So, I am building slowly a 2056 from a 1.7 and rebuilding a side shifter as spares for the worn out set in the '76. Transmission is done and engine just needs the heads. Machine shop would do the welding of a head crack at the spark plug they but declined to deck the heads on the grounds that they were not set up for something that wasn't a Toyota or Ford. I appreciate their turning me down.
CB engine calculator says that at present deck height (a bit high at 0.055) I won't be able to get the compression I want, which is anywhere a bit north of 8. Also one of the chambers had been through something horrible and was deeply pitted - fixing that meant grinding away 3 cc worth of metal - to 62 cc. That meant grinding the 3 other chambers to match, but made compression worse. So, I decided to see what my little Enco could do.
Click to view attachment
Yeah, I cringed too, and for good reason. Fortunately there are (were) milled flats around the chambers to reference from, so I took a 10 thou skim off of the valve cover edge to make that parallel and then flipped the heads chamber up and started milling. I spent a half day per chamber on the whole thing with about a half dozen micrometers scattered everywhere. I ended up taking off 0.025 per chamber which brought me down to 59 cc all around (starting from 62). The last thing I did was to mill away the flats around each chamber to provide clearance for the jugs. I decided not to skim the whole head.
So I have a question. I want to use the sealing rings from the gasket kit because they are made to squish just a little. But they are 29 thou thick. That adds quite a bit to the deck height, since they essentially sit on top of the cylinder. In the end I milled a flat groove for the rings 0.025 deep around the edge of the chambers. Is this going to bite me somehow? I know I should have pics, but I don't have them with me.
Full Version: head on straight
Why do you need the head gaskets?
Lap the heads in and space the bottoms to the desired deck.
Lap the heads in and space the bottoms to the desired deck.
QUOTE(Mark Henry @ Mar 18 2013, 09:50 AM) 
Why do you need the head gaskets?
Lap the heads in and space the bottoms to the desired deck.
Thanks Mark,
I guess I was going with the gaskets for 3 reasons. First some people say to use them, Second they were included in the gasket kit and listed in the manuals, and 3rd because I thought they might improve the seal. I also know that not using them is often advocated too. So I came down on one side of the fence, not being sure.
Bad idea eh? What is the downside of the gasket other than thickness? I appreciate the help.
QUOTE(worn @ Mar 18 2013, 12:53 PM)
QUOTE(Mark Henry @ Mar 18 2013, 09:50 AM)
Why do you need the head gaskets?
Lap the heads in and space the bottoms to the desired deck.
Thanks Mark,
I guess I was going with the gaskets for 3 reasons. First some people say to use them, Second they were included in the gasket kit and listed in the manuals, and 3rd because I thought they might improve the seal. I also know that not using them is often advocated too. So I came down on one side of the fence, not being sure.
Bad idea eh? What is the downside of the gasket other than thickness? I appreciate the help.
This is from Richard Atwells pages.
http://www.ratwell.com/technical/Heads.html
QUOTE
This head related topic probably stirs up more argument that any other. In the 1990's VW released a tech bulletin that among other things recommended the removal of the shim gasket between the head and the cylinder. This gasket is actually made from several thinner gaskets pressed together and when one layer shrinks and burns through a gap forms that allows the combustion gases to escape resulting in eventual head failure.
The consensus on this issue, after much photographic evidence depicting burns in this area, is to remove the head gasket and lap the head to the cylinder and rely upon a carbon build-up to help maintain the seal. Now there is no gasket to fail because there is one less sealing surface but it means you have to get the contact surface absolutely flat because there is no gasket to crush and make up for inconsistencies. It also means that you need to recalculate your compression ratio but that is a necessary part of an engine rebuild anyway.
The gasket (~0.80mm before crush) in not the same thickness as the 1.6mm spacer VW recommends using which begs the question: has VW also recommended lowering the compression ratio or were there further instructions? Well, first consider there is was also a paper gasket at the base of the cylinder and if that measured 0.80mm also then there should be no change to the CR but Wilson says the paper gasket should be 0.20mm thick and so is the metal base gasket included with the rebuild kits so it appears VW did recommend a slight reduction to the compression because overall the deck height has increased by 0.6mm (approximately 7.3:1 to 7.0:1).
AMC has solved the problem of the head gasket by eliminating it as well. They have machined a step into the head in place of the original gasket and this serves to provide a corner and mating surface that obstructs any escaping gases after sufficient carbon buildup which is promoted by the gasket sealer used. The step is about 0.80mm thick (incorrectly shown as 1mm in photo) which is about the same as the gasket that was removed. The head combustion cc is about 50cc on a 2.0L AMC head below the step. Above it's about 57cc.
To summarize, if you elect to remove the gasket you've got some machining to do to your head and some math in order to add the step. If you have an AMC head you don't need the head gasket (AMC even gives you a warning notice with your head). Electing to use the gasket is an acceptable practice on a VW head if you cannot guarantee the seal but only if there is no step cut in place.
See the tech bulletin listed in the references for details.
The consensus on this issue, after much photographic evidence depicting burns in this area, is to remove the head gasket and lap the head to the cylinder and rely upon a carbon build-up to help maintain the seal. Now there is no gasket to fail because there is one less sealing surface but it means you have to get the contact surface absolutely flat because there is no gasket to crush and make up for inconsistencies. It also means that you need to recalculate your compression ratio but that is a necessary part of an engine rebuild anyway.
The gasket (~0.80mm before crush) in not the same thickness as the 1.6mm spacer VW recommends using which begs the question: has VW also recommended lowering the compression ratio or were there further instructions? Well, first consider there is was also a paper gasket at the base of the cylinder and if that measured 0.80mm also then there should be no change to the CR but Wilson says the paper gasket should be 0.20mm thick and so is the metal base gasket included with the rebuild kits so it appears VW did recommend a slight reduction to the compression because overall the deck height has increased by 0.6mm (approximately 7.3:1 to 7.0:1).
AMC has solved the problem of the head gasket by eliminating it as well. They have machined a step into the head in place of the original gasket and this serves to provide a corner and mating surface that obstructs any escaping gases after sufficient carbon buildup which is promoted by the gasket sealer used. The step is about 0.80mm thick (incorrectly shown as 1mm in photo) which is about the same as the gasket that was removed. The head combustion cc is about 50cc on a 2.0L AMC head below the step. Above it's about 57cc.
To summarize, if you elect to remove the gasket you've got some machining to do to your head and some math in order to add the step. If you have an AMC head you don't need the head gasket (AMC even gives you a warning notice with your head). Electing to use the gasket is an acceptable practice on a VW head if you cannot guarantee the seal but only if there is no step cut in place.
See the tech bulletin listed in the references for details.
http://www.ratwell.com/mirror/www.dolphins...m/techbull.html
QUOTE(worn @ Mar 18 2013, 06:28 AM)
So, I am building slowly a 2056 from a 1.7 I decided to see what my little Enco could do.
Click to view attachment
Yeah, I cringed too, and for good reason.
The 2056 heads worked out before as shown here. I was really nervous.
Click to view attachment
So, when it came to my 911 heads to go into the 1980SC with the broken Dilivar studs, I thought long and hard and then did it anyway:
Click to view attachment
A lot more on the line since you can get a set of 914 heads for the price of one of these guys. Took 10.5 thousandths off to get the pitted valley out, starting with the worst first. It also took an investment in a face plate and more indicators and then a lot of worrying and measuring so the dowel fit right. I think most people attach a slice of a cam tower to a back plate, but I didn't have any toasted towers to use.
I also made rams and jigs for valve guides. This used a hydraulic unit from a 1-2 inch sheet metal hole punch from Harbor Freight to pull the valve guides and after dry ice the new guides went in with little resistance using a drift turned on the lathe. Turns out that clean heads don't make a mess in wife's oven at 250 degrees.
3 done so far: wish me luck.
![popcorn[1].gif](http://www.914world.com/bbs2/style_emoticons/default/popcorn[1].gif)
Good job 
.010 flycut on the heads is MAX if you still have some minor imperfections eat it.
It won't matter if they are minor.
If you could find a scrap head to play with I bet you could twin plug that puppy.
Not going to twin plug?
Do it anyways use 9.5(+):1cr P&C's and then use two cylinder base gaskets. That should get you back down to single plug CR.
When you change your mind loosen the head nuts and pull everything up slightly, then snip the extra gasket.
Instant twin plug.
.010 flycut on the heads is MAX if you still have some minor imperfections eat it.
It won't matter if they are minor.
If you could find a scrap head to play with I bet you could twin plug that puppy.
Not going to twin plug?
Do it anyways use 9.5(+):1cr P&C's and then use two cylinder base gaskets. That should get you back down to single plug CR.
When you change your mind loosen the head nuts and pull everything up slightly, then snip the extra gasket.
Instant twin plug.
BTW
What are you doing for head studs?
If you're on the cheap I have a bunch of good devilars (free), My engine had no broken studs but I'm missing one stud from a full set.
I used Supertec studs.
Main bearings I have a new STD set DFL coated, give me what I paid for the bearings and the DFL coat is free.
I have a set 3,2 used STD rod bearings DFL coated, cheap.
May have a few other leftovers bits
BTW if you are doing your bottom end don't toss the #8 bearing, the new #8 tolerances are crap.
What are you doing for head studs?
If you're on the cheap I have a bunch of good devilars (free), My engine had no broken studs but I'm missing one stud from a full set.
I used Supertec studs.
Main bearings I have a new STD set DFL coated, give me what I paid for the bearings and the DFL coat is free.
I have a set 3,2 used STD rod bearings DFL coated, cheap.
May have a few other leftovers bits
BTW if you are doing your bottom end don't toss the #8 bearing, the new #8 tolerances are crap.
QUOTE(Mark Henry @ Mar 3 2016, 04:04 PM)
BTW
What are you doing for head studs?
If you're on the cheap I have a bunch of good devilars (free), My engine had no broken studs but I'm missing one stud from a full set.
I used Supertec studs.
Main bearings I have a new STD set DFL coated, give me what I paid for the bearings and the DFL coat is free.
I have a set 3,2 used STD rod bearings DFL coated, cheap.
May have a few other leftovers bits
BTW if you are doing your bottom end don't toss the #8 bearing, the new #8 tolerances are crap.
Mark,
Thanks. For the twin plug, no I just want a nice 80s Porsche and the cool that it had at the time. Forlorn hope about the cool.
Bearings: it is a 3.0 sc and while I have them in hand I wouldn't mind an offer.
Re: #8 bearings, wtf? You mean the one I bought from the bird should be used as a sinker? Oh, man I am in too deep. Knew it already, but I was worried about my idiocy, not the vendors.
And thanks for posting. A lot of fiddling lining everything up, but a hell of a lot of fun making angel wing fine shavings. I have one more to do.
Do you know what the clearance is between jug and head is? At what point do I have to skim the surround? An easier job, but work nonetheless.
QUOTE(Mark Henry @ Mar 3 2016, 04:04 PM)
BTW
What are you doing for head studs?
If you're on the cheap I have a bunch of good devilars (free), My engine had no broken studs but I'm missing one stud from a full set.
I used Supertec studs.
Main bearings I have a new STD set DFL coated, give me what I paid for the bearings and the DFL coat is free.
I have a set 3,2 used STD rod bearings DFL coated, cheap.
May have a few other leftovers bits
BTW if you are doing your bottom end don't toss the #8 bearing, the new #8 tolerances are crap.
I am willing to round out your dilivar set with those that didn't break. I was incautious and drove one winter night with salt on the road
But it looks like one broke way early long ago on the other side and was replaced while owned by a submarine driver commuting from San Diego to Bangor (WA). I traced him because of his work in an anti nuke rally involvement
.
More
Set up. $40 plus existing cheap lathe
Click to view attachment
more. OK, there is another $30 for the test indicator. The stuff builds up over time.
Click to view attachment
spin up
Click to view attachment
frozen by flash strobe - it is still spinning!
Click to view attachment
Angel hair aluminum - really nice metal
Click to view attachment
And what the problem was
Click to view attachment
I took 0.0105 off, but I don't know whether that is OK with the jugs as is, or whether or not to trim the surrounding face equally. I am gonna unless someone has the clearance specs.
This is for a 911, but these motors find their way into teeners too. Spell check turned teeners into tenors, which I don't think is quite correct. Did I save money. I doubt it. Did I risk thousands of dollars. Absolutely. Was it fun? For me, well yes!
Set up. $40 plus existing cheap lathe
Click to view attachment
more. OK, there is another $30 for the test indicator. The stuff builds up over time.
Click to view attachment
spin up
Click to view attachment
frozen by flash strobe - it is still spinning!
Click to view attachment
Angel hair aluminum - really nice metal
Click to view attachment
And what the problem was
Click to view attachment
I took 0.0105 off, but I don't know whether that is OK with the jugs as is, or whether or not to trim the surrounding face equally. I am gonna unless someone has the clearance specs.
This is for a 911, but these motors find their way into teeners too. Spell check turned teeners into tenors, which I don't think is quite correct. Did I save money. I doubt it. Did I risk thousands of dollars. Absolutely. Was it fun? For me, well yes!
QUOTE(worn @ Mar 5 2016, 06:06 AM)
More
Set up. $40 plus existing cheap lathe
Click to view attachment
more. OK, there is another $30 for the test indicator. The stuff builds up over time.
Click to view attachment
spin up
Click to view attachment
frozen by flash strobe - it is still spinning!
Click to view attachment
Angel hair aluminum - really nice metal
Click to view attachment
And what the problem was
Click to view attachment
I took 0.0105 off, but I don't know whether that is OK with the jugs as is, or whether or not to trim the surrounding face equally. I am gonna unless someone has the clearance specs.
This is for a 911, but these motors find their way into teeners too. Spell check turned teeners into tenors, which I don't think is quite correct. Did I save money. I doubt it. Did I risk thousands of dollars. Absolutely. Was it fun? For me, well yes!
Great skills and good results on the 911 heads,I could see your only issue here would be getting each head machined exactly the same...looks like you have sorted that ?.
Can't see you having clearance issues with that small amount removed.
Marks idea about lapping the T4 heads is a sound one,well proven process if a gasket isn't used,I have personally seen many of these gaskets fail and cause serious damage to the heads....not to mention combustion leakage
.I have a set of 1.7 heads machined for extra compression and 96mm barrels the machinist who only does VW aircooled work told me the type 4 combustion floor is very thin compared to the type 1,he took the max off mine possible,sorry but I can't remember how much.
Keep up the good work
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