The Stovebolt Site Forums The Shop Area Engine Shop Bent push rod

Today I took the side cover off of the newly acquired 235 and found that one of the pushrods is bent. Obviously, this is the perfect time to replace it. Can I look for a good used one to replace it with or do I have to replace all 12 with new pushrods? I don’t know how critical these parts are. Also, do 216’s and 235’s use the same pushrods? Thanks for any advice.

Before you do anything else, check the other valves to be certain they are not stuck, causing another bent pushrod. Oil the guides, tap the valve end of the rocker with a soft hammer or 2 X 4, etc.

There should be many used 235 pushrods available, measure your first.

Ed

In addition to the length vs. deck height (216 vs. 235, 261) the pushrod upper cup is all the same but the bottom will also vary based on what tappet type you have.

I have the same issue. Fortunately, a member of this forum had a used pushrod he could send to me. I have a 1962 235.

I searched the net for new pushrods. Melling MPR-32 and Sealed Power RP-3020 are supposed to be replacements. The Melling appears to be the same length as my stock pushrod (11 5/16") but is 1/16" thicker which is OK with me. The Sealed Power pushrod seems to be longer than stock by 3/16.

I'm pretty sure that the 216 and 235 have different length pushrods. See earlier discussion in the link below. The adjuster screws are the same.

https://www.stovebolt.com/ubbthreads/ubbthreads.php/topics/703038/bent-235-push-rod.html

If you unstick the valve you can straighten the pushrod and reuse it. The idea of checking all of the valves for sticking before moving on is a good idea.

The better call here is to replace them all. The original GM push rods were a solid push rod design and prone to bending, especially if the motor had been sitting for any length of time and/or one or more of the valves were gummed up or even the least bit stuck.

The aftermarket sealed power and melling push rods are a tube push rod and significantly stronger. As an added feature, they are not all that expensive.

I'm making my own pushrods out of 3/8" thick wall seamless stainless steel tubing, since I'm going to need a non-standard length on at least one of the engines I'm building. It's not "rocket surgery" to cut the ends off a stock pushrod and press them into a piece of tubing to end up with whatever length pushrod I need. I used to order those kits from Comp Cams before they got greedy and raised the price out of sight. The tubing is available on Ebay in 3 foot lengths.
Jerry

Sounds like a good idea. Why stainless? How about 4130 Chrome Moly tubing?

https://www.chassisengineering.com/product/mis1143-3-8-x-049-chrome-moly/

12 bucks+ a foot is mainly why - - - - -the tubing I'm using is less than a third of that price, and thicker wall. I'm not trying to set lap records at Daytona here, or turn astronomical RPM! The pushrods I'm making will still be much stronger than original, without giving the old debit card sticker shock!

https://www.ebay.com/itm/182369556935

Jerry

If you go with a thicker wall, how will you press the stovebolt pushrod into it?

Probably get a better price from a local steel supplier - that link was an example.

I'll ream the ends of the tubing, and turn the pushrod shank to get about a .0015" press fit or so for about 1/2" on each end. Then it's just a matter of fabricating a holding fixture to stabilize the end of the tube while an arbor press does its thing. Virtually any fit problem can be solved with the judicious application of high speed steel. Other difficulties respond better to high speed copper and lead.

"There's very few problems that can't be fixed with a 1911 and a .30-06!"
Jerry

OK. That's probably too much machining for the rest of us. BTW, Aircraft Spruce has the 4130 at a much lower price than Chassis Engineering.

.277 ID on a .375 OD tube is 0.049 wall thickness.

If you don't have a lathe, the same results can be accomplished with a set of dial calipers, a hacksaw, a drill press, and a file. The only thing my somewhat more sophisticated procedure does is save a little time. Most people are just too timid to attempt anything other than the installation of a drop-in part. However, those same people are all in on butchering up a frame to install an independent front suspension, or a V8 swap- - - -apparently because someone sells a "kit" to do it. "Go figure!"
Jerry

I suppose all you need to do is ream the tube out with a 9/32 drill and the old stovebolt pushrod should fit inside. Make sure the tubing you buy is seamless.

I use a chucking reamer- - - -drill bits DO NOT make round holes. Yes, just create a step in the ID of the tubing about 1/2" deep for the stub of the OEM pushrod to butt against, and keep the overall length reasonably consistent. The adjusting screw will compensate for minor variations in pushrod length.
Jerry

Spotbiltxo Wish you were up here our local 80 acre junkyard will easily have what you need. Have gone there fornearly 60 years,can always go in and find what I need borrow tools take it off. When I started the owners now were just little kids !

I posted in the “Truck parts wanted” section that I needed a pushrod to replace my bent one. Fellow ‘bolter Mike in Haslet, TX sent me 4 at no charge and they arrived today. I cleaned one up and was about to install it when I casually picked up the old one and compared the two. The new rod is 5/8” longer. I guess we didn’t know there would be any difference. My question is can I use it by backing out the adjusting screw, or is that out of the question? Thanks

That's a bit too much of a length difference. Does your engine have the mushroom-shaped "milk can" lifters, or the more conventional-looking ones? The newer style lifter needs a longer pushrod. Shoot me a PM with a snail mail address and a measurement of the correct pushrod and I'll send you a handful of the right length ones.
Jerry

I think your making a mistake by using stainless steel for push rods. Push rods are heat treated to a certain hardness. Most stainless steel is fairly soft, Stainless is tough but somewhat gummy. The ends of your push rods will probably wear. I was a machinist for 45 years or so and have machined a lot of stainless steel.

I'm not building a race engine with triple valve springs and 300 pounds of valve seat pressure, although I've built dozens of that type of engine. A stovebolt with original pushrod ends press fitted into a piece of stainless tubing will probably outlive my grandchildren with no issues.
Jerry

Spotbiltxo Don't you have a local junkyard you can hit?? We have one in the woods that would have that,if you weren't so far away could just give you one.

Yes, there’s one about 50 miles away, but with the price of gas what it is I’d rather pay postage for one someone could mail me. That’s just my rationale. Hotrod Lincoln Jerry has offered to send me a few. Thanks

Spotbilt xo I know guys that straighten bent pushrods,roll em on glass not the way I would do it. But if you need to get home !! In college years had friends cheat there way home on a piece of leather belt for a rod bearing.

On the way- - - -4 went out in yesterday's mail! I'm modifying my engine's rocker arms to use 5/16" ball-end tubular pushrods, and lifters with a 5/16" ball socket. They will also oil the top end through the pushrods.
Jerry

Received the 4 correct length pushrods from Jerry Saturday. I cleaned one up and installed it Sunday. It fit perfectly. Thanks so much Jerry!

Glad to help!
Jerry