How loose are the rockers suppose to be on the rocker rail? I have a stock 72 350 SBB, while checking the push rods with the rocker rail removed from the head, I noticed the rockers on the rail seemed to be very loose. Is this normal? There seems to be a thin bearing inside the rail pass through for each rocker. Could this bearing wear down causing too much play?
The picture above shows the gap between the rocker and rail. That seems excessive to me. Maybe it's normal...???
The aluminum rockers wear badly. So yes it can be normal wear. The big question is when installed do they preload lifters or are they still loose. If so replace shafts and rockers with later stamped steel units. They need to be installed to really check
These are the stock steel rockers and rail. Yes they still preload the lifter and don't cause any rocker chatter or noise when running, but I do notice that there is not good oil flow to the rockers. My thought process is this possible wear on the rockers/rail may be enough to not fully compress the lifters which then does not push the oil up the push rod for proper lubrication. Also not opening and valves properly thus robbing the engine of power and performance. I may be completely wrong
No those are 1970-1972 aluminum rockers pictured. Later uses stamped steel. . If oil is a problem you may want to put a mechanical gauge on it. If it's low chances are you need a front cam bearing. Replace it with a TA backgrooved.
There's a reason the replacements are steel! Those aluminum rockers started to wear out at 30k miles. The steel rail is likely worn as well.
Those are shot! I happen to have a stamped steel set, super clean, for $55, plus shipping if you are in need.
So now that I know the rockers are shot, and I am making arrangements to get replacement steel one's a few comments and questions: - Do I need to be concerned with the existing pushrods? None of them are bent and all have clear oil passageways. Will these pushrods work with the new set of steel rockers, is the geometry the same? - I'm I correct that I should see better performance from the engine once these rockers are replaced. The valves should be opening and closing properly allowing better gas delivery and exhaust. - Should I expect better oil flow from the push rods to the rockers once replaced? My theory is I will be restoring the full compression of the lifter pistons forcing better oil flow up the pushrod to the rockers. My engine has good overall oil pressure, replacing these loose rockers should bring the valve train back into spec improving the oil distribution. I know these may be dumb questions but I'm always tryng to understand better and it may help someone else in the future.
I would buy new pushrods...they're cheap. Overtime the ball on the ends of the push rods tend to flatten....begin to take on an egg shape.
Measure pushrod length before you think you need new ones. Physically look at the ball ends with magnification for abnormalities. They should be 5/16" ball, both ends. I believe 9.668" long. The ends are welded in and hardened to hold up to wear. Your rockers didn't wear out due to not being oiled properly, more as a result of dissimilar metals, as GM replaced the aluminums with the stamped steel version. I have 14 extras I can throw in the rocker box if you want. I cut two in half, threaded i.d. and made pushrod length checkers!
That would be great Mart please throw in the pushrods. I did clean my existing pushrods but I did not measure them, having extras would be very helpful. Thanks again for being a great forum member.
Already threw them in the box! You should be able to put together a good full set with these 14 & what you have. Should get everything Saturday.
I'm just about to start the aluminium rocker/rail swap over to the stamped steel rockers/rail. I've checked all of the push rods and none are damaged (also have some spare push rods just in case) Is this swap as easy as it appears, just remove the 4 rocker rail bolts, remove the aluminium rockers & rail then lube the steel rocker replacements and bolt them in. Is there anything else I need to consider or do for this swap? Is there a left or right side specific to the rails? I understand while installing the new rail and rockers to tighten subsequently a little at a time until fully seated than final torque each bolt to 25 foot pounds. I want to do this right and hopefully not bend any push rods.
You should not bend any pushrods unless they are not seated in lifter correctly. Never had to seat them but did run a thread cleaner tap inside holes . Sometimes junk gets in there
I installed the stamped steel rockers and took the car for a drive. It seemed to idle a little better, and during the drive it seemed to have a little better get up and go. Not as much as I was hoping for. I did see improved oiling from the push rods which is encouraging. This is an improvement to the worn out aluminium rockers. Next, I plan to retune the timing and carb now the rockers are in better shape and see how she runs. Thanks again to the forum members for the parts and advice.
