davep_96

Ok so I have broke the #2 intake rocker arm stud in half twice in the last week! What the heck is causing this?

Comp cams 284 flat tappet. Vortec heads is what I have.

fast01

iTrader: (16)

If you didn't swap the springs and retainers to accept the lift of that cam your retainers are going to hit the guides, your springs are going to bind or both. When the spring goes solid by either of the above it may be breaking the stud. Those heads in stock form can only take about .480" lift.

ZONES89RS

iTrader: (25)

If they are not biding and for soe reason you have retarded big springs with a ton of open pressure, get some 7/16 studs if you are using 3/8(im sure you are using the small ones).

96lt1m6

iTrader: (31)

7/16 studs is one cure
being sure the bottom of the retainer is NOT hitting the guide boss which is common on vortec heads mixed with high valve lift.
i would say the guide bosses were not machined down and the particular valve is being affected more than the rest.

davep_96

I had my uncle machine the guides, and when the stud broke the first time I had 7/16 studs put in. Screw in type. So all I can think of is that particular guide wasn't machined down far enough.

Btw, some of the other studs have little grooves in them, almost like the rocker arm is/was cutting a groove in them. Small grooves but they are there. Why would this be happening? They don't look like they are going to break or anything, but just wondering.

fast01

iTrader: (16)

What studs did you use and what rockers are you using? The factory Vortec studs are metric and use a self aligning rocker. You had to replace the rockers or at least the pivot ***** when you went to the 7/16" studs. If you're using the factory rockers (I suspect you're not) and only changed the *****, you should be ok. If you changed the rockers and didn't use self aligning ones or didn't add guideplates, the only thing left to locate the rocker would be the pushrod. If this is the case they'll be moving all over the place and could be cutting into the stud. Oh, and even with the guides machined, the springs may still be in coil bind. If they weren't changed when you went to that cam, I'm kinda thinking they are.

TooLateVTEC

iTrader: (2)

Like fast01 said, you need self aligning rockers or you HAVE to run guide plates.

Sounds like your problem may be here.

davep_96

Well he replaced the studs but the rocker arm ends are still 3/8-24. The rockers are from proform, couldn't find them with a quick search but they are self aligning.

I changed the springs when I put the original cam in, but with this cam comp told me I could break the engine in with the current springs, then change them to the required Duals.

fast01

iTrader: (16)

Earlier you said you swapped in 7/16" studs, but now you're saying they are 3/8". If you're using 7/16" rockers on the 3/8" studs they'll still be moving all over the place and cutting the groooves you spoke about. As far as the springs, sounds to me like Comp is saying you're springs don't have enough pressure for that cam. Traditionally, with bigger dual (or triple) springs, you remove the inner spring(s) to reduce the pressure for break-in then replace the inners to bring the pressure back where it needs to be for proper valve control. Break-in with a flat tappet cam is the first 30 minutes of run time. You should have swapped in the proper springs immediately after that. That won't cause your broken stud problem (unless they're binding), but it will certainly cause other problems.

davep_96

He tapped out the holes to 7/16 but the other ends are still 3/8. And the grooves are on the valve side of the stud. And the rockers are meant for 3/8 studs so they are the right ones.

TooLateVTEC

iTrader: (2)

Can you post pics of these grooves your talking about?

PS. After the cam is broken in (half hour) than its time to put the correct springs on.

fast01

iTrader: (16)

I don't mean to offend you or your Uncle, nor question his ability, but were the holes tapped straight and at the proper angle? Sounds like you could be off a little bit, with your #2 more so than the rest. Also, when you change over to screw-in studs on those heads the raised boss that the press-in studs are in needs to be milled off depending on the stud used. I believe only GMPP and Mr. Gasket make studs that don't require the boss to be milled.

davep_96

Yeah absolutely I'll post pics when I get home from work.

And no offense taken, this is my first ever engine build. Went into it not knowing anything about building an engine. Did everything myself though and it was a great learning experience. And I had a machine shop tap out the holes for the studs. The studs look just like what was in there stock. Same length and size.

What happened was I originally had a comp 262h but a lobe went so I upgraded to the bigger 284h. There were no grooves in the studs before the cam change. So I'm thinking the guides weren't machine enough foe the new cam but enough for the old cam.

With comps dual springs, will the spring pockets need to be machined also? Or will they fit? The new springs are a little bigger than the old both height wise and width. And the old springs aren't stock they matched the old cam.

brandoz28

iTrader: (3)

are you running 1.6 rockers? if so did you open up the pushrod holes?

fleetmgr

This sounds like you're binding the front of the rocker arm slot on the stud. Did you get long slot rockers? At this point, you should probably also check to make sure that your pushrods are all still straight. Roll them on a flat surface like a glass mirror to check.

TooLateVTEC

iTrader: (2)

They might need to be machined larger if they arent already done so. The push rod hole also needs to be drilled larger for the bigger lift than stock.

Are you sure where the stud goes through on the rocker, that the FLAT side is facing UP so the rocker arm nut rests on the flat part? Having those on the wrong side would probably cause some wierd problems....check that out man.

davep_96

I bought the rockers about a year and a half ago and im not sure if they were long slot or not. The Proform ones on Jegs right now are long slot but im not sure if they are the same ones i have. Ill try to locate the receipt and get the part number. I can see how not having a long slot would cause the grooves, but would it cause the same stud to break twice? Or is that probably an issue with the guide machining?

Does Comp or anyone else offer a cutter that machines the guide down AND the spring pocket? That way i dont have to buy two cutters. I dont think the pockets were ever machined down and i dont think the new springs will fit. (comp pn 986-16)