Roller rockers, difference between brands?

[skinny z]

How many miles are on the crowers you have? What do you mean crower is of little help? Do they sell the new roller bearings and you rebuild them yourself, or send them in and crower rebuild them? Wonder what that costs.

I just don't understand why scorpion doesn't offer a setback rocker. Obviously there's a market for them. I would bet 95% of the people that build their own engines don't check geometry. Hell my machinist told me just to get the sweep In the center and it would be fine. This guy builds race engines for a living. He has a lot of fast cars out there with his builds in them. Drag, circle track, boat motors and street cars. People come from out of state to have him build their motors and he doesn't have a clue about geometry. It blew my mind when he told me that. I asked him about wearing the guides out and he said it wouldn't. I'm on team mid lift myself as that just makes sense.

Talking about lifters, China has flooded eBay with $125 for a full set of retrofit hydraulic roller lifters. While name brands are $450-$1200 bucks. I bet they sell the crap out of them too, then these idiots wonder why their motor runs like shit. The same people probably buying speedmaster parts like crazy too.

Just short of 27,000 miles on the Crowers. Lots of racing. Lots of highway mileage. Cam with .360" lobes and RPMs to a 6500 shift.
As for Crower being little help, they said "yes". Fully rebuildable. When I asked about an estimate for repair or whether they would sell me bearings, they went silent. Bearings I can source myself. Pushrod cups if needed or roller tip axles...it's not looking good. But from investigating the condition, it's only the trunnions the require attention.
As for why others don't offer a setback version, given the market for Scorpions (seems they're very popular) and my guess is they get installed without a thought to geometry. So why bother. That's just speculation on my part. But you know how it is when the guides go south the machine shop gets the blame. It may be too that are other applications where the mileage doesn't accumulate. Those 27,000 miles of mine were piled on in the space of two years. With the heads off and rebuilt in the interim.
I wouldn't buy a Chinese/eBay lifter to save my life. Or rocker arm, cam, valve spring or anything else that if there's a failure, I'm rebuilding another engine. I'm fully committed to paying for made in the USA. I'm hoping I can save a few points on the dollar exchange (today's mark is $1.37 CDN for a US dollar) between now and the time I pull the trigger. I can wait.

[skinny z]

I just ordered a set from Chris Straub. I looked and I had .100" shorter pushrods in it than I thought, and the sweep was still that close and around .060" wide. So I definitely need the setback rockers. Just so happens, Harland Sharp are going to be making them some next week.

It'll be a definite improvement.
There are two sides to the rocker arm as it's been pointed out although given the engine/rocker arm architecture, I'm not sure how much can be done on the pushrod side. Unless you go to a shaft system. Then there's far greater adjustability. But I work with what I've got to the best of my knowledge. So far the longevity I've imparted on the valve guides at least shows I'm doing something right.
But the harder you drive it, the lesser the lifespan.

[Cobra720]

I have a SBF so it wont be exactly what you are dealing with but I ran into a situation where my geometry put the roller tip of my SBF Scorpion 1.6 rockers to the exhaust side of the valve tip. Now I know that it's perfectly ok to have this issues without any adverse effects within reason. Smokey Yunik has stated that running the sweep off center as long as the geometry is correct to a point is ok. My situation is .100 taller valve and 17degree Brodix heads.

I decided to do an experiment. I did a side by side comparison between Miller, Scorpion and Crower SS and .050 backset rockers.
I was determined to get the best geometry on the pushrod side and the valve side (90* at mid lift). I don't have my notes handy at this time but I remember all the rocker arms were different including the pushrod cup location not just in length but in height. The backset rockers didn't work on my head because the pushrod location moved the pushrod too close to the edge of the hole on the head toward the intake side. The scorpion had a much different pushrod cup height than the millers which were close to 90 degrees on both sides of the rocker arm but roller tip location was still on the exhaust side of the valve stem.
I found the Crower SBC 1.6 rocker arms worked the best. They were about .050 shorter than the SBF from the trunnion to the roller tip and at midlift both the roller tip side and the pushrod cup side were about 90degrees. The witness mark was almost centered on the valve tip with a .040 sweep. So I stayed with these.

With so many head designs, stud and valve angles and throw in +.100 valves narrow stem, and rocker arm manufacturers with no standard, finding an arm to work in a given situation takes some money and time.

Note with the taller valves look for stud length for proper polylock engagement and shank and thread locations on the stud. It's easy to have the trunnion move too high up and into the threaded area. ARP has many sizes to accommodate this.

Iv'e also used lash caps to create more valve tip surface area with success.

[Walter R. Malik]

I have a SBF so it wont be exactly what you are dealing with but I ran into a situation where my geometry put the roller tip of my SBF Scorpion 1.6 rockers to the exhaust side of the valve tip. Now I know that it's perfectly ok to have this issues without any adverse effects within reason. Smokey Yunik has stated that running the sweep off center as long as the geometry is correct to a point is ok. My situation is .100 taller valve and 17degree Brodix heads.

I decided to do an experiment. I did a side by side comparison between Miller, Scorpion and Crower SS and .050 backset rockers.
I was determined to get the best geometry on the pushrod side and the valve side (90* at mid lift).

With so many head designs, stud and valve angles and throw in +.100 valves narrow stem, and rocker arm manufacturers with no standard, finding an arm to work in a given situation takes some money and time.

Note with the taller valves look for stud length for proper polylock engagement and shank and thread locations on the stud. It's easy to have the trunion move too high up and into the threaded area. ARP has many sizes to accommodate this.

Exactly ... that is usually why someone who purchases one set of rocker arms to usually use a major compromise ... and, a lot Professional engine builders have several rockers representing several brands on hand to check geometry BEFORE making the choice and completing an engine build.

Most of the time an engine builder will already know which ones will work well with certain heads and engines because they have already been there.

[skinny z]

I have a SBF so it wont be exactly what you are dealing with but I ran into a situation where my geometry put the roller tip of my SBF Scorpion 1.6 rockers to the exhaust side of the valve tip. Now I know that it's perfectly ok to have this issues without any adverse effects within reason. Smokey Yunik has stated that running the sweep off center as long as the geometry is correct to a point is ok. My situation is .100 taller valve and 17degree Brodix heads.

I decided to do an experiment. I did a side by side comparison between Miller, Scorpion and Crower SS and .050 backset rockers.
I was determined to get the best geometry on the pushrod side and the valve side (90* at mid lift).

With so many head designs, stud and valve angles and throw in +.100 valves narrow stem, and rocker arm manufacturers with no standard, finding an arm to work in a given situation takes some money and time.

Note with the taller valves look for stud length for proper polylock engagement and shank and thread locations on the stud. It's easy to have the trunion move too high up and into the threaded area. ARP has many sizes to accommodate this.

Exactly ... that is usually why someone who purchases one set of rocker arms to usually use a major compromise ... and, a lot Professional engine builders have several rockers representing several brands on hand to check geometry BEFORE making the choice and completing an engine build.

Most of the time an engine builder will already know which ones will work well with certain heads and engines because they have already been there.

I can appreciate that Mr M. It certainly would be handy for even the amatuer engine assembler to have a handful of rockers available to test.
What we learned from similar platforms (SBC) albeit with different heads, cams, etc., was enlightening.

[smokie]

I already installed longer rocker studs from ARP. I'm just waiting on my backset Harland Sharps to show up. My luck, I'll have the same bullshit problem you did and it move to close to the intake side. If that happens, a regular Harland Sharp should work.

I've considered selling these heads and buying a set of atk 210 heads, if they are still profilers with standard exhaust port location.

[skinny z]

You may or may not find this valve guide wear analysis I've been documenting useful.
I kept track of pushrod length, deck height, head milling, lifter pushrod seat height, gasket thickness, etc.
Of note is the change from a 7.15" to a 7.4" long pushrod.
The short pushrod was an attempt to get the pattern centred regardless of width. That proved a failure in the longevity department. The 7.15" pushrod resulted in valve guide wear that was obvious after 5600 miles but just within the service spec. Changing to the backset rocker and a 7.4" pushrod both centred the pattern and achieved pretty good mid-lift geometry on the valve side. It also extended that marginal service life another 18 000 miles.
Presently, with that pushrod and backset trunnion, the new guides are still mint with 8 000 miles on the clock.

Valve Guide Wear Analysis.docx

[HQM383]

You may or may not find this valve guide wear analysis I've been documenting useful.
I kept track of pushrod length, deck height, head milling, lifter pushrod seat height, gasket thickness, etc.
Of note is the change from a 7.15" to a 7.4" long pushrod.
The short pushrod was an attempt to get the pattern centred regardless of width. That proved a failure in the longevity department. The 7.15" pushrod resulted in valve guide wear that was obvious after 5600 miles but just within the service spec. Changing to the backset rocker and a 7.4" pushrod both centred the pattern and achieved pretty good mid-lift geometry on the valve side. It also extended that marginal service life another 18 000 miles.
Presently, with that pushrod and backset trunnion, the new guides are still mint with 8 000 miles on the clock.


Valve Guide Wear Analysis.docx

Always same valve and guide materials? Always same guide clearance as starting point?

[skinny z]

You may or may not find this valve guide wear analysis I've been documenting useful.
I kept track of pushrod length, deck height, head milling, lifter pushrod seat height, gasket thickness, etc.
Of note is the change from a 7.15" to a 7.4" long pushrod.
The short pushrod was an attempt to get the pattern centred regardless of width. That proved a failure in the longevity department. The 7.15" pushrod resulted in valve guide wear that was obvious after 5600 miles but just within the service spec. Changing to the backset rocker and a 7.4" pushrod both centred the pattern and achieved pretty good mid-lift geometry on the valve side. It also extended that marginal service life another 18 000 miles.
Presently, with that pushrod and backset trunnion, the new guides are still mint with 8 000 miles on the clock.


Valve Guide Wear Analysis.docx

Always same valve and guide materials? Always same guide clearance as starting point?

Bronze guides. Originals and replacements.
Clearances set up by two different shops (both higher end and not "rebuilder" type) so I'd say clearances were close to the same.
2nd go around was with a Ferrea intake valve ( F5027) as opposed to the original COMP version ( 6001 ) but by all intents, the same valve.

[smokie]

My new backset Harland Sharps came in today. It doesn't look like it's a offset drilled trunion, so the rocker might be a complete different design. If it will warm up just a bit I'm going to see how they do. Hopefully I don't have to buy another set of pushrods, but fully expect to have to.

[skinny z]

My new backset Harland Sharps came in today. It doesn't look like it's a offset drilled trunion, so the rocker might be a complete different design. If it will warm up just a bit I'm going to see how they do. Hopefully I don't have to buy another set of pushrods, but fully expect to have to.

Part number? I'd like to check them out myself.

[smokie]

I'll get it when I get home. They are exclusive to Straub Technologies.

[smokie]

STR 11500 is the part number, but I can't find them on their website.

Here's the link to them that STR sent me in email. It doesn't offer any help though except to buy. Lol

https://straubtechnologies.com/straub-t ... ocker-arms

[smokie]

I did get an email from Harland Sharp today. Here is what Randy said.

"Our standard Chevy rocker is 1.440 long
We make a short version that is 1.344 Long.

Let me know what you think. If you need something in-between we can do that too.

Randy Becker Jr.
Harland Sharp / Custom Speed Parts"


Sounds like they have us covered, all we gotta do is ask.

[russxr67]

I have checked 9 different brand rocker arms for a big block Ford & Cleveland engines.
Only three give near the same geometry.

Yes, I’ve found the same.
They’re more than likely based on BBC rockers.
The scorpions and the comp 1830’s are pretty bad.
But I have a set of procomp rockers sitting here that came off a clients engine and guess what?
The geometry on that is about as perfect as you will see!