Camshaft question

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1970 La

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Ok this may be a dumb question but what keeps the slant camshaft from walking back and fourth?

This is the first slant build for me, I got it in a basket not sure if I'm missing something here. Don't see no holes in the block for a retainer plate and nothing inside the timing cover. Thanks
 
Ok this may be a dumb question but what keeps the slant camshaft from walking back and fourth?

This is the first slant build for me, I got it in a basket not sure if I'm missing something here. Don't see no holes in the block for a retainer plate and nothing inside the timing cover. Thanks


Short answer: nothing.

Long answer: The cam lobes are ground on a taper (narrow toward front) which pulls the cam gear against the face of the block. But the angle of the oil pump drive gear pushes it forward. In theory it will cancel out and not move.

BUt in practice, it does, and some people have added a bolt on the front of the timing cover to act as a thrust bearing and absorb forward thrust.
 
Well I sure couldnt see what I was missing, thought surely there would be something in the timing cover. Thanks
 
I would have to argue that the oil pump pushed against the cam. The oil pump may have resistance, but it cannot push or exert force, since it is the driven gear and not the drive gear. The cam lobe taper however, is what keeps the cam from walking in the block, when a thrust plate is not utilized. This is why roller cams must have a thrust plate or thrust button, because their lobes are not ground with taper.
 
Actually the resistance of the oil pump, tends to pull the cam to the rear of the engine, as does the taper on the lobes. I personally do not see the need for a cam stop on a slant six, unless using roller lifters. I used a cam stop on one of my engines (just to try). Set it with .007 clearance to the cam. After a season of racing, removed the timing cover, and saw no sign of the cam bolt contacting the stop.
 
Actually the resistance of the oil pump, tends to pull the cam to the rear of the engine, as does the taper on the lobes. I personally do not see the need for a cam stop on a slant six, unless using roller lifters. I used a cam stop on one of my engines (just to try). Set it with .007 clearance to the cam. After a season of racing, removed the timing cover, and saw no sign of the cam bolt contacting the stop.

For some reason I thought the pump gear pulled one way and the lobes the other, wasn't that the whole reason for the stop in the first place?

I agree it doesn't seem to make sense. Do you know of another flat tappet motor that needs cam forward thrust control?
 
I agree it doesn't seem to make sense. Do you know of another flat tappet motor that needs cam forward thrust control?

A lot of slant racers use the cam stop. Again "personally" I don't see the need for one. But if you are concerned, it is cheap and easy to do, and will not hurt anything, as long a it is set properly.

I don't know of any engine using a flat tappet cam (in the block), that has a forward thrust stop, from the factory. But I shouldn't say this out loud. I don't know everything. :eek:ops:
 
Thanks for the reply's guys, I'm just going to leave it stock. I was affraid I was over looking the obvious.
 
I don't know of any engine using a flat tappet cam (in the block), that has a forward thrust stop, from the factory. But I shouldn't say this out loud. I don't know everything. :eek:ops:

I made a big mistake, with that statement. I'm supprised nobody called me out on it. Small block MOPAR uses a cam thrust plate, on the front of the block.
 
I was thinking "small block", having changed a cam recently. Indeed, there is an after-market thrust bearing plate for those who worry about wear. I don't recall how or if the camshaft is secured in my 383, having rebuilt it decades ago.

Any photos of this slant "cam stop" people have fabbed? I am picturing a bolt thru a drilled hole in the timing cover, but hate to molest factory parts.
 
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