[scard]

Apparently the idea of cutting down engine pushrods is familiar and common to many in the know. That wouldn't include me. I'm inquisitive, so I have a trash/disposable pushrod in hand... The "why" is irrelevant. The "how" is what I'm interested in. Step 1, remove one of the ends.

Stuck. How is the best way to remove the end? Heat doesn't seem to be the answer. Cut it off, very carefully on the lathe?

Step 2: Complete step 1 then trim down the tube to the previously determined length in the lathe.

... I'll be in the shop for the next couple of evenings tinkering with destroying pushrods, so let the comments rip.

Step 3: Press fit the end back into the pushrod?

 

[Mike S]

What you described is pretty common in the automotive world, however I have no idea if it is the way to go for a Lyc.

I seem to recall that Lyc produces various lengths of pushrods----and that is how you set the dry clearance.

 

[krwalsh]

I tried...

Our engine was decked back in the late '80s, so it needs shorter pushrods. I played with a set of pushrods for quite some time to do exactly what you're asking. I never got past step #1. When I found out the price of brand-new pushrods in the exact length I wanted (I think it was ~$30/each) i decided that it was worth it to buy new ones.

So, I have 8 or so extras if you want more to practice with!

 

[MNAv8or]

I seem to recall that Lyc produces various lengths of pushrods----and that is how you set the dry clearance.

You are correct, Lycoming produces different length pushrods to adjust the clearance of the dry set clearance. You are more than welcome to tinker with the motors, but you will find it is cheaper to just buy a new set of pushrods once you figure out what sizes you need. Some piston shops will send you a spare pushrod in the size you need to test the fit before you buy.

 

[SHIPCHIEF]

All that aside;
If you follow thru and pull, rip, cut or lathe one apart, let us know what you find.
Some push rods are just pressed together, some look like they get a spot weld once pressed together. I suppose they could be swaged, brazed or set with anaerobic adhesive too. (not talking Lycoming here) Some Harley pushrods are aluminum tubes with steel ends.
No answers here on how they are put together, so if you test one to destruction, please share the result.

 

[zilik]

I have about a dozen pushrods that are all brand new and to long for most engines. Don't ask me why. The last time I looked at them I thought the balls looked spot welded on. I could be mistaking my 289 Ford push rods though. The lycoming units are at the hanger so I could not look at them.

Good luck in your experiment and let us know what you find out.

 

[cajunwings]

Pushrods

Try this: The pushrod end is a ball with a shank that fits inside the tube. clamp pushrod horizontally in a vice with the end you want to shorten sticking out about an inch. Take a plain hacksaw with a fine blade and right next to the ball saw thru the tube down to the shank, let the flat part of the ball be your guide. Rotate the tube so you can saw this gap all the way around. When done you will have a nice even gap between the ball and the tube of about .040". Take the pushrod out of the vice, stand it up vertically on a piece of wood and tap the ball (i've used a brass hammer) until the flat part is against the pushrod. Pushrod is now about .040" shorter. Repeat as necessary. The tube is fairly easy to saw thru, but the ball/shank is very hard, you cannot hurt it or cut it with a hacksaw. This operation takes no more than 4-5 min.

Don B.
RV-9 rebuild in progress

 

[rocketbob]

You can't shorten a Lycoming pushrod because the tips are spot-welded. I've shortened other types of pushrods using an Aloris 1/16" parting tool on the lathe. You just carefully work your way down and when the wall material gets thin enough the rest tears away so you don't ever touch the body of the tip. Then you just tap the end in with a hammer and a couple of blocks of wood.

 

[scard]

You can't shorten a Lycoming pushrod because the tips are spot-welded. I've shortened other types of pushrods using an Aloris 1/16" parting tool on the lathe. You just carefully work your way down and when the wall material gets thin enough the rest tears away so you don't ever touch the body of the tip. Then you just tap the end in with a hammer and a couple of blocks of wood.

That is the direction I was thinking. The one I have doesn't look to be spot welded. Roughly how deep is the body of the tip pressed into the tube?