Took the heap to a show today with nephew...a lot of awesome Foooords (will get pics up later)! On the way home...Comet all of a sudden started running rough...blue smoke out pass side exhaust!!
The 289 has 140 miles on it... I put gloves on and yanked both valve covers fearing a cam lobe headed south. Found the intake rocker stud on #1 intake clean snapped-off (about 3/8”)...rocker was laying there... These are the studs that came in the Edelbrock RPM heads. Motor hasn’t seen north of 4K yet. I think a set of ARP studs is in order!!
Not that I can ID... I spent a lot of time on getting the geometry right - especially switching from the 1.7 to 1.6 rockers. Sweep was less than .040 and just a little towards intake manifold side.
I don’t think I Gorilla-tighted any of the poly locks but even if so I’d think the poly lock would split before snapping a stud.
I guess the earlier studs are dubious...if they’re stamped ARP GTG...if not...they’re not... I guess I’ll get a set of ARP’s and keep honing my lash time!
Yah, I remember you’ve got the Eddy heads also. Not new, I bought ‘em used. IIRC there are three (at least) iterations of the Performer/RPM heads. 1st gen had the “eyebrows” for coolant pass...and got a bad rap for springs chewing up heads...Edelbrock shipped cups to you for free...
2nd gen castings are largely same as current but somewhere along the way they changed rocker studs to ARP. From what I can tell reading stuff, the reddish-purple tinged (from heat treating) studs not marked ARP have a rep for being brittle.
ARP must oxide all their stuff last...it’s always uniform black.
Dang that looks broke near the top. the fulcrum has a flat for the locknut to land in,,,is it possible the fulcrum got flipped 180° & not enough stud threads were in the nut?
poboyjo65 wrote:Dang that looks broke near the top. the fulcrum has a flat for the locknut to land in,,,is it possible the fulcrum got flipped 180° & not enough stud threads were in the nut?
Sorry for your bad luck Rocket. I think Johno might be onto something.
Thanks fellers...I’d be surprised if I had one/any upside down but since the rocker was laying off to the side I don’t have any way to prove I didn’t!!
I’ll order a set of studs & check geometry, etc. again when redoing. I went from 6.9” pushrods with the 1.7 rockers to 7.050 with the 1.6’s. That seemed like a lot but I checked with the adjustable pushrod like 3 times & then with the new ones when installing.
how big was the piece of stud that broke off? those rockers look like same as mine too,are they comp pro magnums? mine seem to have a lot of threads showing ,,,was probably like you said just brittle studs. I think I bought my heads around 2005-2006,maybe earlier, I wonder which gen they are? where is the eye brow? & where would the ARP be stamped? on the nut part of the stud maybe?
Yup, Comp Pro Magnums. The piece that broke is probably 7/16” long...gotta find it & will measure. I need to order new studs...these look the closest to the Edelbrock studs (Link to ARP on top, Edelbrock on bottom):
After thinking about it,if it broke it doesn't matter how many threads were in it,still shouldn't have broke. & since you didnt have any stripped threads.
I think I'd be afraid I'd get the same studs (old stock) of the eddies.that would be my luck.
