factory rocker limitations question

[pclowes]

What are the limits of the factory adjustable rocker arms and shafts with no end support?  I guess I'm asking for max spring pressure and rpm that they would be able to handle. 

[cjshaker]

I don't know if the factory rockers have a limit per se, I've never seen one break, even with some pretty big cams and high spring pressures. Friction and wear at the valve tip starts to become an issue though. The weak point will always be the shafts, especially stock shafts. I can't really give a spring pressure, but I've ran with no end stands many times with cams that would run to 6000 and using fairly heavy valves. I always used heavy duty shafts though. I don't think I'd want to run pressures that run that high with stock shafts without end stands. Using heavy duty shafts like the Harland Sharp shafts I think you'd be ok IF you used the split iron stands that clamp the shaft better. Any cam that can run to 6000 or above and I'd want HD shafts with end stands.

[Posi67]

I had a .600 lift solid that I ran forever with stock adjustable rockers and aluminum stands. Springs were 350# open and I ran it past 7000 RPM on a regular basis. Never broke anything however many have had issues with less cam. spring and RPM so there are no guarantees. I'd think the cam's ramp profile may has some influence on how much is too much for stock.

[blykins]

Used a set of factory adjustables with billet spacers, HD shafts, and end stands on a road race 427.  420 lbs open pressure, 7000 rpm.  No problems. 

[jayb]

Using a totally stock setup I've broken or cracked multiple rocker shafts with fairly low performance hydraulic cams and the associated springs.  It's always the part of the shaft at the end that is cantilevered out there for the 1, 4, 5, or 8 exhaust rocker.  On the dyno mule I did for my Car Craft build, and used for the 390 stroker dyno mule in my book, I used stock parts but added the end stands from Precision Oil Pumps.  Never any problems with that valvetrain, and that was with a .640" lift solid cam and springs that were about 400 pounds over the nose.

My opinion is that rocker stands that support the end of the shaft are essential if you are using stock rocker shafts.  But on any serious build I also upgrade to heavy duty shafts, rocker arm spacers (instead of the factory springs), and a roller rocker arm.

[pclowes]

Thanks everyone for the valuable feedback.

Has anyone tried the inexpensive rocker systems I see on ebay?  I've seen them in both aluminum and stainless steel, advertised under two names, Procomp Electronics or Speedmaster.  The aluminum setup goes for $159-227 and the stainless goes for $253-361.  ( I see used stock setups for around that on ebay.) 

Both are complete setups with end supports and seem to look good in the pictures.  Just wondering if anyone has tried them.

[fekbmax]

I have a set of the stainless steel ones on my truck now for a couple years. I use shafts from POP though. No probs so far. I'd stay away from the aluminium ones though, seen a couple sets of those at the FE reunion, needless to say they were in pieces and not in a good way. The shafts for either setup are junk in my opinion.

[blykins]

I would stay far, far away from anything with the name Procomp or Speedmaster on it. 

[gdaddy01]

yes , thank you

[pclowes]

I have a set of the stainless steel ones on my truck now for a couple years. I use shafts from POP though. No probs so far. I'd stay away from the aluminium ones though, seen a couple sets of those at the FE reunion, needless to say they were in pieces and not in a good way. The shafts for either setup are junk in my opinion.

Checked out those POP shafts.  They have such a heavy wall, I wonder how much spring load they might handle with no end support?

[cjshaker]

If all you're building is a mild street engine with no more than .550 lift and maxing at 5500-6000 rpm or under, you'd probably be ok with just POP's heavy shafts, at least for a while. Anything more and there's just no excuse to chance it. End stands are cheap insurance. Having said that, I ran Harland Sharp heavy shafts with stock iron stands, no spacers and stock adj. rockers in my '68 F250 Highboy with a mild 390 (.540 lift, regular 5500 shifts playing around) for over 20 years with no problem.

[pclowes]

If all you're building is a mild street engine with no more than .550 lift and maxing at 5500-6000 rpm or under, you'd probably be ok with just POP's heavy shafts, at least for a while. Anything more and there's just no excuse to chance it. End stands are cheap insurance. Having said that, I ran Harland Sharp heavy shafts with stock iron stands, no spacers and stock adj. rockers in my '68 F250 Highboy with a mild 390 (.540 lift, regular 5500 shifts playing around) for over 20 years with no problem.

Right inline with my thoughts.  You're right about the end stands being cheap insurance.  I was just thinking about how well the stock system, with thinner walled shafts, performed.  If the budget was tight I was thinking just an upgrade on the shafts alone would go far if the cam, spring pressures and rpm are within reason. What you are saying backs that up.

[ericwevans]

Thanks everyone for the valuable feedback.

Has anyone tried the inexpensive rocker systems I see on ebay?  I've seen them in both aluminum and stainless steel, advertised under two names, Procomp Electronics or Speedmaster.  The aluminum setup goes for $159-227 and the stainless goes for $253-361.  ( I see used stock setups for around that on ebay.) 

Both are complete setups with end supports and seem to look good in the pictures.  Just wondering if anyone has tried them.

Just to add to the experience on these, my dad gave me a set of the steel Speedmasters. 

Nothing has broke on them, however...  after a few weeks I developed an oil consumption issue on the order of 1qt every 100 miles.  Thinking I had broke a ring or rings (the bottom end has a lot of miles on it) I started getting into the engine.  When I pulled the valve covers I had found that 3 of the 4 shaft end plugs had fallen out.  I had thought it was my bad for not checking that they were tight, but then when I put them back in I found out the threads in the shafts are cut wrong for those 3 and the plugs will just screw into the shaft indefinitely.   Turns out the oil consumption was from the tops of the heads being in an oil bath.  Since replacing the plugs with ones with a shoulder that will tighten the oil consumption has gone away. 

I am currently still running the setup while I build my new engine, but needless to say I won't be using Speedmaster again.

[Tommy-T]

Back in the early '80's I had a 454 inch HiRiser in my Mustang.

I ran stock rockers and stands with FPP shafts. I ran a .600 lift cam to 6500rpm pretty regularly with a considerable amount of street driving thrown in.

Never a problem.

I think for a street deal .600 lift or lower, stock shafts with end stands or good shafts without are pretty equal.

[chris401]

Thanks everyone for the valuable feedback.

Has anyone tried the inexpensive rocker systems I see on ebay?  I've seen them in both aluminum and stainless steel, advertised under two names, Procomp Electronics or Speedmaster.  The aluminum setup goes for $159-227 and the stainless goes for $253-361.  ( I see used stock setups for around that on ebay.) 

Both are complete setups with end supports and seem to look good in the pictures.  Just wondering if anyone has tried them.

Just to add to the experience on these, my dad gave me a set of the steel Speedmasters. 

Nothing has broke on them, however...  after a few weeks I developed an oil consumption issue on the order of 1qt every 100 miles.  Thinking I had broke a ring or rings (the bottom end has a lot of miles on it) I started getting into the engine.  When I pulled the valve covers I had found that 3 of the 4 shaft end plugs had fallen out.  I had thought it was my bad for not checking that they were tight, but then when I put them back in I found out the threads in the shafts are cut wrong for those 3 and the plugs will just screw into the shaft indefinitely.   Turns out the oil consumption was from the tops of the heads being in an oil bath.  Since replacing the plugs with ones with a shoulder that will tighten the oil consumption has gone away. 

I am currently still running the setup while I build my new engine, but needless to say I won't be using Speedmaster again.

Eric,
Thats good you didn't have more damage from low oil pressure.