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new distributer-timing woes

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prmac

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Hi, I'm getting my '76B out of winter hiding and readying it for the road BUT...
Last year I took the vehicle into a mechanic knowledgeable in MGs and was told the spindle on my 45D4 distributer was bent and I should replace it. My parts guy got me a good used 25D4. I had problems getting the points right but found it was missing a lock washer. Now I have the car running and I set the distributer so it starts easy but when I put the timing light on it, it is about two inches after top dead center. If I set the timing to the light, the car will not run. The idle is a little erratic once it warm up but keeps running (I have not reset the gaps yet). I have a Webber double side draft carburetor so, since I don't have any vacuum, I closed the vacuum on the distributer.
So my question is: is there something very wrong or should I get a good old mechanic to do a “by the ear” timing?
Also, what do you all think of the Petronix electric add on for the distributer. I had an electronic ignition on it when I bought it but a very non-reputable mechanic threw it away when he AHEM, re-built my engine. And-what should my idle RPM be set at?
 
I think it is possible that the "mechanic" who rebuilt the engine did something to move the timing mark. Someone more knowledgable than I can probably tell you for sure. I would, however, check it out. This is what you can do:

Pull the plugs and remove the valve cover. Turn the engine over until the front two (#1cyl) valves are both up (valves closed). Now back the engine a bit, stick a soft rod, like bronze welding rod, into the spark plug hole and turn the engine until the rod indicates that the piston is at the top. That will give you TDC for #1. Now the timing mark and the pointer should align. If not relly close, put a chalk mark on the balance and use that to set your timing.

Guinn
 
I would suspect that the same klumk that threw away the dizzy has one tooth off on the timeing chain.
 
Is this the first running of the car since the engine was rebuilt? If so, the mechanic may indeed have set the timing chain off by one tooth. The test suggested by Guinn should indicate this. With the #1 piston at TDC, both of it's rocker arms should be loose indicating the valves are closed. At that point the valve clearance should be its maximum. The valve clearance shouldn't be greater either before or after TDC. If it is, I'd be taking the car back to the engine rebuilder as this would confirm jlaird's suggestion.

Sort out the problems with the ignition you have before investing in Pertronix. Pertronix is great, but if you have a significant timing/assembly problem, an electronic ignition isn't going to fix it.
 
The re- rebuild is a few years old now. The car was actually running pretty good with the 45D4 distributer. I was just going in for a valve check last year and while doing this, the mechanic noticed the problems starting in the distributer and recomended replacing it so it wouldn't cause propblems at the worse possible time. It was when I put in the new distributer the new problems began; first it was really hard to tune the distributer and I had to re-do the gap every time I took it out as it began to miss. I really haven't got to give it a good ride since I put in the 25D4. I will do the check Guin suggested today and report back. Of course I just changed the oil so I'm sure I'll have to take off the timing cover- been one of those months.
 
Since you don't have even a first name /ubbthreads/images/graemlins/hammer.gif, I'll just say hey you /ubbthreads/images/graemlins/grin.gif.

[ QUOTE ]
Of course I just changed the oil so I'm sure I'll have to take off the timing cover

[/ QUOTE ]

I don't understand what that would have to do with taking T.C. cover off?? /ubbthreads/images/graemlins/confused.gif

Now, I <font color="red">would</font> suggest that you go back to the K.I.S.S. Rule /ubbthreads/images/graemlins/cool.gif!

As someone else mentioned, get #1 to TDC. With felt tip mark the dist. base vs clamp plate. Verify that rotor IS pointed at #1. Pull the dist. and verify that the DRIVE is AS pictured in Shop Manual. And YES it could be upside down. And YES it can be ONE tooth off of where is SHOULD be. /ubbthreads/images/graemlins/devilgrin.gif BTST.

Report back with pic, if possible.

/ubbthreads/images/graemlins/cheers.gif
Ed
 
While it could be one tooth off... it's unlikely seeing as how the rebuild was several years ago. I'm sure you would have noticed running problems with the 45D if the cam timing was off by one tooth. It's also not easy to put a 25D or 45D dizzy in out of position. There are only two ways it will stuff in the block and I'm not sure you can really put it in "wrong" as the drive dog isn't quite symmetrical.

Start by checking the valves and comparing them to the piston position at #1 TDC as Guinn said. IF all that looks OK, pull the cap off your dizzy and look at where the rotor is pointing relative to the cap. You may want to consider resetting the static timing followed by re-tuning the carb (if necessary) to get back in running shape. However, as mentioned above, start with the simple things.
 
How about the gear thing that feeds from the cam and the dizzy drive dog fits into? Assume Bs have these as well. Thats an easy one to get a tooth off and it will still run just not right.
 
[ QUOTE ]
How about the gear thing that feeds from the cam and the dizzy drive dog fits into? Assume Bs have these as well. Thats an easy one to get a tooth off and it will still run just not right.


[/ QUOTE ]

Exactly!!!

There is a Frogeye and TR-4 Owner on Spridgets that had EXACTLY that!! /ubbthreads/images/graemlins/hammer.gif

Guess who "called it"??? /ubbthreads/images/graemlins/angel.gif

/ubbthreads/images/graemlins/cheers.gif
Ed
 
/ubbthreads/images/graemlins/lol.gif /ubbthreads/images/graemlins/lol.gif

/ubbthreads/images/graemlins/devilgrin.gif
 
Ed, you are quite right- I'm Paul.
I did as Guinn suggested and the markings show top dead center to be correct with the piston. The problem is definetely with the rotor position. Maybe my memory lapsed but I thought number one position on the Distributer was about one o'clock, left of the small coil wire plug. However, the rotor is pointing at 6-7 o'clock. I tried turning the distributer shaft but it seems to only want to go in the one way. Is 6-7 o'clock number 1 position?
 
It really makes no difference as long as TDC fires #1 etc etc.

But you get a answer on how it should be soonish. When questionable check the manual.
 
OK... yes, the drive gear for the dizzy can be one tooth off but this really doesn't matter. All that is affected by this is the relative position of the dizzy housing to the block. You shouldn't focus on this unless the length of the spark plug wires or the vacuum advance tubing limits how much you can turn the dizzy body. If you really want to reposition this, I assume the B-series engine is like the A-series in that you can pull the dizzy and thread a 3/8-24 bolt into the dizzy drive gear to pull it. That would allow you to reposition the drive gear where you want it to be.

Again, if it's only the dizzy drive gear that's off, you should be able to go through a simple static timing and set the dizzy wherever it needs to be to have the correct timing. If you've been doing this by eye and trying to set the rotor position to set your timing... that's your problem. Don't focus on the rotor position. Focus on setting the static or dynamic timing, not rotor position.
 
Agree whole-heartedly. The only thing that would affect "timing" would be a mechanical mis-alignment between crank and cam, the chain being a tooth off one way or the other. Doesn't sound as if that's a problem. The Dizzy could be skewed any number of teeth and still be workable with just rotating it to fire at the appropriate time.

The A and B engines are the same Doug. A locating collar with a countersunk screw holds the drive dog in place.
 
Sounds to me like the problem is with the "good used" 24D.

Who says it's "good"? Sounds like the shaft bushing is worn and the shaft is wobbling and kind of randomly opening and closing the points which will play heck with trying to set the dwell and timing.
 
If the engine ran ok with the 45D, why would you want to change to a 25D? Isn't the 45D an electronic dizzy? Sounds like your mechanic is taking you backwards instead of forward. /ubbthreads/images/graemlins/rolleyes.gif PJ
 
Have your considered replaceing the distributor with the New Pertronix Distributor, that also includes the Ignitor. For $199.99 it is well worth the change and not have to worry about these problems.
 
The 45D4 is just a later version of the Lucas point's type distributors. I'm not sure which models started using ignition modules but I think it's perhaps the 59 and 65 series.

Magaoidh, where can I find information on the complete Pertronix distributor? Is it listed at Retro-Rockets?
 
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