Rocker arm replacement
 

I put about 15 hrs on the rebuilt 454 mag in my 26 scarab, and since have broken 2 of the stock stamped rocker arms. Of course, to save some $ at the rebuild I had replaced only a couple that were cracked around the ball area. The 2 that broke afterwards were on different cyls, and broke out at the ball socket for the pushrod. There sees to be sufficient oil up there. The cam is a Lunati 224/234 dur, .534/.559 lift, with 114 centerline, and stock mag valve springs. Is this too much cam for the stock rockers, and if I replace with rollers, what would be the best type that will still fit under the stock merc rocker covers? Thanks.

Re: Rocker arm replacement
 

What year of 454. I have a set 8 1.7 and 8 1.8 roller rockers. I am about ready to put on Ebay. They have about two hours on them. PM me if interested.

Re: Rocker arm replacement
 

If you are going to stick with the stock stamped steel rocker arms then make sure they are what is called the "long slot" rocker arms that allow for more lift. Also, make sure the balls are groved for better oiling/lubrication and less friction. What you really need are some aftermarket ROLLER rocker arms---they don't creat near as much friction and are much better suited than the stock stamp steel ones!

Re: Rocker arm replacement
 

I would get roller rockers. Stock stamped are usually good to .550 lift.

Re: Rocker arm replacement
 

that might explain why both broken ones were on exhaust valves. With aluminum rollers, which ones need to be ground to fit under the covers?

Re: Rocker arm replacement
 

Off the rocker subject for one second, you mentioned stock mag valvesprings ? Re-used or new ? If re-used how many hours on them ? If re-used why ?

If new, what seat psi's did we set them at ?

--------------------------------------------------

Back to the rockers,
If your old stock rocker arms did not have enough clearance and thus why breaking, check the rocker arm studs for damage, for this is what would be hit by the end 'of the groove' in the rocker arm.

Did we install each pushrod/ rocker arm back EXACTLY the way it came out ?

BTW: Roller rockers would be better , however, new GM long slot rocker arms should be fine in this application assuming everything else is set up correctly.

Re: Rocker arm replacement
 

Have you checked to see if the stock valvesprings are going to coil bind at full lift?

Re: Rocker arm replacement
 

If you have a GenVI engine, (96 or newer) then there are aftermarket roller rockers available made specifically for what you want/need, you need to change the studs also and grind off some corners to make them fit, then adjust. Kits are out there. Search roller rocker conversion.

Re: Rocker arm replacement
 

I just re-read your post. Like stated above I would be worried about coil bind on stock springs used or new. .559 lift I would be surprised if stock springs would work. Are your rocker arms showing heat where they break? Like the color blue.

Very interested can you pm me more info on installing them in a 98 crownline 454 merc!!!