Changing the cam gear

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Model T Ford Forum: Forum 2016: Changing the cam gear
Top of pagePrevious messageNext messageBottom of page Link to this message  By Rich Bingham on Friday, December 16, 2016 - 11:29 pm:

Any tips or caveats on changing the cam gear without a complete engine tear-down ? What's the scuttlebutt on the 7.5 degree advance gears ??


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Saturday, December 17, 2016 - 11:22 am:

You will need to be able to remove the front crankshaft pulley. In my opinion, that will be the hardest part of the job.

Pull the radiator. The fan. Then the pulley, then the timer and timing gear cover. There is a mark on one tooth of the crankshaft gear. Some have the name Ford for the mark and others just a indentation. That mark must line up with a mark on the camshaft gear. The camshaft gear can be installed on the camshaft in either of two positions 180 degrees apart. Either will work because the crankshaft makes two turns to one of the camshaft.

The advance degree depends on your camshaft. Some of the new camshafts are ground with the advance and if you advance the gear, you will be too advanced. So if you don't know the grind of your camshaft it is best to use the standard gear.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Saturday, December 17, 2016 - 11:31 am:

If the engine is still in the car, you must pull off the radiator, then the fan next the front crankshaft pulley. Then the timer and the timing gear cover. Remove the nut in the center of the timing gear and remove the gear. There are two positions the camshaft gear can be installed 180 degrees apart. Either will work fine because the crankshaft turns two revolutions to one of the camshaft. There is a mark on one of the teeth of the crankshaft gear. The mark is either the Ford logo or an indentation. There is also a mark between two teeth of the camshaft gear. Those marks must be aligned for correct installation.

Some of the new camshafts are ground with the advance degree and installing an advanced gear would cause it to advance too far, so if you don't know the grind of your camshaft, it would be best to install the standard gear.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Saturday, December 17, 2016 - 11:34 am:

Something very strange about the forum this morning. I re-opened the thread and did not find my post, so I thought I had forgot to post it and rewrote it. Then posted it. I found the post I had originally sent. It must have been lost somewhere in the cloud!
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Les Schubert on Saturday, December 17, 2016 - 12:15 pm:

Rich
What Norm says is all true and very complete.
Here is my understanding of changing cam timing;
The concept of advancing the cam is to gain a bit of improvement in low end torque. It is reasonable to expect a effect on high end. I have never personally done it on a T.
However I did recently do this to my '81 F150 (daily driver truck) with a 351M. Due to cam chain wear it was probably running a 1/2 tooth retarded before, so probably netted out a full tooth of advance. This won't be the case on your T. Anyway, big improvement all around including fuel economy and power. Sorry I got "rambling " here, but hope it helps


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rich Bingham on Saturday, December 17, 2016 - 01:07 pm:

Thanks fellows, I should have been a little more specific, got the gear cover off, this is pre-starter so there's not a lot of options to grab the fiber gear that's on it. Any thoughts how to figure if I should go for a over or undersized gear ?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Saturday, December 17, 2016 - 02:32 pm:

You will need to grab the gear best you can from the out side or pry it off. If you pry, go a little at a time and turn the motor over as you go so you don't pry in just one spot.
To know if you need an over sized gear you need to know what the tooth to tooth clearance is. The clearance is in the teeth not the outer diameter. The center to center (crank shaft to cam) stays relativity the same. The over sized gear would have thicker teeth to compensate for wear in the crank gear.


Top of pagePrevious messageNext messageBottom of page Link to this message  By gene french on Saturday, December 17, 2016 - 06:05 pm:

Rich:
didn't see this in the above info ... you need to " center" the timing cover during final assembly to assure proper ignition timing if you are using coils and not a distributor ignition ...Merry Christmas all ...Gene French


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rich Bingham on Saturday, December 17, 2016 - 06:13 pm:

I was just about to ask about that, Gene. Is it necessary to have that $35. jig, or are there other methods ?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Saturday, December 17, 2016 - 06:29 pm:

Got a lathe, metal or wood? You could make your own out of metal or good hard wood. Outside; the diameter of the inside of the ring where the timer fits for a slip fit, hole in center; the diameter of the extension on the cam shaft and a recess to fit over the nut that holds the cam on and boss for seal if need be.
The New day brush type timer is a little more forgiving if you are running coils and timer.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rich Bingham on Saturday, December 17, 2016 - 07:09 pm:

Fun to re-learn ! In my past life as a "Model T guy" over 50 years ago, the detail of centering the gear cover was something I missed (must have been in the shop manual, but I apparently didn't pay attention). Never could get the stock timer to work for me, but I ran a New Day without any trouble !

Mark, thanks for the help. ?? I have a lathe . . . didn't think of making one - duh !!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wayne Sheldon, Grass Valley, CA on Sunday, December 18, 2016 - 03:32 am:

Rich, Making the centering tool is a good idea. But, I have not yet done that. About forty years ago, I discovered the need to properly center the timing gear cover. My first T kept burning number four exhaust valve. This problem was not well known those days (probably why you didn't learn of it the first time around?).
I KNEW there had to be a reason for number four valve to burn. I had eliminated all the other things suggested (like manifold leaks, head gasket problems), so, I examined the timing. I discovered that the timer was off center a little bit. I tracked the roller path inside the timer, and realized that as the roller went between the far and close sides of the case, the roller rocked forward and back slightly advancing and retarding the timing. Number four was running considerably retarded compared to the other three. That caused the exhaust to run late and hot, and burned the valve. A New-Day timer does the same thing, but to a lesser degree because the brush does not lever forward and back with each revolution like the roller timers do.
Running on magneto also will mask this problem somewhat, by evening out the timing discrepancy through the AC magneto pulse. However, off center timers still will cause some issues. My first T did not have a flywheel magneto in it. It ran on battery and coils only at that time.

How I fixed it.
A simple proper centering of the cover. I did not have a centering tool, so I used something to else to measure it. I don't recall for sure what it was that time. I have used a few things over the years. My favorite? An antique inside caliper. It does not give me numbers, but is very accurate and stable to about a thousandth of an inch. If I need it? I can get a number by setting the caliper, then measuring it with a micrometer or a modern scaled caliper. Just centering the cam and cover needs to make certain the spacing is the same all the way around. The antique caliper does that very well. Besides. It used to belong to my grandfather, and I like using it.
Other things I have used at times because they were handy? The modern scaled caliper, but it is more difficult to use because it doesn't angle in as accurately. I have also used an antique machinist's scribing compass, and once, even a drawing compass and pencil in a pinch.

However I measured it that first time? I drove the car for several more years, and many many more miles, and never burned another valve.
Drive carefully, and enjoy, W2


Top of pagePrevious messageNext messageBottom of page Link to this message  By gene french on Sunday, December 18, 2016 - 12:49 pm:

Rich:
the valve issues that Wayne describes and other related performance problems can occur and be very difficult to analyze , sometimes due to simple assembly procedures on seemingly unrelated components...the "centering" of the timing cover is one of these "unrelated" components ...I use a centering tool that I built from billet aluminum ...3.02" outside diameter with a thru hole bored to .570 diameter ...this allows about .005 clearance on the counterbore in the front cover and camshaft diameters ...you will have to counterbore the face of the tool to clear the seal area on the front cover ...also, I used aluminum because I have a bunch ...steel or hardwood would also be suitable ...hope this helps ...Merry Christmas all...Gene French


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rich Bingham on Sunday, December 18, 2016 - 03:09 pm:

Wayne, Gene, thanks for the great information. Who would ever think a little thing (maybe not so little ?) as an off-center timer would result in a burned valve !! Gene, I have a chunk of rock maple that will probably serve for a jig. Thanks for the dimensions, makes it handy to begin !


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bill Harper - Keene, NH on Monday, December 19, 2016 - 12:10 am:

I made a centering tool for the cylinder front cover from a steel pulley. The pulley just happened to fit into the recess on the cover. A few minutes spent drilling the shaft hole in the pulley to fit the camshaft and I was in business.






Top of pagePrevious messageNext messageBottom of page Link to this message  By Terry Woods, Richmond, Texas on Monday, December 19, 2016 - 01:15 am:

Rich, there used to be TWO different timing centering tools on the market, one is the expensive repo of the KRW tool, and the other was a cheaper on turned out of aluminum that slid on the end of the crank and rested on the outside edge on the raised boss cast into the cover to center the cam. Texas T parts used to make them. Maybe Birdhaven has them now.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bill Harper - Keene, NH on Monday, December 19, 2016 - 02:10 am:

Hi Rich,

Terry is correct; there are two types of centering tools available, the KR Wilson copy:

/www.modeltford.com/item/3221KRW.aspx

and the less expensive small aluminum turning:

http://www.snydersantiqueauto.com/align-tool

There is an important difference between the function of the two tools which goes far beyond the obvious difference in price.

The KRW tool fits into the recess which the timer shell fits into and guarantees the the cylinder front cover is centered to that recess and the timer will then be centered on the camshaft.

The small aluminum turning fits into the recess which receives the felt seal or the modern lip seal. This hole was not as critical to the Ford engineers as the recess for the timer itself. There is no guarantee that this hole will provide centering for the timer on Every cover, some may be fine, while others less so.

I, and some others, choose to not take that chance and align our covers relative to the timer's recess.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank van Ekeren (Australia) on Monday, December 19, 2016 - 03:41 am:

Mine is timer recess, made from Teflon
I'm sure this was posted before, the importance of having that cover spot on.


Top of pagePrevious messageNext messageBottom of page Link to this message  By gene french on Friday, December 23, 2016 - 09:34 am:

Frank:
thanks for posting this drawing ...I have had this discussion with many model T ers in the past ...like many other performance items ,it is easy to overlook the simple things and blame other items for a problem ...years ago a famous performance expert said something to the effect of ...99% of carburetor problems are IGNITION ! I have wondered how many timers are discarded in favor of another timer or distributor due to the simple positioning of the front cover with relation to the camshaft and this with relation to the magneto pulse...just another area that needs attention and proper assembly procedure ...when an engine is built or a timing gear replaced the front cover should be centered ...Merry Christmas all...Gene French


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Friday, December 23, 2016 - 11:25 am:

Not all aluminum ones use the seal hole to center on. Some center to the correct place. So that makes 3 that are on the market or have been. (I am sure there may have been others too) Check before you buy.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rich Bingham on Friday, December 23, 2016 - 11:38 am:

Again my thanks to you fellers ! It's great to have the range of knowledge and experience available here. Sure saves having to re-invent the wheel and do things wrong over and over before finding a solution.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bill Harper - Keene, NH on Friday, December 23, 2016 - 11:52 am:

Yes Mark, I do remember the "large" aluminum centering tool and most of the vendors did carry it. I don't recall the manufacturer. To my knowledge it is no longer available. If it is, could you please post a link? I suspect some folks may seek it as a possibly less expensive alternative to the KRW tool.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Friday, December 23, 2016 - 04:28 pm:

I would have to look but I think mine came in a Vintique box. It was a gift so don't know the back history or age.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Friday, December 23, 2016 - 08:58 pm:

You also asked about the 7.5 advance gear. I have been running one for a while so far so good. I would suggest if you want to use one install new gear on both the crank and generator.
Except for a touring grind cam (about 280), Schebler carb, aluminum pistons, new valves and the 7.5 advance gear my engine is stock. I have installed a Bosch 600 type dist. but have only done one tour with it so the jury is out to really tell if it's better or not (seemed to be).
My T does ok, goes up many of the hills in high if I can get and keep the speed up but I can feel it's being taxed as it hits the point where it's too fast for low and too slow for high. I am working on a Warford to help in the mid range. I can not point at anything that tells me a seat of the pants difference with it installed but I am sure there is a difference. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By gene french on Wednesday, December 28, 2016 - 04:56 pm:

I posted these photos in the classifieds along with my advert. for the locator tool ...this shows how this tool positions the front cover during installation ...often with a new crankshaft seal inplace it can be difficult to position the front cover ...sometimes to the extent that 1 bolt must be started then a drift punch be used to pry the cover into place ...this tool is then used to adjust and verify the position of the front cover to assure that the timer is concentric to the camshaft where the timer mounts ...always an optimist...gene frenchfront cover toolfront cover tool2


Top of pagePrevious messageNext messageBottom of page Link to this message  By keith g barrier Savannah Tn. on Thursday, December 29, 2016 - 09:28 am:

Bill, Great idea and cheap! KGB


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