High speed miss, rebuilt engine

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Model T Ford Forum: Forum 2015: High speed miss, rebuilt engine
Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Eddie on Sunday, July 26, 2015 - 11:22 pm:

My 26 is finally on the road. Engine has been rebuilt, new Anderson timer, coils have been rebuilt by a fellow recomended by the local T club, new plugs and wires etc.
Engine runs great at an idle, carburator fuel needle adjustment responds correctly when adjusted.
At low speed it seems fine , as you accelerate to about 20 mph it starts to miss.The faster you go the worse the miss becomes.
Not sure where to focus?

Dave


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jack Daron - Brownsburg IN on Sunday, July 26, 2015 - 11:24 pm:

I vote timer.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Les VonNordheim on Sunday, July 26, 2015 - 11:28 pm:

Timer


Top of pagePrevious messageNext messageBottom of page Link to this message  By Les Schubert on Sunday, July 26, 2015 - 11:50 pm:

Dave
Was the front cover properly centred on the camshaft using a fixture?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Pat Kelly Montana on Monday, July 27, 2015 - 12:08 am:

A friend had the same type of problem, he also had a Anderson timer. He put one of my spare New Day timers on and it runs great. See if you can borrow a different timer. We ended up putting a TW timer on his car and life is good. PK


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank van Ekeren (Australia) on Monday, July 27, 2015 - 12:34 am:

Was new valve springs fitted?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Mikeska, Denver CO on Monday, July 27, 2015 - 12:48 am:

Could be a sticking valve or 2.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Eddie on Monday, July 27, 2015 - 09:53 am:

Les

No, I did not have access to an an alignment fixture when installing the timer. What is the process for checking the centering?

Dave


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Monday, July 27, 2015 - 11:17 am:

You can get a tool for this alignment from the vendors. Get the more expensive one which fits in the recess for the timer. The center is drilled to fit the end of the camshaft. All the bolts which hold the front plate must be loose. The plate is then moved so that the tool will fit all the way into the groove in the timing gear cover plate. Then tighten the bolts. It could be a problem to do so with the crankcase bolted on, but worth a try. Try to fit the tool first before you unbolt anything. You might be lucky and have it fit just as is.

Another thought. Did the car miss before you rebuilt the engine? Did you do anything to the coil box or the coils? Did you install new spark plugs? The spark has a harder time jumping at the spark plugs under higher compression. You have higher compression with a rebuilt engine, and when the throttle is opened the compression will be highest. So, it could be anywhere in the ignition system. A faulty coil, a carbon track on the wood in the coil box, or a bad spark plug or as suggested above in the timer.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Monday, July 27, 2015 - 11:31 am:


The tool aligns the timer only indirectly. It really aligns the front cover. It's essentially a metal doughnut or big, thick washer. You use it when installing the cover, but before you tighten the bolts. The hole in the center fits over the end of the cam shaft, then you adjust the position of the cover so the outside of the fixture fits into the ring which will hold the timer, then you tighten the bolts to hold the cover in place. The tool comes in two sizes.


One size fits the inner ring, like this, and the larger version fits the outer ring. If you have access to a lathe you can easily make one yourself.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Les Schubert on Monday, July 27, 2015 - 12:14 pm:

If you don't use the line up tool pictured you get a big variation in individual cylinder timing. The Anderson design aggravates the effects of this issue, but all timers work better when properly centered. You will also gain power when it is properly centred. Definitely worth the effort to accomplish


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Doolittle on Monday, July 27, 2015 - 01:01 pm:

Just wondering. Did you remember to turn the key switch to MAG?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Eddie on Monday, July 27, 2015 - 04:09 pm:

Thanks gentlemen for the tips, I think I will remove the timer tonight and check the centering.

Dave


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wayne Sheldon, Grass Valley, CA on Monday, July 27, 2015 - 05:48 pm:

More than 45 years playing around with model Ts, and I have never gotten a timer centering tool. That is actually pretty ridiculous.
But I will pass along my tip for others that do not have a centering tool handy. I use an antique "inside" caliper. A point to point compass would work just as well, and I have in fact used one a few times. Carefully adjusted? And checked all directions? It works quite well.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Walker, NW AR on Monday, July 27, 2015 - 09:40 pm:

Although the more expensive KRW repop probably is more accurate, I've always used the smaller and cheaper one (in Steve's picture above) with good results. I've installed lots of Anderson timers on engines with the timing cover set up using the small alignment tool without any problems. The instructions with the Anderson mention that they are very sensitive to proper alignment, so that's likely the problem if you didn't use an alignment tool. Depending upon which type you use, the crankshaft seal can throw the timing cover alignment off by quite a bit. If you don't use an alignment tool, it will not be correct.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Eddie on Tuesday, July 28, 2015 - 12:40 am:

Well it looks like I will have to beg, borrow, or purchase a centering tool, I pulled the timer this evening and had a look. I see what you mean, there is no way of centering without the fixture. I have an assortment of dial indicators but nothing small enough to fit.
I recall vagely when I assembled the engine (7 yrs ago) that I centered the timing cover plate so that the oil seal fit properly. Looks like the radiator needs to come off in order to get a good look at the timer plate.

Dave


Top of pagePrevious messageNext messageBottom of page Link to this message  By Art Wilson on Tuesday, July 28, 2015 - 01:24 am:

The inner ring may not be concentric with the outer ring on every front plate since it only was meant to hold the felt washer in place and it's tolerance was not closely held. The outer ring is the one that controls the concentricity of the timer case to the cam shaft so it is best to center it to the cam shaft. I made a centering tool out of 1/2" Baltic Birch plywood that works well.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Wetherbee - Downeast Maine on Tuesday, July 28, 2015 - 12:46 pm:

From what I was told, you can use a Model A Ford distributor body in a pinch...

Never tried it, I have a KRW one, but that's what I was told


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Tuesday, July 28, 2015 - 10:39 pm:

"From what I was told, you can use a Model A Ford distributor body in a pinch...", Model A manifolds, Model A spark plug wrench to install cam nut, Model A carbs...where will it end! LOL (I am joking) I'll have to give that distributor body trick a try.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Wetherbee - Downeast Maine on Wednesday, July 29, 2015 - 12:37 pm:

Who wants a Model A Carb on a T???? I'm running dual Strombergs... Just joking - but that does seem to be the new reality as the younger generation gets involved.

I will admit that both my cars are pretty much bone stock, however one of them does have a Model A carb... (it is also positive ground)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Eddie on Thursday, July 30, 2015 - 03:40 pm:

It seems my timing cover is worn, with the Anderson timer in place, but not clamped tight the timer will move around,(back and forth) about /.030" -.040".
I have 3 spare timing gear covers, which all fit the timer with little clearance. I ordered an alignment tool, and will replace the timing gear cover. Hopefully this will help.
I am guessing with the original timer that had the roller a bit of play in the timer cover would be as much of an issue as the Anderson design. In any case it needs to be correct.


Dave


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