Is taking off all the plug wires a bad idea?

[Cedar Ed]

I am having trouble finding the timing marks,so it's and older '78 GMC 350.Friend say the distributor,or plug wires are off,it runs ok,but put in a new distributor,borrowed a tool,it is a plug/screw that goes in #1 plug,instructions are take out plugs then turn crank by hand until it stops,then I am at TDC,then reinstall distributor,plugs,Then I don't know the next steps,but it should be close to good.Probably using the timing light,but last time we couldn't set it due to not seeing the marks,but it did run o.k,just trying to get it right.

 

[Uncle John]

If you cant find a timing mark, advance timing till it kinda kicks back a little when starting. Then back it up till it doesn't.
Drive it and if it pings (rattles) on acceleration back it up a little till it doesn't.

 

[Uncle John]

If you are absolutely sure its at TDC, put a mark on it with chalk.

 

[Uncle John]

Guess I didn't answer your first question.

If you have to move wires around you didn't install the distributor properly.

No big deal as long as the vacuum advance doesn't hit something preventing setting timing properly.

 

[ft. churchill]

Your way of finding top dead center can put you off 180 degrees. The for sure way is to remove the driver's side valve cover and watch the valve over the number one cylinder. Both valves will be stationary if your at TDC on the firing stroke. If the exhaust valve moves your at TDC center of the exhaust stroke. You can still use your piston stop tool if you wish, lie if your timing marker is gone. I've run them before in a pinch, one or more teeth out on the distributor, you have to move the wires around. It's a royal PITA. Keep foolin' with it you get it right. The previous posts are all good info as well. I usually "road time" my engines anyway as they are not stock and the factory settings are not close. Listen for the pinging and back it off. Another sign of too much advance is hard, slow cranking when starting. To little advance starts easy, runs good at low RPMs then is a weak dog at the upper rpm range. Perfect will be when it never pings and if you go any more advanced it will ping.

 

[Cedar Ed]

When I had the old distributor in, the vacuum advance pointed behind the right wheelwell,now with the new one in,it's more towards the firewall. If I move it back the old way it won't run.With it compensated it runs,ok. Something seem a little off.

 

[Uncle John]

Both positions were wrong.
The vacuum advance should point a little towards the right fender from straight forward.
Find TDC. With distributor out, check position of the tongue (couldnt think of a better word)
on the bottom of the distributor shaft.
That fits into a groove on the oil pump shaft.
Use a long screwdriver to turn the oil pump into proper position.
Install distributor with rotor pointing to #1 wire terminal and vacuum advance pointed where it should be.It probably wont fall right in.
You might have to barely bump the starter till it drops in. You might have to repeat several times.

 

[Overtrained]

Pull the #1 plug out, ball up a paper towel or rag and stuff it in the spark plug hole. Pull off the coil wire or the 12V power wire(HEI) going to the distributor so no spark will be present, bump engine over with the keyed ignition.....bump.... bump.... bump

you will here POOOFF!! and the paper towel will blow out on the compression stroke. Now you are near TDC on the compression stroke.

Check your balancer and move the line on the balancer to "zero", you can do this with a breaker bar on the crank pulley.

Once its on zero you can drop your distributor in, follow this diagram for the correct placement of the rotor on #1 on the cap. Mark the cap and run your wires from there in the following sequence....


1 8 4 3 6 5 7 2 in CLOCKWISE order

Note: As long as you route this order on the cap after you find TDC on #1 cylinder you can make any terminal on the cap #1

 

[Cedar Ed]

I have the HEI,but didn't remove the wire.And haven't used the breaker bar to turn it yet,first thing tomorrow,will give it a try,and compare to diagram. Working on it in the driveway,20 degrees outside.

 

[Cedar Ed]

So if I am off by a tooth,or off by 180 degees ,just take it out and start over by going to TDC then reinstall,and check plug/wire fireing order,and turn oil pump,if needed,just about got it I think.

 

[Cedar Ed]

rotor question

Should the rotor point to the#1 cylinder,or the #1 plug in the cap?

 

[Uncle John]

Should the rotor point to the#1 cylinder,or the #1 plug in the cap?

#1 Wire in cap

 

[Uncle John]

When you install the dist. the rotor will move a little.
You can see why by looking at the gear on the dist. bottom.

 

[Overtrained]

Should the rotor point to the#1 cylinder,or the #1 plug in the cap?

The rotor should sit under the #1 in the cap. As mentioned, you may try and drop the distributor/rotor in near the #1 in the cap and the oil pump shaft wont be lined up.

Try and wiggle the distributor, it may drop in.

If it doesnt, bump the key once and it will drop in.

Once its dropped in it wont be in the #1 position because you cranked it over a bit, put the towel back in the cylinder and repeat the process.

Bring #1 cylinder back up to TDC and check the position of the rotor. If it looks good, put the cap on and mark which terminal is going to be your #1 and run your wires from there clockwise around the cap.

1 8 4 3 6 5 7 2


Let me know how it goes.....

 

[Overtrained]

NOTE: If the dist doesnt drop in on the first ignition bump hit it again until it does.

 

[Uncle John]

NOTE: If the dist doesnt drop in on the first ignition bump hit it again until it does.

True

And you might be 180 degrees off.

Try again!

 

[Overtrained]

True

And you might be 180 degrees off.

Try again!

You get a pretty good pop using the "towel" method to find TDC, its less noticeable on the exhaust stroke which would put you 180 degrees out.

Either way , OP check it after the dist drops in.

 

[Cedar Ed]

Thanks alot I am out working on it,have a friend helping,so I'll get back here later and let you know how it's going.
I think the rotor was pointing the opposite way.

 

[Cedar Ed]

Thanks alot I am out working on it,have a friend helping,so I'll get back here later and let you know how it's going.
I think the rotor was pointing the opposite way.

I'll keep trying!

 

[Overtrained]

I'll keep trying!

Get it squared away?