Yea, it was going from 1.5 stamped to 1.6 rollers come to think of it. Oh well, there should still be a gain. Quick valve opening at the valve and not the lifter (especially heavy hydraulic rollers) is a good thing .

 

This looks like enough to convince me not to get the 1.7s...



Well, the cam is perfect for passing smog here in Cali since I have a smog test I must take this upcoming year and also works well w/ the mild amount of mods I have done to the motor, since I will not be going much further in performance mods after the motor is done.

I've been googling, ebaying, and digging through the many message boards trying to find deals on the Macs w/ cats, the best I could find so far is 700/some unknown shipping amount for the set Anybody that knows of a better deal for these headers? (I know they have no carb number, just going to have to find a friendly smog place in regards to that.)

 

** Update **

Just went by the shop, they told me I've spun a cam bearing, went to check it out and the bearing had grooved the block from the bearing litterally seizing to the cam. For some reason, oil didn't flow properly through the bearing The stock cam is also grooved in places and severly worn due to the lifters slapping the cam and not being held up against it.

They are going to send the block out to another shop to see if they can resurface it and hopefully find someone w/ large enough cam bearing to work. Well, here lies my question, should I work on trying to find the larger size cam bearings or just look into a new block?

I'll be searching, see what lifters you guys recommend also

 

The larger sized cam bearing will do the job, I would do that if that is the only thing really wrong with the block. It is odd that it failed like that.

 

[QUOTE=Jerm]This looks like enough to convince me not to get the 1.7s...




QUOTE]

Well sure if you got a monster cam in there with lots of lift already then 1.7s are a waste of time. Put people who are running stock cams or very mild ones (hotcam) that want a little more lift it should be safe with 1.7s. That 'arnie' is saying its not good with .600 - .650 lift. I would never use 1.7s to aquire that much lift myself.

 

Well at least one person was smart enough to ditch the 1.7 Rocker idea.
You might want to look at SLP headers. They have CARB numbers i believe. They also don't move the cat and are 1 3/4" tubes. If you are gonna try to find a half way crooked shop to do your smogging you might try to convert to a single cat set up. It should pass the sniffer it just wouldn't pass a visual. It would make way better power and give you better header options. Also on that cam people make the hot cam pass and it has very lazy lobes. You could get a XE cam ground close to hotcam specs and it would have way less overlap thanks to the XE ramps. It would pass smog and be a lot bigger than that cam you have. Just a few options.

 

Yea, very odd and is causing me to spend 320 extra to fix the damage

 

I wouldn't mind going w/ the SLP's if they didn't have the leak problem at the d/s connection just above the cat on the 96-97 headers. Have read to many issues regarding that. I may just have to go w/ the Edelbrocks if I can't find a cheap enough price

 

Overlap has nothing to do with "ramps" and everything to do with LSA.

 

Wrong again, but i'm not gonna take the time to explain it to you. Go do some reading up on it.

 

Cam help for Z95M6:

What is a camshaft? It’s the brain of the engine. It regulates the amount of fuel/air mixture that the engine can pull in and push out. It’s that simple. The amount of fuel the engine can efectively and eficiently burn and get rid of, will dictate the power the engine will generate. Not only that, but the cam will dictate where the peak power happens and how flat the power curves will be.

While valve overlap is ground into the cam and can not be changed, the point during the piston’s travel that the intake valve closes can be changed. This is called "valve timing" which is not to be confused with ignition timing. It is also referred as "cam phasing" or "degreeing". When you here the phrase "advance/retard the cam", it simply means to change the position of the intake valve closing point. To advance the cam, you are closing the intake valve earlier in the cycle and retarding the cam will shut the intake valve later in the cycle.

Lobe Separation Angle (LSA) is also called Lobe Center Angle (LCA). This term is often confused with Lobe Centerline, which I’ll address later. The best way that I can describe LSA is to imagine yourself holding a cam in front of you looking at either end of it. Now cut off the journal so you can look directly at the intake and exhaust lobes. You will notice that the bottom of the lobes closest to each other, actually overlap. Remember valve overlap that we’ve already discussed? Now find the center of each lobe at their highest points. Draw a straight line from these points to the center of the cam. The angle these two lines create is the LSA. The angle is expressed in degrees of angle. If you move the lobes closer to each other, the LSA gets smaller/tighter and the overlap is increased. When looking at different cam profiles for an engine, you will always (almost always) see the LSA listed. While this is a very important consideration, the valve overlap is often forgotten. A profile with a tight LSA will also have more overlap and this is what you should be thinking about when picking a cam, but that’s for a different article.

I mentioned that the cam’s Lobe Centerline is often confused with LSA/LCA. I’ll try to explain LC now. Remember when I was talking about cam timing and the intake valve’s closing point? This is the cam’s Lobe Centerline. It is the intake lobe’s center (at its’ highest point) position in relation to the position of the piston at TDC of the intake stroke. The LC is expressed in a measurement of degrees like LSA is. It is usually with 4 degrees of the LSA designation, so it is often confused. When the piston is at TDC intake stroke, the intake lobe will be pushing the lifter up, opening the intake valve. The center of the intake lobe will be around 106 degrees before the piston is at TDC, or the piston’s position of 0 degrees. I’ll try to clarify that last sentence a little. For every two revolutions that the crankshaft makes, the cam will rotate once. All measurements of degrees are actually "crank degrees". One full crank revolution is 360 degrees. When the piston is at TDC, piston position is 0 crank degree and when it is at BDC, piston position is 180 crank degrees. When the piston is at approximately 106 degrees past TDC intake stroke, the intake lobe will be straight up and the intake valve will be fully open. Cams will come with a recommended centerline position from the manufacture. The one in this example is installed on a 106 Lobe Centerline. When a cam is advanced or retarded, the Lobe Centerline is changed. If we were to advance this cam 4 degrees, we would install it at 102 degree Lobe Centerline and 110 degree Lobe Centerline if we retarded the cam 4 degrees. I mentioned earlier that advancing the cam will increase cylinder pressure. It will to a point. When the cam is advanced, the intake valve will open earlier during the exhaust stroke and the exhaust valve will shut earlier during the intake stroke. If the cam is advanced too far, reversion will occur and the exhaust gasses will not be adequately scavenged. Four degrees advance is usually the most that you can safely advance a cam beyond the manufacture’s recommended LC. When the cam is retarded, cylinder pressure will be reduced but the scavenging process is increased. If you are experiencing pre-detonation, retarding the cam will help. It also has a tendency to move peak hp to a higher rpm. Again, care should be taken when changing cam timing. Another consideration when playing with cam timing is piston to valve clearance. When you change the valve events (timing), the clearances will change and should be checked.

Since we talking degrees, I might as well cover duration. Duration is the amount of time that the valve is open in relation to crankshaft rotation. It is expressed in crankshaft degrees. If we have a cam with a duration of 300 degrees, the valve will be open for 300 degrees of crankshaft rotation. There are two methods used to describe duration. Seat-to-seat or Advertised duration and at .050" duration. The advertised duration is the measurement from the very beginning to the very end of the lobe ramps. It is difficult to get an accurate measurement using advertised duration. Theoretically, you should be able to find zero lift of the lobe ramps, but it is harder than it sounds. To simplify this method, cam grinders pick an arbitrary number unique to themselves. It could be anywhere from .002" lift to .008" lift. Because cam grinders wont get together and give us consistent advertised duration lift points, they came up with a standardized method of @.050" lift. When the lobe is at .050" lift, the duration starts and ends when the lobe is at .050" lift on the other side of the lobe. When comparing cam profiles, it’s best to use the .050" duration numbers.

Duration is probably the most important aspect of a cam’s profile to pin down when selecting a cam. Cubic inch displacement, cylinder head characteristics, EFI, NOS, aspiration, compression, drive train, vehicle application and weight, desired peak power, desired engine operating rpm…….etc are all factors to consider when picking a cam. I’ve found that it’s usually a task best left to the cam grinder to make. I’m not going to get into cam selection in this article, but I should talk a bit about the effects that duration has on an engine.

LSA for a performance ground cam is typically between 106-114 degrees. Sometimes even less than 106 is ground for stroker engines. When duration is increased and LSA is constant, the valve overlap is increased. When overlap is increased, vacuum is lower, cylinder pressure is reduced and reversion is increased. These are all undesirable traits for low end and midrange torque. You need cylinder pressure and vacuum for low end torque. Unfortunately, we cant have our cake and eat it too. For high rpm power, duration must be increased but we cant widen the LSA or the valve events will be occurring during wrong points in the piston’s travel. As piston speed is increased, the time that the cylinder can adequately fill and evacuate is drastically reduced. To compensate for this, we must increase the time that the intake valve is open to admit more fuel/air mixture, and the exhaust valve must be open longer for exhaust gas evacuation. The only way to do this, is to increase duration and lift. We are limited to the amount of lift because the lobe flanks/ramps have to spread out or the lifter will not ride up and down the lobe properly. Roller lifters help because they will transverse up a much sharper lobe flank than a flat tappet lifter, but there’s still a limit for them as well. A very aggressive profile is also hard on the entire valve train and camshaft.

Lift is the total height of the lobe. It is a measurement that is described in inches. A lobe lift of .500" is ½". To get the total valve lift, we simply multiply the lobe lift by the rocker arm ratio. A lobe lift of .500" and a rocker arm ratio of 1.5 would give us a total valve lift of .750". If we used rocker arms with a 1.6 ratio, our total valve lift would be .800". When looking at cam profiles, the lift listed is typically total valve lift using 1.5 rockers. If you want to know what it would be with 1.6 rockers, simply divide the lift by 1.5 then multiply the sum by 1.6. .750 / 1.5=.500 X 1.6=.800

As the cam rotates and the lifter makes the transition from the cam’s base circle to the opening flank, a ramp is ground into the base of the lobe on better cam profiles. The ramp provides a gentle transition from base circle to the flank. Ramps were first used for mechanical lifters that ran with a lot of lash. Picture a lifter riding on the cam’s base circle with .012" of free play (lash). As the cam rotates and the lifter hits the flank, the lash it taken up immediately causing a shock to the lobe and a noticeable tap when the rocker arm hits the valve stem tip. The ramp will allow the lifter to ride up on the lobe flank gently. As the lifter is traveling down the closing side of the lobe, another ramp is used to have the same effect on the lifter prior to making the transition from flank to the base circle. What many people don’t realize, is hydraulic lifters need this same gentle transition. When a hydraulic lifter makes the transition from the base circle to the flank, the initial shock will compress the spring in the lifter affecting total valve lift and duration. The opening and closing ramps reduce these initial and exiting shocks. Not all cams are ground with transition ramps and even fewer have closing ramps at all.

 

"Overlap" has absolutely nothing to do with "ramp rates." It has everything to do with LSA!!!!!!!!!!!!!!!!!!!!!!!!! Two cams with identical durations will have different degrees of overlap depending on the LOBE SEPARATION ANGLE! I think what you are confusing is that the XE cams offer high ramp rates which give more effective durations because the valve opens quicker than on regular grinds. If you are recommending an XE grind because of this, you are totally contradicting yourself telling people to forget about using 1.7 rockers! 1.7 rockers increase the effective duration of a cam, exactly what the XE grind does!!!!!!!!!!! If you are going to make recommendations to people asking legitimate questions, please only answer the ones that you really have an idea about what you are talking about. These people are asking because they really want to know the right answer - not some hotshot's wrong opinion.

 

The Xe lobes have the same duration at .005 lift as other cams but have less advertised duration. By having less advertised duration you have less overlap and there for less emissions. The XE 224/230 will have less overlap than a hotcam at 218/228 because the steeper ramps have less advertised duration.

 

Here is a post explaining what i just said too. As it appears Chris your info is wrong. So you can just shut your damn mouth.
http://web.camaross.com/forums/showt...hlight=overlap

 

Well if TurboZ is what you are basing your argument on, I'm sorry to inform you that he is wrong too. The XE224/230 has more overlap than the hotcam. AS for as I can see, the Hotcam has a 112 LSA with 218/228 duration. The comp XE has more overlap purely because it has more duration. But don't take my word for it (you haven't yet regardless of me explaining it over and over again) call a cam manufacturer 1-800-999-0853. Please do all of us a favor and get some more knowledge before you post answers.