Jeff Smith's Garage - Degree wheel basics
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- Опубліковано 29 вер 2021
- Jeff Smith, former editor of Hot Rod and Car Craft Magazines, shows us how to use a degree wheel. The degree wheel is a critical tool for engine building and allows the builder to know exactly where the crankshaft and camshaft are positioned to build optimum power.
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I have always used a piston "stop" degree of 30 + / - in either rotation! Jeff's 47 degrees ensures even more accuracy.... but is not necessary. 30 +/- is near perfect.
Keep in mind that this is not limited to camshaft degreeing.... it also serves as an excellent means for locating true # 1 TDC that can be used for Ignition Timing as well.
What was that socket call
Isn't the degrees of the lobes come with the manufactured cam? I'm not understanding the purpose of the degree wheel. Timing marks sets the cam, correct?
Not necessarily! The keyway in the crankshaft indexes the lower sprocket to the crankshaft....assuming that the keyway is correct.
The "dot" in the upper sprocket is to align with the "dot" in the lower sprocket.
This indexes the camshaft to the crankshaft, the chain locks them together!
To further degree the camshaft, an offset bushing is used at the upper sprocket........ or, we use a lower sprocket with several offseting keyways in it.
Now, to precisionally verify that all is good, we use the true # 1 TDC markings against the camshaft lobe operation, as per the manufacturer's specs.
Can I Use a Degree wheel to time a new rebuild with the heads and Intake Manifold on ?
BuzzJones
Yes absolutely. The biggest difficulty will be establilshng TDC. The msot common tool used is a spark plug piston stop. The only problem is taht with newer heads and flattop pistons that often the piston stop will not contact the piston. What I've done in tese cases is to use a lever-action, over-center tool that was originally designed to remove/change valvesprings. If you use a flat bar to contact the valvestem insted of the spring retainer, you can use this tool to push down on either the intake or exhaust valve and use it as a piston stop. You must be very careful here not to hit the valve very hard with the piston or it may bend the valve, so approach the top of the travel carefully and slowly and under no circumstance use the starter motor to bump the engine - you must do it by hand wtih all the spark plugs out of the engine. But first, try the spark plug piston stop method and see if that works - its much easier to use and quicker.
Summit should have a Kit for that with the knurled nut make life easier and cheaper
Forgot great video's Jeff keep them going Musho Gracia great video
How do you know where to position the pointer?
The pointer is adjustable so that you can split the "stop".
The degree wheel, once attached, should NOT be moved against the crankshaft.
Ok but once again and just like all the other videos, all the videos show how ro install and how to find to find true TDC. There isnt a single video that shows once you find true TDC what adjustments you now need to make
Why does it have to be a video? There are dozens of magazine stories written on how to degree a cam. All you have to do is search for on them on the internet. I personally have written different versions of this story at least five times in my career. This video emphasizes only the step (which is often overlooked for its importance) that it is critical to determine TDC with the degree wheel because if this step is not accurate all of the other steps will be inaccurate which menas you might as well not bother to degree the cam at all. Determining TDC is the critical step.
@@jeffsmith2003 then why do this video?
Nice, clean, and to the point. Nice job. 😎