A few questions about heads

[jstoezel]

Hi:

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I've got that cylinder head where one plug thread has been helicoiled. It used to be a bit harder than the other "stock" threads to get the plug in. Always used grease to get the plugs installed but this time the helicoil gave up. The seat is a bit dirty due to burnt grease but you can see the helicoil came up and tore part of the aluminium seat.

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Can this be repaired? Welded? In a permanent way? something that will be reliable? I really want to reuse these heads, just acquired them.

As a plan B I'm preparing last year's heads and I've got a few questions.

- Removed the valves for lapping and noticed the <insert proper term here>area where the springs seat in</insert proper term here> show some signs of "squeezing". Refer to materal pushed out of the seat in the lower left section of the seat.

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What's this due to? Is it of any concern? Anyway to prevent it from happening.

- Noticed some valves had troubles sliding out of the guides. On the top part where the retainers grab the valve stem (proper term?), the grooves flared out a bit due to the retainers. This was minimal but enough to prevent the valve from going through the guides. I used 1000 grit sandpaper to get rid of the mild flaring and the valves came out easily. However I noticed quite a bit of scoring in the valve guides. Looks like somebody didn't get rid of the flaring before, and got the valves out by rotating them inside the guides (scoring has that typical crossing pattern). Is this of any concern?

Thanks,
Jean

[FV80]

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...
Can this be repaired? Welded? In a permanent way? something that will be reliable? I really want to reuse these heads, just acquired them.
...

You should be able to remove the existing helicoil (very carefully) and replace it with a new one that isn't bent at the top. As a general rule, I NEVER remove my spark plugs unless there is no alternative. I leave that to the engine builder so it will be HIS problem if there are issues . AFAIK, there are 3 ways to "fix" a damaged spark plug thread. If the thread is only partially stripped, you can use Permatex Thread Restorer. It works great in steel and cast iron in other applications (not spark plugs). I have no experience with it in spark plug holes. The heat might be too much for it. Another is Keenserts - a complete threaded bushing from 14mm down to 12mm. They work, but the keenserts rarely stay in the engine like they're supposed to - they generally come out with the plug. Still, it's a reasonable repair and it works. Just sometimes you have to replace the keensert if you need to replace the plug - often you can't get them off the plug without damaging the outside threads. The last is, of course, the helicoil. Personally, I've never had much luck with them, but I do keep them in the trailer for emergency repairs. All methods except the first require that the plug hole be drilled out to 14mm - a tough job in itself. Your's has already been drilled, so I'd go with a new helicoil or possibly a keensert - either way, you have to get the old hc out without damaging the threads in the head.

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...As a plan  B I'm preparing last year's heads and I've got a few questions.

- Removed the valves for lapping and noticed the <insert proper term here>area where the springs seat in</insert proper term here> show some signs of "squeezing". Refer to materal pushed out of the seat in the lower left section of the seat.
...
What's this due to? Is it of any concern? Anyway to prevent it from happening.
...

Due to excessive spring pressure and TIME. Once it's started, not much you can do about it. It's probably the primary reason the heads were replaced. They ARE still usable, but I would attempt to remove as much of the 'extruded lip' as possible so you don't have chunks breaking off and running through the engine.

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...- Noticed some valves had troubles sliding out of the guides. On the top part where the retainers grab the valve stem (proper term?), the grooves flared out a bit due to the retainers. This was minimal but enough to prevent the valve from going through the guides. I used 1000 grit sandpaper to get rid of the mild flaring and the valves came out easily. However I noticed quite a bit of scoring in the valve guides. Looks like somebody didn't get rid of the flaring before, and got the valves out by rotating them inside the guides (scoring has that typical crossing pattern). Is this of any concern?

Thanks,
Jean

This is very common. The end of the valves get hammered from the rocker arm adjuster end. Usually best to run a file or sandpaper around the top of the stem before removing it else you'll damage the guide as it comes through. Sometimes, it's IMPOSSIBLE to get the valve out without doing that. If the valves are not excessively loose in the guide, I would not worry about the scoring. It will make them wear a bit faster, but otherwise should not be a problem (IMHO).

Good luck,
Steve, FV80

[Rickydel]

Addressing the plug issues only, as it seems you may have bigger issues:

If you look at this site, you will find a repair for already helicoiled plug holes:

http://www.timesert.com/html/bigsert_sparkplug.html

Good luck.

RIcky del

[hardingfv32-1]

1) Plug hole: At this point if might be best to have the plug hole welded and re-tapped.

2) It would be my opinion that the metal deformation around the valve spring seat is from the springs not having enough pressure. They are going into an oscillation and moving around.

Brian

[brian]

In addition to the spot on responses, I will add a couple of points.

1. Do not use oil or grease to lube plugs. The heat generated in that area will crystilize the lube and make matter worse. Use anti sieze sparingly or go to an aircraft supply company and buy Champion Spark Plug lube.

2. The spring perch damage is like Brian says, the spring is bouncing around. Either step up on pressures or lower your shift point. I recommend that you never exceed 6500 in 3rd. You can do it, but it will cost you in valve train wear and failure.

3. The valve stems get banged up because the keepers are too loose. And, or you're overreving the engine. There should be a gap between keepers when installed on the valve. If the keepers touch, the valve is allowed to remain loose in the grooves it will jump up and down on each opening. I know there are some other theories on keepers so make your own call. NEVER DRIVE A TIGHT VALVE DOWN THROUGH THE GUIDE! Always file or sand down the stem till it slides through the guide.

You may PM if you have any further questions or need a source for welding.

[jstoezel]

Thanks all for taking the time to write detailed replies. I had hints that valves were floating last season, starting around 6200-6300 RPM.

Brian: ideally I would like this head to be fixed permanently, and re-welding the spark plug hole seems to be the cleanest/more durable solution. Or is it?
I don't know of anybody that does this kind of welding repair locally, but there's a local shop that will install an insert. So it's either I get the heads fixed very quickly with an insert or I ship them away. I will need the heads back in the car within 2 weeks, I'm not sure this is enough time to send the heads, have them reworked and back.

Would it be possible for me to call you to discuss this further? If so please provide me with a contact information and time I can call you. Hope you are comfortable with thick accents, like Stevan Davis says, I do tend to "talk funny".

Thanks,
Jean

[shirleymac]

I had a similar problem last year with a Keensert that failed. It was stuck to the spark plug and in the process of changing plugs it striped the threads on the head.

I had a engine shop that specializes in repairing aluminum heads for drag racing do the repair. He welded the hole closed and then re tap it to the original thread size and diameter. The only issue was after getting the head back was, I'll need to use a longer spark plug for that cylinder. This was because when he welded in the aluminum to make the repair he had to make the area around the spark plug hole a little thicker to keep the strength of the original opening. I have since purchased another set of heads and this set I have on the shelf for a spare.

Tony Siembieda
FV 19
DMVR

[BobShedd]

In regards to the spark plug thread issue - based on my experience with vintage race heads I would either use the timesert " Big Sert " or have them welded. The Big Sert has a mechanical means of locking the insert in place and it will not come out without destroying the head.
Welding - I would suggest using someone who is framiliar with the VW heads and can make it good as new. I have had good experience with Rimco ( S. Calif. ) for all sorts of head repairs ( valve seats, broken valves, etc). 1-855-RIMCOVW or http://www.rimcovw.com

I might point out that one source has told me he won't do any repair execpt welding - the original threads have lasted almost 50 years - lets do it the way the factory did it in the first place. Someone once asked if having one plug hold inserted and one bare alum. threads do you need a different spark plug heat range ( I haven't found this to be true ). I would weld it.

Bob

[jstoezel]

Thanks for all the replies, this is much appreciated.

An update on this, I sent the damaged heads to Brian McCarthy 2 Tuesdays ago, got the heads the following Monday. He worked fast and was available to answer my questions. He fixed the damaged threads and did much more for a very reasonable price.

Thanks again Brian McCarthy, this is great service.

Jean

[jstoezel]

I was cleaning the other set of heads, the ones I race with (cylinders #3 and #4). I noticed something that looks like a crack, refer to picture below. This is intake #4 and what looks like a crack on the left is oriented towards the middle of the head (on the other side of the wall there's a vertical opening with fins).

I'm not 100% this is a crack that goes to the other side of the wall. I had the heads apart a few weeks ago and don't remember seeing this. This is the best picture I could take, not sure somebody can deduce this is a failure crack or something else. How do these heads look like before machining? Is this how these heads typically fail?

Also, the valve guide is machined so paper fin that it seems chunks have gone, and some are about to fall apart.


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