question pioneer valve push rods.

[ace1]

Hi all, me again.

 

On Friday, on the way to the Bill Target rally SPARKY broke an exhaust valve push rod,:mad: at the time I didn't know what was happening, so pulled over and switched off as soon as was safe.

Had a good look round the engine expecting to see bits poking out of the side, but couldn't see anything wrong:undecided:.

After taking off the rear rocker cover it was obvious, so locked off the fuel for that cylinder, wedged the valve open, a very small amount and limped the last mile to the rally.

Anyway, to the question. Are the rods hollow just to save weight, and wear on the lifters, or is there another reason?

I was fortunate that I could call on the resources of a good mate who made another out of solid bar, and this got me the 40 miles home on Sunday.:-D

What material should they be made of? it seems to be mild steel with hardened balls in the end???

 

Any ideas and/or information will be gratefully received.

 

Regards. Alan.

[Edd]

Hi Alan,

 

The balls will be hardened but not sure on the actual tube. The hollow bit will be to save weight which helps stop bounce and also may be to give the system a bit of flex. If you want a correct replacement I should have a spare one. We picked up a scrap 6LW last year and I'm certain it's got the push rods with it.

 

Cheers

Ed

[ace1]

Thanks Edd, that would be great if you had a spare, or two.:-D

I will PM you my address.

 

Regards. Alan.

[ace1]

Hi Edd.

 

Not sure if the PM got sent, please can you confirm you got it ok.

 

Kind Regards. Alan.

[GeePig]

It was lucky that you could have a temporary replacement made - such are the pleasures of old vehicle ownership.

 

I think the reason why the pushrods are hollow is that once you have calculated the total crossectional area needed to transmit the 'pushing' forces, then a tube will be stiffer than a solid rod having the same crossectional area. So, a tube pushrod might end up lighter than a rod type simply because it needs less material to make it stiff enough for the task.

 

trevor

[Edd]

Hi Alan,

 

PM came through and I've replied.

 

Cheers

Ed

[ace1]

Checked all the remaining rods and reset the tappet gaps, all nice and straight,:-D feel much more confident with the engine now. It shakes your faith in the vehicle when something like this happens, but the fact that it would keep running after the rod broke must say a lot for good old British engineering.:drive:

 

Regards. Alan.

[david1212]

....... but the fact that it would keep running after the rod broke must say a lot for good old British engineering

 

not to mention no sensors and silly computer(s) shutting down the engine or putting it in low power / low rev limit limp mode ......

[radiomike7]

It was lucky that you could have a temporary replacement made - such are the pleasures of old vehicle ownership.

 

I think the reason why the pushrods are hollow is that once you have calculated the total crossectional area needed to transmit the 'pushing' forces, then a tube will be stiffer than a solid rod having the same crossectional area. So, a tube pushrod might end up lighter than a rod type simply because it needs less material to make it stiff enough for the task.

 

trevor

 

That is quite correct Trevor but some engines also use the hollow pushrods to supply oil to the top end, the Ford Essex V6 being one that I remember. The cam follower had a window in to an oil gallery and a small hole in the top that lined up with a hole in the hardened ball in the pushrod

[ace1]

Hi Ed.

 

The rods arrived this morning, thanks.

 

Kind regards. Alan.:saluting: