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Re: Rocker arm geometry on a 440
[Re: 1_WILD_RT]
#1414048
04/08/13 12:43 PM
04/08/13 12:43 PM
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Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
BradH
Taking time off to work on my car
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Taking time off to work on my car
Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
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Quote:
I've saved a few pictures from threads about rocker geometry in the past... First the rocker arm length that Andy mentioned... It would be nice it the rocker brands were mentioned ....
Dove / Indy / Racer Brown; Crane Gold; Hughes; Harland Sharp, Crane iron, either Comp Pro Magnum or C.A.T. ripoffs of same.
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Re: Rocker arm geometry on a 440
[Re: AAR-B4]
#1414051
06/08/13 08:55 PM
06/08/13 08:55 PM
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Joined: Dec 2011
Posts: 257
Way North Idaho
1KoolBee
enthusiast
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enthusiast
Joined: Dec 2011
Posts: 257
Way North Idaho
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Quote:
What will you gain by centering the roller contact?
You have added the roller, that will greatly reduce the side-load on the valve stem and save the guide.
Put it together, race it and have fun. 
I agree, especially given the extra large roller on the HS rockers.
I just ran into the exact same issue with my HS rockers on my Edelbrock heads, although mine seem to be slightly closer to center
But even if you went with lash caps, the recessed valve locks and lash caps would run about $80 plus pushrods, which is a lot less than a new set of good rockers.
'68 Bee 383/TF/Factory Air...high school sweetheart
'67 GTX Clone project,500 six pack,Hemi4-speed,Dana
05 Dodge Viper, 505 V-10, 6-speed Tremec
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Re: Rocker arm geometry on a 440
[Re: 1KoolBee]
#1414052
06/09/13 06:34 PM
06/09/13 06:34 PM
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Joined: Oct 2007
Posts: 4,206
New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,206
New York
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In general, I agree that if the scrub path is small and a safe distance away from the stem tip's edge I'd leave it alone.
The roller diameter is a bit of a design puzzle. Most mfg. have settled on a 3/8" OD roller as a reasonable compromise between 2 extremes:
1. A really small roller (like 1/4") punishes the stem tip, and has very few needle bearings actually loaded = early failure. Only a few needles at the top of the roller take the entire load, and they don't actually rotate - they oscillate a few degrees.
2. A really big roller (like 1/2") lives longer, loads many more needles, and locally depresses the stem less in psi (yes, I know in theory it's only line contact!), but that's the worst possible place to add both weight and inertial resistance - the roller must reverse rotation instantly or it scuffs across the stem.
Roller tips effectively increase the stem height (compared to pallet ends, as far as geometry is concerned) by their radius, since the axle is the "end" of the stem.
When you run a big roller, the rocker doesn't change (as to geo), but now the valve is too long.
Warren Johnson played with geo on his "stock" Olds 350 motors 100 years ago.
Boffin Emeritus
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BTW Thank You..
