| Break in rocker arms [message #330674] |
Fri, 06 April 2018 11:52  |
Chris Tyler
Messages: 458
Registered: September 2013
Location: Odessa FL
Karma: 7
|
Senior Member |
|
|
Att eh drags the other night with an old friend we were discussing the problems with flat tappet cams since the demize of the zinc content in most oil.
We have had a number of people we know who have wiped lobes despite using additives and proper break in. ONce they are broken in the failure rate seems to go down.
Mind you in most of these cases they were high performance cams with much higher than stock spring pressure. Conventional wisdom is to break the cam in with lighter springs [I believe the original DZ Z28 engines came with these and the high presure springs in the trunk] but lets face it... thats a PITA
Anyway, he has had good results breaking in engines with reduced ratio [1.3] rocker arms that lighten the initial load. In fact, Im going to borrow his set for my next SBC build. But they are pricey and not a good option for most. also, AFAIK they are only made for small bock chevy
Go to thinking about problems with hte olds engines in our community. I dont claim much olds spesific knowledge, but wondering if this migh tbe a n idea to try.
looking at the olds system it seems similar to a ford style rocker. Was thinking someone with a mill and tig welder could modify something like these rockers and relocate the roller to acheive a lower ratio for break in. and then sell them to the next person inthe community who might need them. It may be tricky to get the geometry right.
https://www.ebay.com/itm/PRW-Rocker-Arm-Kit-0830201-Sportsman-1-6-Roller-Tip-for-AMC-Ford-Oldsmobile/281791398834?epid=630642887&hash=item419c1383 b2:m:m6JVM47QaQjBHP9eLUAKBng&vxp=mtr
Obviously this doent help long time durabilty issues and it is still a pain to chnnge rockers and reset the valves. But its far lesss of a pain then if you wipe the cam lobes, and I would think the better break in would help down the road
THe roller cam set up is the better way, but an expensive option
Knock on wood, I havent had any problems with my flat tappet cam vehicles yet, but if I ever need to do the GMC I might put this to the test
76 Glenbrook
|
|
|
|
| Re: [GMCnet] Break in rocker arms [message #330675 is a reply to message #330674] |
Fri, 06 April 2018 12:28  |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
|
Senior Member |
|
|
The OLDS saddle style rockers are subject to adverse wear on the underside
of the aluminum saddles. Even before they reformulated motor oils. The
aftermarket abounds with replacement rocker assemblies. There are G.M.
style ball stud style, up to full length shaft style, rollers on one end,
rollers on both ends with needle bearings on the pivot. Full roller
camshafts, the whole she-bang. Pony up with your wallet. Just keep the
ratio at 1.6 -1 or under, spring pressures under 160 #, lift under .475",
LSA under 110°, 'sall good.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On Fri, Apr 6, 2018, 9:53 AM Chris Tyler wrote:
> Att eh drags the other night with an old friend we were discussing the
> problems with flat tappet cams since the demize of the zinc content in most
> oil.
> We have had a number of people we know who have wiped lobes despite using
> additives and proper break in. ONce they are broken in the failure rate
> seems to go down.
>
> Mind you in most of these cases they were high performance cams with much
> higher than stock spring pressure. Conventional wisdom is to break the cam
> in with lighter springs [I believe the original DZ Z28 engines came with
> these and the high presure springs in the trunk] but lets face it... thats a
> PITA
>
> Anyway, he has had good results breaking in engines with reduced ratio
> [1.3] rocker arms that lighten the initial load. In fact, Im going to borrow
> his set for my next SBC build. But they are pricey and not a good option
> for most. also, AFAIK they are only made for small bock chevy
>
> Go to thinking about problems with hte olds engines in our community. I
> dont claim much olds spesific knowledge, but wondering if this migh tbe a n
> idea to try.
>
> looking at the olds system it seems similar to a ford style rocker. Was
> thinking someone with a mill and tig welder could modify something like
> these
> rockers and relocate the roller to acheive a lower ratio for break in.
> and then sell them to the next person inthe community who might need them.
> It
> may be tricky to get the geometry right.
>
>
> https://www.ebay.com/itm/PRW-Rocker-Arm-Kit-0830201-Sportsman-1-6-Roller-Tip-for-AMC-Ford-Oldsmobile/281791398834?epid=630642887&hash=item419c1383 b2:m:m6JVM47QaQjBHP9eLUAKBng&vxp=mtr
>
> Obviously this doent help long time durabilty issues and it is still a
> pain to chnnge rockers and reset the valves. But its far lesss of a pain
> then
> if you wipe the cam lobes, and I would think the better break in would
> help down the road
> THe roller cam set up is the better way, but an expensive option
>
> Knock on wood, I havent had any problems with my flat tappet cam vehicles
> yet, but if I ever need to do the GMC I might put this to the test
> --
> 76 Glenbrook
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
|
|
|
|
GMCforum
Search
Help
Register
Login
Home
