awhile, it would sputter out and almost die when it got warm (sitting in traffic kind of warm), not just to operating temp. Since the truck had sat for a year or two before I bought it, I pulled the carb apart and did a rebuild on it. I then took it to a carb shop and had the carb calibrated for maximum performance. Now, I am having a hard start issue, it just doesn't like to start whether its cold or hot. It coughs out of the carb on start up usually, which to me means that the float levels are too low, but they are right in the middle of the sight glasses. On start up without giving it gas, it lights off and dies repeatedly. It takes allot of gas peddle to get it to fire, when it finally fires up, then the RPMs surge between 1,000 and 1200. Fuel pressure is between 6-7psi (stock mech fuel pump). I should also note, that when it fires and runs, it runs great, but likes a high idle, anything below 1000rpm it acts like it wants to die and is even harder to start. I've gotten to a point to where I am thinking it either needs timing or there is an electrical issue. Any help would be greatly appreciated.

Thanks,
Chris

Did it have these problems before you had the carb work? The dying while warm in stop and go traffic could be a heat issue vaporizing the fuel. You might could try a phenolic or plastic carb spacer, and also check the fuel line routing to make sure it isn't close to any heat sources.

Check for vacuum leaks.

460bronco wrote:Did it have these problems before you had the carb work?  The dying while warm in stop and go traffic could be a heat issue vaporizing the fuel.  You might could try a phenolic or plastic carb spacer, and also check the fuel line routing to make sure it isn't close to any heat sources.

Yes, that was why I rebuilt the carb because everything was either new or gone through. The carb was the only thing left, strangely enough, before I rebuilt the carb, it started without pumping the gas and ran great, until it started sputtering out when it got warm. It did have a 1" aluminum spacer between the carb and manifold in which I removed so I could put a 3" air filter on it without cutting the hood. Could that be causing any of this?

I appreciate your help.

Chris

TommyK wrote:Check for vacuum leaks.

Will do.

Open the idle mixture screws about 1/2 to 1 turn out. Sounds like a lean condition, but double check what has been already mentioned. Make sure the air bleeds are clear, shoot some carb or brake cleaner in each bleed then a shot of compressed air(with an air gun that has at least a 4" tube attached).