Rather than continuing to hijack another user's thread, I thought I'd better start a separate one since I have more questions. I'm just a simple backyard mechanic who's willing to try anything but old enough to be more careful these days :-)

I recently bought a '96 F-250 with the 4.9 L inline 6, and I have to change the distributor because the cap bolts were so rusty they sheared right off even after soaking them for a couple days with PB blaster. (Unless someone knows of a fix for this - which I doubt?)

Now, according to the other post, to change the distributor, I do the following:

• Take the cap and adapter off the top of the distributor.
• Turn the engine by hand (crankshaft bolt) until the pointer in the distributor points to the rear about where number one wire was on the cap.
• Then look at the pointer down at the crankshaft damper an position the engine where the pointer points to Top Dead Center (TDC).
• Do not move the engine until after the new distributor is in place.
• Remove the hold down bolt and pull the distributor out.
• Drop the new distributor in and have pointer pointing to where number one wire would be on the cap.
• Start the distributor hold down bolt until you can just turn the distributor by hand.
• Remove the SPOUT shorting bar.
• Hook a timing light to number one wire after you put the rotor, cap and adapter back on.
• Start the engine and turn the distributor until the pointer points to 10 degrees BTDC.
• Tight the hold down bolt and recheck the timing.
• If still at 10 BTDC put the SPOUT back in and check to see that the timing moves some.
• If so remove the light and you are done.

My question is, if I line up the distributor rotor with the number one cylinder, THEN line up the notch on the harmonic balancer with TDC, the rotor on the distributor is pointing to the next cylinder. Is this still right? I don't want to pull the distributor out if I'm not doing this right?

I appreciate your patience and help.

John

Madison, WI

 

The reason for having the rotor roughly pointing to No1 before aligning the crank timing marks is just an easy way of being sure No1 cyl is on the compression stroke.

 

Yea it could be that far off, depends on previous "tune". As stated its just a way of verifying the #1 piston is at tdc on the compression stroke. Number one on the cap can be anywhere, (but get it back in the same area anyway)

You are more likely to be one tooth off dropping the new distributor in in the same spot though. Lift it back out far enough to clear the cam gear, turn the distributor shaft "feel for it" one tooth in the direction you need to go and drop it back in.

You might have to stick something down the hole and turn the oil pump drive shaft just a hair if it won't drop all the way in in that position. Patients is key, trial and error will get it in the right position. Put the rotor on it and use it to turn and jiggle the distributor shaft back and forth as you lightly lower it down into place. Any amount of force won't really help.

 

TDC should be pretty close to the #1 post on the distributor, definitely not an entire post off. While it makes it a little easier to keep up with, the position isn't really that big of a deal as long as the new distributor is installed in the same position/orientation as the one that came out, assuming the engine is not turned at all while the distributor is out.

It can, but remember that the computer gets its timing signals from the distributor, including a reference pulse for cylinder 1. The injection timing, even though it is batch injected, will be incorrect and could cause some driveability problems. The tooth on the reluctor wheel is narrow for #1.

I'm pretty sure this holds true for the OBD-II trucks as well, but I'm not certain.

 

Thanks guys, we'll give it a shot.

 

Was speaking in general but yea the body of the distributor would have to be in the correct location to go with it where ever it happen to be "on the cap" so the PIP is correct. Yea best over all if the distributor is installed in the correct orientation to start with.
Probably shouldn't have brought that up, didn't want to confuse the issue no.

The timing was likely advanced with the old distributor in place, that would put the rotor some distance before #1 cylinder on the cap with the #1 piston at true TDC, not pointing directly at #1 post on the cap. How much depends on the how much timing advance it had been set at 10? 14deg btdc more?

That may explain why its not pointing directly at #1 now, not one post off either no, but should have been noted with the old one still in place. If its off its off one or two teeth is all.

 

My cap bolts sheared also on my other truck. I just drilled through them and put in some screws with a nut on the end. Works fine. Less work.

 

I thought about doing that, but the distributor didn't look much better inside than it did on the outside. The fella I bought the truck from had it since 2004 and obviously hadn't done a thing with it since he bought it. Most of it is a mess, but it's getting there. I have the old distributor out, and had to go find a screwdriver to get down to the oil pump because the shaft doesn't want to line up to let the distributor back down into place - figures. Oh well, this is usually the way things go for me and the next day it gets better ;-)

 

Haha, oh, alrighty then. Makes sense why youre doing it now. Good luck to ya!!