One valve adjustment screw near end of travel (others good)

[Iles Guran]

Hello,

I recently replaced the valve train on my '63 S90 due to having too many issues trying to properly adjust the valve clearance. The old rocker arm tips look like they were reground and not nearly as clean as the new ones (who knows how many times). Without having the previous history of the car, I wanted to make sure that mechanically, the rocker assembly was sound.

I replaced the rocker shafts, rocker arms, washers, springs and adjusting screws and nuts, mounting washers and nuts as well as the aluminum centre piece for the intake rockers. I also put in slightly shorter push rods -- the old set was at the very end of the screw adjustment travel, out as far as possible.

The new setup went together great and all of the valve adjustment screws are now very close to the middle of their travel, except for one; an intake adjuster that's out almost as far as possible. At first I thought perhaps the pushrod wasn't seated properly, but after checking it twice, it is.

I've taken the intake assembly off and checked for oil flow, there is some, but it's definitely not as good as the others (the old ones barely had any).

The engine runs well from what I can tell otherwise, just worried about not getting enough oil to that rocker.

Any ideas what could be causing this issue?

[Ron LaDow]

First, welcome on your first post.
Sounds to me like a rocker ground too often at the valve end. I'd take it off and compare it to one which 'adjusts' properly.

[Iles Guran]

Thanks Ron,

The rockers are all 'brand new' from Stoddard/Porsche. Am I to assume 'new' isn't actually new and simply reground to proper specs?

Cheers,

[Ron LaDow]

Thanks Ron,
The rockers are all 'brand new' from Stoddard/Porsche. Am I to assume 'new' isn't actually new and simply reground to proper specs?
Cheers,

I doubt Stoddard would sell re-con'd parts as new, but I'd still take a look. Like everybody else, Stoddard can make a mistake and ship a bad part every so often. But they tend to fix those right quick.

[Iles Guran]

Ok, thanks again.

I'll take off the assembly, check the rockers and then switch them between the two intakes, see if it's the rocker/assembly or something further down the line. I'll remeasure the push rods as well.

Cheers,

[Iles Guran]

So I removed the assembly, pulled the push rods and measured.

It looks like of the 8 pushrod tubes that I purchased (255.7mm), one of them was a longer version (256.7mm). Strange because they came as a set and don't have any markings on them to differentiate them. Must have been mismatched somewhere down the line.

Working with Stoddard to get the correct replacement part.

Nice easy fix but lesson learned, never assume the parts ordered are the correct ones, measure before install

Cheers,

[ray nelson]

Iles
While you've got it apart check the intake valves. I had to replace all 4 of my intake valves on my '62 S90 because they were soft. I was always needing to adjust the valves and finally pulled the head for another reason and discovered the intake valves were slowly sinking into the head as a result of a deep groove in the valve sealing face. I believe Harry Pellow also mentioned that some S90's were fitted with soft intake valves.
I don't know if there was a recall or not but the car was out of warranty by then anyway.

Ray

[Ron LaDow]

It looks like of the 8 pushrod tubes that I purchased (255.7mm), one of them was a longer version (256.7mm). Strange because they came as a set and don't have any markings on them to differentiate them. Must have been mismatched somewhere down the line.
Cheers,

Shame on me; I assumed that "too far out" meant the toward the push-rod.
But glad you could fix it that easily, and yeah, 50-YO mean everything gets the yardstick.

[Iles Guran]

Thanks Ray,

Something else to add to the 'to be checked' list. I've had to start one for each car since there's always something

Cheers guys,

[Albert Tiedemann]

Hello,



I replaced the rocker shafts, rocker arms, washers, springs and adjusting screws and nuts, mounting washers and nuts as well as the aluminum centre piece for the intake rockers. I also put in slightly shorter push rods -- the old set was at the very end of the screw adjustment travel, out as far as possible.

How did you know at the time of this posting that one or more of the replaced pushrods or all, were shorter than the ones that you actually measured in a later post?

[Iles Guran]

When I purchased the replacement set, I opted for the 1mm shorter version (255.7mm).

My old pushrods where the standard length (256.7mm) and the old setup had the adjustment screws for the rocker arms pretty much all the way out (towards the outside of the car), meaning I needed to make some room somewhere along the line. It was either shorter rods or shimming the stands -- which already appear to have a couple of shims, so I chose the shorter rods.)

When I put in the rods, all the rocker arm adjustment screws were in the middle of their travel, except for one. I was a bit boggle but finally pulled all the new rods and found one to be the longer version (256.7mm).

I hope I answered your question properly.

Cheers,

[Dick Weiss]

During my 58 years of engine rebuilds including some S90s, I've never seen any 3041 intake valves having a hard face
(including other intake valves); Only on the exhaust valves.
The seat width must be correct to minimize impacting a groove on the valve's seat/face.

[Martin Benade]

Certain non-stock cams can beat the valves into the seats pretty fast, I have heard this is due to the valve bouncing as it closes. I have a VW engine that has a cam (lo rpm torque) that has consumed a couple of sets of valves/seats. Probably a bad cam profile along with my running stock springs. It runs so well that I keep using it, now very few miles per year. Also I used to be able to get rebuilt heads for $125 each.

[Albert Tiedemann]

Thanks, Iles, for the succinct reply. I was not aware that you could purchase push rods in different lengths "out of the box" for Porsche 356. But, I did find them on the Stoddard site. A little pricey, though, since you could have shortened the ones that you removed for a whole, whole lot less. How was the clearance between the little notch in the rocker arm stand and the body of the pushrod compromised if at all. The later pushrods have a necked down end.

[Iles Guran]

Albert: I'm not sure I follow your comment as I'm fairly new to the 356 world: How was the clearance between the little notch in the rocker arm stand and the body of the pushrod compromised if at all. The later pushrods have a necked down end.,

As for reworking the old ones, I opted for new parts since I do not know the history of the car, nor do I have the experience to rework the parts at this time (that will come with more hands-on I hope). The pushrods that were in there previously were mismatched (6 of one kind and two completely different, one looking like an original with the 'wood' insert), so I didn't' want to take any chances and simply opted for a new matching set. That way moving forward I at least have some comfort knowing those parts 'should be ok' moving forward.

That's why these forums are fantastic, it helps noobs like me at least make heads/tails of some basic stuff.

Cheers,