Broken rocker stud. wrong length pushrods?

[rdc767]

Thanks guys
The more I look on the web and your posting I am learning alot. I don't think the rocker is rolling back and striking the bottom of the stud. There are no wear marks on the roller rockers.

I found this thread.

http://www.fordmuscle.com/forums/all...plate-fix.html

With not having harden pushrods and a mis aligned pushrod guides caused a bind and snaped the stud.

I found isky adjustable guides at summit. I think the rest of the part list should do it.


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AFR-6104 Isky 5/16" Adjustable Guide Plates ; Qty: 1 set $48.95 $48.95
·This part is temporarily out of stock, but you can order it now. Tentative ship date: 4/16/2009, if your order is placed today.

ARP-134-7101 Rocker Arm Studs, High Performance, 3/8-24 in. Thread, 1.75 in. Effective Stud Length, Chevy, Small Block, Kit $37.95 $37.95

FEL-8548PT-2 Head Gasket, PermaTorqueMLS, 4.100 in. Bore, Ford, 260/289/302/351W, Each $16.69 $16.69

FPP-1262 Gaskets, Intake, Composite, Printoseal, 2.10 in. x 1.28 in. Port, .060 in. Thick, Ford, 260/289/302/351W, Set $21.95 $21.95

FPP-1486 Exhaust Gaskets, Header, Steel Core Laminate, Dual Bolt Pattern Splayed Port, Ford, Small Block, Set $33.69 $33.69

LUN-7078-16 PUSHRODS $115.95 $115.95

[Dwight]

Buy a adjustable push rod and check the length after you get all your parts in. I had a pair of Pro Comp heads and did not check the push rod length. After I wore out the valve guides I borrowed an adjustable push rod and checked the length. I was a 1/10" short. Sold the heads, bought KC heads and I am in the process of putting my motor back together. I was scared of the possibly that the Pro Comp heads had Chinese bolts and springs.

Dwight

The Keith Craft / Brodix heads are a work of art, I hate to cover them up.


See ya'll in London in June

P.S. I used the laminated aluminum header gaskets. Cost about $50 but they don't leak.

[CHANMADD]

The rocker nut should sit in the machined recess in the pivot shaft stud hole.
Also the rods do have to be the hardened variety if you use any type of guideplate. The wear marks on the top of the valve indicate to me that the pushrods could be a fraction shorter to move that wear mark exactly in the middle of the stem.. But if you have cheap studs they are going to break.
John

[Gaz64]

Is it possible you have fitted that pair of rockers with the rocker trunnions upside down?

That may explain the mark on the stud, the trunnion was moving and flexing the stud in the process.
The trunnion has a flat recess for the posilock to seat against.

Your "rocker strike" or contact mark on the valve stem favours the stud side which means the pushrods are too long.

[DAVID GAGNARD]

Originally Posted by Gaz64

Is it possible you have fitted that pair of rockers with the rocker trunnions upside down?

That may explain the mark on the stud, the trunnion was moving and flexing the stud in the process.
The trunnion has a flat recess for the posilock to seat against.

Your "rocker strike" or contact mark on the valve stem favours the stud side which means the pushrods are too long.

That was going to be my question. When installing the roller rocker arms, look "inside" at the part that goes over the rocker stud, one side is flat and the opposite side is rounded. The rounded side goes down and the flat side up. The poly lock rests on the flat machined surface of the rocker arm. You may have had this one upside down... The wear on the pushrods from the guide plates indicates either they are not hardened pushrods or very cheaply made pushrods.

I would install all new rocker studs,a good set of hardened pushrods and check and re-check all your rocker arms for any damage.

David

[rdc767]

The flat side of the roller rocker tunion was up for the poly lock. I can see how this could happen.

The arp studs are longer 1.75 compared to 1.5 for the stock... With shorter pushrods should bring the rocker lower on the stud.

I did wear check with a felt marker on a few location and it looked ok..... Next will be stock legnth.

Most of the wear marks are centered. But some are on the sides. Just from researching Pro comp heads on different forums there are reports that the pushrod guides are off and the studs are off centered too.(cheap machining in china) Looking at the guides you can see it. Isky make a adjustable guides I will try. The rockers look in good shape with no stress marks.

thanks again for the thoughts.
Ron

[Rick Parker]

Ron: The Isky adjustable guide plates are a very good and often overlooked idea. They can be carefully tack welded (Tig) after final adjustment and alignment is achieved to eliminate future movement.
Take your time to get the roller directly centered over the valve stem. Recheck after tightening the stud on the guide plates.
Don't be so quick to denigrate the heads you have. They are marketed at a very attractive price point. Yes they may need to be "touched up" but just treat them as castings and add good hardware, pay attention to details and you'll have a very good set. Many that aren't aware of it, have their pushrods and rocker tips misaligned on 289, 302, & 351's. It is very common. That was the purpose of the shaft mounted rockers being developed along with eliminating the side to side flex in the stud as the valve opening forces are exerted upon it. Cycle the engine and look at the areas where the pushrod gets close to the head itself in the slot. Be certain they do not "bottom out" in the slot (doubt they will) unless you are using a high ratio rocker arm (1.7+). Also keep an eye on the area where the spring is under the rocker arm close to the stud sometimes the rocker will hit on the spring retainer.

You're on the right track....just keep an eye on all the details.