Triumph Sports Cars

Fred, I over reacted to the green/white advice a bit I'm afraid. It was good advice and obviously well intentioned. When I was able to check, there was indeed a green and a white wire. More to the point, even though I am going to replace the coil just because it is so old and decrepit, when I did the resistance check I could not get it to fail. Rock solid no matter how I move the wires.

So... in all seriousness and putting aside the Lucas tomfoolery, unless the contacts themselves were the source of the intermittent operation, (and I slipped those out, pinched them in, and applied anti-corrosion grease) how in the world does the vacuum advance cause a misfire? From the plugs it looked to be pretty consistent on the driver's side of the engine, especially #1 which was not firing at all at idle with the vacuum connected. Resistance was 1000 ohms which is right in the middle of the range the test called for.

Well, this evening I'll get the replacement and suspect I'll have to go another round. Module is next again I suppose. Tomorrow they get a couple new one in that we can test on their machine. Could be a problem there.

Jim

Have a look at the phasing of the cap/rotor and pickup.
The reluctor can slip or possibly the advance can is the wrong one.
This causes the ign. to fire when the rotor is in between posts on the cap.
When the vacuum is applied it makes the out of phase condition worse and sends the spark to the next cyl in line instead.
That could explain your timing mark problem as well.
Stick the dist cap on and mark the housing at any of the plug wire posts. Remove the cap and line the rotor up with that mark. The points on the pickup should be lined up or very close to it.
One last thought. Possibly you have a mismatched distributor or components, even fire mixed with odd fire?
At any rate Lucas just has to be involved here somehow.

Cheers
Fred

Thanks, I'll look at that as soon as I can. Parts went B/O so I cancelled and ordered from Rock-Auto at 1/3 the price. Figured if I have to wait I might as well take the discount. So, not too sure how much I can do while waiting. The rotor has 3 points and I think the stator has 6 so I'll see how they line up. Got it all disassembled on the bench right now. Should be the stock distributor, all the parts match so far to an '82 Buick Regal 231 V6. But I haven't looked to see if the points on the stator are equally spaced. Anyway, the thing about the cap, that makes as much sense as anything. It's got those aluminum tabs in the top and there is more room for variations in those, being bent slightly for instance, than anywhere else I can think of. Still, it was such a dramatic change with the vacuum. Winding it up to where the mechanical would have advanced it still ran smooth without vacuum. So, who knows?

Jim

The mechanical advance doesn't affect the phasing of the distributor.
The three point star wheel is an odd fire part I think. Mix that with an even fire cap and there you are.

I'll measure the distance between the points. If it's odd fire either the points on the stator, the rotor, or both would have to be offset I would think.

Jim

Don't know how I missed this, but the cap does not have the plug towers evenly spaced. And the points on the stator are also uneven, three gaps at about .850" and three at about .515" Fred, I guess you called it. Unless there was something else odd that they did with this, someone put an odd fire distributor in this engine. I guess that would make it run rough.

You know, that still doesn't explain why there was no spark with the vacuum hooked up, but I think I might know what would. The gaps on the stator are wide/narrow/wide/narrow/wide/narrow. The plug tower are wide/wide/narrow/wide/wide/narrow. Looks like a mismatch to me. Then, there is the 4.3 Chevy motor which apparently has 3 versions, an even fire, an odd fire, and a semi-odd fire somewhere in between. Maybe this is a Chevy distributor cap. Or maybe they got fancy with the aluminum tabs on the inside to make one cap fit all. I don't know.

What I do know is that another distributor from the junkyard is going to cost me about fifty bucks, so I'm at the decision point in the other thread. I think I'll put the trigger coil in when it comes and see how it runs. It's an escalating solution. The entire engine from the junkyard if I can find a 4.1 in a Caddy (fairly likely) would be $180, or an extra $130 for a 4bbl intake and carb along with the engine it's attached to, potentially a significantly better one than this that will bolt right in and be complete from stem to stern. Or for another $150 I can get a later lower mileage, more efficient and probably more powerful engine (3800) with it's matching transmission still attached, which will also bolt right in. And if I knew we were keeping the car that is what I would do. Probably the best thing is to take a little vacation, spend some time discussing it with Edith and take enough time to completely sort things out. But I gotta tell you guys, this odd-fire/even-fire business has sort of soured me on the whole idea. I think I've made a legitimate effort to be a fan of the V6 and in the final analysis have been forced to accept that it is a creature of endless and unnecessary compromise. And before you 60 degree guys complain, yes I realize that's a different animal. I also realize that just because this one in particular has led me through a mind numbing array of unlikely symptoms and still more unlikely causes it doesn't mean a well sorted engine won't give excellent service. But I hark back to the days of the straight six, some of which were in the 300 cubic inch range (5L). Despite some impressive national record holder 6 cylinder cars the six was NEVER considered to really be competitive with the V8 in day to day usage. Puts me in mind of Dad's 300 straight six pickup and his 302 V8 pickup. Near identical trucks, but not even close. In my opinion, nothing has changed. I'm damned glad I never got serious about the V6 as a candidate when I first did the conversion on my car. Why compromise purely for the sake of compromise, when a Buick 300 would do the job so much better in every conceivable way?

But being here, now, I'll probably compromise and fix it as cheaply as I can. First things first though, I need to verify that it is indeed an even fire engine, and that it has an even fire crank. Clearly more fun-n-games ahead.

Jim

Have a look at the balancer bolt. 5/8 is odd fire 3/4 is even. 82 and newer engines had metric threads and a knock sensor boss at the rear of the block.

Fred, do you think the 3 lobed rotor (equally spaced lobes) would work ok with the even fire stator? Nothing unique about the coil and 3 lobes should interact the same with 6 points whether they are odd spaced or evenly spaced it seems to me.

The damper bolt has a 1-1/8" head. Does that tell us anything? The intake bolts are 3/8" NC. It is supposed to be an '82 but maybe the the first ones were left overs. I haven't found a serial number yet, the closest thing is a very light stamping "629" as close as I can make it, on the right front cylinder bank front surface. Can't see well enough to tell if there is a KS boss on the back.

The distributor cap is as I suspected. The aluminum contacts inside are offset so that the gaps between them are within 1/8" of each other despite the offset in the towers. So it appears to be the right cap.

If this is an even fire engine, the crank throws on one bank are displaced from where they would have been on the other engine. This is consistent with the results. The #1,3 and 5 plugs showed a dark color after rough idling while the #2,4 and 6 plugs were white.

Maybe the new pickup will fix it.

Jim

It did. The lobes and points have just a smidgen of interference, just barely touch, so as an experiment I went ahead and put it together that way. Once I remembered to install the rotor button it started and ran fine. So the odd fire tri-lobed rotor will work with the even fire trigger assembly. A good thing to know, wiring wise. And since this pretty much concludes the wiring portion of our program I'll also conclude that the remainder of comments belong on the "Considering a V6 upgrade - TR-7" thread and go there.

Jim