timing issues

Let me try this again. . .




A couple things can cause a main seal to come out. . .

Hard acceleartion increases pressure against the back of the seal. A bad PVC valve allows pressure to build up inside of the crankcase. . .

With regards to the front crank seal, the oil pump is directly behind it, creating oil pressure.

When the engine is cold, before the pressure relief valve opens, oil pressure can run pretty high.

How is it that some of these engines will run 350,000 miles before major overhaul, and others do not get 60k between teardowns?

Type of use.

A friend of mine got over 157,000 miles on an original set of front brakes due to feather footed driving. I did the maintenance on the truck from the day he bought it new, so I speak from experience on this. It's not a usual experience, but it happens.

As far as your 50 degree light off on your timing gun. . .

I suspect what you are seeing is RF interference / bleedover from a hotter coil output. Your inductive pickup maybe getting triggered from spurious electrical signals.

One thing you can do is maybe idle the truck at night, with a spray bottle of woter. Spray the ignition wires. If you see flashover / arcky-sparky lights, the wires are trash.

Another thing that might be happening is late coil discharge is traveling internally through a carbon path inside the distributor cap and that is causing an inductive mis-read on the part of your timing light.

You could use cylinder lead four as the gun trigger to maybe bypass this.

You probably know that electricity will find shoriting paths when the amperage is high enough. In your case, it might not be enough to cause a dead miss, but maybe it is heading that way.

Stock caps and wires are set up for stock coils.

Sorry guys for the late post, but it took me a while to work on my truck and the other things that I needed to take care of.

So I fixed the crank gear (timing gear sprocket) and the front main seal. The truck starts right up and I'm still getting a high timing position. From the timing gun that I am using, I'm getting 30 instead of 50. Which is a plus but I know that it must be off. So doing more research I am not getting cross over or jumping in the wires.



So I will try a different cap and wires to see if it is "late coil discharge", but not really sure that is the solution. Any suggestions on cap and wires?

However I'm getting an new symptom, when I start the truck cold (when it's been sitting awhile) the truck starts right up. But when I shut it off and come back five minutes later. It's a hard start, another words I have to hold down the key and the gas pedal and it final turns over. Then when it starts, black or dark exhaust comes out, meaning to me that it is to much fuel. It's like the carburetor is flooded. I do smell a lot fuel too. I also smell rich exhaust when I'm driving and getting poor gas millage. So is it the diaphragm in the Weber carb or the float? Not to sure. So is it just that the timing is still off or the a carb issue too?

1. Try putting the old coil back in and testing your timing. (process of elimination) Maybe your distributor is off one tooth. . . .base idle timing is 6 degrees . . .at 800 rpm. . .are you not able to get that?

2. You may have a bad vent on the bowl of the weber, which is allowing excess fuel pressure to build up when you park the truck when it is hot. It is called "hot soak" or "percolation." It isn't related to timing.

3. The float sometimes needs to be adjusted. . .or they go bad, soaking fuel and getting heavier. I don't know if you have an adjustment window to look into the float chamber.

You might want to put a fuel pressure tester on the fuel supply line to verify that pressure is below 4.5 psi. . .I think that is about the highest the weber's are designed to handle.

I thought about this after I went home last night. . .

You have a Weber.

Just for now, disconnect your distributor vacuum advance.

Maybe you have it connected to the wrong port on the Weber.

You connect the vacuum advance to the wrong kind of vacuum (manifold, instead of ported) and you will see the kinds of numbers at idle that you are reporting.

You want no vacuum supply at idle.

6 degrees btdc

Once you have that, you modify from there.

I think maximum advance, centrifical and vacuum. . .at 2500 rpm. . .is 45 degrees.

With the vacuum line off, you set base timing.

With it disconected, you rev the motor to 2500 and watch to see if the timing advances from the centrifical weights inside the distributor.

Then you connect the vacuum and see where your total advance is.

Late to this post.How did u "fix" the crank gear? If the keyway was wallowed out as u describe, allowing the crank pulley to oscillate, no way u r going to get an accurate timing reading. Only way I know to "fix" the crank pulley would be to either 1. replace the crank or 2. if u r really good weld a small bead on the worn crank snout keyway,and replace the 1/2 moon key and crank pulley if it is worn badly.U need to be really good with a welder to do this.f u did one of those, u have "fixed" the problem.Anything else ???? BJ

I'm glad you said something about total timing, in the very beginning when I put my truck together that's exactly how I did it. But through school and other things I have forgot how to do it. So now you said something, I'll do it that way.

It's also funny that you said something about the "wrong port" on the Weber. On the Weber there is two vacuum ports.



The one on the left I originally had the dizzy hook too (EGR port, the dizzy had no to little advance), but finding this diagram I swapped it to the one on the right. From there my timing has been screwed up but the truck ran so much better. Also reading the diagram on the underside of my hood it said 6 btdc with vacuum advanced connected. So should time it be with or without the vacuum advanced connected?

You mentioned



but if you point the rotor to the #1 spark plug, how can you be off a tooth to cause it to be off that much, (thinking about it, you have to overcompensate for the dizzy being off a tooth) but really would it read 30 btdc?

Today I got a rebuilt kit for my Weber and I was able to put in the new gaskets and cleaned all the jets and valves. It does seem to be able to start up after warm up, however my choke doesn't turn on. So it looks like a swapped out one problem for another. I made sure that I have 12v running to it. So the only thing I can think of is the bi-medal coil in side the electronic choke is that it's not wound tight. Does it have to be wound tight?

I went a head and replaced the the crank shaft sprocket and the keyway. I had to order it from Mazda, it wasn't to bad. The timing did straighten out. But however I'm still getting a weird reading on my timing. 30 bftdc

quoting bluebomber:
Also reading the diagram on the underside of my hood it said 6 btdc with vacuum advanced connected. So should time it be with or without the vacuum advanced connected?

With a stock Nikki carburetor, there normally is no vacuum at idle. . .so whether it was hooked up or not would not matter. . .as there should be no vacuum at idle.

If for some reason you have vacuum occuring, the line should be pinched shut or otherwise disconnected to prevent a vacuum distoring base idle timing.

You probably need to put a vacuum gauge on the line at some point to see what kind of vacuum it is pulling under various loading conditions.

Again, quoting bluebomber:
So the only thing I can think of is the bi-medal coil in side the electronic choke is that it's not wound tight. Does it have to be wound tight?

Under tension, when cold, the spring forces the choke closed. The heating element forces the spring to relax, opening the choke plate.

So there should be some tension on it. . .normally enough to force the plate to within 1/8" from fully closed.

The way I set them up, is invert the carb, and put an 1/8th drill bit into the space between the plate and the side of the carb throat, winding the spring enough to hold the drill in place.

I then unwind the spring until the drill falls out under gravity, then lock the chamber.

Is ur timing lite a multi-meter where it will read 4-6-8 cylinder engines? if so.is it set at 4? after all this, I am suspecting a bad meter rather than timing issues especially if the truck is running ok.30 degrees out lean it would ne backfiring something fierce and 30 degrees rich u couldnt start it--it would be flooded.bj