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Lawn mower has a B&S Intek V-twin 19HP
Model 407777
Type 0137 E1
Code 980422YG

Does anyone know what the spec is for the pushrod length?

It overheated, valve guide slipped, bent one or more pushrods. I got the pushrod part #s, 690981 (steel, exhaust), and 690982 (aluminum, intake).

I was sent a generic kit labeled CT160 (or CTM160, something like that), which is supposed to be the above two part #s but compared to a bent steel exhaust rod that was pulled, the new pushrods look about 1.5mm shorter.

I checked the engine service manual # 273521 and it doesn't spec the pushrod length.

Is there an acceptable range of length that can be adjusted for, is something 1.5mm shorter likely to work okay? I'd just throw it in and try to adjust it but the mower is at my mother's place and I'd like to have viable parts when I get there.

Pretty sure that when you adjust the valves, it will compensate for it being shorter

Yes I know there is some adjustment as I'd adjusted it previously when it burped trying to start it (a few years ago, I did not cause this, lol), but I don't know, if after a couple+ decades of wear (maybe around 600 hrs), if 1.5mm shorter is outside a reasonable expectation of adjustment range.

Dave_C said:

Yes I know there is some adjustment as I'd adjusted it previously when it burped trying to start it (a few years ago, I did not cause this, lol), but I don't know, if after a couple+ decades of wear (maybe around 600 hrs), if 1.5mm shorter is outside a reasonable expectation of adjustment range.

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Are you changing the cylinder that overheated and pushed the valve guide? Did you thoroughly clean the top of engine and cooling fins from debris after it overheated? This mower is 25 years old and has been around the block a time or two.

The old 690981 which supersedes to 597785 is 6.275" (159.385 mm) in length per my caliper.

StarTech said:

The old 690981 which supersedes to 597785 is 6.275" (159.385 mm) in length per my caliper.

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Thanks! I was just reminded that my caliper is only 6", so I had to extrapolate, after beating the old bent pushrod close to straight.

That gives me old pushrod length 159.25mm, two new steel 157.75mm, and oddly the two aluminum are different lengths from each other, about 157.25mm and 158.25mm... gotta luv quality control!

Tiger Small Engine said:

Are you changing the cylinder that overheated and pushed the valve guide? Did you thoroughly clean the top of engine and cooling fins from debris after it overheated? This mower is 25 years old and has been around the block a time or two.

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Changing the cylinder? You mean a new head? I was hoping to just replace the pushrods, dremel a groove on the valve guide while it's sticking out, that would end up just below the level of the head, put some high-temp red loctite on, pound the guide back down and stake it in.

Yes there was a lot of grass muck built up and that has already been cleaned off. I also considered pulling the head, then tapping it and using a set screw as I've seen Taryl and others do on youtube videos, but still trying to decide.

Dave_C said:

Thanks! I was just reminded that my caliper is only 6", so I had to extrapolate, after beating the old bent pushrod close to straight.

That gives me old pushrod length 159.25mm, two new steel 157.75mm, and oddly the two aluminum are different lengths from each other, about 157.25mm and 158.25mm... gotta luv quality control!

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Just out of curiosity are these from Briggs or are they after market? IF form Briggs it does sounds like a quality control issue as Briggs in the past has always been good but ever since the they went bankrupt and the financial investment company took them over I do suspect a lot more items are coming from China.

Also note the 796632 and 796633 cylinder heads have been superseded a few times. They even at one time came as a set for half the price but quickly changed that back to individual heads out of China. Current heads are 84001918 (#1) and 84001919 (#2) and they are not a stock item from Briggs direct. IE slow boat from China.

Dave_C said:

Changing the cylinder? You mean a new head? I was hoping to just replace the pushrods, dremel a groove on the valve guide while it's sticking out, that would end up just below the level of the head, put some high-temp red loctite on, pound the guide back down and stake it in.

Yes there was a lot of grass muck built up and that has already been cleaned off. I also considered pulling the head, then tapping it and using a set screw as I've seen Taryl and others do on youtube videos, but still trying to decide.

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If you cut a groove in valve guide, insert a c-clip into the groove so it stays put. Make sure it is at correct depth of course. You can red Loctite it and peen it also.

As a professional shop I don't do this to my customers. I warranty my workmanship and if the repair don't hold it bites me in the anus.

Beside grinding on the cast iron valve guide will weaken it. Another option I have heard of is to pull the head drive the guide back in place and spot weld the guide inside the valve chamber as these guides are usually pushed out. Even that I don't recommend. But it is the OP's engine and he can take the risks if he wants to as he can always repair it again if it fails again or replace it. Just note there is no replacement guides.

BTW any beating on the valve guide usually means it will need reaming to correct size.

StarTech said:

As a professional shop I don't do this to my customers. I warranty my workmanship and if the repair don't hold it bites me in the anus.

Beside grinding on the cast iron valve guide will weaken it. Another option I have heard of is to pull the head drive the guide back in place and spot weld the guide inside the valve chamber as these guides are usually pushed out. Even that I don't recommend. But it is the OP's engine and he can take the risks if he wants to as he can always repair it again if it fails again or replace it. Just note there is no replacement guides.

BTW any beating on the valve guide usually means it will need reaming to correct size.

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I don’t do this repair this way either for a customer. It is a new cylinder head, clean top of engine of debris, etc.