Question on Crane Gold rocker arms for 440? PROLEM SOLVED!!! Finally

[chargerbr549]

In our shop we built up the original 440 for a guys 69 RT Coronet a while back its been and its possessed or something it doesn't want to run for very long without something going wrong. Its had problems keeping pushrods were there are suppose to be and bending them all too often and sometimes kicking out a lifter. First he had a mild hydraulic flat tappet cam and then he went to a hydraulic roller cam (.545 lift) most of the valvetrain was changed except for the crane gold rocker arm set-up, the pushrod area has been clearanced and they are not hitting the heads valve to piston clearance is plenty, valves are not sticking, the rocker arm geometry is spot on right in the middle of the valve and the pushrod length is right where its suppose to be, with the flat tappet cam we used the crane pushrods and with the roller cam it has custom length smith brothers pushrods lifter preload is about a half a turn from lash, spring pressure is at 380 lbs open 160 lbs seat. At first we thought we was just over revving the motor since he does run it very hard but he has an MSD box with a 6000 chip in it so it should take that ok but right now you can't get very many miles on it and sometimes if you let it sit for a while after its been running great and then fire it up it will backfire through the carb and then spit out a pushrod and kick out a lifter (not cool). Do you think the cheesy springs that they have seperating the rocker arms could be moving around  and causing excessive lash? You can take and squeeze the rocker arms together compressing the spring with very little effort, do you think eliminating the springs and putting in spacers would cure the problem? Everybody is pulling there hair out on this one.
    I have had these same crane gold rocker arms and cheesy spring set-up on my 440 with the 284/484 for about 15 years with not problems, whats up?

Kevin

[firefighter3931]

Kevin, what heads are on this engine ? what machinework was done ? How is the retainer to guide clearance ?


Ron

[histoy]

I had problems with the Crane gold rocker arms.  They wouldn't stay positioned over the valve stem.   Ruined 3 rocker arms.  Replaced the entire set, and still had similar problems.  I took the round washers (shims) from the first set and added them to the flimsy springs on the second set.   The additional pressure held the rocker arms in place and solved my problem.

[chargerbr549]

History, my gut says that rocker arms are moving around but not positive.

Ron the heads are cast iron 906's machined for comp spring seats 4772-16 (i believe) 929-16 valve springs set at 1.865 installed height 741-16 retainers with 616-16 +.050 locks and ferrea 5000 series single groove stock 2.08 int and 1.74 exhaust valves, it has .100 retainer to seal clearance at .545 lift. Its running sealed power forged six pack pistons and it has well over .100 piston to valve clearance and the block and heads had only minor milling just to clean up the surfaces, if I remember right the pistons were about .018 in the hole at assembly. Help me the chevy guys in the shop are getting annoying. LOL

Kevin

[Challenger340]

Thats weird !
Tough doing diagnostics via the internet, so just some things to check, but sounds like you've already checked a bunch.
I'm NOT trying to insult anybody here, just ideas.

"Left" & "Right" Rocker Orientation is correct offset ? Very unlikely.

Rocker Tip running "over the edge" of the Valve @ lift ?  Not Likely, but maybe check.

Retainer to Rocker Clrc. with the + .050" Locks ? Unlikely, but check again maybe ?

Pushrod Clrc ? ( I know, you already checked that) Unlikely.

Pushrod "Cup", where it seats on the adjuster, hitting the bottom of the Rocker @ Lift ? Possibly ?

I always Cut Spacers to shim the Rockers, just as protocol, because I got no hair left to pull out !

[375instroke]

Should the rocker tip be centered on the valve when closed, or should the tips travel between closed to open be centered?

[firefighter3931]

History, my gut says that rocker arms are moving around but not positive.

Ron the heads are cast iron 906's machined for comp spring seats 4772-16 (i believe) 929-16 valve springs set at 1.865 installed height 741-16 retainers with 616-16 +.050 locks and ferrea 5000 series single groove stock 2.08 int and 1.74 exhaust valves, it has .100 retainer to seal clearance at .545 lift. Its running sealed power forged six pack pistons and it has well over .100 piston to valve clearance and the block and heads had only minor milling just to clean up the surfaces, if I remember right the pistons were about .018 in the hole at assembly. Help me the chevy guys in the shop are getting annoying. LOL

Kevin

Well, it sounds like all the right things have been checked and there is lots of clearance in the areas where there needs to be. Piston to valve and retainer to guide are the critical ones.....i was pretty sure that you had checked those but just wanted to make sure. 

I'm at a loss because this is a combination that should work like clockwork. I've used the spring (spacers) on crane rockers in the past with zero problems. Maybe the next thing to try is a solid spacer....it can't hurt. The only other thing that comes to mind is valve float but that doesn't seem likely given the dual spring setup unless the springs are really tired.

Is it the same pushrods that keep becoming damaged ?



Ron

[Musicman]

Just out of curiousity... what kind of shape are the lifters in... sounds almost like your pumping up over time and sticking there 

[chargerbr549]

The cam, lifters, pushrods, valve springs set-up for the roller cam all have no more than 200 miles on them, with the flat tappet cam set-up I remember that he bent a couple of pushrods but he replaced them himself so im not sure what cylinders that it was on but with the roller cam set-up it did it both times on intake and exhaust on number one cylinder and popping the intake lifter out of the bore. The lifters appear to be in great shape but we are going to replace that set and put in spacers between the rockers and see if that fixes things. It also has a cam button and the cam is not moving back and forth causing problems that way.

Kevin

[b5blue]

Valve guides checked? Mine got sloppy and bent push rods like bananas! 

[mally69]

 

[chargerbr549]

UPDATE: So far so good (knock on wood) it's stayed together, we installed spacers between the rockers instead of the cheesy springs, put in thicker walled pushrods and put new lifters in #1 hole so we will see how it does over the long haul.

Kevin

[375instroke]

Baby those rockers.  They're collectors items now.

I'll ask my question again: Should the rocker tip be centered on the valve when closed, or should the tips travel between closed to open be centered on the valve centerline?

[chargerbr549]

Well it wasn't too long after my last post he bent another pushrod again and these were the pushrods that were stronger than the first two sets and they should be able to take around 600 lbs open spring pressure. Well the first set was the crane pushrods and the last two sets were smith brothers pushrods and talking to smith brothers they said that if it keeps bending the intakes (although the first couple of times it did it it bent the intake and exhaust pushrods which it must have bent the intake first and then took out the exhaust) and bends it upon start up the timing must be too far advanced and kicking back. He had set the initial timing around 18-20 degrees according the recommendation of the barry grant 850 race demon carb he put on it, so he put a new MSD ignition that will start around 0 degrees and the then it will goto about 20 degrees after its running. So for the last month he has been driving it and hasn't had any problems (KNOCK ON WOOD AGAIN), so I hopefully can say PROBLEM SOLVED! I learn something new everyday.

[b5blue]

Yeah!!  Interesting info too! 

[firefighter3931]

Thanks for the update Kevin 

Fwiw, i've had many engine's kick back and never bent a pushrod.    That's an interesting theory 



Ron

[chargerbr549]

None of us in the shop thought that was the answer but so far he hasn't had any problems, I have had several engines with alot of intial timing and never had a problem and have never heard of people bending pushrods that way but like I say learn something new everyday.

Kevin