Hi all,

I have a 76 F250 "Trailer special" with the 390. Bought it with 103,000 original miles. Anyway, I just replaced the timing set because I thought the timing chain had slipped. I was wrong.
My problem now is that sometimes when I step on the brake, the truck dies. I think that it has to be a vacuum problem, but I am not very familiar with vacuum "stuff". Anyone have any thoughts?
Also, does anyone know of any Ford truck enthusiasts in the Norfolk Virginia area. I know that there have to be since we have a F-150 plant here, which is where my truck was made 27 years ago. Thanks for any help

Rob

 

Welcome to FTE! Sounds like a nice pickup...

Does it die if idling in park and you hit the brake? Do you have power brakes? If so, remove the vacuum hose to the brake booster and plug the intake port. See if that changes it. Be careful if you decide to test drive like this - brakes are VERY hard to apply when booster is disconnected... If that cures the problem then you need a new booster ($100), when they go out they cause a huge vacuum leak...

Is this the symptoms that led you to replace the timing set, or is this a new problem since the timing set replacement?

Let us know what you find.

Marty

 

Well, here is the full story (bear with me).
A few weeks ago, the wife drove the truck, no problems. A couple days later, I jump in and the truck is very hard to start and once started, very hard to keep running. At first I thought fuel problem, changed the fuel filter, and no change. However, there was plenty of gas getting through the carb.
So when I was able to get it started, it was running very rough, and spitting black stuff (carbon?) out the exhaust. Even when I managed to get it warmed up, it was rough and hard to keep running.
Well, a few days later, a friend is over, who happens to know more than me about Fords, so we throw a timing light on it. Well, we had to turn the distributor about an inch in order to get it to 8 degrees BTDC. Well, it was still running badly and we deduced that the timing chain must have slipped. So that is what precipitated the timing set replacement. However, once I was into the timing set, everything was aligned, so it had not jumped. However, the play in the chain was beyond acceptable limits, so it was not a total waste of time.
Anyway, before replacing the timing set, when we were working on it, was when I noticed the brake pedal killing the engine. We did already remove the vacuum hose from the booster, and that did not make a difference. That is pretty much the whole story. I am getting ready to attempt to start it for the first time after the work I did. Wish me luck and thanks for your help

Rob

 

If you have the carb that has the fuel bowl in the front, you might have the same problem that I have with one of my trucks. The fuel flows to the front of the fuel bowl and starves the carb.

See if you hit the brakes real slow vs hard if that makes a difference.

If it's the fuel bowl, you can use fuel cell foam (Holley makes it in a slosh kit) to keep the fuel level or make a metal plate into a baffle to keep the fuel from sloshing.

 

I suspect you may have sheared the distributor drive pin. It holds the gear on. Sometimes they will break and the gear turn a little before grabbing again. If so it will eventually slip again. Usually caused by a worn out dizzy. You have to pull it and look at it closely to tell as the end pieces may still be in the gear