Are head and cylinder gaskets compression gaskets? Options

[Mark Henry]

If you want head gaskets in one of my T4 engines find another engine builder. (IMG:style_emoticons/default/bye1.gif)

I hear GEX offer good prices.... (IMG:style_emoticons/default/biggrin.gif)

[ClayPerrine]

If you want head gaskets in one of my T4 engines find another engine builder. (IMG:style_emoticons/default/bye1.gif)

I hear GEX offer good prices.... (IMG:style_emoticons/default/biggrin.gif)

You are the one who builds the motor. You have to stand behind your work. So do what you feel is right.

I will do the same.

[stevegm]

I didn't mean to invite a debate. This issue has been widely discussed. Everybody can make their own decisions for their engines. For me, I will use a head gasket on a street engine. And I will suffer the consequences if it blows out. I was just curious if the head gasket, and base basket, are compression-style gaskets, needing to be replaced after untorquing.

[Mark Henry]

New T4 AMC heads come with a big warning card in every box "Do Not use head gaskets".

BTW I just tossed out a couple dozen new head gasket sets. (IMG:style_emoticons/default/biggrin.gif)

[Jake Raby]

You can lead a human to knowledge, but you can't make them think.

[TheCabinetmaker]

Words to ponder

[mbseto]

You can lead a human to knowledge, but you can't make them think.

No one's led us to knowledge yet, they've just said 'do what I say'. I was hoping someone might address that question of whether the head and cylinders need to be lapped together. Can I do it by hand? Depending on the tools required, gaskets might be the option I can afford.

[injunmort]

^well said. my experience would lead me to lap the cylinders into the head with grinding paste to get a uniform surface. on a 1930's norton 500 single, easy to do without upsetting the cylinders and rings. on a type IV, not so much as you would have to remove cylinders and lap them into the head to get a uniform surface. i use the gasket because it is easier to get a tight mating surface without disturbing the ringland. on a blueprinted, heavily modified engine with lots of aftermarket components and custom machine work, i can see it. a stock street motor not so much.

[HAM Inc]

The reason VW said to stop using the head gaskets is, the differences in expansion rates of the bi-metal relationship between the heads and jugs combined with the inevitable shuffling (relative movement between the heads and jugs) during operation causes the laminated aluminum gaskets to delaminate. That buletin was not written with performance engines in mind, but stock.

Once they start delaminating, they allow combustion gasses to escape, which quickly etches a big path that very often leads to serious damage to the head.

Here's the reality about lapping jugs into heads: If the finish in the heads from the flycutting is rough the lapping will smooth it, but if the surface is so rough that it needs that then how much confidence do you have in the machine works accuracy with regard to both chambers being the same height AND on the same plane. Also, lapping will remove metal from the heads, but do little if anything to ensure the jugs are flat.

If you choose to lap, make a paste out of ajax and count your revolutions so you can use the same technique on each postion. If a light lap doesn't clean up the both surfaces, time for a trip to the machine shop.

Many engine builders toss the gaskets and spray the heads with aerosol coppercoat a few minutes before assembly. Overspray will not hurt anything.

That's the low down on gaskets. Proceed with your engines as you wish.

[Mueller]

Head gaskets installed on my current torn apart motor, pics below show deformation of gaskets and damage to head. Pro built motor, not a lot of miles based on how clean the motor was inside and outside under the tin.

(had a flat cam, the reason for the teardown)

Top pic shows one gasket that has deformed.
Other pictures show head damage, luckily caught before gasket failed completely allowing gases to escape and burning small ridges into head as they leave.

I will now have to make a flycutter to fix the head.

(IMG:http://www.914world.com/bbs2/uploads/post-87-1467432455.jpg)
(IMG:http://www.914world.com/bbs2/uploads/post-87-1467611405_thumb.jpg)
(IMG:http://www.914world.com/bbs2/uploads/post-87-1467611518_thumb.jpg)

[injunmort]

i could be wrong but what i see is a deformed gasket from improper torquing sequence, not a gasket failure. looks like one side was over tightened causing the gasket to deform. you can see the result.

[rudedude]

pretty good eyes to see improper torque

[HAM Inc]

i could be wrong but what i see is a deformed gasket from improper torquing sequence, not a gasket failure. looks like one side was over tightened causing the gasket to deform. you can see the result.

Look pal, DIY's come here for advise. There are a host of professionals in various specific fields that apply directly to some of these questions who help our fellow 914 lovers.

In this particular case the O.P.'s question related to a very specific apect of an engine build. This issue was addressed by VW 40 years ago. It's actually settled technology.

And as if that weren't enough, at least 3 engine professionals - myself included -with well over 50 years of combined T4 engine experience chimed in to help advise the O.P.

I have no problem with your disagreeing with me. I really don't care. But you do a diservice to the O.P. and others tryiing to learn when you argue from a position of ignorance.

You've done this on other threads as well and have exhibited the kind of behavior that contributes to the spread of misinformation that the internet has, sadly, become famous for.

I know a lot of professional aircooled VW engine builders, and not a single one of them uses head gaskets on a typical build. Are you the one professional exception, or just an internet troll? That's a rhetorical question. Based on your technical postitions, I already know the answer.

[stevegm]

(IMG:style_emoticons/default/popcorn[1].gif)

So, it sounds like I need to consider not using head gaskets. I researched this some time ago, but, it seems that the consensus here is not to use them. Maybe somebody could post the process that needs to be performed to leave them out? Can this be done by a "garage mechanic" like myself? (IMG:style_emoticons/default/biggrin.gif)

[injunmort]

i do use the gaskets, i think you mean aircooled vw engine builders, sorry i dont worship at your altar, that does seem to bother you and i aint your pal.

[ClayPerrine]

There seems to be a difference of opinion here and it is not going to be solved over the internet.


Do what you think is right, and I will do what I think is right.

(IMG:style_emoticons/default/deadhorse.gif) (IMG:style_emoticons/default/deadhorse.gif) (IMG:style_emoticons/default/deadhorse.gif) (IMG:style_emoticons/default/deadhorse.gif)

[Mark Henry]

My lapping procedure is actually quite simple.

I use valve grinding compound, not because I think it's the best, but because I have a huge can of it that was given to me. I put an even coat on the sealing surface of the cylinder, place it in the head and turn it a couple times (no pressure)complete turns, then check to see that I have an even coat.
I then turn it so it facing the direction it will be installed. I grab it with both hands and rotate back and forth the limits of my wrists, I put slight downward pressure to make sure the head doesn't lift or cock in the bore.
As I start I look at the clock, I keep a steady cadence and I do the same amount of time on each cylinder. The amount of time will depend on your compound, mine is fairly aggressive and I only have to do 1-2 minutes each bore. Once I have a clear, even lap it's done.
I mark every cylinder and bore so they stay in order, very important.
Cleaning has to be spotless, again very important.

If you are doing a real good job you should also have your case bores surfaced/decked, I do this as a part of every build now, as I find many are out of spec.

The last detail is do a freaking CR check, (plus deck height) and shim it for a correct CR.
Google engine calculator and plug in the numbers, I can do the math, I don't need a calculator.
Head CC you can buy the plate kit or make one out of 1/4" clear plexi, you can get a CC syringe from a drugstore, just tell them what you want it for, tell them you don't want the needle and you want the biggest they have. PITA because 10cc is likely the biggest they have, but in a pinch it works. Just don't lose count. Oil will kill the rubber stopper, you can use water, but put a drop of Dawn dish soap in it to break the surface tension.
You can get custom shims made by RIMCO and EMW keeps a stock of shims. You can use up to 3 of the thin factory shims but no more. They must be shimed exactly the same.

That's it, I've never seen the need to go full rotations. Many years ago I talked to a swiss trained master machinist friend about my procedure and he agreed with it, BTW same guy who gave me the big can of lapping compound.
My heads never leak, at least not till it's time that they should be rebuilt anyways.
Been doing it this way for years.

[N_Jay]

(IMG:style_emoticons/default/popcorn[1].gif)

So, it sounds like I need to consider not using head gaskets. I researched this some time ago, but, it seems that the consensus here is not to use them. Maybe somebody could post the process that needs to be performed to leave them out? Can this be done by a "garage mechanic" like myself? (IMG:style_emoticons/default/biggrin.gif)

For those of us watching from the side lines, I think this captures the question.

If you buy a typical set of cylinders and don't have access to have the top surface re-machined, and you heads are freshly done by a competent (but probably not a specialist) machine shop, are you more or less likely to have issues with or without head gaskets.

And if you are leaving the head gaskets out, do you have any additional prep required??

To roll all the way back to the OP, if his engine was built with head gaskets, what is the chance he can reseat the heads without them?

How much risk is there due to the slight increase in compression and/or the slight decrease in effective deck height?

[stevegm]

Exactly. Leaving them out is not as simple as . . . well, just leaving them out. And the proper process needed to leave them out is beyond the scope of my expertise and tools, in this area. I have built quite a few street engines over the years, always put them in, and never had a problem. Also, as I understand it, most of the problems that have arisen using them, have occurred after quite some miles (tens of thousands). Most of us aren't putting that many miles on our 914s these days, unless it is a daily driver.

Having said that, there seems to be a large enough of a concensus that they should be left out to cause me to want to reconsider my traditional choice. I respect the learned engine builders here, and certainly want to benefit from their expertise.

[stugray]

Head CC you can buy the plate kit or make one out of 1/4" clear plexi, you can get a CC syringe from a drugstore, just tell them what you want it for, tell them you don't want the needle and you want the biggest they have. PITA because 10cc is likely the biggest they have, but in a pinch it works.

I found one at a farm supply in the "veterinary/medicine" department.
It was ....wait for it...... 60ccs.

In my area the store is Murdoch's I don't know what you have in the GWN.