Shorten 273 pushrods experiment

[67Dart273]

Finally got my worthless tail down the stairs to the lathe for a short time

I "hope" to have "in the end" an LA roller block with LA heads and 273 rockers, using factory roller lifters. So, "shorter" pushrods.

The pushrods looked like they had spot welds around the pressed in ends, and turns out that's just what they were. I think this just might work.

Frankly, I'm not sure you even need to re-weld them, there doesn't seem to me there's any way they would come back out again.

 

[Snake]

well its worth a try right.

 

[nm9stheham]

If you rev things, you never know if there might be a bit of slack that opens up for an instant. I would tack them in place just to make sure that part stayed stable.

 

[RedFish]

Movement would mushroom the end of the tube.

 

[Rapid Robert]

Good innovation! Keeping It Simple Sam, there was a reason they were welded so I would restore that function & re weld em when you get the length finalized

 

[Inertia]

Shortening works well,, Once length has been determined, I use a valve stem trimmer to square the ends ensuring a perfectly square fit.. I also re-spot them..

The same mehod can be used in many aftermarket pushrods, removing the end, trimming, and freezing the insert before installing into tube to eliminate need for spot..

cheers

 

[nm9stheham]

Del, how are you getting the cup ends off? Are you machining down through the welds? I want to do the same thing but I can't shorten them all that much, only .300", and I won't get all the weld area off. Plus I don't have a lathe....

How thick are the tube walls?

 

[67Dart273]

The ends are hardened of course, and the welds "interfere" with a clean cut. I may try some alternative tools. I just used a HSS tool to cut through it, and tried not to go much below the weld, which occupied, I guess about 70% or so of the length of the insert. So if .3 is all you need, "that might be tough."

Because the piece is so small, short and irregular, it's difficult to get a good clean cut to get rid of the weld without damaging the insert stem.

Don't know the wall thick. Have to measure.

I think the guys are right though, probably will need to re-weld them, as the pounding will probably mushroom the tube end.

Time to get practiced up on my TIG!!

 

[nm9stheham]

Tnx; yeah, I'll have to do something else as I can take off only 60% of the weld.

Think I am going with the Comp Cams K75805-16 semi-finished p-rods, 6.5-7.5" long with 5/6" ball on one end, and then buy the Comp Cams 5C5P-16 5/16" cup ends to finish them off. $121 from Summit for the 2 parts sets, in stock. .080" wall, so should be plenty strong for our approx 280-300 lbs open spring pressure and modest lift and rates.

You can get these semi-finished rods in lengths from 5-6" to 10-11" BTW.

 

[RustyRatRod]

I am like you, I really LOVE makin things work and all, but "IF" any of those come apart........

I mean as cheap as new pushrods are..................

 

[Bad Sport]

Yeah, I would drill a hole and plug weld it.

 

[nm9stheham]

MIG might be better to keep the amount of heat applied lower. Strength is not a big issue here, IMO, just stability.

 

[AJ/FormS]

Swedge and press. That's the MOPAR way. At least the cut-yer-own kit was like that. It's been in the engine over 100,000 miles now, and 16 years, this fall.

 

[67Dart273]

Swedge and press. That's the MOPAR way. At least the cut-yer-own kit was like that. It's been in the engine over 100,000 miles now, and 16 years, this fall.

You have any more specifics? I guess you are talking about the old Direct Connection / MP kit? No experience with those.

 

[B3RE]

Tnx; yeah, I'll have to do something else as I can take off only 60% of the weld.

Think I am going with the Comp Cams K75805-16 semi-finished p-rods, 6.5-7.5" long with 5/6" ball on one end, and then buy the Comp Cams 5C5P-16 5/16" cup ends to finish them off. $121 from Summit for the 2 parts sets, in stock. .080" wall, so should be plenty strong for our approx 280-300 lbs open spring pressure and modest lift and rates.

You can get these semi-finished rods in lengths from 5-6" to 10-11" BTW.

You can get new chromoly cup/ball pushrods from Melling, Part# 500224. They aren't welded, so just pull the tips out, cut the tube, and press the tips back in. I've done this in the past when using 273 rockers on heavily milled blocks and heads, and hydraulic cams.

The Comp kits are not a cut and press type kit. The id of the tube has to be sized in order to press the tips in with the right amount of press fit. Also, the tool they make to size the tubes is nothing more than a specially ground HSS drill bit. How many hardened pushrods can you size with a cheap drill bit? I did about five before it broke.

 

[nm9stheham]

Yep, I saw the tool (decided to forego that at the price and for what it does), computed the ID, and understand where I need to take the ID for the interference fit. We'll see how it goes; I suspect we'll manage it OK. There are other 'fish in the sea' when it comes to bits. Tnx for the Melling info!

 

[Inertia]

Del, how are you getting the cup ends off? Are you machining down through the welds? I want to do the same thing but I can't shorten them all that much, only .300", and I won't get all the weld area off. Plus I don't have a lathe....

I use longer 6 cyl pushrods,, grind the weld off,, if you blemish the insert,, doesn't matter,, trim exiting tube,, square end with valve stem grinder to nec LA length, install insert, plug weld compressed in a vise..

cheers

 

[nm9stheham]

Yep, I considered several alternatives, including the /6 p'rods. Since the /6 p'rods don't have to be particularly strong with their soft stock valve springs, I decided to go with the heavier .080" wall rods.

 

[Inertia]

Yep, I considered several alternatives, including the /6 p'rods. Since the /6 p'rods don't have to be particularly strong with their soft stock valve springs, I decided to go with the heavier .080" wall rods.

Yep,.. this was an inexpensive way to use 273 rockers with hydraulics(as in Del's case), back in the day before all the aftermarket stuff became avail,, but it seemed to me the 5/16 tube wall thickness between V-8 and 6's was the same, 225's anyway..,

Here's a link to a similar thread by Pishta, on shortening pushrods,, which may be helpful to some..

http://www.forabodiesonly.com/mopar/showthread.php?t=297318

cheers..