The Stovebolt Site Forums The Shop Area Engine Shop new aluminum cam/gear

i went with the drill and tap method on my new cam and gear, but even after 'freezing' the cam, and heating the gear to 200degsf, it still doesn't even begin to go on by trying to 'pull' it on with the bolt. so, if i have to press it on, what's the advantage of drill and tap? id 1.275, od 1.281

heat to 400F

400?! aluminum exponentially expands in relation to temp?
the instructions say heat to 200

I used a press when i installed mine.
I think the thrust plate clearance is 4 thousandths.?

yeah, clearance is listed as .001-.005

but i'm still wondering about the sense of the drill & tap if the gear still needs to be pressed on, and consequently off, if needed. for the bolt to make sense, the gear would need to be able to go on and off with lite taps. otherwise, changing the gear would still require removing the push rods and lifters

400 would make me nervous unless I know the alloy and heat treat.

right, what alloy. but most al alloys, when welding, are routinely pre-heated from 350-500f

my experience has been 200 will not always make them drop on, or go on with little reistance. did you drill and tap the cam just for the gear installation? i have heard heating in oil is better than just an oven but i don't know how the gear would know the difference. i had to end up applying a little more heat to the center of the gear, this was on the 3rd try. i have never reused a cam that had been driven on but i have removed a couple that others have done and it took a fair amount of heat to make it pop loose with a puller on it. might double check no interfearence from key. i personally, would hate to break a bolt off in the cam trying to press gear on. good luck

not break a bolt off in the cam? - i'll say!
and that's my fear at this point
the key is fine, and i can press it on, but that defeats the supposed purpose of the bolt. i remember my renault from yrs ago that lost some teeth from it's fiber gear. remove the cover, undo the bolt, pull the gear with your fingers, push the new one on, bolt....bingo

All heat treating of aluminum is over 500F, so heating to 400 will be fine. If your fearfull of 400, then heat to 350.

fearful of 400; then heat to 350?
whyyyy i outta.....<;-#

but that still doesn't address the drill & tap non-sense of the bolt. increase the id of the gear?

just curious, where did you find out about drilling and tapping the cam to install the gear? i have heard of drilling and tapping the gear and cam together where they contact- to stake the gear in place. is that instilation you are trying a high tech way of doing it. i am not pretending to be a pro but aluminum conducts heat really fast. when it contacts that "cold" cam it shrinks pretty quick. i bet before you could get a turn on your bolt. good luck, i hope next time you try it goes smooth.

no, not to stake the gear, and not hi-tech. the drill and tap is commonly mentioned, along with the same for the crank and damper, from a variety of sources. heck, that '60s renault came from the factory with it

interesting, all kind of stuff i don't know. i hadn't heard it mentioned about the cam gear before but had seen many times about drilling and tapping if the crank already isn't for damper.

There is no shoulder the cam gear pushes up against, just the contrary, it is held back for clearance. I can't see installing a bolt on a gear that is already a medium press fit, when you couldn't tighten the bolt up anyway and risk loosing that critical clearance.

I have been around since the dawn of time and have never seen this procedure for drilling the cam to hold the gear on.

Stuart

they can't leave the bolt in could they? wouldn't it rub against the timing gear cover? think of the washer required as well. i thought he was just using it to install the gear and it would be removed. maybe i misunderstood.

right, the .001-.005 clearance. and that could be more easily set with a bolt vs a press, then locktite. my memeory of the renault doesn't recall any clearance

no, you understood correctly, but i left out the mention of a little peening to the cover in order to make clearance for the washer and bolt head

Set the clearance??? The clearance is a result of the difference in thickness between the spacer ring (supporting the gear against the front journal face) and the retainer flange. To reduce clearance grinding or facing the spacer ring is the only possibility I know of.

My post was not correct. There is a shoulder the cam gear is pressed to. Curt has outlined the correct procedure. Sorry for misleading anyone.

Stuart

'setting' the clearance = the difference between their respective thicknesses. my awkward choice of words caused the, 'huh'?
and my intention was to say that using a bolt to pull the gear flush with the ring, vs using a press to do it, would be more precise(easier) than a press, bec there is a 'hand feel' when the gear and ring come into contact with a wrench, and that doesn't exist with a press. so, theoretically, the gear could be over-pressed. possible stress crack, distortion? could happen. overly concerned? could be
my question is really about the sense of the drill and tap idea for easy gear removal in the event of damage to the teeth. bec, if the gear doesn't come off by removing the bolt and finger- pulling it off, then there isn't much sense to do it. which ties in tapping the front bearing cap and drilling out the cover for ease of removal, so that one doesn't have to drain the oil and remove the pan
under what most likely conditions would one want to remove the cover? change a damaged cam? if so, then the cap tap is of no real value bec one would most likely want to remove the pan to inspect the bottom end. change the cam for performance? then pressing or bolting is moot. change the gear due to damage? with a bolt on, the p-rods, lifters and cam don't have to be removed. that sounds like a sound, 45-60min job to me. otherwise, a pressed on damaged gear, as you know, would involve at least 3x that. similarly with a crank drill and tap for ease, in the event of a damper replacement