Lunched my distributor!

[CDN OpelNut]

Originally Posted by B-townOpeler It sounds to me like you are not allowing for the rotation of the dist as you install it. If you install the dist. with the cap off you will see the rotor turn about 20-30 degrees as you push it down in. This is because of the helical gears on the crank and dist. shaft. so you actually back the dist. rotor off about that amt. (20-30 degrees or so) before you install it and it will rotate to where it should be when it is in all the way. It that what happened maybe?

Thanks - I'm aware of that. It's a relative thing. After I install the distributor, I rotate it to align the rotor with the correct firing position in the distributor housing. Because the dist has to be rotated to #3 firing position, installing it in the normal position with the oil pump gear slot at 4:30 causes the vacuum canister to interfere with the block.

I'm also going to check that my timing chain is not off a tooth. I think there is a chance that I need to advance it as far as I do to compensate.

On the plus side, I spent my lunch picking up a nice timing light.

[First opel 1981]

Originally Posted by CDN OpelNut Thanks - I'm aware of that. It's a relative thing. After I install the distributor, I rotate it to align the rotor with the correct firing position in the distributor housing. Because the dist has to be rotated to #3 firing position, installing it in the normal position with the oil pump gear slot at 4:30 causes the vacuum canister to interfere with the block. I'm also going to check that my timing chain is not off a tooth. I think there is a chance that I need to advance it as far as I do to compensate. On the plus side, I spent my lunch picking up a nice timing light.

The timing chain has nothing to do with the position of the distributor. The distro runs off of the crank.

[wrench459]

Originally Posted by RallyBob I've seen so many engines destroyed by 'guesstimating' ignition timing it's not even funny. Just last week my friend set the timing on his '69 Camaro (383 stroker with all forged bottom end), and he set it to 52 degrees because it 'sounded right'. I brought my timing light over and set it to 38 degrees before he drove it. It wouldn't have lasted a trip around the block!

Oh hell so he didn't see the increase in power from backing off the timing then.

[kwilford]

Originally Posted by CDN OpelNut ...On the plus side, I spent my lunch picking up a nice timing light.

Did you happen to pick up a variable timing version? With one of those, you can determine the vacuum and mechanical advance, by "dialling" the timing light to get the marks to line up, and then checking the advance you dialled in. They're a bit more expensive than the standard "fixed" timing light, but well worth it when you are trying to determine the mechanical advance at various rpm's or at throttle settings caused by the vacuum advance.

JM2CW

[CDN OpelNut]

Originally Posted by kwilford Did you happen to pick up a variable timing version? With one of those, you can determine the vacuum and mechanical advance, by "dialling" the timing light to get the marks to line up, and then checking the advance you dialled in. They're a bit more expensive than the standard "fixed" timing light, but well worth it when you are trying to determine the mechanical advance at various rpm's or at throttle settings caused by the vacuum advance. JM2CW

Yep - I swung by Canadian Tire and picked up the best one they had - digital, tach, advance retard etc. I'll have a look at it tonight.

[CDN OpelNut]

I went to the garage with the intent of starting the GT so I could pull it into the garage facing to other way so the exhaust could exit while I checked the timing. No Go. Not starting.

I wanted to verify all the initial set-up anyway so here I go. I'm going to document all this so let me know if you see anything amiss.

1. Check the cam installation to make sure the chain is not off a tooth. I find this easier to check with #4 TDC so I lined up the flywheel ball and checked that the cam pin is at 12:00. Looks good
2. Rotate the engine until the flywheel ball appears again to determine #1 TDC. Cam pin at 6:00.

The first photo shows cam pin location at #4 TDC.
The second photo shows the best view of the flywheel pointer. With the sidedraft manifold I have to locate the ball with my finger. I'm not thinking I'll be able use my new timing light.

The cam installation appears fine. On to the distributor install.

[CDN OpelNut]

Gene sent me a '75 distributor without the vacuum advance to use in place of my trashed one.

I went through the usual step of orienting the slot in the oil pump gear at 4:30 to arrive at the correct #1 firing position for the distributor when installed.

When it seated, it was way off where it should have been. When I looked closer at the distributor, there are a couple of differences that I'm thinking may have an impact on its operation.

First, I notice that the slot in the shaft is in a different location relative to the shaft lobe than on my old one. You can see my original in the first photo. The slot is directly in line with the lobe. In the second picture you can see that the slot is well in advance of the lobe. What's up with that?

[CDN OpelNut]

The other thing I noticed when comparing the distributors is that the "blade" at the bottom of the shaft that engages the fuel pump is in a completely different position. I don't think this will do anything as long as the firing position of the rotor is correct but it throws the whole "slot at 4:30" tip out the window.

You can see in the photo that with the slots at the top of the shaft in the same position that the blades at the bottom are not.

Can anyone tell me if this is normal? I would have thought that these things were consistent with all the dizzys.

Fresh start tomorrow.

[First opel 1981]

Originally Posted by CDN OpelNut The other thing I noticed when comparing the distributors is that the "blade" at the bottom of the shaft that engages the fuel pump is in a completely different position. I don't think this will do anything as long as the firing position of the rotor is correct but it throws the whole "slot at 4:30" tip out the window. You can see in the photo that with the slots at the top of the shaft in the same position that the blades at the bottom are not. Can anyone tell me if this is normal? I would have thought that these things were consistent with all the dizzys. Fresh start tomorrow.

Are they both Bosch? I can tell by looking at the housings and the shafts that there are lots of differences between the two. You should be able to install the new one but the general settings will need to be thought out. Of course saying that because is easy because I swap parts on machines all the time. Trying to tell someone how to do it isn't my strong suit though.

[CDN OpelNut]

Originally Posted by First opel 1981 Are they both Bosch? I can tell by looking at the housings and the shafts that there are lots of differences between the two. You should be able to install the new one but the general settings will need to be thought out. Of course saying that because is easy because I swap parts on machines all the time. Trying to tell someone how to do it isn't my strong suit though.

Yes they're both Bosch. I had the new one in the car last night and it running great once I got it started and rotated it a whole bunch clockwise. Just went back out tonight and it would not go.

(I also re-read the Compu-fire instructions and noticed that there is a correct orientation for the disc which I paid no attention to yesterday so if it was wrong that may have had an effect as well.)

Edit...

From another thread:

Originally Posted by calvin NOTE If you take your vacuum advance off like I did be sure to cover the hole (and any other holes) where it went not to let light through or you will end up like me, very frustrated and wondering why your car won't start for 2 days because there is too much light and its messing up the optical unit.

I'll have to see to that. (although I don't think this matters for the Compufire as it's magnetic)

and from Bob's distributor specs:

1975 - 25 mechanical advance
5 degrees static timing
No vacuum advance unit
30 degrees total

So perhaps the lobe-notch thing is the 5 degrees static timing

[hrcollinsjr]

Originally Posted by CDN OpelNut The other thing I noticed when comparing the distributors is that the "blade" at the bottom of the shaft that engages the fuel pump is in a completely different position. I don't think this will do anything as long as the firing position of the rotor is correct but it throws the whole "slot at 4:30" tip out the window. Can anyone tell me if this is normal? I would have thought that these things were consistent with all the dizzys.

Don't know about normal but the position of the "blade" has no effect on the timing, the gear near the bottom of the distributor shaft engages the gear on the crankshaft and keeps it in time. I set the distributor in where I think I want it and if it doesn't seat all the way I rotate the engine with "slight" pressure on the distributor and it should drop right in when the "blade" aligns with the oil pump shaft. When I say slight pressure I basically am holding it in place to keep it from moving around when I rotate the engine.

Harold

[hrcollinsjr]

Originally Posted by CDN OpelNut From another thread: I'll have to see to that. (although I don't think this matters for the Compufire as it's magnetic) and from Bob's distributor specs: 1975 - 25 mechanical advance 5 degrees static timing No vacuum advance unit 30 degrees total So perhaps the lobe-notch thing is the 5 degrees static timing

The opening should be closed to keep road grime out if nothing else! If it's controlled by a magnet, Hall effect, the light shouldn't make a difference as you stated.
Factory spec static timing is that you point the rotor at the little line in the top rim of the distributor housing with the flywheel timing mark lined up with the pointer. Rotating the distributor counter clockwise 2 or 3 mm is probably going to get you close, but you STILL need an advance timing light to be sure.

Harold

[CDN OpelNut]

I figured that the car had been running a few nights ago so whatever the differences in the distributors, it has to work - so onward.

I borrowed some white nail polish from my wife and marked the pointer and ball, and the crank pulley just in case.

I reinstalled the distributor, and like before, rotated it to #3 firing position as has been covered in the various Compu-fire threads. Picure below.

When I cranked the engine, it was a bit disturbing in that once in a while, it would kind of thud, and then slow or stop turning and the thud could be seen in movement in the gear shift. It's not sudden like an impact, but almost like resistance or a missing flywheel tooth or something.

Anyway, I ignored it and adjusted the distributor and eventually, it caught and ran pretty smoothly. No noise or sign of any issues in the motor and actually, it is much easier to maintain an idle speed around 1000 rpm that before.

I hooked up my new timing light and the pointer and ball were very easy to see. It's a bit rough at 0* so I set it at 10* and locked it down.

It seems good, but I won't sit easy until I try it tomorrow as I was in the same place 2 nights ago. If I get the same behaviour on starting again I'll post a video.

[hrcollinsjr]

Originally Posted by CDN OpelNut I hooked up my new timing light and the pointer and ball were very easy to see. It's a bit rough at 0* so I set it at 10* and locked it down.

That should put your total advance somewhere around 35 deg. Right in the ballpark of what you need.

Harold