88 ford B700 370 timing and parking brake issue

[MJSchwartz]

New to the forum. I have an 88 f700 we use as a transport vehicle for the rafting company here in CA. Recently I was tasked with some basic maintenance that included setting the timing and adjusting the carb due to a dieseling issue. After setting the base idle at 600 rpm I hooked up my timing light and realized that I can’t find a timing pointer! I’m unsure if I’m looking in the wrong area or if it came off or was removed. I have looked all around the harmonic balancer and can’t see anything that looks like a timing pointer.

The second issue I’m having is when I flip off the switch for the parking brake I can hear a humming and the brake releases but then there is a click noise about every 10 seconds with a correlating pulse felt through the brake pedal.

Any advice is appreciated. I will try and add some pics tomorrow if that helps.

 

[dbsoundman]

Welcome! Details on the exact engine you're dealing with would be very helpful here, buses came with a wide variety of engines and no one really has an index of model and year to engine type. Even then, there were singular model years of specific buses that came with two completely different engine types (ex. Cummins or Cat).

Regarding the brakes, details again please: hydraulic brakes or air brakes? I'm guessing hydro based on the description but it seems a little weird to have an electronic actuator involved in a parking brake on a 1988 bus.

 

[Jolly Roger bus 223]

you can get after market pointers to put on your engine.
what carburetor?
what distributor?
have you checked the power valve in the carb?
fuel level in the carb float bowl?
choke hanging up?
pull the plugs and look at them? pay attention to what plug came from what cylinder.
look up the chart online and it will show you pictures of the different colors or conditions of the plug to help diagnose.
check the coil.
plug wires.

 

[MJSchwartz]

The bus is powered by a Ford 370. The carb is an Edelbrock, l would imagine a 650 but I plan on looking it up by the numbers, manual choke functions properly. The distributor is pointsless with a reluctor. I haven’t touched the carb or plugs because it cold starts, idles, and revs just fine. Before I plan to do anything else, change anything, or adjust anything, I need to get the base timing set. I have checked the usual getting spots, local parts stores, rock auto, general google search, and have turned up nothing for what pointer to use or where it’s supposed to be located/installed.

As far as the brakes are concerned they seem to be some type of hydro brake setup, and the parking brake is actuated with a switch. There is also a electric motor on the master assembly. I’ll take pictures in a bit and post them today.

 

[Jolly Roger bus 223]

look up hydromax brake systems and see if that matches what you have

 

[Jolly Roger bus 223]

also to find the location of where the pointer and associated bolt holes are bring number 1 piston to top dead center on compression stroke.
clean off the balancer to find the timing marks then the bolt holes for the pointer should be in that area.

 

[Jolly Roger bus 223]

as far as the dieseling it could be the throttle return spring weak?
the curb idle set to high?
carbon deposits in the engine that create hot spots and allow it to keep running.
or even you need to run a higher octane fuel or octane booster.
could try a seafoam treatment.
also once you find a pointer try a little more advance with higher octane fuel and set the advance with the vaccum line pulled and plugged.
i would start with the return spring and a seafoam treatment if this is something that has just shown up and no body has had there hands under the hood for awhile unless the distributor hold down was loose and the dizzy could slip on its own.

 

[Jolly Roger bus 223]

one more while its in my head and then i gotta get back to work.
if there has been electric fans added if they are not wired into the system properly then i have seen them back feed the system and cause the dieseling issue.
i recommend wired into a switch where you can manually control them.
also until you figure the dieseling out you can hold the brake and shut it down in gear and then park usually wont diesel if shut down in gear.
maybe i helped some and maybe not let us know.

 

[Kentucky Dreaming]

Another idea. I had an old Jeep pickup with AMC 360 engine. it would diesel on shutdown when I first got it. (it was 10 years old at the time.) I needed to take the passenger side exhaust manifold off to do something, I don't remember why after 30 years.

The manifold came off in 2 separate pieces. It had broken completely in half between the number 2 and 4 cylinders. Got a new one at a junkyard and no more dieseling. It had been blowing hot exhaust gas on the head on those two cylinders.

If you even suspect an exhaust leak, take a close look. Mine was coated with oil that had been leaking from the valve cover for years so I didn't see the break until I actually unbolted it.

Good luck. Let us know what happens...

Marty