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Long vs extra long slot BBC stamped rockers

8K views 26 replies 13 participants last post by  GOSFAST 
#1 · (Edited)
Looking for input on 1.7 ratio stamped rocker that will handle .600+ lift. Found one post where Vintage Musclecar was running Crane nitro-carb steel long slot with ~.618 lift. Most info I find generally states long slots are only good for sub-.600 lift applications. So then I see the crane "extra long slot" steel & ductile iron stamped rockers (less durable but much better than OEM and much cheaper than nitro-carb steel) but no data on max lift. Who else is running stamped rockers with over .600 lift at the valve?

Crane # 13801, steel & ductile iron, extra long slot, max spring OD 1.56"
Crane # 13801C, nitro-carb steel, long slot, max spring OD?

Cam I plan to run is spec'd at .600/.570 lift at the valve.
Springs are 1.55" OD with a 1.56" OD retainer.

if I missed any important info, let me know.

Thanks,
Kevin
 
#2 ·
How much spring pressure? Stamped steel rockers dont like high pressures. Your signatur says hydraulic roller coming soon.
 
#9 ·
Yes open pressure is what op needs to watch out for. Stamped steel longslots work good to around 350lbs open maybe little more.
Yes, .600/.570 229/241 HR coming soon. The springs recommend and advertised from CStraub are 1.540" OD Single w/damper 130# @ 1.900" but he says they will install at 1.900 and be right a 150# on the seat. Not sure what open pressure is.

https://www.summitracing.com/parts/crn-13801c-16

I don't know how hard these things are supposed to be, but I do know a good file bounces off like a basketball on a concrete floor.
Those are the ones Vintage Musclecar (Eric) is running....quote from him:

https://www.chevelles.com/forums/13...ve-run-long-slot-rockers-bbc.html#post3405780
Not technically GM rockers, but I'm running .618/.638 (gross) lift on Crane Nitro Carb long slots on my 496 if that helps
https://www.chevelles.com/forums/13...ve-run-long-slot-rockers-bbc.html#post3406092
Crane advertises their steel rockers as suitable for use all the way up to their 131541 cam which has .648/.669 lift (gross, .622/.643 theoretical net)
 
#4 ·
Those nitro-carb rockers are good. I've seen and worked on engines with those at 600 lift and 140++ seat pressure. kept track of lash, and rotated the intake to the exhaust. from time to time. It's pretty much always the exhaust that die. You can see them turning dark in the socket area.

of course, nobody is spending millions advertising them, so they don't show up with all the latest, greatest, supertrick stuff in the magazines. Doesn't mean they're not good, but may not be the most profitable for the makers.
 
#7 ·
Yes open pressure is what op needs to watch out for. Stamped steel longslots work good to around 350lbs open maybe little more.
 
#11 ·
I understand most people's inclination for roller rockers but I would like to keep my stock valve covers and as mentioned other respectable folks are running the same setup with comparable or more aggressive lobes.
 
#12 ·
#15 ·
i remember back in the 80s running my 454 on the street with a big mech cam using gm rockers because i didnt have alot of money . i kept punching pushrods through them when i over revved it doing massive burnouts on the street to be cool. i saved old stock ones and ground the slot myself. the thick comp cams with the roller tips used to be what everyone used. i guess a lot of guys run stamped rockers without issues after reading this
 
#17 ·
you can get 1 Elgin rocker RK-507 to test the fit cheaply, I broke my share of ball rockers back in the day. They were solid lifter engines, what happens when you use hydraulic lifters? do the lifter internals survive the rocker seizing and bending the pushrod etc?
 
#18 ·
Just closing this thread out. My heads were set up with 165#/385# springs. Due to the open spring pressure of 385# I decided to go with roller rockers versus the stamped steel for basically $100 more plus a set of $65 taller valve covers.
 
#22 ·
Not sure what roller rockers you got. My Comp Pro Magnums fit under stock chrome covers with a 5/16 gasket. Mr. Gasket sells them. Easier than gluing two together.
 
#19 ·
If you have heavy BBC intake valves then go with the stock long slot rocker arms, it will aid in more RPM due to less weight on the tip at high RPM over roller rockers.
 
#26 ·
#25 ·



You don’t notice the thicker gaskets. I did have to remove drippers.


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