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New is not always better with Push Rods.....

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mjobrien

mjobrien

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OK I was shown something interesting today on my BN1, th old Pushrods let's call them Original and some new ones have similar characteristics but differ in the depth of the socket at the top. That is the adjuster goes into the older ones a little deeper than the new ones.

I was comparing them only after I bent one ;( and pulled the head to check for damage - None :wink:

So in sourcing do I replace one rod or replace all rods with older style if I can find them? I never had the original ones to begin with.

Not sure what others experiences are with rods jumping out from under the rocker, I think it's because I had two stock valves.....

One step forward and two steps back.
 
A little known fact about the original pushrods.

The rocker end adjuster was fitted to the pushrod cup tightly enough that it trapped oil in the joint such that as the pushrod started to lift, the trapped oil MOMENTARILY cushioned the rocker to valve engagement. The oil leaked out of the joint as the lift pressure increased. This noticeably reduced "tappet" click to make the engine quieter.

Because of this, when adjusting valve lash, the pushrod end of the rocker must be pushed down sufficiently to squeeze the oil out to get a true lash reading. If the oil cushion is left in the gap, valve lash will be larger than indicated by a gage.

It appears that the new rods may have their sockets sufficiently oversize to prevent this oil cushion.

Not sure what to suggest. If the tappet quieting feature is not important, Use what ever you have. If this is important, use original dimension/spec rods & rocker adjusters. I'm still running the 50 year old rebushed rockers & adjuster balls. The pushrods are original & were slightly straightened to remove a tiny bit of bow on a few of them.

If a valve sticks open, the rod socket & rocker adjuster ball could disengage.
D
 
Dave,

Thanks, I'll look around and see what I can find, interesting facts about the old ones and seems logical when you consider the difference in cup size.

As always appreciate the insights and depth of knowledge....

Michael.
 
I seem to remember hearing in a situation like this it is best to go with a fresh complete set - either style. The key being a complete set so that everything is the same from the start.
 
Talked to Moss and the ones they have measured larger (cup dimensions) than the ones I have, so I ordered a set and will replace all of them at once. I'll let all know how it goes.

Michael.
 
Dave Russell, that would go some way to explaining why years ago I would set the tappet clearance, only to turn the engine by hand and find the clearances of a few minutes from previous setting out!
A wealth of information you are Dave
 
Update....


New Denis Welch Gasket, studs, bolts and washers. New Pushrods from Moss - Walla... It's back running and I had a chance to take it around to block! A two mile journey after 18 years of not running.....

A few observations to close this thread.

Pushrods from Moss were very close if not identical to the originals.

Denis Welch head gasket is a great way to go and so far all is well. I did have a little leakage at first but it seemed to stop after I re-toqued the head bolts one more time.

I'm sure more adventures are in store as I put a few miles on the chassis.

Oh BTW - This is the FIRST TIME I have ever driven this car or any other Healey for that Matter - What a Blast!

Youtube Links

https://www.youtube.com/watch?v=uxffLCYyYkQ

https://www.youtube.com/watch?v=m0JKJLZigeM

https://www.youtube.com/watch?v=XIkTR3axN5E

https://www.youtube.com/watch?v=39lwy9pVDBw


Michael.
 
Michael,
Looks great. Glad you're not forgetting to have fun. I was in the same boat. I'd never driven a big Healey before I put mine on the road. I've put almost 1000 miles on mine since I finished (well, almost finished)the rebuild. It gets even better. Now instead of saying to my wife, "hey, this would be a nice trip in the Healey", I say "Hey, let's take the Healey, grab your hat". The first time I flipped the OD switch (at least the first time I filpped the switch and it worked)I had tears of joy. It really has been worth the money and time, and I'm only starting to meet people on the road.
 
mjobrien said:
Update....

Oh BTW - This is the FIRST TIME I have ever driven this car or any other Healey for that Matter - What a Blast!

Youtube Links

Michael.
Click to expand...
Hi Michael,
I'm as thrilled as you are. What a wonderful feeling to finally go for a "drive".

I think I already told you what a super job you are doing on the car, but it's worth saying again.

If you ever had doubts, this will provide the momentum to keep going. Even the MRS. can see that it's actually going to be a car, & a good one at that, again.

Regards,
Dave
 
Thanks, its with a lot of help from a lot of people on this Forum.... So it's a blast to share the progress. It goes without saying on these 100/4's Dave, your help has been amazing…

Michael.
 
What a great video, almost as good as being there, but not quite, great fun isn't it, I never drive my 100 without a body, but did bop around with the tunnel off quite bit when I was troubleshooting the O/D, you can really hear avery little mechanical noise the car makes.

Enjoy, keep us posted (more videos would be great) and come here if you need any more help as well.

Greg
 
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