Mercriuser 140 timing gears

[Grub54891]

Mercruiser 140, 1985 Serial number:6920193 I'm in the process of " refreshing" the gaskets/seals in my 140. Upon removing the timing cover,found a couple chipped teeth on the fiber cam gear. No big deal...or so I thought. Ordered the new gear,found it to be about .30 thousands larger in diameter. Thought it was just wear,but there is no way the cam will go in,and mesh with the crank gear. My main concern is there a different spec for the marine motor. I thought the gm motor was the same as far as the cam gears go.I dod get the new fiber gear from the local napa. Everything else matches- tooth count ect. Anyone run into this issue,or do I have to get the crank gear to match up? Crank gear is steel and in good shape otherwise. Anything I look up for parts or specs comes up the same,even at napa.

 

[alldodge]

Mercruiser 140, 1985 Serial number:6920193 I'm in the process of " refreshing" the gaskets/seals in my 140. Upon removing the timing cover,found a couple chipped teeth on the fiber cam gear. No big deal...or so I thought. Ordered the new gear,found it to be about .30 thousands larger in diameter. Thought it was just wear,but there is no way the cam will go in,and mesh with the crank gear. My main concern is there a different spec for the marine motor. I thought the gm motor was the same as far as the cam gears go.I dod get the new fiber gear from the local napa. Everything else matches- tooth count ect. Anyone run into this issue,or do I have to get the crank gear to match up? Crank gear is steel and in good shape otherwise. Anything I look up for parts or specs comes up the same,even at napa.

There is no difference in the marine and truck motor. Gee wiz .30 is a large difference, my first thought is someone put the wrong gear in the box. Similar thing happened with a CAT trackloader. Bought a new exhaust manifold and the sent me the wrong part even though the box had the right number on it. CAT ordered another and the same wrong part came in again. CAT then did a complete physical inventory and found only the two they sent to me were marked wrong out of 96 across the world. Man what our the odds,

 

[thumpar]

The 140 was only used in marine and industrial applications so it couldn't be mixed up with an auto part. If you have the old one you might take it to Napa and see what they can figure out. The ones around here are pretty patient and work to figure it out when it comes to stuff like that.

 

[Grub54891]

Thanks guys, I,ll have to get it to napa and check it over better this week. And its going to be a busy week at the marina. haulout season here we come!

 

[Scott Danforth]

.030 in diameter is only .015 per side. Sounds like wear to me. The tining gear should be the same as the 153, 196, ,230, and 250

 

[Grub54891]

I agree about the wear factor,but it won't let me slide the cam in,seems to want to shave the teeth off the fiber gear. I'm having my work buddy cheack it on monday. I've installed stuff like this before,just never a fiber gear. I may be to cautious about it.

.030 in diameter is only .015 per side. Sounds like wear to me. The tining gear should be the same as the 153, 196, ,230, and 250

 

[Scott Danforth]

I would upgrade to a set of aluminum gears myself.

 

[Grub54891]

I would upgrade to a set of aluminum gears myself.

That thought has crossed my mind also.

 

[achris]

I've been trying to find an answer.... The 250 (Mercruiser '165') had an aluminium cam gear as standard. The part numbers for the gears on the 165 and the 140 are different, so I've had to match them up a different way.

Here's what I have found. On the Summit site, the cam gear is the same for the 250 ('165') as the 153 (Mercruiser 120).... Mercruiser part numbers for the 140 and the 120 cam gears are the same... Ergo, the aluminium '165' cam gear will fit your 140.... And that's the way I'd go.

Best of luck,

Chris.....

 

[Scott Danforth]

Chris, the "165" gear actaully was the 292 gear that was then backwards pushed to the other inliners. available at any automotive store.

 

[Grub54891]

Ok,so the fiber gear is different? I hopefully can return it but I've pressed it on the cam already. If aluminum gear will work I'll order that instead.

 

[Scott Danforth]

grub, the fiber gear in the 3.0 was the GM standard since 1953 when the 153/196 motors cam along. However it is a carry over from the original stovebolt 6 216 developed in 1929. the fiber was used originally to keep the gear set quiet with the straight cut gears. While it is perfectly OK, and GM used it in millions of motors, like with everything else, the motors evolved. the aluminum gear came along in 1962 with the development of the 292 I-6. It was then back-pushed to the 196/230/250 for performance use.

the fiber gear will work fine if you have it. However like I said, my personal preference is the aluminum gear. I can run higher RPM's and run a hotter cam. However the iron gear is also a good choice. However since you have already installed the gear. at this point I would run it.

remember when driving on the new gear, hold the camshaft so you dont push the rear cam oil plug out. I normally have the motor apart and simply pull the cam to press them on (or drive on with a block of wood and small mallet). However I have also put the gear in the oven and the camshaft in the freezer. Did you drive the gear on with the cam in the block? or with the cam out of the block?

FYI - from my inliner archives

the Cloyes part number for the quiet helical cut gears is #8-1016, the straight cut noisy gear is #8-1018 (these may be either aluminum or iron cam gears with a steel crank gear)
the Melling part number for the aluminum cam gear is #2524 and the crank gear is #2501 (these are aluminum cam gears with steel crank gears)

 

[Grub54891]

I removed the cam,pressed the old gear off and put the fiber one on in the press. The cam wont go back in as the gear is not meshing or allowing enough clearance at the teeth. I'm going to order a matched set this week and be done with it. Thanks for all the info guys!