tpi_roc

Alright guys, another respectable users apon compairing notes informed me that sportsman II's aren't so friendly to 1.6RR's. Well the Roller Rockers stay, so that means I need a different pushrod length, but my quesiton is about whats acceptable. In trying to achieve a perfect geometry where the roller tip begins at the 'back' of the valve stem and rolls forward to the 'front' of the stem (back = toward intake, front = outside of block/exhaustside) It appears im going to need to run about a .100 shorter pushrod (+/-). Currently My roller tip starts just exhaust side of center, and rolls further to the exhaust side, it stays ON the valve stem, but there's no contact on the intake side of center of the stem.

How concerned should I be with this geometry? Should I prolong my engine install and hunt for the so far inexistant pushrod length, or is this ok? will the valve stem rotate at all to even wear or is the valve going to stay in the direction its pointing now?

Thanks

RB83L69

I would suggest that you buy an adjustable push rod, and find the optimum length by trial.

As the rocker depresses the valve, it starts on the intake flange side of the stem, moves across toward the exhaust flange side, then returns toward the intake side once it passes the point where it is exactly perpendicular to the stem. "Perfect" geometry would be where the contact patch throughout that motion is as small as possible, which would correspond to equal excursion on either side of perpendicular. Using an adj push rod, a checking (low pressure) valve spring and some gear marking paste or white lithium grease, it's easy enough to find this point.

Almost always, push rods longer than stock are needed with bigger cams. Rocker ratio makes no difference. The head castings can have a major impact. I doubt that shorter ones would ever be required though.

Comp I know makes push rods in .050" increments over a very broad range. You can get any imaginable length from them. Check their catalog on their home page www.compcams.com

tpi_roc

Yea I knew this was my directon... and I know what ideal is, but how BAD is how its set up now?

Its a small range of movement, it just happens to be at the outside edge of the valve stem

tpi_roc

Here's how it is at full lift...

You can't really see the roller it got *kinda* fuzzy but its at the outside edge of the valve stem.

RB83L69

It doesn't matter that it's at the outside edge. What matters is how much it moves across the top of the stem. The less sliding across the top (which is the thing that creates guide wear, by causing side load) the better. The stem does not care whether it gets pushed at the center or near one side, as long as it gets pushed straight down.

tpi_roc

Ok, with a lack of proper tools I'll say the "movement" is about 1/4 of the diameter of the valve stem.. not to bad...


But it IS on the outside edge, and im afraid that will the smallest amount of heat expansion, rpms' or float, that it'll drop off the edge and I'll ruin a whooooole lot of money.

poncho9789

To go on the safe side buy a adjustiable pushrod or you can buy pushrods untill you get the right geometry. At about the middle of your lift your roller should be at the very center of your valve tip. Any more and you risk having problems from valve guides and you could also have problems form having the rocker putting preasure on the very edge of the valve and crackiing the valve.

I had to learn all of this stufff really recently and I talked to a old guy that had been building race engines for a long time and he said it is better to do it right the first time when it comes to valvetrain geometry.

Good luck rock hope you get everything set just right.

tpi_roc

Well... I did a little test, things dont look so good..

I pulled off the rocker arm nut, and pulled out the pushrod, I then slide the rocker up and down the stud trying to find the *IDEAL* position where the roller tip was in the center of the valve stem..

It never happened.

It always stays on the outside of center

not good

Vader

Did the heads get machined for studs "in the field" or did they come that way out of the box? If they were fully-prepped Sportsmans, the studs should be in the correct locations, and I'd start looking for different rockers. Perhaps a forged steel set would be better than the re-used beer cans?

I started looking at your thread a few days ago and I was perplexed by the apparent need for shorter push rods, too. That almost never happens, but I'm not that familiar with the design of the Sportsmans or S-IIs (one can learn something every day).

What kind of rockers are mounted there, anyway?

tpi_roc

They're out of the box sportsmans, I can't see why they'd come from the factory with machining necissary. I was thinking by lowering the rocker on the stud that it would pull the roller tip in, but it didn't at all....

So it almost looks like the only possible fix is machine work..

I seriously doubt steel rockers are going to have the tips in any better location, why would they?

tpi_roc

Doh sorry missed the last part


Yea I guess for the sake of finding an answer vs the fear of the flames I'll release the info that they are in fact crane 1.6 RR's

tpi_roc

ok guys, here comes a twist

I went and fiddled with it more on lunch, this is what I came up with.

If I slide the rocker arm all the way down the stud it does IN FACT get better (pulls the roller tip closer to the center of the valve) the reason i didn't notice this before is because I had the nut threaded on and sliding it down this far moved the rocker to an angle where it would bind with the nut.

I put on a set of roller tipped (not RR's) 1.5's and adjusted the lash, the tip landed right in the center of the valve and on lift moved outward. This isn't necissarily perfect, but alot closer to it. The pushrods are crane hardened 7.818's

Im assuming that some 7.800's would be perfect with the 1.5's

So I can safely run the 1.5's, but they're far from optimal, they're not roller rockers, and they're not 1.6's, my springs are set for 1.6's (lift wise)

So from an eye shot It appears that I could get the roller tip in the right spot of the valve stem if I had a pushrod that was about .300 shorter (7.500 total), but this brings up the question, is the rocker angle at 0 lift appropriate? because its now going to be slanted so to pull the roller tip in to the center.

What is the wisest choice. I could run current pushrods / 1.5 roller tips and not be able to take back the pushrods and loose that money. Or i could try to get 7.500" pushrods, and run the 1.6 RR's with possibly the wrong rocker angle

What would make the most sense?

(From the above picture you can visualize the angle the roller rockers would be at if i had them slide down *almost* to the base of the stud ((there's enough room left for them to do they're rockin thang)) )

Inwo

I think you should play it safe until you can figure out the proper geometry for your engine. Run the 1.5s with the pushrods until you do the math and all that. Why risk it, it's a lot of money to waste if something goes horribly wrong that you didn't expect.

tpi_roc

The theoretical math is basically done

granted I didn't take measurements but I've checked and compaired and found a way to get the roller tip where it should be on the valve stem, but is the rocker arm slant/angle an important enough factor to be concerned with that at the new adjusted much lower (.300") pushrod length.


Assuming the rocker angle is fine being that close to the base of the stud all i'd then need is to locate some 7.500" pushrods, and some locking nuts for the rockers that are a bit longer so i dont run into that bind I spoke of

RB83L69

You need to get the push rod length to where the tip of the rocker slides across the tip of the valve stem the shortest possible distance. That's the only important thing. Where the tip lands on the stem is irrelevant, as long as it's all the way on the stem.

Think about rocker ratio for a minute... to make a higher ratio, you have to either (a) increase the length of the part of the rocker between the stud and the valve stem, or (b) decrease the length of the part of the rocker between the stud and the push rod seat. Sounds to me like whoever made the rockers you have did a little too much of the former. I would not build a motor with incorrectly designed parts like that.

Checking tool: http://www.competitioncams.com/catalog/277.html get the "hi-tech" one

Push rods in every imaginable length and then some: http://www.competitioncams.com/catalog/274.html

DO NOT try to locate the rocker tip on the valve stem by wacking out the rocker angle; your valve guides will disintegrate in a very few miles from the side load. Look at how far off of a straight-down line the rocker tip moves in when it's way far down the stud.

tpi_roc

I understand what you're saying, but the problem is with the 1.6's that I have they dont travel across the valve stem a tremendous length, but they do come WAY to close to the edge, which could have far more disasterous effects than some valve guide wear (unavoidable anyways)

tpi_roc

2. Determine correct valve train geometry
What is the correct length pushrod for your application? The one that produces correct valve train geometry. What is correct valve train geometry? When the rocker arm roller tip rolls from the intake side of the valve tip, across the center of the tip (at approximately mid-lift), to the exhaust side of the valve tip (at full lift) and back. See Diagram A.

I'm not trying to discredit your theory, in fact I agree and its something that most would easily over look, the minimum amount of travel on top of the valve stem the better!, However it seems that comes as a side effect of your other geometry settings. I found out today at lunch that I CAN get the roller tip back towards the center of the valve (where 90% of the builders believe it belongs) but whats unclear is what angle on the rocker at 0 lift is acceptable? or does it matter at all?

Vader

Sorry I missed it the first time I read through it, but if that is the rocker angle at full lift, your push rods are likely way too short, not long.

I've used this a guide to correct geometry:



That would mean that your rocker is mounted way too low (close to the head) which seems to be verified by the fact that the fulcrum point of the roller tip continues to travel outward as lift increases. It should begin to travel outward as the valve begins to open, then roll back toward the rocker stud as lift increases past the 30% point. Am I being clear, or just rambling? At least I know what I mean... Let me know if I didn't explain that well enough.

Vader

BTW - Valve guide wear should be minimal with roller tipped rockers, not to mention valve tip wear.

tpi_roc

That picture you posted will help in visualizing how I managed to get my roller tip back to the center of the valve stem.

Simply by shortening the pushrod you will rotate the rocker a few degrees and pull down the back end of it, this will drag the roller tip inward on the valve stem, and thats how i managed to get it towards the center...

But at zero lift is it considered bad to not have a flat rocker?

Anyways, trying to work with / follow what you said, assuming my pushrod is to short (which is very possible considering i can move the angle of the rocker enough in either direction and it will lessen the distance out from the fulcrum) i haven't been able to get the roller tip to move towards the center by raising the roller rocker (lengthening the pushrod) so that would mean i'd need longer studs, which would flex, and we open pandora's box..

Whats the fix for a scenerio like this.

Even with longer pushrods i'd still have an angled rocker arm at 0 lift, just angled the opposite direction.

RB83L69

Vader's diagram shows clearly what I was trying to explain in words...

The tip of the rocker arm moves through an arc. Ideally, you want the center of the arc (which is where the contact point is all the way to the "outside" at mid-lift. That will give minimum side loading on the valve. Another reason for aiming at this point is that it corresponds to maximum valve lift; if the rocker is "tipped" too far either backward or forward, the lift will be less then theoretical. In the extreme case where the rocker is perpendicular to the valve stem, the lift would be near zero, because all of the rocker's motion would be in the wrong plane.

I prefer to get the rocker "level" at the halfway point rather than the 1/3 point. The rocker shouild certainly not be "flat" or "level" when at rest.

Stock push rods are almost always too short when used with a performance cam. The reason is that in order to make a cam "bigger", they don't make the tip of the lobe taller; if they did, eventually it would reach a point where you couldn't install the cam because the lobe wouldn't fit through the bearings. Instead, since lift is the difference between the back and the tip of the lobe, they make the back shorter. As the cam gets smaller in diameter the push rod sinks farther and farther down, and the rocker tips farther back. I've seen motors where the rocker was tipped so far rearward that it hit the retainer near the stud. My personal rule of thumb for estimating push rod length is to add .050" of push rod for every .050" of lobe lift above .275". It's not exact of course, but it's close most of the time.

tpi_roc

Well this is all great information that will certainly get put to use, if someone can just tell me how to get my damn roller tip off the edge of my valve stem

tpi_roc

Ok guys, Thanks for humoring this thus far.



The above picture is the valve at max lift (A)

Now if it returns to 0 lift, or the base circle it will become about (B)

(B) is just about 90°, so to get where I belong at 0 lift (100° or so) where it should be (90° at half lift and 80° at full lift) I would infact need a shorter pushrod correct?

Vader

You actually need a LONGER push rod so that you can raise the mounting position of the rocker arm on the stud. This will force the rocker to swing in an arc that is closer to perpendicular during the valve actuation.

The attached diagram shows the exaggerated effect of having the rocker mounted too low (short push rod), causing the rocker tip to swing outward as the valve is actuated:

tpi_roc

Yea i had the oppertunity once i got home from work to really look at it.

I can tell how/why I need a longer pushrod, and I do, but it certainly doesn't help out the placement of the roller tip, just the geometry, which brings me right back to square1, wtf is going on to make my roller tip extend so far out....

Does anybody know what companyes move the pushrod side of a 1.6RR in more and leave the valve side alone?
(if there are any)

The 1.5's are alot closer to the center, but still aren't on the intake side of center.

Its official, crane makes horrible products.

Matt87GTA

This is a GREAT thread folks. Yet another reason why I should get my Cranes off my engine.... I noticed the same thing on mine when I put it together with the Gold Race Rockers. I went to a 7.300" pushrod (.100" longer than stock) and got the geometry set up nice, but the rollers definately reside on the exhaust side of the valve stems. I mentioned it to some of my machinist buddies and they said it really isn't anything to worry about unless it is so close as to come off the stem, which mine don't appear to be quite bad enough to do. They also told me that the Comp Cams Pro Magnums are much better at placing the tip of the rocker where it should be.....

Crane

tpi_roc

Thats exactly what I think i need, a more precise, better engineered roller rocker where the tips in the same place as a 1.5, but the back side is moved in more for the 1.6 ratio. Crane sucks.

my rockers aren't hanging off the corner of the valve but their damn close, and i feel with any amount of rpms/heat they'll pop right over and the damage could get expensive.

tpi_roc

Problem solved

Slow89Iroc-Z

care to elaborate on how you solved the problem?

tpi_roc

A micrometer, a phone call, and a whole lot of bein pissed


Looks like I was sold a set of ford rockers

A technician at crane gave me the dimensions/measurements of their rockers in this series, I ran home to measure them and compared notes, the distance from the center of the fulcrum and the center of the roller tip falls within fords tollerances (1.432"-1.442") and not anywhere close to chevy's tollerances (1.380"-1.390")

What a PITA this has been

FstBrd6point3

U sure they were 1.6 too from the start?? I am almost positive most fords, especialy 5.0 used 1.7 factory

tpi_roc

1.6 is stamped into them.

johnsjj2

So you still getting different push rods?!! :sillylol: Just trying to lighten the stress level.

tpi_roc

:nono: :nono:

Vader

Comp Cams forged CrMo steel "Pro Magnum" rockers will have everything you are looking for, and they are actually lighter than the Crane Gold Race rockers in reciprocating mass, and about eleventy-jillion times stronger (don't you LOVE forged steel?). For about $30 more than the "Gold Race" rockers you can have a serious set under your covers.

Remember that the "Gold Race" rockers were even too weak for the factory Chevy LT4 engines until GM forced Crane to re-engineer them to a higher standard. I'd still be suspicious. And I'd bet the regular "Gold Race" rockers (without the Bow Tie emblem) have not been improved, either.

Crane has a decent history of cam grinding and an excellent selection, but I think they've gone over their heads on the rockers (pun intended).

tpi_roc

haha, a pun I probably wouldnt' even have caught

Personally I'm not t hot on cranes anything, their cam grinds never seemed par with comp, and I've thus far have had problem with every product of theirs I've bought. I think comp has the market, and rightfully so.

Not to mention cranes horrible lack of product support.

Twistopher

Did you get those rockers in the original box that crane shipped them in? I am not interested in the rockers but I am wondering if possible mislabeling of parts can happen with other products they have. With machining differences of .01 of an inch causing possible damage, sometimes even when it looks right it can be the wrong thing. I am talking about cams more specifically. I am just wondering. I have encounter problems with companies screwing up in the packaging department and sending the wrong parts in the right box. Just wondering...

tpi_roc

No I didn't.

I placed a want ad in the classifieds, was contacted, and sold these rockers, the guy said he ran them in a "400hp 355cid" SBC, I'll admit the roller tip does land ON TOP of the valve, but nowhere near the center, the distance from the fulcrum to roller tip is .050 longer than its supposed to be. Maybe he was less picky, maybe he didn't notice, or maybe by some freak chance his valve train was slightly off and these helped compensate. But they certainly dont fit my block, and they deffinatly measure out to be ford rocker specs. He says they were bought from summit with a SBC part number on them. The error could have happened anywhere from leaving crane to him lieing to me (not accusing) but as far as where the problem began its lost in history. I wouldn't worry about anybody running into the situation I did, I doubt its at all common, but TALK ABOUT A PISSER OFFER! This entire thread, (and a few more) and it boiled down to me having ford rockers on a sbc. Hell im shocked I even figured it out

RB83L69

That is interesting. I wondered where this one was going to go. I'm glad you didn't take the seemingly easy way out and try to scab it in somehow with push rods; obviously you would have just ended up with more problems in the future, possibly even major destruction.

I bought a full set of Comp valves once, got a set of Chrysler exhaust valves labelled as SBC intake valves which I guess goes to show it can happen to anybody.

I second Vader's recommendation for rockers though; no aluminum rocker comes anywhere close to the durability of those Comp steel ones, without any penalty in weight or performance.

tpi_roc

I completely agree, however the price differences are pretty big between the series I bought and the comp forged steel ones. On the lighter side of things I bought an adjustable pushrod tool to measure what length I'd need, and I pulled out my trusty old 1.5 roller tipped stamped steel rockers, turns out the crane hardened pushrods that I had on hand (7.818") were just about the perfect length, with a very small wear pattern right in the center of the valve stem. Unfortunatly they're not 1.6's so I'm below the Seat pressure rating the valve train was setup for, and I dont get the benifits of a roller fulcrum untill this guy takes them back or I sell them.

Anybody know some ford owners?

Vader

Just look in your rear view mirror...

Twistopher

Vader: When I first started to read all your posts I was almost convinced you were a computer since you could just reply with very specific information which usually solves the problem point blank. Your knowledge is very impressive. But you cant be a computer if you have a sense of humor like that last post. Well I always though Windows 95 got pleasure out of crashing on you.


tpi: If the guy you bought them from wont take it back... Shoot me an email. I have friends that own mustangs and they are always looking for parts. Glad to hear they might not have come out of the box incorrect. We had it happen before with a generator motor which I think boiled down to be an old ford motor of some sort. Wasnt pretty. Thats why I was just wondering.

tpi_roc

The guy I bought them from is being increadibly imature, his Idea of fixing the situation was to start slinging insults as though he didn't insult my intelligence already by mailing ford rockers to me disguised as SBC's.


So consider them up for sale

and consider Randy Shipp a bad person to deal with.

Morley

Or go high buck and get Crower's stainless steel rollers.

~M~

Vader

Morley,

That would work fine, too. After seeing all the failures of aluminum under severe duty, and reading all of the problems in these threads, I'm nearly convinced that aluminum isn't the answer for a street car. Steel is just plain tougher and more forgiving. Whether they're sold by Comp, Crower, Lunati, or whoever.

The better designed steel forgings are actually lighter in the critical areas, so they perform better than the aluminum anyway. We won't even get into the flexing and fatigue of aluminum, and how it robs lift and power.

anesthes

iTrader: (12)

hrmmm

Morley

Yep, steel is definately the way to go with a component like rockers. They are subjected to such extreme operating conditions and long run times that Alum just dosen't make sense. Now for a race engine that is going to be torn down and have critical components replaced after just one or two races alum. would be fine.

anesthes

iTrader: (12)

Morley,

How about these?? I can get them for around 180.00 plus shipping from a distributor.

http://www.catpep.com/catproducts/ro...nlessroker.htm

Motor City Mike

I also have the Crower ss rockers on my 9 second street driven big block, and haven't had any problems, and my set-up holds it's valve lash perfectly (mechanical roller). It's been proven that there is no power gain (in most circumstances) using aluminum over steel rockers, but they are certainly less reliable.

I have set-up a few serious engines where correct valvetrain geometry absolutely has to be determined (due to many non-stock parts, extensive machining), and it seems that RB83L69 has the correct method. I also go by the half lift method, and simply make sure that the imaginary "line" going from axis' of the tip and fulcrum of the rollers (on a given rocker @ 1/2 lift) are perpendicular (90 degrees) to the valve stem. Use an adjustable pushrod until this condition can be obtained. Then send in the adjustable pushrod(s) to have some made to length. Don't just measure the overall length and call someone to have some made, because this is not the "true" length of the pushrod. Also, spend a couple extra bucks and get the one piece PR's (not the three piece ones with the "pushed on" ends) - they're also much more reliable.

On my big block which has Dart 360 heads, the exhaust valve stems are 1/4" longer than stock (for the raised exhaust ports), so longer pushrods must also be used to restore correct geometry. The problem is the valve stem and rocker stud are not parallel, so as the rocker arm is raised on the stud (to install the longer pushrod), it moves the roller tip on the rocker outwards, across the tip of the valve stem. Therefore, even though I have restored my geometry, the roller tip rides on the "outward" portion of the valve stem tip of all the exhaust valves. As long as the contact pattern from the roller on the valve stem tip doesn't come close to the edge (less than a 1/16"), It'll be perfectly fine.

Great thread guys.

MCM

Morley

That's a good price, but before you go spending the $$ on them, make sure they have rebuild kits for them. The needle bearings will have to be replaced from time to time, though not as often as alum rockers themselves would need to be replaced.