SE 575 Install vs. SE 536 Install

[niels]

Here is my plan as per Dan's (NRHS) advice. Stage 2 heads, 10.5:1 domed pistons, and a performance cam. This will be paired up with existing Stage 1 modification which are V & H slip-ons, a Hypercharger, and a Yost carb kit.

If the SE 536 cams fit as far as piston to valve clearance then I am thinking the SE 575 cams should be fine for this clearance also since the exhaust TDC lift figure is slightly lower.

I know I have to clearance the rocker box for the springs. Are there rocker box clearance issues for the SE 575 cam on the pushrod or valve side of the rocker arm?

What about tappet clearance for the SE 575 cam, does the flat need to be lengthened?

Dan said that for the SE 536 the cam lobe might have to chamfered for bottom end clearance?

What are the bottom end clearance concerns for the SE 575?

Could I get away with an easy install for the SE 575 or does this cam require extensive clearancing?

Any thoughts or input on the Red Shift 567 or N9 would be appreciated also?

Thanks,

Niels

[aswracing]

The 575 has less exhaust TDC lift tha the 536, but more on the intake side. With our pistons, you're probably good, but I'd sure check it anyway.

Since the SE 575 is a small base circle grind, it's cam box clearances are pretty similar to the 536, not worse as you might expect. Same with the tappet flat, the small base circle helps there, I doubt you have an issue. Take a few seconds and check it anyway though, it's simple.

Clearance on the pushrod side, underside of the rocker box top, is probably OK on a rubber mount, but I'd check it anyway. On an 03 or older, it's definitely an issue with either of those grinds.

The 567 is a milder grind than the 575. It closes the intake valve earlier. It's a standard base circle so cam box and tappet pin clearance are more likely to be an issue, in fact, I can about guarantee that you'll be in trouble on both.

The N9 is a bitch to install, with lots of overlap and hence lots of TDC lift. Check EVERYTHING if you use N9's. Also make sure we know you're using them, because we'll likely have to sink the bejeezus out of the valves to get you enough valve to valve clearance. If I remember right, they are small base circle, so the cam box is likely to be easy, but the top end definitely needs lots of attention to use N9's, or the S&S equivalent.

The 575 is a wonderful grind for a Stage 2 10.5:1 motor and I highly recommend it. My '96 Buell S2 makes 105hp with Stage 2 heads, 10.5:1, and 575's.

[niels]

Thanks again. When I have the money NRHS will have my business. I really appreciate all the help.

Niels

[smackie]

cam box clearance? not sure what this means
just trying to make sure i am on the same page....

[sporty58]

When you go beyond about .500 lift on cams you may have some issues with them hitting the engine cases. (depending on the base circle on the cams) It is a really simple matter to grind a little off the cases or the back of the cam lobe but if you don't you will screw up the new cams and maybe a bunch of other parts. The main places they may hit is right at the top around where the cam meets the lifter and the bearing races.

[aswracing]

smackie, here's what sporty58 is talking about:

http://www.nrhsperformance.com/images/bosses.jpg
The underside of the lifter bosses often need a little grinding to keep the cam lobes from contacting.


http://www.nrhsperformance.com/images/pinionraceclearance.jpg
Big cam lobes also may try to hit the pinion race, which protrudes from the case slightly. It sticks out farther on 2000-up motors.


http://www.nrhsperformance.com/images/chamferedlobe.jpg
If the lobe is contacting the pinion race, you're much better off to modify the lobe than the race (this is a Red Shift 567 BTW). Notice the chamfer on the lobe above. Modifying that race is difficult and risky. I've seen people do it and trash the bearing in the process.

http://www.nrhsperformance.com/images/tappets.jpg
The other thing we're talking about is tappet pin clearance. The tappet pin rests against this flat on the tappet to keep the tappet from rotating in the bore. But a bigger cam lobe lifts the tappet farther and on stock lifter, it can run out of travel. Aftermarket lifters as shown sometimes have longer flats.

Small base circle cams help with all these clearances because they achieve their extra lift, at least in part, by letting the lifter down farther as opposed to raising the lifter more. The 575's are small base circle so it makes them simpler to install.

But small base circle cams often introduce one other problem, for which I don't have a good picture, and that's the clearance between the bottom of the tappet and the top of the cam bushing. When the lobe sets the tappet down, the roller needs to keep following the lobe. But sometimes with a small base circle cam the lifter will hit the cam bushing and thus not come all the way down. Easy to fix with some careful, slight grinding on the tappet on the underside of the axle support boss.

Much more on cam installation here:

http://www.nrhsperformance.com/tech_xlcaminstall.shtml

[smackie]

aaron, thanks for the info.
is there also an issue with the rockers hitting the rocker box cover on the RS 567's.

I am working on getting stage 2, 1250 kit (just heads and cylinders with my current SE 551's and SE ignition), but wanted to go with the 567's when money accrued again...would you reccomend this (as compared to the SE 575's) as far as performance?

and lastly I planned on doing it anyway, but what kind of pushrod lentgh as compared to stock would i need for the 567's

thanks again.

[aswracing]

aaron, thanks for the info.
is there also an issue with the rockers hitting the rocker box cover on the RS 567's.


On an '03 or older, yes, absolutely. On a rubber mount I doubt it, but I'd check it anyway.

It's a pretty simple thing to clearance, here's an example:

http://www.nrhsperformance.com/images/rockertopclearance.jpg

It's generally only on the pushrod side that they have an issue, unless you're using real long valves or otherwise have excessive stem protrusion. But a 567 Red Shift will almost certainly need clearancing on a pre-rubber mount. Even SE 536's need it.


I am working on getting stage 2, 1250 kit (just heads and cylinders with my current SE 551's and SE ignition), but wanted to go with the 567's when money accrued again...would you reccomend this (as compared to the SE 575's) as far as performance?


The 575's have more overlap, which makes them more sensitive to the exhaust system, and a later intake close event which will tend to move the powerband up somewhat. They're a little more cam overall, and the Stage 2 head can certainly take advantage of them. But really, the two grinds are pretty close to each other, there's not a huge difference. The 575's are substantially cheaper and are also easier to install into the cam box due to the smaller base circle.


and lastly I planned on doing it anyway, but what kind of pushrod lentgh as compared to stock would i need for the 567's


Pushrod length is a function of cam base circle, the height of the top end (after head milling, thin gaskets to optimize squish, etc), and valve stem protrusion. Valve lift itself doesn't have anything to do with it, as some people think.

The 567's have a stock base circle, so if the top end is at stock height and the stem protrusion is withing the stock range, the stock pushrod length should be fine.

If, however, we had to sink your valves to get valve to valve clearance (not needed with 567's, but needed with 575's), or we milled your head to get more compression, or you used thin gaskets or left out your base gaskets to get tighter squish, then the ideal pushrod length will change accordingly.

You have to remember, the tappet has about a .100" operating range where it works fine, from about .050 preload to .150 preload on the plunger. So you can make some changes without worrying too much about pushrod length.

Most often what happens is the pushrod needs to be shorter, due to head milling and thin gaskets and valve sinking. We stock a premium quality heat treated chrome moly pushrod in .040 shorter than stock for precisely this reason, as we see it so often. If a person needs some other length, though, we don't stock'em but we can get'em in a few days.

A smaller base circle goes the other way though, by itself a small base circle would call for a slightly longer pushrod. But only slightly. Most small base circle cams are .050 smaller, which affects the pushrod length by .025. So it's pretty small.

[smackie]

aaron, thanks again,

been giving myself a headache trying to figure out what to do with the budget. and what to do in stages...

and this didnt help!! :)

i really appreciate the info though i learn something new here every day...

[pa22]

On an '03 or older, yes, absolutely. On a rubber mount I doubt it, but I'd check it anyway.

It's a pretty simple thing to clearance, here's an example:

http://www.nrhsperformance.com/images/rockertopclearance.jpg

It's generally only on the pushrod side that they have an issue, unless you're using real long valves or otherwise have excessive stem protrusion. But a 567 Red Shift will almost certainly need clearancing on a pre-rubber mount. Even SE 536's need it.



The 575's have more overlap, which makes them more sensitive to the exhaust system, and a later intake close event which will tend to move the powerband up somewhat. They're a little more cam overall, and the Stage 2 head can certainly take advantage of them. But really, the two grinds are pretty close to each other, there's not a huge difference. The 575's are substantially cheaper and are also easier to install into the cam box due to the smaller base circle.



Pushrod length is a function of cam base circle, the height of the top end (after head milling, thin gaskets to optimize squish, etc), and valve stem protrusion. Valve lift itself doesn't have anything to do with it, as some people think.

The 567's have a stock base circle, so if the top end is at stock height and the stem protrusion is withing the stock range, the stock pushrod length should be fine.

If, however, we had to sink your valves to get valve to valve clearance (not needed with 567's, but needed with 575's), or we milled your head to get more compression, or you used thin gaskets or left out your base gaskets to get tighter squish, then the ideal pushrod length will change accordingly.

You have to remember, the tappet has about a .100" operating range where it works fine, from about .050 preload to .150 preload on the plunger. So you can make some changes without worrying too much about pushrod length.

Most often what happens is the pushrod needs to be shorter, due to head milling and thin gaskets and valve sinking. We stock a premium quality heat treated chrome moly pushrod in .040 shorter than stock for precisely this reason, as we see it so often. If a person needs some other length, though, we don't stock'em but we can get'em in a few days.

A smaller base circle goes the other way though, by itself a small base circle would call for a slightly longer pushrod. But only slightly. Most small base circle cams are .050 smaller, which affects the pushrod length by .025. So it's pretty small.

Aaron, I am using the .536 in my 90" conversion. I am using a set of Custom Chrome rocker boxes also, (the top rocker doesn't seem to have any more clearance than stock). I clayed the top and around the "ball" on the pushrod side of each rocker arm intake and exhaust and had very little contact with the clay, almost unmeasurable.
Could my lifters have bled down turning the engine over for other reasons (piston to valve clearance etc.) not causing the valves to open all the way, hence no contact with the rocker top on the pushrod side? Am a little worried now but still can get at the rocker box to clearance it.

[aswracing]

It's entirely possible. It sure is easy to get fooled when making top end clearance checks while using hydraulic lifters. Something you really have to watch for.

I'd say 536's will cause a contact problem with the pushrod side of the rocker to the underside of the rocker box top about 50% of the time. If the valve stem protrusion is on the short end of the spec, you'll probably see it. I'm talking 03 & older only of course. I haven't seen it be a problem on the rubber mount bikes' rocker boxes.

[pa22]

It's entirely possible. It sure is easy to get fooled when making top end clearance checks while using hydraulic lifters. Something you really have to watch for.

I'd say 536's will cause a contact problem with the pushrod side of the rocker to the underside of the rocker box top about 50% of the time. If the valve stem protrusion is on the short end of the spec, you'll probably see it. I'm talking 03 & older only of course. I haven't seen it be a problem on the rubber mount bikes' rocker boxes.

My rockers are the 03 and older type. Would interference be noticable turning the motor over by hand with the top cover on or just running? Guess I'll pull the tops and double check, just to be sure.
Thnx. Aaron.

[aswracing]

Generally what happens is it touches real lightly and puts a little ding in the underside of the cover when the motor runs. Often it makes the rocker box top leak as well.

I once had someone bring me a bike that had 536's in it and he had chronic leak problems from his rocker box tops. He had taken it back to the dealer, which had done the work, multiple times, and they had replaced the rubber and the washers around the bolts and at one point even put some silicone around the bolts. But he still had leak problems.

I pulled the tops off and they had nice little dings from the rockers hitting them. I ground some clearance into them, put it back together sans silicone, and he never had a problem again. He also got a nice noise reduction. They guy thought I was a genius or something, but in reality, the dealership tech just had little experience with this stuff and didn't know what to look for.