Cam Gear

S

SkylarknMerc

Junior Member
My Mercury 255 has starting issues.
FUEL ✔️
Compression ✔️
IGNITION 👎
The conclusion ce to be timing jumped. So the suspect is the
FIBER cam gear.
My question is can I get away with just change the Cam gear
only with a new FIBER gear or would I have to change out the
Crank gear too?
 
Do yourself a favor and get an aluminum timing gear. The word is that the currently available fiber gears are foreign made and will go 5000 miles if you're lucky. The rap on aluminum gears is that they're noisy. I'm running them in two engines, including my '51 coupe, and I can't hear anything different. (They used to sell "noisy" cam gear drives for SBC's just for the "race noise" they made.)

If you have to have a fiber gear, I have a nice looking used one I took out of a good running '51 Merc engine when I put it in the '51 in 2016. I just put in the aluminum gear and used the old crank gear; no problems since.
 
Go to one of the vendors here that sell NOS parts and see if you can get an aluminum gear with the Ford script and or part number. I built a 276 a couple years back and used my old crank gear with what was for sure a new aluminum cam gear. After about 3500 miles it is still way too noisy for my liking. At startup it was quite disconcerting, but has very gradually improved to where it is now. (Loud). My take on this is that the cam gear came in a box of mixed ford parts from my early ford years, and since it had no name or number whatsoever, I will venture that it came from Western Auto or JC Whitney or some such and was of inferior manufacture. I have strongly considered looking for a NOS fiber gear and swapping it in. BTW, I am using 59ab reverse cut gears, not the normal 8ba gears on advice of some members here.
 
If you can, try to get one of the French flathead aluminum cam gears. They are made much nicer than the original Ford ones. When you see them side by side, the quality of the French one is obvious.

Either will work, but the French one is nicer.
 
Do NOT use a reproduction fiber gear! I use NOS or NORS but NEVER the repops. Had a rebuilt Merc. engine destroyed a few years ago by a repop gear disintegrating.
 
You will need to get the fragments out of your oiling system prior to running that engine again.
 
I put in new crank and cam gears when I rebuit my 255 merc for the 41. I went with aluminium as the guys here sugested. They came as a set and I expected them to be noisy but they seem to be fine . I dont notice any difference. I think maybe there are some lesser quality sets being sold or runnig a used crank gear with a new cam gear could cause them to be noisy. Either way ,as I said, mine are quiet. Tim
 
tubman said:
Do yourself a favor and get an aluminum timing gear. The word is that the currently available fiber gears are foreign made and will go 5000 miles if you're lucky. The rap on aluminum gears is that they're noisy. I'm running them in two engines, including my '51 coupe, and I can't hear anything different. (They used to sell "noisy" cam gear drives for SBC's just for the "race noise" they made.)

If you have to have a fiber gear, I have a nice looking used one I took out of a good running '51 Merc engine when I put it in the '51 in 2016. I just put in the aluminum gear and used the old crank gear; no problems since.
Click to expand...

Thank You! Just
what I need to know. Looking for a simple, tried and true solution. I wasn't looking forward to taking the front end of the crank apart.

My man thank you.
 
the fiber gear wears the crankshaft gear differently than the aluminum gear does.
Pretty near impossible to jump just one tooth with either gear and and still stay in time enough to have reasonable compression— the usual result is several teeth and camshaft not turning at all.—- perhaps check distributor gear
 
I know that timing chains are known to 'jump' as the chain wears, but one tooth of a timing gear set jumping over the next would certainly cause catastrophic damage to the softer timing gear, such that the engine would would have more problems than just hard starting. Just a thought as I have not experienced this situation.
 
I had the fiber gear jump one tooth on my stovebolt and still made it five miles home , but it was clear something was very wrong and it never started again until it was corrected with a new gear. Tim
 
Kurt in NJ said:
the fiber gear wears the crankshaft gear differently than the aluminum gear does.
Pretty near impossible to jump just one tooth with either gear and and still stay in time enough to have reasonable compression— the usual result is several teeth and camshaft not turning at all.—- perhaps check distributor gear
Click to expand...

Distributor gear looked 👌.
But funny enough you bring up compression. The needle did on the compression gage would seem to moved out of sync. Then there was a " Bloop" sound the would sound like it went down the exhaust pipe. That's when my friend called it. Said the Crack was in compression stroke while the exhaust valve was open . Hence why the needle was out of sync, small jump at initial crank then when the valves closed I would get a big jump on the gage, then the bloop going down the exhaust.
 
You must log in or register to reply here.
Back
Top