Broken Rocker Stud

[Auto Anatomy]

I SWEAR I was just riding down the interstate when I heard a loud bang and the engine started running terribly. I could have bet money the engine popped, but thankfully it was just a broken rocker stud.

The engine is nearly stock with a 270 cam and Isky valve springs.

I'm the guy that always builds back better, even if it means somewhat overkill for a mild street engine. I've seen chatter about ARP rocker studs but can't seem to find any information on them.

Is there anyone who has a set of ARP rocker studs they'd like to sell, or a line on any?

Thanks!

Sean

[caraholic4life]

Contact Ken Hand aka Vairmech,

While at the Helen Springfest event a couple weeks ago, Ken had on hand some of his Roller Rocker sets as well as his "Shaft Mount Roller Rocker Kits"

These may be just what you are looking for. Ken prefers e-mail as communication through a P.M. may be slower.

I don't recall ever seeing a rocker stud fail like that in a Corvair but apparently it has happened as shown in your photo.

Here is contact information Ken has as a part of his signature.

Ken Hand
Handy Car Care
248 613 8586

YS-318
Vairmech@aol.com

[toms73novass]

Was this a original or a new aftermarket? I have heard of the repop ones breaking.

Also, if the rockers are aftermarket did you check that there was plenty of room in the lower slot that it would not contact the stud at the higher lift of your cam.

[Auto Anatomy]

Was this a original or a new aftermarket? I have heard of the repop ones breaking.

Also, if the rockers are aftermarket did you check that there was plenty of room in the lower slot that it would not contact the stud at the higher lift of your cam.

Original stud and original rocker. Have not checked the slot but will do so asap

Sean

[Auto Anatomy]

Contact Ken Hand aka Vairmech,

While at the Helen Springfest event a couple weeks ago, Ken had on hand some of his Roller Rocker sets as well as his "Shaft Mount Roller Rocker Kits"

These may be just what you are looking for. Ken prefers e-mail as communication through a P.M. may be slower.

I don't recall ever seeing a rocker stud fail like that in a Corvair but apparently it has happened as shown in your photo.

Here is contact information Ken has as a part of his signature.

Ken Hand
Handy Car Care
248 613 8586

YS-318
Vairmech@aol.com

I saw Ken's rockers at Springfest and drooled over them a few times. May be a bit overkill but maybe worth it depending on price. I reached out to him.


Sean

[erco]

Hey Sean: I enjoy your channel, great vids. Nice to hear your are putting some miles on "the Flooded Corvair". You really need a pithy new nickname. Start with Floody and go from there. Floodershy if you're Bronie. :) Run a contest on your channel to get names.

As mentioned, this is a rare failure and unlikely to recur. Millions of stock rocker studs out there agree. Don't hesitate to use a stocker and motor on into another palmetto sunset.

Give my regards to SC, my '67 Monza and I are both originally from Charleston but we live in LA now. I don't miss the humidity and bugs.

[Auto Anatomy]

Hey Sean: I enjoy your channel, great vids. Nice to hear your are putting some miles on "the Flooded Corvair". You really need a pithy new nickname. Start with Floody and go from there. Floodershy if you're Bronie. :) Run a contest on your channel to get names.

As mentioned, this is a rare failure and unlikely to recur. Millions of stock rocker studs out there agree. Don't hesitate to use a stocker and motor on into another palmetto sunset.

Give my regards to SC, my '67 Monza and I are both originally from Charleston but we live in LA now. I don't miss the humidity and bugs.

Thanks! I do enjoy driving the car and plan to drive up to the nats in Dayton, OH this year. Should be around 450 miles each way.

I'm open to a new name for the car, may have to make a poll and see what people like best.

SC is great and the privet is in bloom (and smells amazing). I miss the lack of bugs living in CO, but it's nice being back in the south and closer to family. Enjoy LA (I'm assuming NOT Louisiana or Lower Arkansas)!

Sean

[Frank DuVal]

Stock stud, but what is that nut?

[66vairguy]

Stock stud, but what is that nut?

Good catch Frank. I noticed that too. Over the years I've had stock and reproduced rocker arm nuts that varied in tension during adjustment. Too tight and I put nuts in too tight box, too loose and they go in loose box and I install nut from tight box or vice versa. That way I get about equal nut turning tension. IF THE NUT IS TOO TIGHT IT CAN CAUSE THE STUD TO DEVELOP TWISTING FRACTURES THAT CAN LEAD TO A FAILURE. I wonder if that extended rocker nut went on too tight!!!

Occasionally a rocker will fracture and of course a higher lift cam increases stress. I'd pull the pushrod and see if it is bent (even slightly) indicating a clearance issue. If pushrod is fine I'd install another rocker stud.

I've never had a stock style rocker nut come loose (as mentioned I swap them out if too loose or too tight). I'd probably get rid of those "long" rocker nuts - just me!

[Auto Anatomy]

Stock stud, but what is that nut?

It's a polylock. Basically a nut with a setscrew in the end to keep the nut from loosening. You set the valve lash as usual and then lightly tighten the setscrew to keep the nut from backing off.

Sean

[caraholic4life]

Stock stud, but what is that nut?

I also noticed the long stud stye nut. My initial thought was that the reminded me of the Poly Lock stye rocker nuts but all the components were not there. My next thought was that these were someone's idea of a "High Performance" part.

I am NOT well versed in this area but looking closer at the rocker arm, it appears that the slot looks more like one found for a small block Chevrolet motor with a shorter slot in it.
I seem to recall the shorter slot rockers being sold as replacements for the Corvair rocker arms at one point in time and may have had a different ratio as well. (1.5 VS 1.6 ?) Do not take my word on this and Please correct me if I am wrong about it.

[66vairguy]

Stock stud, but what is that nut?

I also noticed the long stud stye nut. My initial thought was that the reminded me of the Poly Lock stye rocker nuts but all the components were not there. My next thought was that these were someone's idea of a "High Performance" part.

I am NOT well versed in this area but looking closer at the rocker arm, it appears that the slot looks more like one found for a small block Chevrolet motor with a shorter slot in it.
I seem to recall the shorter slot rockers being sold as replacements for the Corvair rocker arms at one point in time and may have had a different ratio as well. (1.5 VS 1.6 ?) Do not take my word on this and Please correct me if I am wrong about it.

Interesting! Did they drill the Corvair oil hole in the SBC rocker?

I've read the old 1.5 vs. 1.6 ratio argument started with an incorrect interpretation of the GM drawing. As the rocker "rocks" one end is longer from pivot vs. the other so the ratio actually changes as the rocker ends move through an arc, hence the changing ratio. I HAVE NOT CONFIRMED THIS!!!! Has anybody done the geometry???

[Auto Anatomy]

Interesting thought, but as far as I know the rockers on the car are original. At least, I haven't replaced them. I do have a couple original ones that I can compare with.

Sean

[Auto Anatomy]

Measured the rocker slot and it's identical to the original ones I have on the shelf, so I assume they're OEM parts. The slot is ~ 0.600" in length.


Sean

[sethracer]

Chevy slightly changed the design of the rocker near the end of production. All stock in the replacement part warehouses eventually changed to the new style. The later design had a wider, but shorter contact face for the valve tip. I don't believe there was a change to the ratios. I always save the rocker/ball combos from early engine Corvairs, since they rarely went over 3000 RPM in their Powerglide life. (Subject to oil being supplied) Best for higher lift cams.

[toms73novass]

Looking at your pictures have you pulled another rocker? The wear that is on the pushrod and pocket of the rocker is not normal. Also the contact point with the valve does not look right. I don't know if this happened as it was beginning to break.

One more thing the one on the shelf, to me, stamping wise, looks original but the one from the engine looks different (could be picture perspective). Your rockers might be a aftermarket replacement that look similar. Ken Hand is the pro on identifying rockers!