I've had three polylocks come loose and the tips of the push rods have broke. I removed a fourth rocker and found that pushrod tip had crack and fell apart when I removed the rocker.
I'm using Comp Cam's rockers and push rods. Two push rods in the photo have tips that are starting to wear flat.
I'm thinking that I measured wrong and I'm using push rods that are too long and/or the rockers can't handle the .555 lift. By looking at the wear patterns just below the pushrod tips, it looks like they're hitting the rockers. There is a wear groove on the rockers. Can anyone concur with what I think is the problem. Thanks.

These are hardened push rods so there is a tremendous force being produced.
The locks coming loose are causing the breakage but I'm thinking the push rods are too long.

 

Can you take a better close up pic of the damage. I can't see anything.

 

Can try clearancing the rockers with a die grinder. The rocker is clearly hitting the fat end of the pushrod.

 

More pics.

 

I agree you could clearance the rocker but I would double check the rocker geometry. Pushrod length might cure the problem.

 

First of all is your rocker geometry right with those rockers pushrods? Can you take some pix of the tops of the valve stems? Those rockers should be able to handle .700 lift if everything is right.

My first guess is your pushrods are too long and/or your geometry is off. But the more I look at it I think you may be nearing coil bind, something is hammering those pushrods flat.

 

More pics. Geometry was checked the best I could do. Looks like the wear on the valve tip is in the correct spot. The springs match the cam per se, had to shim to get correct spring height. See what you mean about maybe coil bind.

 

Geometry look good. Either you have coil bind or the retainers are hitting the guides, seals.

Jmo.

 

Added pics of new rocker on right with used on left. All rockers have the same wear spot.
I checked the space between the bottom of the retainer and seal and had plenty for my lift, there was close to .900 clearance. I'll have to check the spring for coil bind. Even though the geometry looks good, I may go a little shorter on the pushrods (9.800 down to 9.750) just to see if that alleviates the abnormal wear on the rocker arm. Or just grind the spot out like mentioned. Now my valve covers barely fit, have had issues with the locks hitting the covers so a little shorter push rod might help. I most definitely have to go the cheapest route.

 

I've read that a cam with more than 520 lift requires machining of the top of the guide.

 

Let us know, have you already tried using 2 valve cover gaskets on each side? Comp sells a shorter poly lock.
Fwiw, obviously your geometry is right so if you had to use that length pushrod to get the right geometry, then those may be the wrong rocker. When correct the rocker is used it should sit on top of the valve and pushrod with plenty of room to move, negating the possibilty of the pushrod hitting the cup area of the rocker.

 

I agree, a shorter push rod may help. Also I see were the push rod is hiting the rocker. Like said above, clearance the rockers in those spots.

Gene

 

Thanks for all the reply's
The guides were machined but I can't say how much. All the machine work was done before I bought the motor.
I'm using one gasket for now, a thicker rubber one i got at Napa. Seems to work but two would be better.
I have a feeling these rockers were made for thinner pushrods, maybe 5/16", I got the 3/8" versions. I've started to grind out the rockers to make room for the pushrods, I may have to buy a few more new ones.
Not sure if all studs are the same besides the size, these heads had Harland Sharp rockers before. I didn't change the studs or guide plates.

 

Installed new shorter 9.750 vice 9.800 push rods and modified the rockers to make room for the push rods. I tightened the poly locks by snugging the locking screw then turned the adjusting nut a little bit.
Only took about 10 mins of driving before a lock let loose. I guess I'll start by replacing all the locks with ARP types. Need to make sure the studs are flat at the ends. Or maybe just replace those"Ford" rockers with something different.

 

What bothers me is why the poly's are letting go. How many threads do you have engaging the barrel?

Also, are you sure you've got 1:6 ratio rockers? They look a little short to me.

 

One more thing, assuming you are using a hydraulic cam what are you using to gauge how tight the poly barrels need to be tightened? In other words, on a solid cam I adjust for .002"-.004" (whatever lash is, can't find cam card right now) and then turn the jam nut with a long allen wrench to tighten it into place. What procedure are you using?

 

There's a lot of threads, the locks loosen up but they don't come off. They're 1:6 ratio.
I got a Hyd cam. I turn the adjusting nut until zero lash then go 1/2 turn more. Before i get the full 1/2 turn I turn the locking screw until it contacts the stud then I turn the adjusting nut the rest of the way.

I haven't pulled a valve cover yet, engine still hot but it sounds like one came loose. Will verify. Seems to happen if I get on it a little bit (3000-4000 rpm).

 

Dan, you might try locking them down using your method and then cinching down on the allen lock screw even more. When I do mine I have a long handle allen wrench and turn it until its hard on my hand to keep turning. The only other way I know of is using your method, except when turning the extra 1/2 turn you turn both the barrel & lock at the same time. This jams the lock in place.

Also, your rockers look to have a fat bearing housing, most likely they ARE made for 5/16 pushrods. Still, if you can clearance them I would. Or get a set designed for the 3/8 rods. Pm me if you decide to go this way, I'll get you the right part number.

Steve

 

Well I typed too soon. Locks are tight. Now the rockers wiggle or are moveable side to side not up and down, where there is no load on them, valve closed. When I set them they didn't move. The lifter is probably bled down I guess.

Looks like the I blew another header gasket. The stock type I had installed. I guess it blew when I goosed the throttle. Bottom center section. Here we go again.

I did clearance the rockers.

 

Sounds to me like you've got 2 problems that a set of Edelbrocks would fix lol! Well good luck with all this Dan, did you give any thought to putting an extra flange between the head and the header, using 2 gaskets per side?