The Stovebolt Site Forums The Shop Area Engine Shop Well poop! Timing gear bit the big one.

Got half way to the farm, lost power, and ba-boom out the exhaust. Pulled over, cranked to restart, starter turned the engine freely, then another ka-boom.
I pulled #1 spark plug and bumped the starter until the rotor was lined up with #1 spark plug wire. I then stuck a big ziptie into the #1 hole to confirm that the piston was at the top. It was not even close to the top!
Could there be anything else wrong other than a chewed up timing gear? The distributor shaft does turn when I stomp the starter pedal. It has a fiber gear with 20,000 miles on the total rebuild of the 235 high pressure '53 engine. Will the crank gear still move a partially chewed up cam gear, resulting in turning the distributor shaft?
I am looking for a simple fix which I haven't thought of before I go to all of the trouble of taking the timing cover off (as well as the oil pan, yad, yada, yada.)
Carl

Grab the distributor rotor and try to turn it. It's possible (but unlikely) that the drive pin on the distributor gear could have sheared off. A better way to check on the cam timing is to pull the valve cover and look at the valve action. Get either the #1 or #6 valves "rocking"( exhaust closing and intake beginning to open) and check for piston position. If the piston is not at or very near the top, the timing gear is most likely the culprit.
Jerry

darn Carl! You have bad luck! Is this the same truck that you were trying to get the brakes working correctly?

Chris

Could the distributor clamp have been loose enough to allow the distributor to turn and be severely out of time. It wouldn't have to be much for the piston to be down in the cylinder.

If it is the cam gear replace with aluminum. IIRC the car engines use the fiber gear, trucks got aluminum. The fiber gear ran a little quieter.

Roy Rogers nailed it. When I pulled the distributor a while back to take it apart to see why the rotor would not snap all the way back from the mechanical advance counter weight spring tension, and put it back in, I did not get it pushed down far enough.

The goofy-style distributor clamp will go where ever it wants on the distributor lower tube. So if you take that off and don't put it back where it belongs, you will engage with a little bit of the oil pump and a little bit of the cam gear.
Add to that, the sloppy nature of the goofy distributor clamp, the works can push itself up and out of engagement with the gear and jump time, leaving you bad.
Today I monkeyed with it until the distributor dropped all of the way down before I tightened the hard-to-get-to machine screw which is what clamps the clamp to the distributor, and now I am back on the road baby!

While I had the old distributor out, I compared the tension of the counter weight spring compared to a new distributor I happened to have on hand and went ahead and put the new distributor in.
The springs in the old distributor where not strong enough to overcome the slight resistance caused by the spring on the ignition points. Now that to me, is weak.

Also, I replaced the hard-to-get-to slot head machine screw with an Allen head screw. Makes life much easier and allows for ease of applying more torque on it to keep it in place.
Thanks for all of the advice, and thanks for playing along.

Carl

"I love it when a plan comes together!" Good show! It's also possible the advance system was gummed up so badly the springs couldn't do their job.
Jerry

Actually, I test, not guess (hahahahahahaha, I heard that somewhere. ), and I opened it up and it was clean in there, but the springs seemed really weak too me and they were much weaker compared to the ones in the new distributor.
Thanks Jerry. The "Test not guess" deal which you remind us about from time to time has changed my way of approaching engine problems. It is too easy to be distracted by trying to jump around looking for the "magic fix". This is especially fruitless when you have more than one problem going on at the same time.
Carl

Back in the dark ages when we used a distributor tester to check the centrifugal and vacuum advance operation, each distributor had its own advance curve- - - -a certain number of degrees of advance for a particular RPM. Even things as simple as different rear end gearing, tire size, or transmission type could require a different advance curve. That's why there are different model numbers stamped on the breaker plate.
Jerry

Nice piece of work to Roy Rodgers. Kudos. Posts like this that can save members a ton of time money and grief.

I was going to suggest the 1/4-20 Allen bolt (about 1-1/4” long?) but you already thought of it.
I’ve changed a few lately, makes adjusting timing a lot easier. If only I’d thought of it 20 years ago.

Good news for you Carl! Isn't it great when things seem dire but turn out to be minor?

Thanks for sharing your situation, the problem solving part of this forum is what keeps me coming back.

"Even things as simple as different rear end gearing, tire size, or transmission type could require a different advance curve. That's why there are different model numbers stamped on the breaker plate."

This quote is interesting to me and has me wondering how does one determine a) that the timing curve needs to be adjusted and b) how do you determine how to advance or retard to make things optimal when it comes to distributor springs? My guess is a dyno test? Is there a way for a novice to make these sort of tweaks without a dyno?
mark

Thanks, I've always heard "sometimes even a blind hog finds an acorn". Glad you figured out what happened.

I do have a question, if the timing gears had stripped, does the 235 camshaft have a place notched out to allow the crankshaft to clear, or is that the 216, or am I dreaming? (Could be the latter, I've been known to do that.)

Seems to me I vaguely remember one or the other (or maybe both) had clearance issues with a crank weight and had a slight notch in the cam to allow the crank to clear it.

Tell me to go back to bed and wake up if I'm so far off the mark I can;t see the goal.

the 235 had notches. At least the one I bought did.