The Stovebolt Site Forums The Shop Area Engine Shop Broken Rocker arm Shaft ?

Greetings all, A week ago i was driving my 1951 5W. down the road and i heard a loud clanging sound coming from the engine valve cove,r i was able to limb home, only to find that the front rocker arm shaft was snapped at the third post/bolt location nearest the coupler/oil pipe.
No idea how this happen. the engine is a 1955 235-6 that is completely redone( about 3,000 sunday miles) Anyway a received a new shaft from Kanter and without messing with any of the adjustment bolts/nuts i gently removed the front and rear rocker arm assly. to install the front shaft, easy enough. retorqed the post bolts and went to start the engine. The engine seemed a bit hard to start ? stalled out twice on the road almost like it wasn't getting any fuel. turned the idle srew up a bit and carb. ( Hollywebber2Brl.) seems to struggle. Checked timing/ plugs / all the usual stuff. went out again No power in third and fourth. (granny Low)

do i need to re-adjust valves? I ran engive with valve cover off. everything seems tight and in place every rocker arm was ozzing oil thru the little holes on top. any help.

shaft was broken were bolt goes thru it, suspect bolt loose or to tight or no oil to that area ?

After removing the rocker are assembly, Yes, you do need to re-adjust the valves..

Please follow Bill`s advice and adjust the valves.
Then get back to us so we know wether or not it is fixed. There may be more problems but do the valves first

Running the 235 on the road without readjusting the valves will result in either excessive rocker arm noise (rockers too loose), or power loss ( rockers too tight).

You should inspect all the parts before driving it anymore. I've never heard of breaking a rocker shaft, and trust me, I've found strange ways to ruin a 235.

Remove and dissassemble entire rocker assembly. Check all parts for excessive wear or damage or signs of cracking. Check for bent pushrods & bolts. Inspect valvesprings, retainers, locks on cyl head. If everything looks good, reassemble rocker assembly and set clearances cold. Method depends on if solid or hyd lifters. Let engine run with valvecover off until it reaches operating temp. Set valves again. Now go drive, I bet the low-end power will come back.

I just went thru this with my new 235. Setting the valves too tight will make the engine do all sorts of crazy things. Idle rough, stall, hesitate, bog, etc.

good luck

chip

if anything leave them a little lose, my 80 yr old man always sai better to hear them than burn them

Absolutlely leave them a bit loose if you are unsure. I don't trust my valves unless I can hear them slightly. I have a straight six BMW with 155k miles, an inline 4 motorcycle with 45k miles, and my stovebolt with who knows how many miles, all with solid lifters and mechanical adjustment, and all running perfectly smooth with slightly tapping lifters and absolutely no valve train problems. The BMW won't pass emissions and gets bad gas milage if you set them too tight, stovebolt and bikebolt are exempt.

In addition to inspecting the pushrods, remove the side covers and check the lifters. If they're the original style solids, they come apart at the cap on the top, which is pressed into the body.

Greetings all, read all the responses and have to agree, i thought i'd take the easy route and not adjust, but realize it must be done. I'm leaning toward rockers being to tight that is causing low end loss as CHIPHEAD suggests.

The engine by no way has been pampered prior to the shaft breaking, drives are usually 60-70 mile trips with no overheating or any engine noise whatsoever.

also "silly question " solid or hydralic lifters? how do you tell? Engine is 2nd series 1955. being that the truck is a 1951 all my manuals are for that year range 47-53.

I'd like to do the work myself, of course, with the Stovebolt BBoard as a guide. talked to some "old" garage mechanics and i was told to adjust with engine running. trick was to get an unused valve cover cut the top upper half and bolt it down, this would eliminate any splash from oil and give you plenty of time to adjust ? thanks for any help. J :confused:

Check for lubrication when you adjust the valves, you should get a slow drip next to each rocker. A lot of times the oil passage to the rockers plugs up on 235's.

4ontheFloor,
yes, I do get oil seeping thru little holes on top of all the rocker arms, does this suggest that i have Hydraulic lifters ? Cough ! sorry the air out here in san bernadino is extremely bad due to those nasty fires.

Nope, all that means is that your oil passages work, which is good. The lifters are down in the block by the camshaft. There is no way to tell which they are from the rocker arms.

Who said adjusting valves was easy !, I've made three attempts to adjust the valves per shop manual for intake and exhaust clearences with engine hot and off and still not getting
power to third and fourth, what gives ? can I get a PLAY BY PLAY . I love my truck and my foot is sore from kicking it due to frustration.

I've read numerous articles on subject, but can't seem to get it right. I'm pretty sure the lifters are solids on the '55 truck engine. I do the exhaust rockers first and found one valve/spring that rises as I loosen the nut and adjusting srcew and therefore I can't adjust that valve clearence, what does this mean?
help.

If the motor has solids, this is how I set them:

Engine hot/warm and off: Line up the rotor in distributor with a sparkplug tower on cap. This is the cylinder which is about to fire, and both valves will be closed. Set the intake and exhaust clearance on that cylinder. Then bump motor over until rotor lines up with next sparkplug wire on cap. Then set the intake/exhaust clearances for that cylinder. Follow rotor around firing order until you set the valves for all 6 cylinders. That way you know you set the valves when they are closed. It is imperative that you set the clearances with the lifter on the "base circle" of the cam lobe in question when the valve is closed.

If you back off on an adjuster and the valve/valvespring starts to move, then that valve's lifter is not on the base circle (seated) and that valve is still open. (unless you had the valve set way too tight the last time.)

What do the books say to set the clearance to? For a stock cam, try .010" on intake and .012" on exhaust. More clearance if aftermarket cam. May clatter a little more than stock, but you'll know that the valves are closing and the slight extra noise won't hurt anything besides your ears.

Using the method for 6 cylinder engines that Racecarl posted here is much easier Chip. You will have to look up the clearances for whatever engine you are working on..

With the engine heated up and at TDC # 1, Adjust the valves in this order..

#1 Intake & Exhaust
#2 Intake
#3 Exhaust
#4 Intake
#5 Exhaust


Spin the motor over by hand one revolution, the ball will be on the pointer again, now you are at # 6 TDC

Adjust

#6 Intake & Exhaust
#5 Intake
#4 Exhaust
#3 Intake
#2 Exhaust



Another way to remember the order is on # 1 TDC start from the front and do the first three, skip one, do one, skip one, do one, skip one, do one.. Leave the back three untouched. Then spin to # 6 TDC and start from the back and do the same thing..First three, skip one ,do one, etc..Leave the front three untouched, you did them on the first pass..