Probe Shaft Mount Rockers

[Lynn Larsen]

I had originally spec'ed a set of Jesel Sportsman shaft mount rockers to go on my AFR 205s. But, as you all know, I've had to reduce my motor budget. Probes can be bought for right at $500 where as Jesel and Harland Sharp SMRs go for $700. Crower's and T&D start at ~$1K. So, I'm thinking that the Probes are certainly more in line with my pocket book and I'm thinking that SMRs, even Probes, will be more stable at higher RPM than any stud mount rockers.

I've looked on a couple of boards and have found precious little about SMRs in general. Mostly just, "Go with Jesel." The only thing I found was 3 years old and said the Probe bearings had crumbled (Probe uses a pair of 1,100 foot pound capacity Torrington captured needle bearings now.) Has anyone here had any recent experience with Probe's product? I found a guy who has a set of used Jesel Sportsmans for $500, but they are for Vic Jr. heads and will probably need to be shimmed, but should work. Several vendors have the same part no. for Vic Jr. and AFR. Any other words of wisdom on shaft mount rockers?

Thanks,
Lynn

 

[Lynn Larsen]

I just talked with the guy who has the set of Jesel shaft mounts for sale, used, at the same price as the Probes. He had them listed as part no. 506060 which is the part number that is for Vic Jr. and other inline valve heads. This guy used them on a set of Brodix heads, so they should be able to be shimmed to get the proper geometry. I was asking him about shimming them with the stand link that jesel provides with their Sportsman Series rockers. Well, come to find out, these are the older style Sportsmans that have a single common shaft that all of the rockers ride on. I am not a valve train expert or anything even close, but it would seem to me that this would provide for more stable valve control/action than the individual shaft type rockers sold today. Any opinions on this? BTW, he said the setup is a couple of year old, but were in great shape; should I be concerned about this?

Here is the kicker though: I have a Jack Roush 3 piece intake that I am going to use on this motor. The guy said that if you use two gaskets, stock type EFI valve covers will clear the rockers. BUT will my intake clear EFI valve covers with two gaskets?? One of the reasons I decided to go with shaft mounts is that I thought, if anything, they would be lower and more compact than stud mount rockers. Any opinions on clearance

Thanks,
Lynn

 

I have a Roush intake and here is my plan:

I intend to use a set of TEA ported Trick flow twisted wedge heads. They flow more on the intake than the AFR's, the exhaust is pretty close and they have a stock location exhaust port.

I am going to use Yella Terra Platinum single shaft rockers.

They are a rocker that bolts down on a rocker stand that is located by a roll pin, so the rocker is almost as stable as a true shaft rocker setup.

Yella Terra also makes conventional style shaft rockers and they are fairly inexpensive. The parts are made in Australia, but lots of people say that the quality is good. They also were the OEM for the steeda shaft rocker setup.

I hope that combination will fit because that seems like the cheapest way to get a good flowing head, a stable rocker system and stock exhaust port location.

Yella Terra said a tall valve cover may be required for this setup, but I will probably make a custom steel valve cover to get the lowest possible profile.

Good luck.

 

[Lynn Larsen]

Dan,

I have a feeling that the valve covers will end up being some kind of customized solution as well. The guys at Jesel told me that their shaft mounts were definitely shorter than stud mount rockers. This was one of the basic features I was looking for from shaft mounts, other than the obvious advantages.

I'll take a look at the Yella Terra stuff. I do recall seeing some rockers as you describe these. Some of the Chevy BB Sportsman Jesels are like this. They have a single pedestal per rocker. The pedestal design and how it maintains its orientation to the valve will be key. Sounds like you and I are looking for the same things. I'll pass on anything I find out.

Lynn

 

[Lynn Larsen]

Dan,

I took a look at the Yella Terra stuff. Very intriguing and they do have a part number for AFRs. Have you talked to a machinist about drilling the holes for the dowel pins? The design is an upgrade to stud mount, but an engenius one. I would like to know what, if any, the possible side effects could be of drilling the pedestal pad.

Lynn

 

I don't think drilling the pedestal should have any real side effect. I think the roll pin is probably 1/8". That isn't a very big hole and it should be towards the edge of the pedestal.

I'm going to ask TEA if they will add the holes to their CNC program, but that will only be possible if the rocker stud and valve location tolerances are close enough.

I would guess that I could drill the holes with a cordless drill. The standard instalation uses a tool to allign the rocker stand, then the stand is used as a drill guide.

I don't know if these rockers are much better than a good stud mount rocker, but I like the fact that they only have one degree of freedom.

For your AFR's, I would look at their twin shaft rockers. Since they are tied in pairs, there is no roll pin hole to drill.

I think they are probably very close to a jesel in terms of quality, they are probably a bit heavier, but I think they have a much better reputation and guarantee than Probe.

Now that I have decided on a rocker setup, I looked for the best available push rods. They are a three piece design made by 3M. The tips are alloy steel and the shaft is a Al/Al2o3 metal matrix composite. Their light weight and higher resonant frequency contribute to adding 1-200 rpm before valve bounce on a spintron. I want those pushrods, but they are $80 each, that is $1440 for a V8. I guess I will have to compromize.

 

[Lynn Larsen]

Dan, I think the twin shaft are the ones with the AFR P/N. So that is a good thing. Yes they are: Yella Terra AFR Twin shaft 7/16" (1.6), P/N:YT 6610. I have sent them an email asking for more information on design, pricing and dealers. Where did you purchase yours?

I think they would be better than stud mounts; especially at higher rpms. It is possible that with the large trunions they might weigh a tad more. Their description on the website says that they are more compact (shorter), so this should be good thing in terms of clearance with the JR intake. Maybe a set of EFI valve covers will fit. It would be real nice to be able to use a set of cheap covers vs having custom ones made.

If you get the 3M pushrods, you'll have to tell me about them 'cause they are way out of my price range!

Thanks,
Lynn

 

I have not bought a set yet. They are distributed by a couple of wholsale distributors. You will have to order them through an engine builder that has a resale liscense.

Steeda sold their shaft rockers for $350 I think. The AFR version should not be much more, but Steeda might have had high volume pricing.

I think they have a good chance of fitting under the rocker covers because I think it's the poly locks that hit when you use stud mount rockers. Since these bolt down, the pushrod adjuster becomes the high spot.

I am also looking at longer than stock valves to fit a nice set of valve springs. I will have to get taller rocker stands and trim them to get the proper geometry.

I know these rockers are taller than the Crane pedestal mount roller rockers that fit under the valve covers and I'm going to add .080" of valve height. I don't know how much clearance those valve covers have, but if there is 1/4", I think it will fit. If there isn't, I have to look at how much clearance there is between the valve covers and the intake.

Even if I can make everything fit, I still have to worry about valve adjustments. I might not be able to get to the adjusters without removing the intake. That would be a big hassel, I can just immagine taking the intake off and ruining one of the special gaskets, or creating a vacum leak when I put it back together.

I hope it fits.

 

I'm not going to get those 3m push rods. But I have been looking for a source of Al/Al2o3 tubes.

If I can find a supplier of material that has a similar proportion of reinforcement material and similar mechanical properties, I might make a set of push rods.

3m wanted $60 for a 12" x 3/8" tube of unfinished MMC material. It requires diamond cutting tools. Even if I could get two pushrods out of one tube, it would cost $480 for the tubes, plus machining and I would have to make the ends.

If I can find a supplier that will sell me the required tubes for around $100, I will investigate the cost of making the ends. If I can get a full set for about $500, I will probably do it.

They would be the perfect compliment to the light weight solid roller lifters, hollow stem valves, titanium retainers, beehive valve springs and soft ramp cam that I will be using. I estimate that those parts should make a valve train that does not float untill well past 7,500 rpm and should require minimal maintenence because the seat pressure will only be 155 lbs.

All of the 7,500 rpm hydraulic roller setups that I have seen seem like they are so close to the edge of lifter collapse that I think they would probably require more maintenence than a super light weight valve train with a soft ramp solid roller.

But before I jump in, I have to talk to my cam grinder and see if those parts will perform like I hope they will.

I know a hydraulic roller with 130 lbs on the seat and a feavier valve will work at more than 7,000 rpm. I'll have lighter valves, lighter lifters and more spring pressure. Hopefully that will be enough.

 

[Lynn Larsen]

I understand exactly what you are talking about: shaft rockers under that Roush intake and periodic lash adjustment /ubbthreads/images/graemlins/frown.gif There is a racer on CC that has one; here is what he said:
<font color="orange">
"... I read it* over and over before plunking down the coin on my manifold. The reason I still did was because I felt the intake was not given a fair shake, and I was right. I have more power with this intake than my ported GT-40 ever had, and if I ever get my fuel system fixed (time, got all the parts) I will be able to get it to go around the corner as fast as it can now go in a straight line.

I love the looks, power, and eventual ram-air that mine has, I just wish that valve cover gaskets weren't a 4 hour job -MC www.SilverHorseRacing.com" </font>

* There was an article in some mag where a guy put a Roush intake on a motor with stock heads and cam. It didn't do all that great; surprise, surprise!

On the other hand, after the first year, you shouldn't have to adjust the rockers more than a couple of times a year. I plan to get some gasket material and make a bunch of sets. I haven't looked at the intake in a while, but I wonder if you can take the middle section (including injectors,fuel rails, etc) off without taking off the upper plenum?? It would be nice if you could just unhook the fuel lines, sensor wires and intake ducting and then take every thing off but the valley manifold. We'll see.

BTW, I did find some good words about both Probe and Yella Terra on Corral today. The one common comment about Yella Terra was that they are virtually silent. Both sets had users who were very happy with them. I think either will work well for me; it will come down to price and clearances I think. Although, I am going to consider the warranties on them fairly heavily also.

Lynn

PS BTW, have you looked at the Comp Cams "Bee Hive" springs? They are supposed to have much better harmonics. Partly because of the oval wire shape which also allows the spring to resist stress better. And, because they taper down to a smaller diameter at the top, they use smaller retainers (lighter!) and have better rocker arm clearance.

 

Those gaskets are going to be expensive. The Graphite gasket material is not cheap. I know you can buy it through McMaster Carr. I would be tempted to make a set of rubber gaskets to see if they would hold up.

With a solid roller, I think I would need to pull the intake pretty often untill I'm sure that the lash is not changing.

The Comp bee hives are what I want to use, but I want to try the big block chevy spring. It has 25 lbs more seat pressure than the LS1 beehive springs, the base is the same size as the stock TFS Twisted wedge spring, and there are off the shelf +.080" length hollow stem valves from ferrea that will work with their 1.880" installed height. There are conflicting numbers on Comp's web site, but if I look at the good numbers, it looks like you don't have to worry about coil bind untill past .700" lift.

Since the seat pressure is low for a solid roller, I'm going to use a cam with soft ramps and about .625" lift. Hopefully those ramps and the lightweight parts will let it rev and hold it's lash longer than my maintenence interval.

 

[Lynn Larsen]

There is a supply house here called Raleigh Rubber and they have every imaginable type of gasket material. I plan to work with them, and of course shop their prices, to come up with the right material or combination of materials (some products are layers of different materials.) What is really nice is that they sell small amounts to truck loads just like McMaster-Carr. The difference is I can walk around the warehouse with them, then touch, feel and see the materials.

I have now heard from someone who has used all of the rocker types except Crower and T&amp;D which are both out of my price range anyway. They have all said that they liked the product they had and would use them again! One guy had Harland Sharp shaft mounts with a Jack Roush intake. To quote:"<font color="orange"> when i had my 347 with a roush intake i used harland sharp shaft mounts(400bucks?)and factory cast valve covers that i had to do some external grinding on along with some grinding on the bottom of the roush middle intake......but all cleared. ....shaft mounts are the ONLY way to go.i will never use anything else again. i know they are expensive but its worth it in my opinion.</font> One thing he said that you might want to be aware of: with the HS used on a pedestal mount head, the limit was 350lbs of spring pressure. I think most of the others use stud mount receivers with the possible exception of the Yella Terra single shafts, so be sure and ask if you are in this situation.

The bottom line for me is that I think any of these shaft mounts will do a good job for me and be superior to the alternatives. Like I said above, it will come down to price, height and warranty. I am still waiting to get pricing for the Yella Terras, but I only heard back from Australia in the wee hours of the morning. It sounds like they are sold through machine shops only. I can only hope that they are as cheap as Steeda was selling them for in the end: ~$300. Those were only available in 1.5, I think. It may have been 1.65, but which ever it was, it wasn't 1.6. The more I have looked at them, the more I like them. We'll see.

Lynn

 

Yella Terra told me that the single shaft rockers were good for up to 1000 lbs open pressure. That seems very high, with a 1.7 ratio, that would put 2,700 lbs of force on the shaft bearings. I won't try that. My open pressure will be less than 450 lbs, probably more like 380. It just depends on how much lift I run.

Also, here is a theory that I think I'm going to use. The mass of your lifter is a constant, and the difference between rockers of different ratio's is very small, so if you go for a higher ratio, your lifter does not move as far , so it's speed is reduced. This reduction in lifter inertia should allow you to rev a little bit higher.

I think NASCAR engines use this approach because all of the used Jesel rockers from NASCAR seem to be 1.9+ ratio. The 1.7 and below ratio's seem to be used just to break in the valve train before they really abuse it with the high ratio rockers.

Another bennefit is that since your lobe lift is reduced, you can grind the same valve lift with a larger base circle. When you add it all up, you get a cam that should be easy on the lifters and give you a few more RPM before the valves float.

I have just arranged to buy two valve covers. One is a '95 Mustang drivers side, the other is a '98 explorer ( which ever side does not have an oil fill tube). That will be the raw material that I will use to make my custom valve covers.

With OEM appearing valve covers and CNC ported (formerly) smog legal heads, I might be able to keep my car from being impounded if a police officer ever sees under the hood. I just hope they miss the full length headers, because my car is built to fool the incredibly stupid.