Divot worn in Valve Stem Options

[frank_c]

Hello,
I started replacing the Pushrod Tubes yesterday, and I noticed that the top of the stem of #4 intake valve has a divot worn in it from the rocker (#4 valve stem & rocker adj screw photos below). The other three valves on this bank are fine, and I haven't pulled the rockers on the other bank yet.

I purchased the car about a year ago, and here is some engine related info based on an engine build sheet, the receipts that came with the car, and what I can see:

• 2.0 with euro P&C
• Weber 40 IDFs
• WebCam #86
• Standard Aluminum pushrods
• Standard 2.0 rockers

I do not see valve springs listed on the build sheet, so I am assuming that the single spring currently installed is the OEM spring, and not an HD spring.

So, I have two goals here:

1. First is a short-term fix as I plan to take this car to the Hill Country Rallye in Mid-March - so no big tasks that might go off-script. Car will be driven 600-700 miles during this event.
2. Second is post-rallye where I plan to move to 1.7 rockers with swivel-feet, chromoly PRs, set valve geometry, and whatever else folks might suggest while I'm in there (solid rocker spacers?). And can this valve be saved? Am I looking at pulling the head to either repair or replace the valve?

For the short-term goal, if I leave things as-is this will obviously make setting the valve lash on that valve challenging. So I would like to hear folks' opinions on the use of a Valve Cap on that one valve (and any others with similar issue I may find). If I install a cap, should I replace the rocker adjustment screw for that valve as well? Or is there any other short-term option that does not involve pulling the head? Or just run it as-is knowing that #4 intake may not be getting full lift, and tear into it after the event?
Example valve caps: https://www.cbperformance.com/product-p/1522.htm

I also have some questions regarding the long-term fix, but I'll leave that for another thread when that time comes.





Thanks,
Frank

[Ninja]

I'd rate that as toast...

Unless you know the age of the valve springs, I'd replace them before I ran it again.

On that I'd expect R+R heads, valve job, new valves (as required, auto change any sodium critters), springs, retainers, keepers, swivel feet adjusters and guides as needed.

Pull heads, clean the crap out of the combustion chambers, and look for cracks before spending any money. Exhaust side near plug is the usual propagation point.

It MIGHT be possible to machine the damage off of that stem, but it looks trashed to me.

Put it back together as is and drop a valve at 4500 RPM...


I've got a box stock 31K 914 that runs OK and I won't run it again until I replace the springs/retainers/keepers. Some of mine sat open (in compression) for 33 years.

Too many resurrection threads on here have been terminated over dropped valves.

[Ninja]

I would not use steel pushrods in this application.

There are two levels of upgraded aluminum pushrods available. You need the cheaper version.

Most of the time the steel rods require a cold adjustment of zero lash.

In my book, this is a recipe for disaster.

The cams base circle has to be DEAD NUT perfect and if the valve or the seat wears AT ALL the valve is now held open on base circle.

Burned valves will be the final result.

I tested my stock 31K mile stock 914 camshafts base circle and came up with a variation over .002"!

If you have .006" valve clearance this variation effectively means nothing and is not service affecting.


As the engine heats up this clearance increases when steel pushrods are used so zero cold does not mean zero hot but it's still a BAD idea.

There is no margin for error with zero lash. (IMG:style_emoticons/default/ninja.gif)

[frank_c]

Quick update:
I pulled #1 & #2 rockers tonight and all the valves on that bank look good (whew). So, maybe I should have asked this question at the start - what might have caused this issue on just this one valve? Insufficient oil getting to it? Valve stem not hardened properly? Too much valve lash?

Regarding the valve stem caps, I looked at the valve more closely, and it appears that the length of stem exposed above the keepers is shorter than the height of the caps. I'd have to get measurements to be sure, but I certainly wouldn't want the cap pushing down on the keepers instead of the stem.

@Ninja ,
Thanks for your replies. I'm aware of the zero lash requirement with steel pushrods (and the inherent danger of such), but I suspect most folks will recommend that I move to heavier valve springs due to the non-std cam, and most everything I've read states that if HD springs are used, it is best to also use steel/Chromoly PRs as the AL ones may bend.

If/when I go through the effort of pulling the heads, then I would simply replace the valve (probably all of them) at that point. Of course this quickly becomes a slippery slope because I have a displacement increase on my future to-do list, and I would be very tempted to just do the bump while I have the engine that far apart.

[Jack Standz]

Thanks for your replies. I'm aware of the zero lash requirement with steel pushrods (and the inherent danger of such), but I suspect most folks will recommend that I move to heavier valve springs due to the non-std cam, and most everything I've read states that if HD springs are used, it is best to also use steel/Chromoly PRs as the AL ones may bend.

There are better options these days. For example, you could run beehive springs which is a way to control valve action without overly high spring pressure or dual springs. If this is for you, do some research as there are different beehive springs available and you will need to perform some customization.

But, if you go with HD springs or dual springs, you can still run aluminum pushrods (we run them on our 2056 with HD springs and plan to do so on our 2615 project motor which will use a cam similar to yours). There are different types of aluminum pushrods. Some "standard", some quite heavy duty pushrods, tapered aluminum pushrods, etc.

BTW there are 911style adjusters available for 2 liter rocker arms, so no need to go to 1.7 liter rocker arms.

[Superhawk996]

“ First is a short-term fix . . . “

There is no short term fix.

You are proposing driving 600-700 miles with an engine that is actively shedding hardened metal debris into the oil.

Plan an engine rebuild accordingly.

[frank_c]

BTW there are 911style adjusters available for 2 liter rocker arms, so no need to go to 1.7 liter rocker arms.

Are there 10mm swivel adjuster available that are now considered good quality? When I looked into these previously, the general consensus was to stick with the OEM 8mm adjusters from a 911 (and hence the need for the 1.7 rockers).

[frank_c]

There is no short term fix.
Plan an engine rebuild accordingly.

I guess a short-term fix was wishful thinking. It looks like at the very least I'll be pulling that one head. Now the challenge will be if I can get the valve replaced and everything back together in six weeks.

I don't believe there are any machine shops in my area that will work on these heads. I have sent parts to European Motorworks in Hawthorne, CA for some other T4 machining work. Has anyone used them for valve work before, or is there a shop that is highly recommended for this? I've used Ollies in the past for my 911 work, but when I contacted them recently about some T4 flywheel work they declined.

[Ninja]

Automotive Machine in Cleburne TX

https://www.automotivemachine.com/

Place started as a VW specialist 50+ years ago.

Fred is using them. He's close to you. You should touch base with him if you haven't yet.

http://www.914world.com/bbs2/index.php?sho...=368359&hl=

@friethmiller

[friethmiller]

Automotive Machine in Cleburne TX

https://www.automotivemachine.com/

Place started as a VW specialist 50+ years ago.

Fred is using them. He's close to you. You should touch base with him if you haven't yet.

Not a good time to be asking me about that, Rick. I'm currently waiting on word back from Eric (the owner of Automotive Machine) about my engine. Maybe I'm impatient here but he's had my engine parts for 13 months and all he says is that I'm on his short-list or it'll be underway soon. He's only machining parts, not rebuilding the motor. It's (IMG:style_emoticons/default/bs.gif)

UPDATE: I heard back from Eric. My case work is underway. I'm sure it will be 100 degrees in my garage by the time I get everything together for the rebuild (IMG:style_emoticons/default/headbang.gif)

[Jack Standz]

BTW there are 911style adjusters available for 2 liter rocker arms, so no need to go to 1.7 liter rocker arms.

Are there 10mm swivel adjuster available that are now considered good quality? When I looked into these previously, the general consensus was to stick with the OEM 8mm adjusters from a 911 (and hence the need for the 1.7 rockers).

https://www.tp-technologie.de/produkte%20ve...ellsch%20en.htm

You can find these in the USA from other vendors. Good quality? These are made from tool steel.

[Ninja]

Automotive Machine in Cleburne TX

https://www.automotivemachine.com/

Place started as a VW specialist 50+ years ago.

Fred is using them. He's close to you. You should touch base with him if you haven't yet.

Not a good time to be asking me about that, Rick. I'm currently waiting on word back from Eric (the owner of Automotive Machine) about my engine. Maybe I'm impatient here but he's had my engine parts for 13 months and all he says is that I'm on his short-list or it'll be underway soon. He's only machining parts, not rebuilding the motor. It's (IMG:style_emoticons/default/bs.gif)

UPDATE: I heard back from Eric. My case work is underway. I'm sure it will be 100 degrees in my garage by the time I get everything together for the rebuild (IMG:style_emoticons/default/headbang.gif)

I agree!
13 months is unacceptable for ANYTHING!!!!

Longest wait I've ever had was 3 weeks...
Engine was a 7M-GTE turbo Supra with severe damage.

But I haven't sent anything to them in a couple of years.
There was a REASON I chose to be an AC specialist.
I could have specialized in anything except interior upholstery.
Not having to depend on the work of "others" was one of the parameters.

Last thing with AM was a 3G-STE Toyota MR2 turbo block. Hone, vat, CNC deck (deck was at an angle from previous machine shop carelessness and required addition work to verify angle).

Less than 1 week

Sorry you didn't receive that.


OK, AM is actually one of the FEW machine shops good enough for me.
95% of the work I've done in my life they did the machine work if I didn't.
Only thing that ever stopped me was not owning the equipment...

They are NOT perfect but fixed any issues I brought up to them.

I held ASE Master Machinist as long as ASE had the category (they DON"T anymore, now they have "Parts specialist").

13 months is not acceptable in my book!

Rick

[frank_c]

Automotive Machine in Cleburne TX

Thanks for the contact info, it's good to know of a shop that can do T4 work that is not several states away.

After seeing Fred's post about the 13 month wait, I called European Motorworks this afternoon about replacing the valve. They said they could get to it right away, so I'll probably go that route unless I hear of some horror story about them. They currently have my flywheel & pressure plate for balancing, so I'll see how long it takes them to turn that job around.

[Jack Standz]

BTW there are 911style adjusters available for 2 liter rocker arms, so no need to go to 1.7 liter rocker arms.

Are there 10mm swivel adjuster available that are now considered good quality? When I looked into these previously, the general consensus was to stick with the OEM 8mm adjusters from a 911 (and hence the need for the 1.7 rockers).

https://www.tp-technologie.de/produkte%20ve...ellsch%20en.htm

You can find these in the USA from other vendors. Good quality? These are made from tool steel.

Just adding that if you run 911 style adjusters, you will need to modify the rocker arms to give enough clearance to the adjuster without binding. This is the case with both 1.7 and 2.0 adjusters.

[JamesJ]

Automotive Machine in Cleburne TX

Thanks for the contact info, it's good to know of a shop that can do T4 work that is not several states away.

After seeing Fred's post about the 13 month wait, I called European Motorworks this afternoon about replacing the valve. They said they could get to it right away, so I'll probably go that route unless I hear of some horror story about them. They currently have my flywheel & pressure plate for balancing, so I'll see how long it takes them to turn that job around.

"I called European Motorworks this afternoon about replacing the valve. They said they could get to it right away, so I'll probably go that route unless I hear of some horror story about them."

Run away, run away!
I've heard about a half dozen of those stories, including yours truly, since you asked.
PM me if you want to chat.