Engine Advancement

Adding a topic about this because my interest is high at this point.

RichieRichOverdrive wrote:

Yep, one tooth advanced, not sure how much that is in degrees. For the ignition I just pulled the flywheel key and spun the flywheel ahead like two teeth, so about 6 degrees. Engine seemed to like all of that. That advance seems like a lot on the cam, but if you look at the data sheets on the racing cams it’s still not anywhere near as radical as them. My cam was opening the exhaust at the very bottom of the power stroke, the precision cams 212 alt cam opens like halfway down the power stroke.

This has peaked my curiosity.

When you say you advanced one tooth on the Cam.  Is that turning the CAM clockwise or counter-clockwise?

Advancing timing on the flywheel.  That's turning it clockwise if I remember it right.  I've heard some of the "honda clones" people retarding the timing to add more torque.  I wonder if that really works?

To advance you move the part (flywheel or cam) ahead in time, in the direction of it's forward rotation so the "event" (spark or valve timing) happens sooner so yes you are correct it's clockwise while looking directly at it! The cam in all actuality is turned counter-clockwise but when you're handling it you're actually looking at it upside down.

It's generally accepted that advancing is hotter and or peppier, retarding is colder and or torquey-er, that goes for cam and or spark. Problem is every engine is different even 2 identical ones because of variances in the manufacturing process that could make them a degree or 2 off from each other which would make a bigger difference than you'd think!

If you want to have some fun with it all and learn alot about a specific engine you have kicking around then blueprint your cam and spark timing! You can download a printable degree wheel, resize it to fit on an old cd/dvd, make yourself a pointer and go to town! The only tool you need for the cam is a dial indicator on a sturdy base, for spark you need a timing light.

All this talk has had me thinking about making my own fully adjustable cam, I have a plan on how to pull it off but I need 2 cams to build one so I'm currently accepting donations in the form of steel, one piece L head single slug camshafts! Lol

Just like @brianator said, the cam has to get to where it’s going before the crank. The one tooth on my oppy really seems to have made a nice difference. It’s not like it’s irreversible either.

I’m not really sure why you’d retard the ignition on these engines. I don’t think they like it. I think @prancstaman mentioned it possibly having benefits in one of @redlinemotorsportts threads somewhere.

I had thought about cutting up two cams to make one with an adjustable cam gear (Like how the billet flywheels have adjustable ignition timing) but I decided it was too much work considering I’d probably set it in one spot and never mess with it again

RichieRichOverdrive wrote:

I’m not really sure why you’d retard the ignition on these engines. I don’t think they like it.

It helps stave off pre-ignition and detonation which is a byproduct of high compression and cylinder temperatures so I guess it depends what he did to his engine and again because of variances in the manufacturing process ot could've been too far advanced from the factory.

Leaving it alone is what you're supposed to do with a cam once it's dialed in! Lol. My idea is a 3 piece with adjustable lobes so it would be like having DOHC adjustment on a single cam. The idea is that once I've figured out the specs I can either weld it together or use the specs to go shopping for one close.