Panhead Head Problem

[Glenn]

Now I'm going to make a big mistake and tell how I stagger the rings. The gap on the oil expander is lined up with the wrist pin.or at 9:00 o'clock The bottom "scraper" rail is at 7:30, Top rail at 10:30 Top ring at 1:30 second ring at 4:30.


is that all am or pm and that an awful long time spacing out each ring

just thought I'de lighten it up a little

[Snakeoil]

If the piston ring seal is not equal in both cylinders, then they both will have different fuel mixture requirements. You could say that you have a low compression single cylinder engine up front and a high compression engine out back. As the engine RPM increases, I would expect the leakage around the rings to have less impact because the speed of the piston would make up for the leakage to some extent. The velocity of the gasses coming thru the intake is much higher and hence the leak has less effect. You are also using a different fuel circuit at a higher engine speed. You might be adjusting the carb to provide the perfect mixture for the air flow into the front cylinder and since the mixture is coming from one carb to both cylinders, the back one will be off a little. This could account for the occasional miss on that cylinder. You would not be able to tune it out without having an effect on the front cylinder.

So, there is a chance here that your lumpy idle and your measured front cylinder air leak are related.

I've done a lot of troubleshooting for big power plant equipment, mostly gas turbines. All I can tell you is when you have mutiple problems/symtoms, you have to address them one at a time. You can fix mutiple known problems at once, which makes sense when you are tearing things apart. But you will never truly know what caused your observed problem. If you suspect a leak in the front cylinder, make sure you fix that problem. While you are in there, look for anything that could be wrong. Compare the old heads to the new heads. Look for other telltales of something acting up. It's really hard to sit far away and be able to tell somebody what to look for. Often seeing something will point you in a direction that you would not have considered. Nothing beats being there with the equipment.
As for the smoke, could be the rings have not properly seated in that front cylinder yet. Are you running synthetic oil? I would not recommend it for break in. Put regular oil in for the break in.

Good luck.

[rousseau]

Glenn
This would all be PM as I am not a "morning person".

RVP
somthing else-- did you check the ring end gaps when you installed the new pistons?

[RvP]

Last Installment

This will be the last installment since we did find something overlooked and will need some time to either fix or replace. When the head gasket was removed the piston had absolutely no carbon on it, still don’t understand how the piston can have no carbon and be absolutely clean but it is. The surprise was the bottom of the head gasket has wet oil from the oil return hole to the cylinder. There was even a small wet trace of oil from this location on the head near the spark plug. If the head is tight and the gasket sealing we would not expect traces of oil under the gasket with a trail inside the head.

The head counterbore and cylinder spigot were measured. The head counterbore is not consistent and varies by 0.010 around the head but is still 0.004 deeper than the tallest wall of the cylinder spigot. Given the head gasket is around 0.028” thick this should not be a problem.

What is a problem is the head rocks left/right on the cylinder with no head gasket. The rocking is so bad we can get an 0.020” feeler gauge between the head and cylinder on the outer mating surface if rocked to the extreme. Given the head gasket is 0.028” thick, it is doubtful the gasket is being sufficiently compressed in that area. If you are familiar with this year panhead there is only about 1/8” of gasket between the oil return hole and the cylinder. This is the area that does not appear to be compressed.

We put a straight edge on the head and the straight edge does not fit flat across the head near the intake bolt hole, it rocks left/right. The high point seems to be the bolt hole itself. Even more curious is the bolt hole near the intake is not as deep as the other bolt holes and the head bolt is around ¼” higher in that one hole relative to bolts in the other holes.

Everywhere else on the head appears flat. It was harder to measure the flatness of the top of the cylinder across the bore due to the raised spigot but walking around the bore there were no signs of rocking with the straight edge.

This is not so obvious when the head gasket is on. Since these heads have had so many defects when purchased new I do not know what the owner will decide, replace the heads with another brand or continue to sink money into these heads assuming this is the last problem with them.

One more thing, the ring gap was checked and correct prior to installing them.

[RvP]

An Update

OK, I lied, one more installment, I just got a call with an update…..

The rear head rocks also when it is placed on the rear barrel without the gasket the same amount as the front. A set of old stock heads were borrowed and placed on the barrels and they do not rock at all, they sit flat with no movement. Unless we are way off base, heads that rock side to side do not sound like they will seal properly to the gasket.

[Snakeoil]

Warped heads = not good.

Although you've already proven it's the heads and not the jug decks, for future reference if you wanted to check the jugs for flatness, put them on flat plate and then put a dial indicator on the deck surface and with the magnet off, run it around. It will also show you if the base flange is parallel to the top flange.

I'd also be curious if the heads had the same volumetric capacity given all the other "issues" they've had.

If you saved all the parts that you had to replace, I'd bring them back and show the dealer. He might take them back. Or, he might give you some of your money back and let you keep the heads. Then you can take them to a shop and have them machined flat.

If it were me, I'd try to get my money back. Then I'd search for a set of original heads and rebuild them. Try reputable shops that won't sell you their junk heads. I can give you a name in upstate NY that all my friends with panheads swear by (not at). He so busy his wife answers the phone and unless she knows you, won't let you talk to him. He calls you back later when he gets a moment. He's also built some heavily modified panheads so your flywheels and such won't bother him. He might even give you a few tips. He might even be willing to save your tired old original heads.

[RvP]

Rookie Mistake = Lesson Learned

Well I admit, we made a rookie mistake but a lesson well learned. In the future when I am fitting any gasketed surface, fit them without the gasket first to see how well they mate. Never assume that if it’s shiny and right out the box it is a good part.

Thanks for the tip on how to measure the flatness of the barrels. I do have access to a granite slab and dial indicator here at work. It sits in the dusty corner of the electronics assembly room and I should make use of it more than the company does.

Returning the heads has not been successful the first time it was found the valves were scored, valve guides loose and valve stems mushroomed. The middle man that they were purchased from said he called the distributor/manufacturer and they could not be returned or pro-rated since they had been used although briefly. When the distributor/manufacturer was called directly they would only speak with their point of sales, not the person that purchased them 3rd party. This is why they were not returned at the first sign of trouble.

The owner of the Panhead is a member of the AMCA and reads the forum. I have been doing the writing because he is a man of few words and felt I could describe better the events and paths we have taken. We both appreciate the offer you (Rob) have made to put him in touch with someone that you highly recommend in the NY area. The next move is his deciding where his time and money is best spent with resolving this head problem.

Thanks again to everyone who took the time to provide very useful suggestions. Had we not gone down the paths put forth I don’t think we would have discovered the heads were not flat. Thanks again.

Ronald V. Papasso
#3129

[rousseau]

Ronald

I'm going to repeat myself from an earlier post. "Do yourself a favor and pull the jugs off."

Its only 8 more fastners and a couple of gaskets. Take a good look at those rings. (enter your cliche' here) Better to be safe than sorry.

Dennis Rousseau
AMCA#11302

[Snakeoil]

Scored guides and mushroomed stems sound like faulty parts to me. Just the stems would have told me I was sold junk parts.

You can always try the small claims court route. Might make the dealer rethink his first rejection of your claim.

I think in an early post you said these were from V-Twin. They have an email address for info on their website. info@TeddCycle.com A well worded email explaining your problems and the pain you have suffered just might find it's way to Tedd. Can't hurt, that's for sure. Squeaky wheel and all that stuff.

Are you sure they are really V-Twin parts? Any chance the dealer sold you parts made on Melmac by aliens? Threat of small claims court might get his attention. And if Tedd's parts say V-twin on them in the casting and yours don't, hmmmmm. Go after the SOB.

We had a shop that opened up locally. Bunch of jerks that must've watched too much American Chopper on Discovery. Did a lot of bad work, took money and never completed work. Lasted less than a year. Not sure what happened to them, but would not be surprised if they were buried somewhere next to Jimmy Hoffa.

Good luck,

[Snakeoil]

For some reason while I was in the shower this morning I was thinking about your problem. I realized that I told you to check the flatness of your jugs on a surface plate with an indicator. It occurred to me that there is a spigot at the bottom of the jug. The spigot would require you to rest the lower jug flange on a set of ground parallels to be able to check the relationtionship between the bottom flange and top flange. If you don't have a set of parallels to use, you might try finding a piece of cold rolled square or rectangular bar stock of suitable thickness to allow clearance for the spigot. Lightly flat file any dings away. Then check it with a micrometer to see if it is parallel. I would think that a new piece of cold rolled would be parallel within 0.001 inch and should be fine for what you are doing.

And, after you check the top flange, flip it over and check the bottom the same way. If the bottom is warped so that it creates a gap between the bolt holes, the parallels will rest on the high points and you won't pick it up when you check the top.

Sorry for the oversight. Have a jug sitting right in front of me so no excuses other than misfiring synapses.

[RvP]

Thanks for the tip

We have not pulled the jugs yet and I did not remember the bottom of the jug is not flat either! Thanks for the suggestion.

Ron Papasso
#3129

[flthead]

old rust better head to the library ....

[Snakeoil]

Nice work!!