loose cam gear

L

larry harding

Senior Member
a friend is helping rebuild an engine for another friend. they found that one of the dowel pins that locates the cam gear is loose and the hole in the cam slightly out of round. is there an easy fix for this without removing or replacing the cam? do any of the suppliers carry on oversized dowel? any suggestions appreciated. anything on youtube about this?
 
Since you asked for the "easiest" way to fix this problem - not necessarily the "best" way - I recommend you remove the timing gear (if you haven't already done so), first lining up the index mark and indent on the crankshaft and camshaft gears for more accurate reassembly. Then using carburetor spray cleaner, clean out the hole where the dowel pin came from, as well as a new dowel pin if you have one. Allow to dry and then use compressed air to further clean the dowel hole. Then take the green sleeve locker adhesive and put a few drops on the dowel pin where it goes into the camshaft. It will be a loose fit since the hole is wallowed out, but don't worry about that at the moment. The sleeve locker takes quite a while to set up, so you have some time to re-install the fiber timing gear over the camshaft's threaded snout and align the gear's two holes over the dowel pins. Because the dowel pins are staggered in their placement, you can't put the timing gear on 180 degrees off. It will only go back on one way. The camshaft's snout will center the timing gear and the pins will seat it properly. You may have to wiggle the timing gear a little to get the new dowel pin to enter its respective hole in the timing gear. But once it's in the hole, the sleeve locker will keep the pin centered. Then tighten the camshaft gear lock nut. Allow the sleeve locker to cure in the open air for at least 24 hours.
This should work unless the hole is so wallowed out that the new dowel pin doesn't touch any of the hole's metal for the sleeve locker to bond against. If this doesn't work for some reason, you are only out a couple dollars for the sleeve locker and some time. The green sleeve locker is tough stuff and once cured requires heat to break the bond. Racing guys use it to repair broken valve rocker stands. I have used it to seat a loose hardened valve seat and it held for years afterwards. Of course, the best way to fix your problem is to remove the camshaft and drill out the hole for a stepped oversized dowel pin, which will probably have to be specially made on a lathe.
Marshall
 
Pondering further your predicament since this morning, let me muse a bit with some "blue skying". There are two dowel pins on the camshaft that keep the timing gear from rotating around the camshaft's threaded snout. The gear is further secured to the front of the camshaft by the large nut. If one of the dowel pins is simply missing, why wouldn't the other dowel pin and the large cam nut keep the timing gear from spinning on the camshaft? I mean, how could it possibly move in either rotational direction as the cam spins, assuming the center hole in the timing gear isn't also wallowed-out and is a tight fit over the camshaft's front snout, as they usually are? If the remaining dowel pin is tight in its respective cam gear hole, that alone should keep the timing gear from moving. The large cam nut is icing on the cake to keep the gear in place.
I am certainly not advocating leaving the second dowel pin out, but envision what I am saying. THEORETICALLY speaking, instead of trying to make an ad hoc repair to the wallowed-out dowel pin hole, why wouldn't simply removing that pin from the damaged hole work so that the pin's looseness doesn't continue to compromise the fiber timing gear? The remaining dowel pin and the large nut guarantee no timing gear movement. Isn't that the whole idea? Or am I missing something here? I don't think I have ever heard of a loose camshaft dowel pin causing such damage to its anchoring hole. Any solutions offered will be exploring untrodden territory on this website, me thinks. :)
Marshall
 
i haven't actually been by to see the damage yet. he called me to see if i could make a staggered pin to replace the lose one. my question is how is one pin loose and the over one still good? he also thought the pin needed to be made of drill rod, but i thought those dowel pins were just mild steel(cold roll?) i am thinking... a good pin with some locktight or j b and a tight nut should last a long time.
 
Chances are a single pin will be more than adequate
You will need to make sure to install gear in proper position(timing)
Use a hex cam gear nut and tighten properly

J
 
I would use red thread locker before re drilling if you have never used it you would be amazed how well it works.
 
You must log in or register to reply here.
Back
Top