TU and F4 Camshaft Follow-on Discussion

[acannell]

Understandably, "lots of gotchas", but this is an incredible conversation.
A conversation that baffles me as to why it hasn't occurred before this.
IT HAD TO HAVE, my mind tells me.
There must be some kind of tool that camshaft manufacturers use, similar to what you describe.

Or, if we have the programmers among us,
maybe a program that would allow custom cams to be virtually tested prior to being built.
In this way,
we could throw ideas for cam specs at the program, and see results before the cam even exists.

Im a beginner on lathes, but from I know, modifying the camshaft to change the lobes into circles with high precision concentricity and diameter, and a good finish, is well within the region of basic lathe work.

I chucked a scrap cam I had up in my ancient Atlas 10F lathe from 1944, and hey it fits! I tried making cuts and the hardened surface cuts reasonably as a first stab. But I can tell I need a follower rest and probably a steady rest to do this task properly. I dont have either of those, but now I have an excuse to buy them lol! In fact now I have an excuse to buy several other lathe goodies too like a quick change tool post and whatever else I would "need" for this..hey maybe a tool post grinder lol


I figure it would be a fun project to modify one of the camshaft lobes properly on the lathe, then mill out an "adjustable" lobe and see how it all works out and fits in an actual head. Its a good lathe project and I've been looking for one.

Since I basically hijacked this thread now, to bring it back to relevance, if there was this "adjustable cam", what would the durations and likely LSA adjustment range need to be? Where in "cam space" would experimenting on the fly at the racetrack/dyno yield interesting results?

As far as software, I'm sure there are simulation packages out there for camshaft design..problem is I bet they require a pretty bad a%% understanding and a ton of work to set them up and interpret the results. I would say we as TD/TM'rs are probably best suited to empirical testing lol

[jrbexhaust]

Moparzrule - When you test the car at the track on the 15, are you going to run the cam you now have installed, then switch the cam at the track? Then see how it changes?

[jrbexhaust]

Rob is the only one that has addressed Todd's points. Is there anyone that has completely degreed there cam in (no matter what cam they have)? Not degreeing a cam in is like not caring if your timing belt is installed a tooth or two off. The smallest changes can effect whether or not the cam should be advanced or retarded. When my head was ported to flow even more than it already did, I switched turbos, and went from a header to a ported manifold, the cam was advanced 2'. Without knowing where it was installed before the changes, there is no way to know where to go after the changes unless you redegree it.

[jrbexhaust]

I would love a new cam that could unleash more power. My set up is ready for more cam.

Chris - I would buy one, but like others, I would like to know all the specs after it is installed and degreed in properly. If you have a credible volunteer, I'd take him or her up on it. I truly believe it would sell more cams in the near and distant future. It would help me decide to buy one or not.

[acannell]

Is there anyone that has completely degreed there cam in (no matter what cam they have).

Even a stock cam? I could degree the stock cam if anyone wants to see that....would that be useful info for some reason?

[jrbexhaust]

It could be to you if you're running a stocker and have modified the engine. But, I should've been more specific. I was referring to performance replacement cams. The point is that if the cam isn't degreed to your specific engine, you are probably leaving something on the table. Plus, you can advance or retard the cam (tune) the cam to your liking. Maybe your car comes on really hard early and just burns tires. You can adjust the cam to make the power come on slower and higher in the rpm band aiding in traction issues. And vice versa.

[OmniLuvr]

If your head or block has been milled then there can b a difference, especially how many times its been done (we do all have about 25 to 30 year old heads on our engines, known to have "headgasket" problems) and i have mine machined just about every time ive replaced the gasket...

[moparzrule]

Moparzrule - When you test the car at the track on the 15, are you going to run the cam you now have installed, then switch the cam at the track? Then see how it changes?

yes that's the plan.

[knownenemy]

This thread contains some really great information that is overlooked on many occasions.
Degreeing the cam is VITAL(IMHO) for efficiency of the engine.
If "base timing" is set using only the factory marks, we will get a running engine,
but it'll never be as close to perfection as an engine that the cam has been set.

In the case of my engine, I'm going to set TDC of the rotating assembly, and degree the cam to that.
This way I know with 100% certainty the engine is correctly set up to be timed.

[turbovanman²]

I never bothered with my 8 vavle, I just moved it around it around until it performed like I wanted. TIII cams, I degree'd everyone that had adjustable cam gears. When I build my 8 valve, I"ll degree it.

[wheming]

As an aside, could someone post the proper method to degree an 8v cam? I've never done one, but I've replaced one. All I did was install the factory gear on the keyway. The gear has the timing mark. How do you select different centerlines to install? Offset keys? Adjustable gears? Both? Cutting new keyway? Marking new timing mark on gear?
Even just a link would be handy if you don't want to bulk the thread.
Thanks.

[Khajjathefang]

As an aside, could someone post the proper method to degree an 8v cam? I've never done one, but I've replaced one. All I did was install the factory gear on the keyway. The gear has the timing mark. How do you select different centerlines to install? Offset keys? Adjustable gears? Both? Cutting new keyway? Marking new timing mark on gear?
Even just a link would be handy if you don't want to bulk the thread.
Thanks.

I'd be interested in this. Usually just get it close and fiddle with the adjustable till it feels right

[Shadow]

As an aside, could someone post the proper method to degree an 8v cam? I've never done one, but I've replaced one. All I did was install the factory gear on the keyway. The gear has the timing mark. How do you select different centerlines to install? Offset keys? Adjustable gears? Both? Cutting new keyway? Marking new timing mark on gear?
Even just a link would be handy if you don't want to bulk the thread.
Thanks.

You need specialized tools to perform this, dial indicator gauge, solid adj lifter, degree wheel, to name a few.

I will be degreeing in a cam in the next little while. I will post pics of entire process IF Someone doesn't beat me to it!

[glhs727]

Make a youtube video!!

[turbovanman²]

Then we'd have to hear him talk, bad enough with his typing,

[chilort]

As an aside, could someone post the proper method to degree an 8v cam? I've never done one, but I've replaced one. All I did was install the factory gear on the keyway. The gear has the timing mark. How do you select different centerlines to install? Offset keys? Adjustable gears? Both? Cutting new keyway? Marking new timing mark on gear?
Even just a link would be handy if you don't want to bulk the thread.
Thanks.

Yes, offset keys or adjustable cam gear. This is the answer as to why most are never degreed. Slap it all together with the factory parts, turn the key, drive. Ma Mopar never really meant for these to be degreed.

[sdac guy]

The process for degreeing in a cam centerline is described in the MP 2.2/2.5 engine book. If I get a chance I will scan it in and post it. But as Shadow said, it does require a few special tools (and plenty of patience).

I've always used the MP offset cam keys to get it close (or right on) but an adjustable cam sprocket would also be an excellent choice. I don't think the MP offset cam keys are still available. So if you don't have a set, then the adj. sprocket would be the only way to go.

Barry

[acannell]

AFAIK, and I dont really, "degreeing" the cam is an industry/jargon word that means two things: measuring the camshaft to compare how it was actually machined to how its supposed to be, and synchronizing the cam to your crankshaft so that its intended position in the engine cycle is as..well, intended.

So I would think what you need to do this are:

1- a way to measure relative camshaft rotation (not "absolute". absolute engine timing locations get measured with the following)
2- way to measure valve displacement
3- a way to measure piston TDC

As far as tools:

#1- a computer printed circle with tick marks every 1/2 degree, glued to a stiff piece of something and attached to the cam sproket. Then, a fixed pointer attached to the head. Now you can measure cam rotation.

#2- a dial indicator and magnetic holder from horrible freight..$20 to $30 total

#3- your choice of the zillions of ways to measure piston TDC...if you have the head off you could use a dial indicator and directly measure it, then make some marks somewhere to record that permanently on the block/pulley/flywheel. or you could measure it through the sparkplug hole using a home made piston stop and your crummy degree wheel and divide by two until you nail it

now you place your dial indicator so its parallel with the valve axis and touching the retainer and observe when there is 50 thou displacement...record your degree wheel location. then keep rotating until you get back to 50 thou. subtract the new degree wheel rotation. you just measured your valves duration at 50 thou lift...repeat for the other valve/lobes...do some arithmetic to compute LSA and overlap

i just made all this up so dont try at home

[acannell]

oh, and the adjustment part..

so now you know exactly where your valves do what they do including "centerline" which is the point where the valve changes direction...use your adjustable cam sprocket or offset cam keys to rotate the cam relative to the crank so that centerline occurs where your friendly cam designer said it should be in the engine cycle

[sdac guy]

No offense intended, but if you don't KNOW the exact procedure, then you really shouldn't post up your opinion on how it is done. Much of what you posted is far from the real procedure, and only leads to confuse the issue. Please stop.

BTW, first wrong thing, the degree wheel goes on the crank, not the cam sprocket.

I just found the procedure in the MP book, but it covers quite a bit of space, far too much to type in. I will try to get it scanned and posted tomorrow sometime.

Barry