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> Another 'crack head'..., uh...I mean 'cracked' head
SpecialK
post Sep 4 2004, 12:16 PM
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Just got these heads in the mail (IrkBay special), "professionally reworked" the PO said (supposedly "Not" cracked...similar to a "No" rust car). The crack hasn't propogated to the outside and I had plans to slap them on my FFC car. My question is, are these still usable in their current condition? Or should I not bother installing them (note: Porsche 914 repair fund for the FFC is currently in the RED, everything around the house seems to be going south at the same time) (IMG:style_emoticons/default/headbang.gif)

I saw a post where Jake described welding them to 12mm, are we talking about the spark plug hole dia.?


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ArtechnikA
post Sep 4 2004, 12:29 PM
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QUOTE(Special_K @ Sep 4 2004, 10:16 AM)
I saw a post where Jake described welding them to 12mm, are we talking about the spark plug hole dia.?

yes.
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SpecialK
post Sep 4 2004, 12:42 PM
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QUOTE(ArtechnikA @ Sep 4 2004, 10:29 AM)
QUOTE(Special_K @ Sep 4 2004, 10:16 AM)
I saw a post where Jake described welding them to 12mm, are we talking about the spark plug hole dia.?

yes.

Thanks, that's what I thought...any input about the crack?

Here's another thought that just popped into my head (Man....I hate when that happens (IMG:style_emoticons/default/blink.gif) )

Is it feasible to use the cylinder and some medium/fine compound to "lap" the heads by hand to mate the cylinder tops (kind of like lapping the valves)? Or am I wasting time, and making a big mess?
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Aaron Cox
post Sep 4 2004, 12:45 PM
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Is there a crack from one cyl to the next? kinda looks like it in the photo (IMG:style_emoticons/default/ohmy.gif)
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SpecialK
post Sep 4 2004, 01:00 PM
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Sorry, try this pic.


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Brad Roberts
post Sep 4 2004, 01:11 PM
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Did you point this out to the person who sold you these ?? You need to weld that up prior t install. You will end up blowing spark plugs out of the heads... not fun.


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Cap'n Krusty
post Sep 4 2004, 01:40 PM
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I concur. Gotta weld, drill, and retap. Furthermore, I would NEVER lap in a head with a cylinder. You lose all that precision mill work you just did by just dropping a cylinder in the bore and & spinning away. Where's the sense in that? Maybe your eyes, arms, and hands are calibrated better than mine, though. If you didn't do a good job with the mill, you're screwed anyway ................ The Cap'n
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SpecialK
post Sep 4 2004, 03:58 PM
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QUOTE(Brad Roberts @ Sep 4 2004, 11:11 AM)
Did you point this out to the person who sold you these ??

Not yet! But you can bet I will!! What is it with Ebay (IMG:style_emoticons/default/ar15.gif) bastards misrepresenting their crap! That was one of the "questions to seller".

Yeah, yeah...I know. That's what I get for buying stuff off of Ebay (IMG:style_emoticons/default/slap.gif) But parts for these cars are as rare as frog hair out here.



Q: no cracks I take it??? W*** L****** answered on: Aug-07-04

A: "As far as I know, neither set have any cracks as they were done by a professional shop."

I wish I knew which shop he took them to, that way I'd sure that I NEVER sent any of my sh*t there!!



And Cap'n you're probably right about the DA "lap the cyl. to the head" idea. I must enjoy creating more work for myself. (IMG:style_emoticons/default/alfred.gif)

LOL....I just realized that the "kick in the butt" emicon is named Alfred (IMG:style_emoticons/default/lol2.gif)

Okay Jake...How far will I have to bend over to get the holes welded and retapped
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Joe Bob
post Sep 4 2004, 04:28 PM
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How much did ya have to pay?

I still have an orphan head that was rebuilt.....NO CRACKS..... (IMG:style_emoticons/default/smile.gif)
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billswim
post Sep 4 2004, 05:55 PM
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I concur with Brad on the crack. Don't install it as is, you'll be pulling that head off again in short time. However, we have had good luck with lapping the cyclinders into the heads. Its an old racing trick. The stock head gaskets are crap any ways. By putting a cylinder into the spicket of the head and rotating the cylinder lots with light pressure, you create LOTS of little peaks and valleys to hold the combustion pressure. However you need to do the math on the compression ratio to keep everything running on the stuf that passes for gas these days.
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Tom Perso
post Sep 4 2004, 07:48 PM
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Lapping the cylinders into the head is highly recommended. If you are doing it enough to make a deck height change, you've lapped too much.

Just enough to mate the surfaces and give something the carbon to bite to to make a seal.

Tom
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SpecialK
post Sep 5 2004, 11:44 AM
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QUOTE(mikez @ Sep 4 2004, 02:28 PM)
How much did ya have to pay?

I still have an orphan head that was rebuilt.....NO CRACKS..... (IMG:style_emoticons/default/smile.gif)

They were around $300 shipped Mike, what did you have in mind?
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SpecialK
post Sep 5 2004, 11:56 AM
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QUOTE(Tom Perso @ Sep 4 2004, 05:48 PM)
Lapping the cylinders into the head is highly recommended. If you are doing it enough to make a deck height change, you've lapped too much.

Just enough to mate the surfaces and give something the carbon to bite to to make a seal.

Tom

So I should just use some regular valve lapping compound, and let the weight of the cylinder itself create the downward force (head sitting combustion chamber up and level)? I wasn't wanting to change the CR, just get the best sealing surface between the head and cylinder. Would it be a good idea to count the rotations of the cylinder, and keep the number of rotations consistant between combustion chambers? And keep the cylinder (number it or something) with the combustion chamber it lapped?


Thanks for the responses! (IMG:style_emoticons/default/beer.gif)
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Joe Bob
post Sep 5 2004, 11:57 AM
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I have one...the cht side that is rebuilt. Looking for 350 ish....
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SpecialK
post Sep 5 2004, 12:16 PM
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QUOTE(mikez @ Sep 5 2004, 09:57 AM)
I have one...the cht side that is rebuilt. Looking for 350 ish....

Thanks for the offer Mike! I need to check on what the repair cost is going to be before I go writing any checks. Looks like I need to head to the classifieds and sell some 914 goodies I have laying around to get the "toy fund" back up. Life would be sooo much simpler if people would just be honest about what they're selling. (IMG:style_emoticons/default/headbang.gif)
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Joe Bob
post Sep 5 2004, 12:25 PM
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I need a MOMO steering wheel..... (IMG:style_emoticons/default/smile.gif)
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Engman
post Sep 5 2004, 12:35 PM
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Which side do you need? I have a used set with some slightly bent cooling vanes that I can send you. We can figure out whats whats later.

M
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SpecialK
post Sep 5 2004, 12:39 PM
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QUOTE(mikez @ Sep 5 2004, 10:25 AM)
I need a MOMO steering wheel..... (IMG:style_emoticons/default/smile.gif)

Sure! I've got a MOMO that's designed to look exactly like a stock plastic 914 steering wheel. VERY RARE, "NO CRACKS" (IMG:style_emoticons/default/bs.gif)
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