broken push rod

[Bruce W.]

Hey guys, i have a 61 270 hp car. one push rod broke? Any idea as to what would cause this to happen and any suggestions on replacing this. Is there any suggestions on where to get a new one? saw a whole set listed on amazon for 36.00 dollars. seems to cheap to me.
Bruce

[Joe R.]

Re: broken push rod

Well 270 is a solid lifter motor so valves could need adjusting, Rocker Arm could be bad and camshaft could have a worn lobe or bad lifter. RPM could be too high for an old guy or just all of the above. If you had a push rod with a welded ball it could have popped off. They were discontinued some time ago.

Take the valve train apart and tell us what you find.

JR

[Duke W.]

Re: broken push rod

Hey guys, i have a 61 270 hp car. one push rod broke? Any idea as to what would cause this to happen and any suggestions on replacing this. Is there any suggestions on where to get a new one? saw a whole set listed on amazon for 36.00 dollars. seems to cheap to me.
Bruce

That's an uncommon failure assuming the valvetrain parts are all OE equivalent. Post a photo of the broken pushrod and rocker arm. Inspect the rocker arm for damage. You can buy a Sealed Power OE equivalent pushrod at nearly any parts store. You can find the part number at napaonline.com, and it should be considerably less than 36 bucks.

Search the web for Hinckley Williams valve adjustment and check valve adjustment. Does it have an OE equivalent Duntov cam?

Duke

[Jim D.]

Re: broken push rod

Hey guys, i have a 61 270 hp car. one push rod broke? Any idea as to what would cause this to happen and any suggestions on replacing this. Is there any suggestions on where to get a new one? saw a whole set listed on amazon for 36.00 dollars. seems to cheap to me.
Bruce

Rock Auto sells Sealed Power RP-3093 push rods for $1.13 each.

[Joe L.]

Re: broken push rod

Well 270 is a solid lifter motor so valves could need adjusting, Rocker Arm could be bad and camshaft could have a worn lobe or bad lifter. RPM could be too high for an old guy or just all of the above. If you had a push rod with a welded ball it could have popped off. They were discontinued some time ago.

Take the valve train apart and tell us what you find.

JR

JR------


Welded ball pushrods for small blocks are not discontinued. They are still available from GM under GM #14095256 for $18.83 each GM list. These SERVICE all 1955-85 small blocks and replaced all earlier designs as of 33 years ago. These were also used in PRODUCTION on 1985 Corvettes.

1986-96 Corvettes also used welded ball pushrods, although of a different length than earlier (due to conversion to hydraulic roller lifters). These were and remain GM #10046173. Gen III/IV small blocks use welded ball pushrods, too. These were and remain GM #10238852.

So, to say the least, welded ball pushrods are "alive and well" and have been working perfectly in millions of small blocks for more than 30 years. If they suffered from the ball "popping off" with any regularity that design would have died a LONG time ago.

High quality welded ball pushrods (such as the GM parts) are actually superior to the traditional style. Traditional style pushrods are "180 degree", meaning the tip can only rotate through about 180 degrees at its interface with the rocker arm socket. Welded ball pushrods are "270 degree" pushrods. Also, the welded ball tip is perfectly round whereas the traditional style may not be as perfect.

[Tom D.]

Re: broken push rod

https://www.forums.ncrs.org/showthre...hlight=altoona

Bruce: Please see above for several good valve train comments offered, related to a recent failure in my '60 283. I bought the whole kit of stuff from Lunati ten years ago - Yes, the rocker ratio is 1.5 to 1. The solid lifter cam is supposed to be a "replica" of the Duntov "097 cam". It's possible I had too much valve lash gap on intake valve number 7. I have it fixed and hope to make Altoona this month, in a trailer. BTW, I only ran the engine about 5 hours since installation of the cam and valve train. We judged the push rod to be re-usable for now. Because of this failure, I plan to take the heads off in the winter time.
(I admit the subject of this discussion does not reflect what you want to review - That's my fault for not starting a new discussion. )

[Mark E.]

Re: broken push rod

Bruce,

As suggested, give more detail about how the pushrod failed (bent, tore, cracked,...), with photos if possible, and when it failed (RPM, load).

[Joe R.]

Re: broken push rod

Joe,

The welded ball push rods I am referring to are not the present design you refer to as welded ball pushrods. The later ones have a hardened tip welded in the push rod that is referred to as a ball. But just a hardened tip.
The most famous welded ball pushrods were in the BB and were a source of many a failure.

JR

JR------


Welded ball pushrods for small blocks are not discontinued. They are still available from GM under GM #14095256 for $18.83 each GM list. These SERVICE all 1955-85 small blocks and replaced all earlier designs as of 33 years ago. These were also used in PRODUCTION on 1985 Corvettes.

1986-96 Corvettes also used welded ball pushrods, although of a different length than earlier (due to conversion to hydraulic roller lifters). These were and remain GM #10046173. Gen III/IV small blocks use welded ball pushrods, too. These were and remain GM #10238852.

So, to say the least, welded ball pushrods are "alive and well" and have been working perfectly in millions of small blocks for more than 30 years. If they suffered from the ball "popping off" with any regularity that design would have died a LONG time ago.

High quality welded ball pushrods (such as the GM parts) are actually superior to the traditional style. Traditional style pushrods are "180 degree", meaning the tip can only rotate through about 180 degrees at its interface with the rocker arm socket. Welded ball pushrods are "270 degree" pushrods. Also, the welded ball tip is perfectly round whereas the traditional style may not be as perfect.

[Joe L.]

Re: broken push rod

Joe,

The welded ball push rods I am referring to are not the present design you refer to as welded ball pushrods. The later ones have a hardened tip welded in the push rod that is referred to as a ball. But just a hardened tip.
The most famous welded ball pushrods were in the BB and were a source of many a failure.

JR

JR------

The attached depicts the exact configuration of the 1955-84 GM #14095256 pushrod. The other pushrods I previously mentioned for later engines are similar except for length.

[Joe L.]

Re: broken push rod

JR------

Pushrods for 8.1L big blocks, Mark 5 big blocks and later Mark IV big blocks (as well as SERVICE for most earlier Mark IV big blocks) were also welded ball construction and similar in configuration to the the small block pushrods I depicted above.

GM #12556295/12556296---8.1L Big Block used in PRODUCTION and still available in SERVICE.

GM #10106423/10106425---Gen 5 Big Block used in PRODUCTION and still available in SERVICE

GM #14075629/14075631---later Mark IV Big Blocks in PRODUCTION and SERVICE for most earlier Mark IV

[John M.]

Re: broken push rod

Welded ball pushrods for small blocks are not discontinued. They are still available from GM under GM #14095256 for $18.83 each GM list. These SERVICE all 1955-85 small blocks and replaced all earlier designs as of 33 years ago. These were also used in PRODUCTION on 1985 Corvettes.

Wow. I suddenly feel more connected to the solid axles.

[Jim L.]

Re: broken push rod

Traditional style pushrods are "180 degree", meaning the tip can only rotate through about 180 degrees at its interface with the rocker arm socket. Welded ball pushrods are "270 degree" pushrods.

Joe, can you explain this a little more? I've never encountered a pushrod which couldn't be rotated n X 360 degrees, where "n" can be an arbitrarily large number.

Jim

[Joe L.]

Re: broken push rod

Joe, can you explain this a little more? I've never encountered a pushrod which couldn't be rotated n X 360 degrees, where "n" can be an arbitrarily large number.

Jim

Jim------

I'm not referring to rotation about the pushrod's long axis (i.e. the axis that one rotates the pushrod when, say, finding the zero-lash point when adjusting hydraulic lifters). I'm referring to the rotation of the pushrod end, "for-and-aft" within the socket of the rocker arm as the rocker arm moves through its arc.

[Jim L.]

Re: broken push rod

Jim------

I'm not referring to rotation about the pushrod's long axis (i.e. the axis that one rotates the pushrod when, say, finding the zero-lash point when adjusting hydraulic lifters). I'm referring to the rotation of the pushrod end, "for-and-aft" within the socket of the rocker arm as the rocker arm moves through its arc.

Oh, of course! Wasn't thinking of that.... Thanks, Joe.

[Mark E.]

Re: broken push rod

Jim------

I'm not referring to rotation about the pushrod's long axis (i.e. the axis that one rotates the pushrod when, say, finding the zero-lash point when adjusting hydraulic lifters). I'm referring to the rotation of the pushrod end, "for-and-aft" within the socket of the rocker arm as the rocker arm moves through its arc.

I don't understand the distinction...