This thread has made me nervous
http://www.914world.com/bbs2/index.php?act=...=ST&f=2&t=33950

I have my engine ready to pull in the morning to do top end rebuild and after reading this thread about lapping the cyl to the heads I am getting worried.

I am having my heads re-built and buying new P&C's. What is the proper method when bolting the heads back on? Use seals or lap them. I have no idea how to lap somthing properly except my wife so what do I do? I watched Jake's type IV teardown and assembly and he made mention of not using the seals because of the buliten but didn't say anything about lapping either.

I am tempted to take my pulled engine down to my local VW shop and having them do all the work because I am scared LOL

Luke D

QUOTE (LukeD @ Jun 27 2005, 05:06 PM)

I am tempted to take my pulled engine down to my local VW shop and having them do all the work because I am scared LOL

what method does the shop endorse???

Both methods obviously work otherwise Jake, nor Mark or the Cap'n would still be in business.

Is someone helping you build the motor? Are you getting advice for it from the shop?? If so, use thier recommended procedure so if something does go wrong, you won't hear "I told you so"

QUOTE (Mueller @ Jun 27 2005, 07:17 PM)

QUOTE (LukeD @ Jun 27 2005, 05:06 PM) I am tempted to take my pulled engine down to my local VW shop and having them do all the work because I am scared LOL what method does the shop endorse??? Both methods obviously work otherwise Jake, nor Mark or the Cap'n would still be in business. Is someone helping you build the motor? Are you getting advice for it from the shop?? If so, use thier recommended procedure so if something does go wrong, you won't hear "I told you so"

yep, the thread even says... either will work... if you want more of the same 3 opinions shoptalk forums will have a TON of them. relax..

I am doing the work myself aside from sending my heads off.

Anything to watch out for when replacing the P&C's and using the same rods?

If I drop the engine off I am looking at about $800 in labor not including parts.

I would rather use that money for other things but if it has a better chance of being done right then it is money well spent. But after watching Jake's video I know I can do it but doing it perfectly right is another story.

LukeD

Luke,
Dont sweat it.
Use the seals or dont but dont lap your heads .
When are you dropping that puppy I'll give you a hand.

When I rebuilt my motor I tossed the head gaskets and lightly lapped the head and cylinder with some valve grinding compound. Seems nice and leak free so far...

Well, decisions have been made,

Heads are going to Rimco
Buying 96mm P&C's probably J and E's
Not using head seals


After Kelly "echocanyons" calming me down on the phone from uncontrolable hyperventalation I am confident, with his help, we can do the job properly.

Thanks buddy, after we're done we are going out for drinks on me so I can

Luke D

Pics to follow on my Top End rebuild thread

kelly lapping the heads to the cylinders is the best thing you can do even if you do use the seals. what the lapping does is it ensures the tightest possible fit. when i did the rings on my old 1.8 i lapped them in, and as you lap you can see the high and low spots, i was only getting about 80 % seal before i lapped, and 100 % after.

as for the original question jake and a few others including VW say no seals, but i did use the seals on mi 1.8 and they were fine for the 30 k mile i kept the engine for.

Scott,
Not much experience with the type fours only type ones(&356 T1's) but...

Why does the factory head not fit without machining? Warping?

If lapping the heads should be done with every build why would you use a seal between, if you use one does the seal seat and make up the difference?

How much should the heads be lapped and how do you know when your piston will have enough clearance...what are the tolerances?

If a thorough inspection show the heads to be straight why would you need to lap them? How thorough inspection is needed and what is entailed?

If they are torqued down properly they should seat, shouldn't they?

Instead of lapping why not use a copper seal or spray/brush on copper coating to make up the difference and hold the seal without cutting your heads down?

Is a lap job part of every head job? ( I know it sounds bad)

there is also another thread going on this too, if everything is brand new and has been machined perfect the the lapping would be un nessessary. but if the cylinders are not trued they can be off by a little ( dont know what a little really is ) basicly lapping them in is just perfectly mating the 2 surfaces. if the surfaces where a perfect match then they would not need it. as for the cutting of the head, if it removes .0001 material to true it up then its not a big deal. but if it takes .001 then that head cylinder combo has more problems.

as for the head gaskets that is a toss up, i used them because at the time thats what was done.

also the gaskets would not really fill any imperfections, and you would not want any sealant between the heads/cylinders/seals due to the fact as soon as it burns off you just lost head torque and maybe even the seal that it made

Are you talking about lapping the cylinder or the head?

I just think there has got to be a better way than removing material from the heads.

For this particular application he is having his heads professionally refurbished and Luke is using new P&C's. Would the truing of the face of the head be part of the process (prolly a questoin for the shop doin the work)

I am not sure about the other seals but the copper seals or copper paintable seal would not melt and is used by many on other types of applications to compensate for the potential gaps between the heads.

QUOTE

Are you talking about lapping the cylinder or the head?

well sort of both but i am sure most cutting happens on the heads, i would bet the actual lose of material in less than .0001.

QUOTE

I just think there has got to be a better way than removing material from the heads

not to perfectly mate the sufaces, if trying to remove major imperfections yes there is

QUOTE

For this particular application he is having his heads professionally refurbished and Luke is using new P&C's. Would the truing of the face of the head be part of the process (prolly a questoin for the shop doin the work)

yes the heads should be trued, and hopefully the cylinders are true too, but as some one in the other thread said it is like lapping a valve just to get a perfect seal

QUOTE

I am not sure about the other seals but the copper seals or copper paintable seal would not melt and is used by many on other types of applications to compensate for the potential gaps between the heads.

yes a copper seal would not melt but any rtv will burn over a short period. as for other engines using head gasket and rtv they dont have temps up to and over 350 degrees

once again the amount of material removed is less than you would remove with a piece of 600 grit sand paper

QUOTE (Headrage @ Jun 27 2005, 05:07 PM)

When I rebuilt my motor I tossed the head gaskets and lightly lapped the head and cylinder with some VALVE GRINDING COMPOUND. Seems nice and leak free so far...

Lapping heads as with lapping valves, it's best to use a valve LAPPING compound, not a valve GRINDING compound. And I'am not talking symantics here, Cloves has valve lapping compound's, it's a double sided can with both a coarse and fine compound's, and the coarse is still finer than the valve GRINDING compound.
I, just recently needed some lapping compound, couldn't find any Cloves, as I need it NOW, but did find a source of some other brand, that was just to order.

Luke, I recommend, even though the cylinders are new, especially cause the cylinders are new, to have the tops trued, and have the cylinder lengths matched, REAMCO can do this, since your sending your heads there. Get a quote, before hand.

Please dont mistake what I wrote for using RTV or any silicone based sealant as a head gasket.

I did say that a paintable copper coat with or without the seal to make up for the imperfections would be better than removing material.

I do agree that if there are large obvious imperfections/damage that is should be addressed by machining, If the head wont seal anyother way machining is your only option right?

QUOTE

well sort of both but i am sure most cutting happens on the heads, i would bet the actual lose of material in less than .0001.

OK so lapping is more or less like polishing right?

I guess I was thinking that it entailed machining the face of the head.

yup polishing is basicly like what you are doing, no real material removal

just make sure that your machine shop flycuts the heads well and insures that the tops of your cylinders are perfectly true. with that done, there should be no need to lap.

Are these things Rimco will ask if I want or are they implied?

Do i Just Send them my heads And they call me with what needs to be done?

thanks

Luke

Does anyone know how the "carbon seal" Jake uses functions? I thought it was some kind of groove or bevel where the head and cylinder meet.

QUOTE (nebreitling @ Jun 28 2005, 02:58 PM)

just make sure that your machine shop flycuts the heads well and insures that the tops of your cylinders are perfectly true. with that done, there should be no need to lap.

Has anyone, besides me, done a close inspection (magnafied inspection) of heads after they have been flycut?

It's, a cheap fast way to cut heads, and in all reality, it's not a quality job, and it's not the machinist, it's the flycutter, it's not a precision tool.

Thats why I perfer copper head gaskets, not only do they help seal cast iron and aluminum, there great for setting up compression ratios. I, set up a motor 1 time, and the piston stuck out of the cyl .020, and with copper gaskets I got the CR I needed.

CNC end mill, would be a nice quality way to cut heads, I can't aford that, so I use gaskets

So, lapping the cylinders, would be a benefit, if your not useing head gaskets.

This is my opinion, and others my disagree, even though there wrong.

This is why I like this Club

QUOTE (V6914 @ Jun 28 2005, 11:44 PM)

QUOTE (nebreitling @ Jun 28 2005, 02:58 PM) just make sure that your machine shop flycuts the heads well and insures that the tops of your cylinders are perfectly true.  with that done, there should be no need to lap. Has anyone, besides me, done a close inspection (magnafied inspection) of heads after they have been flycut?

Yep, doesn't matter how good a mill is, you are still cutting material that is harder in some areas that others. The tool will always try to ride over the hard spots.

Still won't use a head gasket, the copper ones are a hair better than the stock gaskets, but in my book that's just a pinch above shit.

QUOTE (Mark Henry @ Jun 29 2005, 02:48 AM)

QUOTE (V6914 @ Jun 28 2005, 11:44 PM) QUOTE (nebreitling @ Jun 28 2005, 02:58 PM) just make sure that your machine shop flycuts the heads well and insures that the tops of your cylinders are perfectly true.  with that done, there should be no need to lap. Has anyone, besides me, done a close inspection (magnafied inspection) of heads after they have been flycut? Yep, doesn't matter how good a mill is, you are still cutting material that is harder in some areas that others. The tool will always try to ride over the hard spots. Still won't use a head gasket, the copper ones are a HAIR BETTER than the stock gaskets, but in my book that's just a pinch above SHIT.

I, take it that the hair your referring to is a but hair, since you also mentioned shit, but then, a pubic hair is just around the corner.

I, know someone, that is a Certified Aviation Mechanic, he rebuilds aircooled Airplane Engines.

The quality of machine work used on those heads, is art work (VERY EXPENSIVE). Did you know, they use head gaskets. Just think about all that shit flying around above our heads.

The issues with the gaskets is that they add ANOTHER expansion rate to the engine that already hass too many dis-similar expansion rates without them.

The stock gasjkets are 3 pieces of .007 thick aluminum and if you expose them to ANY heat, or ever overheat the engine they fall apart, blow and melt parts.

I am going over the process of omitting these gaskets in my new handbook on "Sealing the Type IV engine" and it should be done in 2 weeks and out to the printer...

The methods and practices I go over will keep your heads sealed off and will do so without the gaskets- The right way.

This thread brings back memories. It has been a long time since I have rebuilt the top end of an aircooled engine.

I vividly remember though lapping cylinders and heads on a few Type Is I rebuilt. You start off with fresh, new, used, whatever, heads and cylinders; spread a real thin smear of lapping compound (you do not need much) on the rim of a cylinder; seat it into the head and work it side to side about 30 degrees around 10 times; rotate 45 degrees from the starting position and do another set of 30 degree side to side reps; repeat all the way around a couple of times. The movement becomes smoother as you continue each set.

Check the contact area between the cylinder rim and the seat area in the head just after the first set and you will see spots where the lapping compound has not touched the head surface. Check it after a couple of sets and you will see a nice clean continuous lap ring where the cylinder rim completely contacts the head surface. Keep each cylinder matched to its lapped head position. Clean, clean, clean the lapping compound off of everything! I don't think you want that stuff hanging around the combustion chamber.

I can't imagine that you take off anything but a tiny fraction of material. I agree with Jake, adding a gasket would just add another element in the works to expand/contract. I vaguely recall that some Type Is called for the gaskets and others didn't (1200 vs. 1500 vs. 1600). I wouldn't be surprised if I got that wrong though.

Sorry for resurrecting this old thread, but the "carbon seal" may be a reference to the 3.2 Carrera spec for a .0015-.0035" taper across the sealing surface of the cylinder that causes a gradient in the clamp load when torquing everything down. We use this spec with Nickies on everything but the 930 and later cylinders (since 99% of guys prefer to flame-ring them, so we provide a precision ground surface to start with).

If the surfaces are perfectly machined it's true, you don't need to lap. So the catch is have you ever seen "perfectly machined" surfaces? Are you sure? If all machined surfaces were perfect then why would anyone use gaskets anywhere? And even if the surfaces look perfect your eyes aren't good enough to tell if they really are. In fact you won't know if they are or aren't unless you lap them. Absolutely no other way. And it's sensless to worry about or even think you're removing any significant, or even measurable, material by lapping. Think about it, if you have to remove a measurable amount of material to get the machined surfaces to match then they sure weren't "perfectly machined" to begin with, were they?

So it takes you twenty minutes to know that you have a good (they're never perfect) mating surface before it's all reassembled. Remember how bad that "oops" during startup feels? You might not have needed to lap them, but that bad feeling that the "oops" causes is exactly how much it's worth it to make sure it's right as you go along. I have an even better quesiton for you: why NOT?

QUOTE

I have an even better quesiton for you: why NOT?

Because you dont know if the lapped sealing surfaces are co-planar. Or if the cylinder tops are co-planar as mounted in the case. The heads will come from the machinist ready to use, and if not, lapping is not accurate enough to fix it. By lapping, the best you can do is waste your time. Listen to the Cap'n - dont do it.

Finally I got tierd of waiting for the weather to cool off. I pulled my pass head and here are some pics. The number 2 is on the left and it is the one giving me problems. There were no "head gaskets". I was also having a problem getting the ehaust valve on this cylinder to hold it's adjustment. 60PSI compression test.

Second

Recommendations? I know it is probably hard to tell what is wrong in a picture like this but I am completely lost as to what to do with this head.

Luke D

QUOTE

I am completely lost as to what to do with this head.

Luke,

Here is my free advice:

You were planning on sending off the heads to be rebuilt. Send them off.

They should clean them up for you and will probably fly cut the sealing surfaces (where the cylinders seal to the head).

It looks like #2 cylinder was leaking at the cylinder/head interface (carbon buildup). I would inspect the top portion of that cylinder to make sure it isn't burned or otherwise eroded or damaged.

From doing my own research on this topic, you may want to take all 4 of your cylinders to the machine shop and have all four trued (sealing surfaces squared off with respect to each other) and have them all matched in length (sealing surface to sealing surface). This will allow the newly fly-cut single head to seal up properly to two individual cylinders when the head is torqued down. I would also suggest that the cylinder base gaskets be matched in thickness to insure that the head seals properly on the two individual cylinders.

What I understand is to use the cylinder base gaskets, but omit the cylinder head gaskets.

As far as the lapping goes, I'm unsure.

On one hand, I can understand the concept of making sure that the mating surfaces will be a much better match with each other. On the other hand, can you be sure that you are holding the cylinder perfectly perpendicular to the head as you rotate and lap it into the head.

I agree that the lapping process should not remove much material and to stop the lapping process as soon as the entire sealing surface is a consistant ring.

I would think that just as important would be the cylinder base to case mating surface. While this would not create a compression leak, it could cause an oil leak.



Again, just my 0.02

Just took the head down to a machine shop. Valve guide on number 2 exhaust is real loose. Needless to say that the valve wasn't seating properly in the seat and the guy doesn't know if he can grind it enough. He is going to call me monday and tell me if it needs a new seat or not. In which case I have to ship to Rimco.


Luke

would one use machinest's dye on both the head and the cly seating surfaces? when the dye is gone from both items you are assured the faces are dead on?

k