Cam / Crankshaft degree wheel - which to buy?
- Thread starter Agnelli
- Start date
Dr.Jeff
True Classic
I find that most of the ones made for automotive engines are way too big for our little engines. I use one made for motorcycles and like the smaller size better. But any wheel should be able to get the job done. You will likely have to make a little fixture to use any of them.
MikeHynes
True Classic
I use an 11" diameter Moroso wheel that I bought at a local speed shop.
I think you could use one that's about 12" in diameter before the wheel hit the snail mount, but 11" works for me. For anything bigger than 12" you'll have to remove the snail mount and you might have to shorten the tensioner bearing mount stud.
I don't think using a wheel bigger than 12" in diameter is worth it unless you want to mount it to the flywheel?
While you're at it I have an experiment for you...
Mount up the degree wheel and check for TDC using a piston stop.
Then check for TDC again using a dial indicator on top of the piston to determine TDC by noting max travel.
Tell us which method gives you more accurate and repeatable results.
I think you could use one that's about 12" in diameter before the wheel hit the snail mount, but 11" works for me. For anything bigger than 12" you'll have to remove the snail mount and you might have to shorten the tensioner bearing mount stud.
I don't think using a wheel bigger than 12" in diameter is worth it unless you want to mount it to the flywheel?
While you're at it I have an experiment for you...
Mount up the degree wheel and check for TDC using a piston stop.
Then check for TDC again using a dial indicator on top of the piston to determine TDC by noting max travel.
Tell us which method gives you more accurate and repeatable results.
Agnelli
True Classic
Thank you, extremely helpful. I will abide and go with </=11"
**Next Question, particularly for Mr. Hynes: I am game for my experiment assignment. Can you please recommend a good dial indicator? I've seen recommendations for 1/2", but want to know what you suggest in order to perform the test. And while I am at it, prevailing on you to describe the protocol to determine TDC by noting max travel.
MikeHynes
True Classic
Agnelli I think you'll see how a degree wheel larger than 12" won't work well.
As for recommending a dial indicator - I use a Harbor Freight indicator. It works for me, maybe not the "best", but for the price, it's good enough.
Here's a pic of a set-up that I might use if I was going to use a dial indicator to determine TDC. There are MANY different ways to stick a dial indicator above the piston.
While the Harbor Freight indicator isn't expensive, the piston stop I use is even cheaper, and, it's easy to make.(There's a nut on the bolt under the bar)
Before you can do any timing, for example cam timing, you have to install the degree wheel, then determine where TDC is.
To determine TDC using a dial indicator you simply place the indicator above the middle of the #1 or #4 piston (middle is important) then turn the crank over until the indicator shows the piston is at the top of it's travel. (Hint: Good luck. It dwells at TDC long enough to make determine TDC - within a degree on the crank - difficult.) Once the piston is at the highest point of travel, then rotate the degree wheel (without moving the crank) until the pointer is on 0 and that's TDC.
To use the piston stop first you have to set-up your pointer. Place the tool you're using to "stop" the piston such that the stop (small bolt on mine) contacts the piston on the middle of the piston (middle is important). Then turn the crank until the piston contacts the stop. (Don't over do it, don't bend the stop!) Once the piston stops read the degree indicated. Write it down. Then, turn the crank in the opposite direction until the piston contacts the stop again. Note the degree indicated. Then (math required here), add up the number of degrees between the two measurements, and divide by two. You're looking for half way between the two. Half way between the two will be TDC. Move the degree wheel, or pointer half way between the two, to indicate TDC there. Then do it over again to confirm you've got it right. Sorry if that's not as clear as it should be. Maybe this guy can explain it better?
Your assignment, should you choose to accept it...is to tell us if you think using the piston stop is a better, more accurate way to determine TDC, or not. There seems to be some difference of opinion about which way is best/more accurate.
As for recommending a dial indicator - I use a Harbor Freight indicator. It works for me, maybe not the "best", but for the price, it's good enough.
Here's a pic of a set-up that I might use if I was going to use a dial indicator to determine TDC. There are MANY different ways to stick a dial indicator above the piston.
While the Harbor Freight indicator isn't expensive, the piston stop I use is even cheaper, and, it's easy to make.(There's a nut on the bolt under the bar)
Before you can do any timing, for example cam timing, you have to install the degree wheel, then determine where TDC is.
To determine TDC using a dial indicator you simply place the indicator above the middle of the #1 or #4 piston (middle is important) then turn the crank over until the indicator shows the piston is at the top of it's travel. (Hint: Good luck. It dwells at TDC long enough to make determine TDC - within a degree on the crank - difficult.) Once the piston is at the highest point of travel, then rotate the degree wheel (without moving the crank) until the pointer is on 0 and that's TDC.
To use the piston stop first you have to set-up your pointer. Place the tool you're using to "stop" the piston such that the stop (small bolt on mine) contacts the piston on the middle of the piston (middle is important). Then turn the crank until the piston contacts the stop. (Don't over do it, don't bend the stop!) Once the piston stops read the degree indicated. Write it down. Then, turn the crank in the opposite direction until the piston contacts the stop again. Note the degree indicated. Then (math required here), add up the number of degrees between the two measurements, and divide by two. You're looking for half way between the two. Half way between the two will be TDC. Move the degree wheel, or pointer half way between the two, to indicate TDC there. Then do it over again to confirm you've got it right. Sorry if that's not as clear as it should be. Maybe this guy can explain it better?
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Dr.Jeff
True Classic
@MikeHynes , Nice write up. Really dumb question but I'm being sincere. Does stacking magnets like that actually make the 'pull" stronger? I've never tried it and honestly wondering if it does? If nothing else the added weight of the stack will help. Thanks
MikeHynes
True Classic
Those are head stud washers, not magnets. You could use shorter bolts instead of the head studs with a stack of washers under the nuts, but you don't really need to tighten them up very tight and I just used what I had on hand.
Dr.Jeff
True Classic
Ha, my mistake. I have a bunch of magnets that look just like those washers in your pic. Without seeing the top of the stack I could not tell there was a bolt in them.
Using a couple of strong magnets might actually work, similar to how the dial indicator base attaches. That may allow more flexibility in how/where the tool is mounted. But they would need to be pretty strong magnets, which is why I thought you stacked them. So does anyone know if stacking magnets makes them stronger? I'm trying to think back to my introductory physics course but nothing comes to mind on this question. I seriously doubt it would (the reason I asked Mike in the first place).
Agnelli
True Classic
Mike - I ordered and received a dial indicator from McMaster Carr, looks nearly identical to yours. It was quite interesting rotating the crank both clockwise and counterclockwise to zero in on TDC. You can feel and observe the latency / dwell effect of the crank, rods, bearings and pistons/rings moving. I agree with the notion that taking the extra effort to use either the dial indicator and or dead stop method is more accurate than relying on factory markings.. I now have a reference point for TDC with the dial indicator, and the next step is to fabricate a dead stop, and when my new Moroso 11" degree wheel arrives, compare the results.
With the dial indicator I've had better results zeroing the indicator pretty much anywhere in the dwell range, then turning the motor over again. Mark the angle at which the indicator reads .2", keep turning up through zero and back down again, mark again at .2", TDC is halfway in between. This works for the same reason the pistn stop method works - the measurements are being made where the dwell is smaller.
Agnelli
True Classic
Thanks Eric. Crank pulley indicator pointer and vernier cam pulley arrive tomorrow, at that point I'll have everything ready. Did a lot of reading planning to certainly get an accurate TDC, but the next challenge was how to degree a cam without a cam card. Apparently there is a way. Certainly going through the process will afford a much better understanding of the valvetrain.
"DEGREE A CAM WITHOUT THE CAM CARD AVAILABLE!"
nitroimage.proboards.com
"DEGREE A CAM WITHOUT THE CAM CARD AVAILABLE!"
DEGREE A CAM WITHOUT THE CAM CARD AVAILABLE! | Saskatchewan Motorsports Forums
Quite useful info for those interested. If you can get the cam card, then do so. If not, you can degree the cam without it. Most cam cards have the following information. Without a cam c
nitroimage.proboards.com
Agnelli
True Classic
Mike -
How exactly did you mount the degree wheel? I have acquired the exact same wheel. To what did you attach that bolt, then on to the crankshaft?
CnC79X19
True Classic
MikeHynes
True Classic
I did have the machine shop do it for me. They didn't have any trouble getting it done. Most of the race cranks I have use this mod, some have different size bolts/threads. I used a small block Chevy balancer bolt for the last crank I had prepped.
5/8" Hex Head Bolt (7/16"-20 x 2-1/2")
It's not ideal having a bolt that uses a 5/8" socket on a metric engine, but they are cheap, plentiful, and readily available.
5/8" Hex Head Bolt (7/16"-20 x 2-1/2")
CnC79X19
True Classic
Thanks MikeI did have the machine shop do it for me. They didn't have any trouble getting it done. Most of the race cranks I have use this mod, some have different size bolts/threads. I used a small block Chevy balancer bolt for the last crank I had prepped.
5/8" Hex Head Bolt (7/16"-20 x 2-1/2")
It's not ideal having a bolt that uses a 5/8" socket on a metric engine, but they are cheap, plentiful, and readily available.