The Stovebolt Site Forums The Shop Area Engine Shop removing gear from camshaft

Is it possible to remove the aluminum gear from a camshaft (at home) without damaging either the gear, cam or retaining plate that secures the cam to the block? Or is it just best to get a machine shop to do it?

-ftyler

Set the cam in a vise, cam down supported by the gear resting on the vise jaws. Heat the gear with a propane torch and the cam should drop out, so you will need something under the cam to keep it from hitting the floor. To put it back together reverse the process, but you can heat the gear in the oven.

My machine shop also advised not to exceed 300 degrees F or you risk altering the heat treat of the aluminum. I won't go into details, but I suggest having a pro do it - stuff happens. :rolleyes:

Guys,

Just came back from the machine shop. They said that because the gear is aluminum it would more likely than not be damaged or completely break in the removal process. They said that the retainer plate sometimes has a tendency to bend or break also. This shop, while highly regarded by locals as being good, obviously does not specialize in Chevy inline 6s.

Fred I'll try your approach. They wanted to sell me a new Cloyes set for $55. Did not recommend just buying the timing gear without the crank gear as it can sometimes generate noise (so they say).

Thanks for the advice!
-ftyler

They are right on the noise thing, helical cut gears will be noisy if they aren't broken in together. On the breakage, they might be just covering their butts and wanting to make a sale. I would try to get it off and if it comes off easily re-use it and if it takes excessive heat or force then get a new set. If you have a fry-daddy or a deep pot and a hot plate you can fill it with mineral oil, heat the oil to 350 degrees or so, and then dip the whole gear and cam shaft end in there to heat it. That will keep the aluminum from getting overheated. Just make sure to wear heavy gloves and long sleeves so you don't get burned by the oil. It's also a good way to heat it for installation because ovens tend to have hot spots.

I have a big problem with the replace both gears because of noise practice. The crank gear is steel, cam gear is aluminum. Since the aluminum is considerably softer, wear on the crank gear will be negligable. The cam gear will wear to match the crank gear, whether it's new or old. I recommend putting on a new cam gear, every time it goes on or off it loses some metal and has that much more reason to come loose. And as for heating the aluminum, don't get it red and let it cool at room temperature. Keeping it below 500 is a good practice, but if you are heating the gear and not the cam it should drop off long before you reach that temp.

A lot of the older shops kept a hot plate for the aluminum gears. Didn't take up much room, worked pretty fast, very little maintenance, and they were cheap.

Replace both gears logic can go beyond noise. I had two sets side by side - a Sealed Power and a Cloyes, both for the 250. The teeth were on different angles and one would not mesh correctly with the other. It was only a few degrees, and on the table it was easy to see, but they were close enough that you COULD assemble it.

Then do it all over again in 30 minutes of running.

Chuck, the Chevy parts manual lists one aluminum cam gear from 63-70 250-292 as a replacement. The book mentions 63-66 292's to replace the gears as a set, as the replacement gear will not work with the original crank gear .So, depending on the year, you may be wise to replace the set or at least look real close.

Ftyler,

It can be done easily at home if You have a press. I did this several times, no problem. Just put cam assembly in the press, make sure the cam plate is adequated seated in the press stands and do it. To assemble it back You can even heat the gear or press it back. No big stuff. And our fellow Tony is completely right, the aluminum gears out of 250/292 of the pointed years do fit the stovebolt.
As for the noise, just one comment: the later gear out of the 250/292 has the same pitch and teeth measuraments as the early 235/261. Just like the fiber gear thatr goes on the 153 Nova engine. Here in brazil we use to have a "special" timing gears that were used in the 250S engines, a high performance local version, and these gears have a diff pitch. Looking at the stock gear, it has a small surface that looks if it is still a part of the external circunference, and the performance ones seems to have all teeth with a sharp point. So if You mix the wrong ones, a weird noise will happen, not to mention that a big lash will be there. I see no need to swap both gears as long as You are sure about the type You have.

Unfortunately I don't have a press. The only thing I've tried so far is the propane torch and haven't had much success. I'm gonna give a try again between Christmas and New Years' and see what happens.

Otherwise I'll see if I can match the number cast on the timing gear and buy a replacement.

-ftyler

Propane may not be hot enough. Do you have an oxy/acetylene set and a small "rosebud" tip? MAPP gas might work also.
Aluminum dissipates heat FAST, so you will need to heat it fast; before the heat runs to the cam.
Seems like the cam would drop right out of the gear.
Good Luck

gmc248,

So far this hasn't worked. The propane "bottle" apparently is not the answer. I have an uncle who recently acquired a press. I'm afraid of breaking either the gear or the retaining plate behind the gear. The crankshaft is a 67-72 cut, as it has the 3 dowel pin holes and half inch bolt holes. According to what Tony said buying only the aluminum gear should work.

But how difficult is it to remove the crank gear? :confused: This is my last stumbling block before final assembly. Worse case I've thought about trying to drill out the cam to remove the gear. But it obviously has as many risks as using the press. I really don't care about the integrity of the stock cam as much as the cam gear.

-ftyler

ftyler,

You'll need a puller to remove the crank gear. No big deal. Even if You do not have it, rent one. Don't worry about breaking neither the gear nor the retaining plate. Disassembling it on a press is no big deal at all. Just make sure the parts are properly seated in the press stands an go full ahead.

That cam gear is on tight which is good for operation, but bad for removal & re-install. Now I really recommend a new cam gear, you're going to lose metal off the gear when you pull it. From what you say you are putting in a new cam. If so, the gear is about $25 and a good parts store can steer you to a shop that will put it on for a small sum.

If you must pull the gear, you can use a puller for the harmonic balancer. Most are set up to pull with a two or three bolt pattern. If so, you should be able to use it to pull the gear. Use the biggest bolt that will fit thru the puller with washers and nuts for the screw access holes in the pulley. After this is all set up and ready to pull, heat the gear and it should pull right off.

But this brings up another question: How are you then going to re-install the gear?

reinstall...??? Good question. Here's my plan:

bake the gear in the oven at 300-350 for 15 mins. Leave the cam outdoors for a while (because the temps here in Georgia will be in the 30s all day today and tomorrow - believe it or not). Then put the woodruff key in place, remove the gear from the oven and it should drop in place.

I don't think getting it on will be nearly as difficult as getting it off. If I weren't so skeptical about gearing angles, noise and such I'd just buy a new cam gear and be done with it.

Then again the experience gained in using the puller could be helpful for future sake.

That sounds like my plan. I thought the gear would just drop into place. All went well but for the last 1/4". No press, trying to hurry before the gear cooled, and though I know better, I grabbed the swinging press. Just about there, one last tap (OK more than a tap) and an ear on retaining plate broke off. It is cast iron and didn't like the hammering.
Without a press, don't try it. Just spend the money and have a machine shop do it. If you need to replace the cam gear, do them both - it's not that tough to do the crank gear.
Don't be like me. Do it once and do it right.

I'm just trying to avoid pulling the crank (removing rods, pistons, etc.), which seems to be the only effective way to pull and replace the crank gear. This crank gear has no holes. I'm guessing that there is a crank gear puller designed to accomodate this. :confused:

ft,
My crank gear was the same. If the oil pan is still on, carefully mask it with duct tape and anywhere else you don't want metal filings. Drill and tap (I used 5/16 drill and 3/8-24 tap) two holes 180 degrees apart and use your steering wheel puller. Careful as the drill nears the end - you don't need holes in the block or main cap. A masking tape marker on the drill bit at the thickness of the gear is a help. The gear drilled easily, and the job took 20 minutes. There is no room to get a jaw puller behind that gear with the crank installed (I tried modifying one, but with the tips at 1/8" thick they popped before the gear budged.) While I was there, I tapped the crank as well and it makes installing balancers a lot easier.

Follow up

Good news! This issue is finally over. Took the cam to my uncle's house today. 10 minutes of propane heat, a press and 12 ton bottle jack later and the gear came off almost too easy. Pressed on the higher performance cam just as easy. Thanks for the help guys!

Gret to hear another small success has been accomplished

Just a note about the instruction that were included with my new fibre timing gear. It says that the aluminum timing gear is an interference fit and describes how to heat it and drop it on. It then goes onto say that if the aluminum gear is pressed on, the interference fit will be distroyed.