I've degree'd a few cams, but it was on high end builds with high Compression and tight piston to valve clearance. Had to recut the piston valve notch on 1 engine. on stock/ street performance builds I didn't degree the cams, cam selection is a tradeoff in a street performance build, you get it in the ballpark. if you want to degree the cam and experiment, I'd suggest a split timing cover so you can make cam adjustments. Get the engine running / broken in, dial in your timing - try different springs and weights in the distibutor, dial in the carb. When you get it running perfect, advance or retard the cam at the timing gear and tune it all over again, see if you made a gain or not. A g-tech pro is a good way to dial in a car without dyno tuning. Most guys don't go to this level of tuning, they build the engine, put it in, set the timing, float level, idle and go. I think it's fun, but it's a lot of time.
as some physists ( my brother in law is one of them ) , I know say mathmatics and the laws of physics do not lie , but its the gremlins of variables ( humans) that screw it up , if we could control the variables it would work perfect to calculations . hense people like us who fine tune the motor or the engineers who look at the problem and try to solve it . who would think we would use the thin rings we use today with the cylinder compressions we do in the modern motor , I remember when my dad said the days of buying a 10:1 engine were gone , but my O/T Car has a 10:1 V-8 motor in it and it has the thin rings too .. as for crankcase pressures they have the problems some what resovled but it raised another problem in the process . and I do not consider anything you say as a personal attack . heck your like talking to my old engine builder and my College professors , except most of yours comes from actual work experience .
You can't change the laws of physics...but you can try to understand them better, so you can anticipate what effect the changes you want to make, will really have. That's called engineering.
Definitely true. If you have a bunch of time and are extremely curious, you could establish what you determine as crankshaft TDC for cylinder #1 and check the timing on the cam for that cylinder. Next steps would be to index your degree wheel to TDC on each cylinder, and then check the valve timing events for that cylinder. You'd also need to check whether or not the four crank throws (V8) have 90 degrees of separation. And like JOECOOL said, variations in lifter bore angle will also affect the timing of the valve events. Chances are likely that there will be some variance, albeit small in most cases. I normally check cam timing on cylinder #1, and then look at the fifth firing cylinder (V8) just to see how close things are. Rarely are they spot on, but even more rarely are they off far enough to worry about.
thats the why reason why when electronics came in VVT works so well , Cummins actually had VVT system up and running on big slow diesels ( 2500 rpm max) back in the late 60's and it made a massive improvement in the powerbands of the motor , but the size of it was too big to package for a car at the time as it was purely mechanical and also had to be gear driven and made lots of noise . ( thats the rattling you hear coming out the front of a older cummins )
I know I'm semi-slow here, but how does one degree a cam? On most 4 bangers with a block mounted cam, there usually sits in one location. Old volvo's run the cam on gear, and newer runs them in the head with a T belt. On serious projects is custom to run them with the belt wheel that is degree-able. Never had much to do with them. The never engines have a sport cam (fast road) and a -3degrees version, that's pre degreed on the mounting flange/keyed track. The twin cam engine they ran an intake came as exhaust, and a custom ground for intake. Fiat Twin cam in the 70s it was the custom to retard the exhaust a full tooth to get more power. Edelbrock claimed, to get more power out of his street driven flathead engine by retarding the stock T5 Merc cam 7 degrees by a mistake on night working on it.
You can change cam timing by buying or making an offset key, so you can change the relationship between the shaft and the gear.
Okay, that I get. But how does one do the whole process of degreeing a cam, with a degree wheel. I understand how the key works, but I don't se to what end? Because we rearlly do it over here. And custom ground cams are very rare. We buy them to a certain spec, lube mount, run. And the whole breaking in a cam is new to me. We pressurize engine, time ignition, adjust valves, let it inflected till hot, adjusts and re torque and drive it responsible the first 5000km with zincs or graphit oil. And bobs you'r uncle. So I ask because it's new to me.
LOL I defy scientific theory with every step I make. Every good physicist knows that dumb trumps knowledge any day. Most of us think that todays modern inventions are the product of intelligence and the truth be known they are the product of someone trying something that cannot be done because they were just too dumb not to try. Good of you on the personal attack. My Ol' man once said that I was like having a porcupine around, I was prickly even if I liked you. I did learn from the masters. The process sounds complicated but really it is not. it can become time consuming until you fell comfortable with it. First you find TDC, you find this by rotating your engine in one direction up against a stop then in the other direction up against the same stop, usually this stop is something screwed into the spark plug hole. There will be a difference in the two readings as a rule and TDC would be a reading in the middle of the difference, so you turn the degree so that zero is that place directly dead center in that difference. Now you have to know your valve opening event in degrees. Star with your intake valve opening event. use a dial indicator on the lifter, when it moves the dial indicator check your degree wheel. it should read the same as the even you are checking, if not then it is off buy whatever amount it is reading different by the known value. You can check your numbers by continuing to rotate the engine until the valve closes, as if you know the opening event you should also know the closing event. Most guys stop there, I usually go onto the exhaust valve and check my numbers again repeating the procedure only using the exhaust lifter and the specs for the exhaust lobe. Then you can adjust your cam timing accordingly. All of this becomes moot if you are just bolting an engine together to drive around in, it becomes very important when you want an engine to be optimized. maybe someone else has a batter or different way to explain it. Cam break in is a way of burnishing the lobes as well as mating the tappet (lifter) to the cam lobe. It is only really important on a flat tappet cam shaft. On a roller cam it is not necessary. One lubes the cam lobes with break-in lube, it is a thin grease with fine grit in the emulsion. Once the engine is primed it is run at a high RPM for a designated amount of time. it is best to vary the rpm by a few hundred up and down during this process but only every once in a while, not constantly like stirring cheese sauce. Most cam shaft suppliers have a certain amount of time that they designate, but if you have been around long enough you learn to listen to the cam shaft, you can hear a change in note when the cam breaks in. it is subtle but there is a difference, best to stay with the recommendations, it varies from one manufacturer to the next but is about 20 to 40 minutes on most new cam shafts. I usually dump my oil right after and put clean oil in because I don't like the grit floating around in my engine but most say that it is not necessary. *500 miles is normal for the first oil change. *804 to 805 kilometers you are probably OK @ 1000 KM
Joe Cool in post 25 reminds me of why I find the highest cranking compression. It was decades ago when I was reading about a fellow named Willy, who I think worked at Isky, telling about phasing of the cam for highest cranking compression. It made sense to me then and it still makes sense to me.
Sorry for the threat jacking! Never did that or heart about it! That is great. Never knew I had to do that. That's great. We spin the motor over with spark plugs out, check valves pass and put the rest together. And drive it.
I've often wondered if the compression method was valid , I've some older pals that choose that method. I still degree wheel my race engines. This discussion could go on for light years & reminds me of an old retired master mechanic friend teaching me to logically view other ideas.... I corrected him for saying motorcycle wrong. "motorsickel" he replied? Yes, I said motorcycle. He paused smiled & said you ever ride a "Bycikal" I thought for a moment bicycle .... wow ..... Similar 2 wheeled devices with different pronounciations? You know he might be right! Naaaah. He seen me fighting a pattern on a 9 inch ring gear once .... Said move over & set a perfect pattern in no time. Just because it's an old idea, doesn't mean it won't work. He without saying a word more than once, shown me alternate ways to accomplish a task. That compression idea probably was around a few centuries ago but got burned up in the Library fire at Alexandrea! Flux
Dan, back in my day of motorcycle dragracing, we had double overhead cams. We could fine tune the motor with a few degrees of cam timing to match the combination of our mechanical limitations. Of course, you are working with a single cam OHV motor, but the physics of combustion are the same. We would advance the intake cam and retard the exhaust cam until we got the best MPH with a given combination. If the 60ft times layed down we would bring it back until it would launch. Then we'd change ign. timing, jet, gear, pipes, duration, lift, centerline and a host of other things, until we set a record or two. All that to say this, if you are using this to show the kids about cam timing, get a copy of Comp Cams "DESK TOP DYNO". You can change all of your mechanical perimeters in the cyber-engine and see what effect it has on power, without turning a wrench. Then you can apply your findings to the real engine. The kids will get the best of both head knowledge and experiencial knowledge as well as Dad may learn some things too, plus you will be connected to your kids. That is priceless! Kids usually being a little more computer savy will pick up the idea about 100 times faster if they can see it on a screen. I wish I'd had that when I was a kid, but instead I learned the hard way. Burned up a lot of parts, tires and gas, but had one heck of a lot of fun! BTW, the laws of physics will work on stone-stock motors as well as pro-stock motors, the real question is... do we know all the laws of physics? Not yet! lol
LOL the laws of physics are like tax laws forever changing and always a mystery to all except the publisher.
All camshafts kind of look alike until you degree in a cam and then you find out which ones are boat angers and which ones are the real deal. You can really learn a great deal about center lines, ramp speeds, and many other things through decreeing in a cam. Problem one of the best books I ever read on building race engine preparation was written by Waddell Wilson and the cam parts were written by John Reed of Reed Cams. This book was written in 1984 Jimbo
My cigarette won't stay lit. Montanal we are no doubt identical twins. Do you like stale cornbread and milk?
I like cake and milk, but I usually like honey on my cornbread! I think we are identical twin cousins...
1st of all its fun! If you really want to learn "sum thin" set it up with checking springs and a checking pushrod and then use robust springs and pushrods.
Why didn't somebody tell me??? Are yous guys holding out on me??? I'm gonna take my degree wheel and go home! lol
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