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Discussion Starter #1
model# is in sig

so I am new to fixing small engines so bear with me

its a briggs ohv, exhaust on top intake on bottom I believe?

by accident I ordered a exhaust rod

looks the same size and all, should I try it or better to just order another one?

the alum intake rod was only slightly bent, bent enough to throw the rocker off, I bent back and started it back up but was scared it was a bad idea. Is it ok to use the bent back rod for now?

So three options. Use steel rod? Use re bent alum rod? Order a new alum one and save myself the headache?
 

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I'm guessing they use steel for the exhaust because it gets hotter than the intake.
Since aluminum has a higher thermal expansion, they probably "lengthen" more equally??

Since the compression release is based on the intake valve clearance being correct, it might make the engine hard to crank when hot if the valve clearance increases???

Just musing here.......
 

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My dad had the same confusion with his Troy Bilt single cyl Briggs. We thought it could have something to do with a misfire or something. The weaker aluminum would bend instead of damaging a lifter (if it has them) or gouging the cam.

Bill makes a good point, but the thermal expansion of aluminum is almost twice steels expansion.
 

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The pushrods should see equal heat, the rockers get oil sprayed on them that draws away the majority of the heat. Is the aluminum one solid and the steel one hollow? If so, they should be about the same weight, and if they are close enough to the same length that the valve adjustment works, then I can't see any reason why a steel one couldn't be used.
Looking around online, it may be to increase the valve float rpm with a weaker valve spring, which would put less stress on the cam, but it shouldn't cause undue wear in normal use. If it floats the intake valve at too low of an rpm, you could either swap it's spring out for an exhaust side one or just go to the aluminum pushrod.
 

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the exhaust valve spring is stronger than the intake.. this is Y one is steel...& one alumin.. replace that bent push rod with a NEW ALUMIN. one.. make ur engine OEM then..

u prolly have a worn spot in the rod where it riden in the guide & it bent there...that rod is so thin now it bent..
 

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Discussion Starter #6
thanks for te replies, i ordered a new one, was only around $10 with shipping

4x4 the alum one feels hollow and the steel one seems solid, the steel one is alot heavier

like i said i'm just a homeowner who enjoys fiddling with engines, i'm a novice and still learning how engines work

that being said, does anyone have any insight on why the alum intake rod would bend? and what I should do to prevent it in the future?
 

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I'm not really sure why it would bend. Possibly a "diesel" effect where the fuel combusts (without spark/ignition) while the exhaust valve is open which could/would push hard on the valve which would bend the push rod. That's all I can think of.
 

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CHEVY&SEARS..they wear thin where they go thro the steel guide ..this makes them real weak..
 

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Sounds like a design flaw. Are there upgrades available?

Mike
 

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I've always replaced the pushrods with steel, never had a problem with compression release or anything else, just don't bend as easily.
 
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