Broke Comp Cam promagmun rocker

I broke a rocker this weekend. Pat, do you still recommend Crower roller rockers. I have 1.7 stud mounted rockers. Used in 496ci 9.5:1 engine with solid roller cam with .650 lift, about 298 duration. Should I use aluminum or stainless. Crower also has centerline rockers in each type. Luckily I caught this before it dropped any junk into the engine. I was going to use Crowers originally but I've had this new set of Comp Cam rocker laying around the shop for a few years. Figured I might as well use them. Dumb. Thanks, Keith

cam not to big so spring seat and open is not very hi most aluminum rockers will do the job stud rockers i used. Crane golds . Harland Sharp. Scorpion.PBM andHowards .all will hold up good . the Crower.s are very nice. any rocker in this list will work if you get the mild lift right . you say you busted steel body a ultra pro magnum Comp rocker? check your valve train for coil bind . check push rods. i would send that rocker back to comp i would think they would want to look at it . i use this rocker in two builds looks good no come backs

Here is a basic guideline for spring pressures:

Recommended Valve Spring Pressures: Engine Builder

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Originally Posted by 1gary

Here is a basic guideline for spring pressures:

Recommended Valve Spring Pressures: Engine Builder

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thats nice gary .he was not ask about that .i said for that size cam all rocker arms will hold up as that cam many not need a big spring i base spring rate off how much rpm needed to hold the lifter on the lobe. he has springs. he wanted to know what rocker would hold up

Your right Pat.Just thought if he was experiencing coil bind it would break things.

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Originally Posted by 1gary

Your right Pat.Just thought if he was experiencing coil bind it would break things.

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who knows ? as he busted one rocker arm i would say that if he did run i to coil bind or ran out of room retaner to valve guid ? that spring was setup wrong . if he went in to valve float with a roller cam that bad to bust a rocker he better start looking it the pins in the lifters cam lobes pushrods as well has bent valves

Thanks for the quick reply. The rocker I broke was the older design promagnum. Before I had these on the engine I had a set of Unknown brand aluminun rockers on the engine for 2 years. They were ok but seemed to be getting a little loose. I checked for coil bind back when I put the engine together. Can't remember seat pressure right off. It is what Comp cams recommended when they ground the cam. Cam is a custom grind billit. Shift point is 7000 Valves are +.100 manley sever dutys. The heads are heavily ported and flow benched 781s

yep if steel core cam i like abit more seat and open then they may call for with ss valves 3/8 stem valve heavy valve train parts if it,s going upstairs . yes do not run no name rockers .if you stick to that line up i listed you will be ok . from what i seen your not the first to bust the older ones .i will say i do like there new rocker take the time to setup and check the mild lift after you get the new rocker arms

Although Pat has said "mild" lift twice now, I'm thinking he means "mid" lift.

Have had lot of Comp rockers break on marine engine builds. Which cyl by the way?

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Originally Posted by techinspector1

Although Pat has said "mild" lift twice now, I'm thinking he means "mid" lift.

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why yes i do :). i would never use the comp old rocker on a boat in. but seen T&D fail in time in off shore use .in fact i never used much of Comp rockers or roller lifters i think both there roller lifters and rockers are better built in the last couple of years

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Originally Posted by turbo2256b

Have had lot of Comp rockers break on marine engine builds. Which cyl by the way?

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The one that broke was #8 Exhaust.

If I use Crowers should I soak them in cat pee for awhile. Yes, I remember :-)

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Originally Posted by BigBlockBird

The one that broke was #8 Exhaust.

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seeing how them rockers were used before less you marked were they lived before put them back in order ?i can not see how you could read any thing in to this . but i can see the Ex side failing first in time . but i am all ears if he can shed any light why one rocker would fail on just one hole before any others if its valve train harmonics. i loved to see any proof he has on this as i been building bbc for many years now my luck with top end of bbc been very good.i have many out there running very hi rpm

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Originally Posted by BigBlockBird

If I use Crowers should I soak them in cat pee for awhile. Yes, I remember :-)

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sure if your cat has alot of zinc in his peee:D

Most of my BBC experance is with marine builds. Most of the time number 7 cyl fails, next most often is number 8 cyl. So this was in the back of my mind, was one of these cylinders were it failed. Usally a valve hits a piston with little evidence as to why. Have my thoughts about it.

High load conditions with a solid roller is an issue initself as many of the valve train componets need checked and replaced more often.

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Originally Posted by turbo2256b

Most of my BBC experance is with marine builds. Most of the time number 7 cyl fails, next most often is number 8 cyl. So this was in the back of my mind, was one of these cylinders were it failed. Usally a valve hits a piston with little evidence as to why. Have my thoughts about it.

High load conditions with a solid roller is an issue initself as many of the valve train componets need checked and replaced more often.

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well yes and no i not trying to get in a pissing contest with you. as i do not know who you are so i give you the benefit of the doubt. in that i do not know how many offsore engine you built . i built some marine blower engines and built many carb marine engines. i was a dealer in hi rent off shore used bbc big chief parts.blocks other parts. and the hi HP merc stuff many HD cranes ,and t&D .jesel stuff has past threw my hand over the years .along with many delwest valves. crower Hippo liftes. jesel bowtie all were soild roller engines with very good hold out not many if any number 8 rockers that i ever seen fail they were very good about number them. i been building engine and machining engines for many years. had many bbc with 700+. sold rollers that been street/strip. blower and turbo bbc Nos. been doing then for over 30 years .the hold out on parts as very good .. lifters so/so at low RPM no oil . but that was before hippo.old comp roller rocker and lifters were not very good for that use . as for 7 hole that is was with a 4/7 swap cam ? to say that 7an 8 fails it is common for the rod bearings to fail on some guys engines .but over the years just when you think you seen a pattern to failure . i seen just as many in other location as well .i seen fail. if you have any spin-tron testing or if you can tell me its harmonics. i like to see the test .like spring rate what spring . what cam lobe number.core size .base circle.fire order of cam .belt or chain timing set or gear if so 3 gear or 4 . valve alloy stain less . titanium. inconel ? many years ago i was told by one of the bigger builders of race off shore boat engine to never use steel body roller rocker arms in boat engines :)

Not saying necessarly the rockers failed on 7 or 8 but was most often failers in those cylinders for no apperant reasons. Result was pistons and valves hitting. They were engines I didnt build. Some I redid heads on after the fact. Didnt get to see all the dammage. Speaking with Kirt Urban years ago on his advice began installing 3/8" coolant lines from the rear of the intake to the front crossover or in boat ran the lines out the transom sometimes. He stated lost many engies on the dyno without there addition. I had been doing it on SBFs for years. Also gasket matched coolant hole between the head and the block. One in the front right and one in the left rear. I do know this evened up temps between the cylinders based on plug readings and valve coloring. Sometimes thinking was the rear cylinders higher temps weakened the springs while the others still held fast allowing the 7 or 8 cylinders to float to a valve.

Personally I have truset Crane for the most part as they had done R&D for the big three as well as many other venues such as Mercury Marine. I also discuss cams with Engle for the most part speaking to them your speaking wit ha cam grinder not a computer jocky or program.

urban worked at wheel to wheel ? why they hit back were. i think it,s whined up when the engine RPM fee wheel then when the prop lands back it the water. blower engine it alot harder on the crank. blower on one end prop on the other.i have no proof but talked about this with other engine builders . as for crane stuff there rockers and wide bodys they made for merc are good and they made all the copper coated roller cams core .when they closed down there others now that build better core like JC cores . for springs on race stuff it.s pac. psi .isky . i have my customs grinds done by Erson or Horwards .and use moral lifters

Thats another thought but seemed anything could fail winging the throttle coming out of the water. I have retired at this point. Have a few projects to finish up. Paint a 14" Exciter, rerig and sell. Install turbos on my SBCs in my offshore. Work on my cars and trucks sell off some of them. Hit some open track days. help a few friends with car builds.

friend of jon best ran two bbcs in off shore boat that had turbos on it jon k. i did a 540 twin turbo about 6 years go was at mike m. in the big D when they lost the clutch .and blew up the 5 speed lenco guy drives it on the street in ohio :) did some work on the buick v6 turbo stuff a friend made the heads intake blocks vavle cover .the 540 bbc is in photos in my gallery

I posted a picture of the broken rocker on Comp Cams Facebook page. They contacted me right away and asked me to send in my rockers. They might give me a new set of their redesigned Ultra promagnums. The new ones look like they are made tougher and they are black. My old ones were stainless silver. Hopefully they are better. I was very lucky I caught it right after it broke.

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Originally Posted by BigBlockBird

I posted a picture of the broken rocker on Comp Cams Facebook page. They contacted me right away and asked me to send in my rockers. They might give me a new set of their redesigned Ultra promagnums. The new ones look like they are made tougher and they are black. My old ones were stainless silver. Hopefully they are better. I was very lucky I caught it right after it broke.

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that.s great . even if it .s half off on a new set that is a good deal . the new rockers are by far much better i have used them. i like them and will used them again

Comp Cams replaced all my rockers with the new style. No questions asked. This is great.