Distributor 180 off...

[Morris]

So I think I fell victim to classic blunder #1 and mis-aligned my distributor after rebuilding my 1500 engine.

I am not sure yet where I went wrong, but if it is that I aligned the distibutor gear at the "wrong TDC" do I need to realign the gear, or can I get away with flipping just the distributor?

 

[DrEntropy]

Put th' plugwires in the cap at 180-degrees around!

 

[Morris]

HA-HA! Brilliant!

 

[ecurie_ecosse]

Been there,done that!! It's amazing how standing on your head can resolve a problem.I had to rotate the cap to get any sign of life at the plugs.

 

[Bugeye58]

You can re-wire the cap and get away with it, but why not just reinstall the gear correctly?
Jeff

 

[Morris]

I won't be rewiring the cap. That would be harder for me than reinstalling gear.

But, couldn't I just pull the distributor, turn the rotor 180, and reinstall? This would be much easier than reinstalling the gear.

My real question is this...

The timing mark on the pulley passes the #1 TDC mark twice per cycle. You time the distributor gear by setting the crank at #1 TDC, then aligning the slot on the gear to the line on the block. I believe this is supposed to happen at TDC before #1 begins it's power stroke. I am pretty sure I did that, but I may have set it at TDC when #1 was starting it's intake stroke. If I did, would I need to remove and reinstall the gear, or can I get away with "flipping" the rotor 180?

 

[DrEntropy]

I don't believe you can put the dizzy in but one place. If you got it off on assembly (no crime, BTW) you have to pull the shaft to realign it. This being a 'rumphy mill, I can't recall if that's a BIG or little job, so I'll defer to Jeff's superior knowledge here. But rearranging the wires to suit the mechanicals works... I've been flummoxed before by that trick when a car would show up and I couldn't make heads nor tails out of the way the dizzy HT side was sitting. The cam/dizzy turn at half the speed of the crank, BTW. /ubbthreads/images/graemlins/wink.gif

 

[Bugeye58]

Doc, the distributor goes in just like a B. It's no big deal to index the gear, once you are sure #1 is at TDC on a compression stroke. The drive gear slot should be pointing to 1 o'clock, with the large offset to the bottom.
Jeff

 

[DrEntropy]

Thank you Jeff... I couldn't remember. Now I know WHY! It's the same. Then it'd be just as easy to set it right. Suss #1 with valve timing and TDC, pull the gear out and "fuss" it back into proper position!

"Cuthbert's th' parrot o' yer Great Aunt!"

 

[Kurtis]

On a 1275 engine... should the slot also be pointing at roughly 1:00 at #1 TDC?

 

[Bugeye58]

Kurtis, on a 1275, the slot winds up at 2:00, with the large offset at the top.
Jeff

 

[Kurtis]

[ QUOTE ]
Kurtis, on a 1275, the slot winds up at 2:00, with the large offset at the top.
Jeff

[/ QUOTE ]

Hmmm... is it possible for it to go in lined up at 1:00 with #1 at TDC (without the cam being out of time with the crank)?

The reason I ask... mine seems to be at 1:00 when #1 is at TDC.

 

[Bugeye58]

Kurtis, I can''t remember how many teeth there are on the drive pinion. I think there are 8, but I'll check tomorrow. If there are 8, installing the drive one tooth out would put it at about 12:30. The distributor will still install, but you may have trouble setting the timing correctly.
Jeff

 

[Kurtis]

But assuming there's enough rotational movement in the distributor, it should time normally?

 

[Bugeye58]

Kurtis, if that is the case, then it should time normally. I'm going out in a bit to look at a 1275 I have on a stand now, with the head off. I'll pull the drive and count the teeth, and play some games with a distributor.
Jeff

 

[Kurtis]

Thanks Jeff.

I've been having a discussion with some folks on the Spridget e-mail list about a timing dilemma I'm experiencing.

After getting the car back on the road recently, I timed it by ear and then fine tuned it on the road – advancing/retarding until it was just on the verge of pinging under heavy acceleration in high gear. I then realized there was a dynamic timing spec for this engine, so I pulled out the timing gun, dusted it off and hooked it up. When I pointed it at the lower part of the harmonic balancer at idle, the TDC mark was nowhere to be seen. By moving around to the right side of the engine, I managed to catch a glimpse of it in approximately the 4:00 position (should be 10° BTDC – or just before 6:00).

At first, I thought my harmonic balancer had slipped, so I shut it down, and lined it up at #1 TDC. Bingo, the TDC mark lined up perfectly with the 0° pointer. When I timed it to 10° by retarding the timing (a lot), it ran, but not nearly as well.

Several guys on the e-mail list immediately suggested that the drive dog was off a tooth (which I suspect is true after looking at some pictures I took of it following the installation). However, if the distributor body has enough free movement to time the thing properly, I can’t fathom how the position of the drive dog would have any bearing at all on the TDC mark while timing.

I have a spare distributor, and I’ve been playing wit it, trying to visualize the scenario. The spark posts (in the cap) and the trigger mechanism (on the points plate) are fixed relative to one another as are the rotor (that contacts the spark posts) and the cam lobes on the distributor drive shaft that trigger the points. Therefore, the points always have to be in the correct position (assuming the gap is set correctly) when the rotor reaches a spark post (and vice versa). What am I missing?

Sorry to highjack this thread with such a long post, but this has really been bugging me, and I need someone to either tell me I’m not crazy or explain why I am!
/ubbthreads/images/graemlins/crazyeyes.gif

 

[DrEntropy]

HUH?!?! You must have made one POWERFUL incantation as you screwed that thing together... What you're describing as to where the #1 spark is hitting makes that a ~magic~ engine! Did you put the T/Light pickup on the "other" wires and look just for fun yet?

 

[Kurtis]

I'm going to go out and double check it today when I get the chance... It sure seems crazy I know, and I'm sure I'm doing somthing stupid.

But there's no way the drive dog being off a tooth could result in this weirdness... is there???

 

[Bugeye58]

Kurtis, some preliminary findings.
I verified the engine was at TDC, using both the timing marks, and a dial indicator. Marks line up as advertised.
There are 9 teeth on the drive pinion, so one tooth out is 40 degrees. I installed the drive 1 tooth out,CCW, and reinstalled the distributor. Without disturbing anything else, I turned the crank to get the rotor lined up with the original #1 on the cap, and my timing mark was now at about the 4:00 position. Although nothing has changed on the cap, the orientation of the drive cam lobe on the distributor relative to the housing has moved by the 40 degrees.
Ergo, your drive pinion is installed 1 tooth CCW. When installed correctly, at TDC, the rotor is pointing roughly at the top bolt of the rear alternator / generator mount.
At 10 degrees BTDC, it's about halfway between the two mount bolts. I think the issue that is so befuddling is that the relationship between the distributor shaft and the housing changes, relative to the crank position. That's the whole reason for indexing the drive pinion in the first place.
Hope this has been of some small help.
Jeff

 

[Kurtis]

Thanks Jeff...

I wish I could say it all makes sense to me now, but it doesn't. I'm headed out to the garage to reposition the drive dog. It looks like that is indeed the culprit.

Sparks and magic.
/ubbthreads/images/graemlins/crazyeyes.gif