Snapped a rocker stud on the new motor.

[MacsW33]

I went for a very short ride the other day. Pulling out of subdivision I shifted into 3rd and heard a snap in the engine and then a knocking in the top of motor. Immediately shut it down. Pulled the valve cover and rocker stud was snapped. I think this motor has the cheap screw in studs. I want to upgrade the studs. Are the Manley stronger than the ARP? I probably would be okay with ARP but I want the best with the solid roller.
Thanks,
Mac

 

[boxerdog]

When you say "cheap", what are they?
Are they 3/8" or 7/16"?
How old are they?

 

[1964SuperStocker]

I hope he doesn't say 3/8. Who makes cheap screw in studs anyway? Screw in studs are by design stronger than the factory press in studs but they do make 3/8 screw in studs.

 

[Don Jacks]

Yes they do both make shouldered and non shouldered 3/8 studs.ARP is considered the BEST out there.Show Cars has both available.

 

[tenxal]

I just worked on a 409-409 that had the non-hex head threaded studs in the heads. One of the studs backed out and coolant got into the engine along with the rocker getting loose. Several others were starting to show signs of leakage as well.

 

[johnnyriviera]

REALLY take a good look at that valve. I had a rocker stud back out, it kicked the rocker off. Everything looked fine on the valve stem, so I got a new rocker as mine got a bit marred, a new stud and reassembled everything. Two weeks later at the track, about the third pass, that same valve stem broke and...........well I can share the pics if you have the stomach for it.

Either the momentary slapping of the rocker slightly bent, or fractured my valve stem,

I know if this ever happens to me again, I'm replacing the valve. Would have been way cheaper. Perhaps you don't, but I would look closely.

 

[4speedman]

What type of rocker arms and valve spring pressure are you running.

 

[El Rat]

Som ting Wong! Start over and evaluate the valve train. My guess is you will find the problem. If it’s above your pay grade take it to a GOOD mechanic.

 

[427John]

I agree,you need to check out your valvetrain,unless you are running astronomical valve spring pressures rocker studs don't just snap just like pushrods don't just bend there was a reason it did that.

 

[MacsW33]

First off just a FYI I bought this motor already built. It was not my decision on the components installed. Any way So yea 3/8 studs. These snapped at the rocker. Pretty sure these are the $25 set that showcars sells. Hence (cheap).

 

[La Hot Rods]

How many threads are engaged on the poly lock?
Looks like not many threads

 

[MacsW33]

It does not look like much.

 

[64ss409]

Nothing to do with the broken stud, but the rocker next to it is not centered on the valve stem. Or maybe you loosened it?

 

[MacsW33]

Loose

 

[tenxal]

Pretty sure these are the $25 set that showcars sells. Hence (cheap).

Showcars strikes again.......

 

[Don Jacks]

For WIW the cheap rocker stud that Show Cars sells are the shoulder less type.I'm with James,wrong studs installed[too short],possibily cheap ARP look alike small block studs.

 

[heddrik]

Don, are there ARP 3/8" studs for 409, or do 409s use the small or big block studs?

 

[Skip FIx]

ARP makes studs with different length top and bottom threads, so you can measure yours and add some length where you need it. All BBC are going to be 7/16.

 

[heddrik]

Thank you fellow Texan. I'll use 3/8, not sure if cam I will use will require longer or not, Have to ask Don .

 

[32witha409]

ARP makes studs with different length top and bottom threads, so you can measure yours and add some length where you need it. All BBC are going to be 7/16.

100% agree, I broke a OEM press in pined stud (bad move leaving them in the first place ) and went to 7/16. I had to make sure the head end when past the pin holes so they didn't leak and that the polylock engagement was correct when choosing the right stud. The set screw needs to close to the top end of the PL. There are quite a few options. Oh and I also pressed dowel pins into the OEM pin holes in the head with red locktight. Might be overkill but it doesn't leak.