Cam questions

[carpenterbill]

This is my first post as a member so let me start by saying hello. Hello. I actually have two questions. First about cam timing and big cams. I am building a 45 stroker motor with some KNS cams. KNS suggests advancing the cams to trap more cylinder pressure. I am going to initally try a crude timing adjustment by jumping the cam one tooth so I dont have to split the case and use mopar pinion keys. When I jump the cam one tooth, do I jump it a tooth and then readjust all the other cams to it, or do I just jump the cam and leave the others. In my mind I need to advance all the cams or else only one valve of four would change timing. Maybe Im just having a dummy moment.

The other question I had concerns the idler gear. If I plan on running a magneto is there any reason to reinstall the idler gear?

Thanks guys

[Rubone]

Bill,
Be aware that every other cam rotates in the opposite direction. You can't just move a cam. And a tooth is quite a bit. I have built stroker 45s in the past and never changed the timing on the cams. But I never ran KNS cams. If you intend to try it I would only advance the intakes, not the exhausts. So like I said, the intakes rotate opposite to each other so you will need to figure out the new timing and mark things accordingly. I would put a degree wheel on it to see what you are actually getting.
As far as the idler gear goes, you need it to run a generator. If your machine is a racer or some variation with no lights leave it out.
Robbie

[carpenterbill]

Thanks, It is my intention to put this motor in a racer without light. I guess I can leave the idler out. As someone who had 45 strokers, you feel it is not necessary to advance the cam timing. The reason I asked is KNS website states "Cams can be slightly advanced for best cylinder pressure, which will give more overlap". I guess I can just run the cams per spec timing. Thanks for your help.

[carpenterbill]

I think I just answered my own question. There are 28 teeth on the cam, that number divided by 360 is ~13. So a jump of one tooth would be a 13 degrees, or way too much.

[knuckleheadtim]

That's actually 26 degrees of crankshaft rotation, so it's waaay too much.

[KDR]

The advance or retard would have to come off the pinion drive gear for this to work in such small increments. It would have to be specially machined in 1 to 3 degree increments advanced or retard and sold as such. I don't know of anyone who is making such a special gear for this type of application. I had thought about it at one time, but the cost to make it verses demand wasn't worth it. The other option would be to cut the lobes off and re-index them. I wonder what KNS is referring to?

[Rubone]

With a later Panhead stroker or the like with the pinion mounted on a taper with a key, an offset key would work to advance or retard the entire valve train. No such thing on a 45!
Robbie

[flat-happy]

actually you can do it with an offset key on a 45 but it is a lot more complicated. you have to use the offset key on the pinion shaft to flywheel location then retrue or at least check the flywheels for run out

[Rubone]

Good point Stillman! However, then you also change the timing on the oil pump.
Robbie

[KDR]

That's one way of doing it, but the problem with doing it that way is.....if you don't like the results....you're screwed. That's a lot of work to try to find out if the bike will run better with the cams advanced...straight up....or retarded. The pinion gear can be swapped in a short time.

[flat-happy]

there is always a lot of work between first place and second place and really none of that type of work is important unless that is what you are trying to achieve. you would never notice the difference in everyday riding anyway. racers were usually on a very strict budget and the offset key was the cheap way to go. it's all about throttle response and where the horsepower curve is when racing.

[rwm]

try paul at american cycle fab in berwick pa and get one of his 45 oil pumps he claims they move a lot of oil

[carpenterbill]

Thanks for all your input guys. It sounds like I should just run the cams and timing per spec. Just as background I am trying to build my first racer and get started into local vintage racing. Im starting with a T&O build bottom end with 4 1/2" stroke. Using KNS cams and plan on larger intake valves, etc. I was debating on making another thread about the usefullness of pop-up pistons or to just keep the T&O stroker pistons. Trying to absorb as much info as possible. Thanks.

[Rubone]

What kind of vintage racing are you talking about Bill. AHRMA won't allow the stroker, so it must be something else.
Robbie

[carpenterbill]

Not sanctioned racing. For example every year here in WV we have Mountainfest which hosts a vintage race.