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mill your own heads?


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21 replies to this topic

#1 Uberoo

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Posted 13 July 2009 - 09:54 AM

I have an 84 EA81 wagon (my avatar). Anyway I am assuming it has two severly blown headgaskets. The coolant dissapeared going up a long steep hill.It never read hot, just when it got to the top it didnt have any power so I checked it out.the radiator was cold and most of the oil was burned off the block.Anyway, then I tried to crank it and it spun like it had no compression.I am hoping its just the heads warped so much that the headgasket wont seal,rather than the pistons warping...I wont know until I tear it down.Money is tight so I cant afford 30 bucks a head to have them milled flat.Ive heard you can use a flat piece of glass with some sandpaper glued to it to "mill" the heads.Anyone ever tried that?Can that method get the heads flat enough to seal up with the headgasket?If I can't fix it, I suppose I can remove everything not aluminum from the engine then get some money for the EJ22 swap I am planing...Allthough in the meantime I would rather fix the thing because there is a mudbog competion next week I might like to run in :grin:

What sandpaper is best to use?What surface roughness does the aluminum head/block need to be?If need be I suppose I could make sure the block is flat too.(I am pulling the motor to do a good job.I have an abundance of time but very little money.. as always..

#2 Jerry DeMoss

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Posted 13 July 2009 - 10:59 AM

Save yourself the headache and extra expense of later buying another head and go have it machined at the machine shop. About $40 per head is what most shops charge.

#3 grossgary

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Posted 13 July 2009 - 11:35 AM

There's actually some really neat write ups in here about doing it yourself. Can't remember who, but one of the Alaska guys I think wrote some specific and interesting info on doing it.

I don't recommend it at all, but I've helped out a few friends that didn't want to spring for any more than gaskets, so I gasket slapped them without doing anything. To my knowledge all of those cars are still running, one guy is getting ready to sell his, it's been running for 5 years now no problem after gasket slapping an XT6.

I'd recommend the Fel-Pro permatorques like all us EA82/ER27 guys use all the time, don't know if they have those for EA81? I would be more worried about using cheap gaskets.

I've done enough "gasket-slap" jobs that I wouldn't be that concerned about it. Particularly if you're taking the extra step of trying to flatten them up a bit. Again, I'm not recommending it and I don't personally do it - but I do understand folks situations. And you very well may have more time than money, in which case if you have to do it again it's not a big deal. And there's a good chance (in my experience) you won't have to do it again.

#4 Gloyale

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Posted 13 July 2009 - 11:52 AM

You really need to check them with a straight edge and a feeler before decideing on what to do.

If they lost that much coolant and got hot enough to not run, they may be cracked, have burned valves or seats, or be warped really bad.

I have done too many "it'll be fine" jobs that weren't to think this would be a good idea. I'll gasket slap an engine that runs but just get's hot, but one that doesn't run.........you need to inspect before deciding what to do.

#5 grossgary

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Posted 13 July 2009 - 12:18 PM

good point - all the ones i've done were previously running daily drivers that were loosing coolant. none were significantly "blown", wouldn't run, or sat for a long time, etc.

#6 GeneralDisorder

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Posted 13 July 2009 - 07:50 PM

Assuming no cracks, you can do it.

You need a bit of 1/4" thick glass - large enough for the paper.

Make SURE the glass is clean. You will want to start with a 600 grit and work up to a 1200 grit for the best surface finish.

Use it like a big sanding block - use a LOT of WD-40 (both to secure the paper to the glass, and as a cutting lubricant), and clean the paper OFTEN with the same WD-40. Solvents can't be used as they will destroy the paper. You need to use wet/dry paper obviously. I can't stress enough how often you need to clean the paper with aluminium heads - every 5 strokes or less. It is critical to the finish that the particulate be washed away frequently.

It's labor intensive and takes some skill, and many folks will tell you it can't or shouldn't be done - people these days are very often spoiled by the easy access to machine shops and power tools. There are a LOT of old-world techniques out there that work very well but are not well known and are no longer practiced except by a few old timers that probably shun internet access. Fortunately I work with most of them I think....:rolleyes:

I have lapped plenty of valves to a perfectly flat mirror finish using 1200 grit paper - so perfect the valves would hold back solvent with only a metal-to-metal seal and I could see my image in the reflection. The trick is in the application of even pressure, and making sure the cutting surface is clean and well lubed.

It would be best if you could get paper large enough to run figure 8's with the head - using the weight of the head to insure even pressure. I have even seen machine shops run heads on a belt sander for a "resurfaceing" operation :eek:. Done properly it does work though. You just have to have the right mindset and do some thinking and prep-work to set yourself up for the operation. I think I would probably go buy some sanding belts and cut them so I had a long surface on which to pull the head back and forth and a peice of glass sufficient to run the head at least twice or three times it's own length back and forth. With a good cleaning every 5 strokes and a few hours of labor you should see nice results.

Just make sure you don't take off more than .010" off each head. I beleive that's the max to still get a decent fit on the manifold. More could be done but you might have to oval out the manifold bolt holes.

GD

#7 nipper

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Posted 13 July 2009 - 07:58 PM

Assuming no cracks, you can do it.

You need a bit of 1/4" thick glass - large enough for the paper.

Make SURE the glass is clean. You will want to start with a 600 grit and work up to a 1200 grit for the best surface finish.

Use it like a big sanding block - use a LOT of WD-40 (both to secure the paper to the glass, and as a cutting lubricant), and clean the paper OFTEN with the same WD-40. Solvents can't be used as they will destroy the paper. You need to use wet/dry paper obviously. I can't stress enough how often you need to clean the paper with aluminium heads - every 5 strokes or less. It is critical to the finish that the particulate be washed away frequently.

It's labor intensive and takes some skill, and many folks will tell you it can't or shouldn't be done - people these days are very often spoiled by the easy access to machine shops and power tools. There are a LOT of old-world techniques out there that work very well but are not well known and are no longer practiced except by a few old timers that probably shun internet access. Fortunately I work with most of them I think....:rolleyes:

I have lapped plenty of valves to a perfectly flat mirror finish using 1200 grit paper - so perfect the valves would hold back solvent with only a metal-to-metal seal and I could see my image in the reflection. The trick is in the application of even pressure, and making sure the cutting surface is clean and well lubed.

It would be best if you could get paper large enough to run figure 8's with the head - using the weight of the head to insure even pressure. I have even seen machine shops run heads on a belt sander for a "resurfaceing" operation :eek:. Done properly it does work though. You just have to have the right mindset and do some thinking and prep-work to set yourself up for the operation. I think I would probably go buy some sanding belts and cut them so I had a long surface on which to pull the head back and forth and a peice of glass sufficient to run the head at least twice or three times it's own length back and forth. With a good cleaning every 5 strokes and a few hours of labor you should see nice results.

Just make sure you don't take off more than .010" off each head. I beleive that's the max to still get a decent fit on the manifold. More could be done but you might have to oval out the manifold bolt holes.

GD



What he said. It really is a lost art, but on a simple engine like this I say go for it.

nipper

#8 Yo'J

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Posted 13 July 2009 - 08:49 PM

Be careful. 1/4" glass will bow a lot, measurably.

#9 GeneralDisorder

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Posted 13 July 2009 - 09:41 PM

[quote name='Yo'J;839043]Be careful. 1/4" glass will bow a lot' date=' measurably.[/quote']

It will, but backed up with a good solid table and the weight of the head on the glass it won't bow enough over the required distance to amount to anything.

But yes - if you are building swiss watches or space ships then you would want a certified granite surface. We have one at work - the slab is 4' square, 8" thick, and has a certified flatness within .0001" - about $6000 for that 750 lb paper weight.....

But we aren't building swiss watches or space stations are we?

GD

#10 Txakura

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Posted 13 July 2009 - 10:06 PM

wouldn't an aluminum oxide abrasive be best?

#11 GeneralDisorder

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Posted 13 July 2009 - 10:11 PM

wouldn't an aluminum oxide abrasive be best?


I don't know that it really matters much. As long as you get high-quality paper in the desired grit and clean it often..... I'm not an abrasive expert though so perhaps there are advantages of one vs. another that I'm not aware of.

But seriously - NOT a Swiss watch here. We aren't regrinding Hubble's mirror guys!

GD

#12 grossgary

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Posted 13 July 2009 - 10:18 PM

Yeah, this is getting really technical, which is a good read, but this guy wants to fix his car cheap. Like I said, every single car I've done nothing to has held up fine. There are shops and dealers that gasket slap EJ25's. I don't recommend that, I'm just saying it's not always super-end-of-the-world-critical, so I think with the info given he'll do quite well to get a good seal.

#13 Log1call

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Posted 13 July 2009 - 10:47 PM

Use a bit of ten mill thick glass the size of a wet and dry sheet. Get some one-fifty grit to start and have the glass and paper on top and move then diagonaly as well as left to right and up and down. Use plenty of crc or kerosene for lube and washing. You are more likely to find corrosion pits are your problem on a subaru's short heads. If they are warped at all get a clean surface all over and then carry on till any pits are gone. Two-fifty grit will be plenty fine enough to finish off with. The finished surface is meant to be slightly marked/dull, not a mirror finish(which will take hours to acheive and is not desirable anyway).

I always run the glass and paper over heads before deciding whether they need to go to the shop for a grind. The shops like it that their grinding stone doesn't get fouled and often I don't need to have them ground anyway. Softness of the heads is more likely to be an issue if the heads have been real hot. You might like to ask someone how good heads should sound or behave when you tap them.

There is a lot of sales propaganda about about having to grind heads everytime but it is bull************. If the heads are flat, and don't have corrosion pits, then they are fine.

Edited by Log1call, 13 July 2009 - 10:52 PM.


#14 Txakura

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Posted 13 July 2009 - 10:48 PM

al oxide is at the hardware store, just keeping it to similar metals... but ya'... overkill I 'spose. pretty cool it can be done by hand at all, I'm in the same 'time vs money' situation so I can relate - hope it works out

#15 GeneralDisorder

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Posted 13 July 2009 - 11:01 PM

Yeah - mirror finish really isn't desirable for heads - not sure what I was thinking when I said that. It's what I use for disc-valves that seal metal-to-metal and need to be air-tight.

As stated - start with a lower grit and work up. 120 is good to start, and 220 is probably the minimum you want to finish with. I would probably finish with 600 personally. I HAVE had heads profesionally milled, and when it's done with proper machinery you will be able to see your reflection in them. You can get into all kinds of discussions about surface RA and crap, but really these old composite gaskets on the EA engines will handle just about whatever surface you give them as long as it's flat.

GD

#16 Yo'J

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Posted 13 July 2009 - 11:42 PM

It will, but backed up with a good solid table and the weight of the head on the glass it won't bow enough over the required distance to amount to anything.

But yes - if you are building swiss watches or space ships then you would want a certified granite surface. We have one at work - the slab is 4' square, 8" thick, and has a certified flatness within .0001" - about $6000 for that 750 lb paper weight.....

But we aren't building swiss watches or space stations are we?

GD



As long as hes not on a 8" glass shelf, on a piece of ply, sittin' on a set of sawhorses, shoving his weight across it, yeah.:lol:

#17 Txakura

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Posted 14 July 2009 - 09:46 AM

:lol:

#18 Gloyale

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Posted 14 July 2009 - 10:45 AM

Use a bit of ten mill thick glass the size of a wet and dry sheet. Get some one-fifty grit to start and have the glass and paper on top and move then diagonaly as well as left to right and up and down. Use plenty of crc or kerosene for lube and washing. You are more likely to find corrosion pits are your problem on a subaru's short heads. If they are warped at all get a clean surface all over and then carry on till any pits are gone. Two-fifty grit will be plenty fine enough to finish off with. The finished surface is meant to be slightly marked/dull, not a mirror finish(which will take hours to acheive and is not desirable anyway).


150 and 250 grit are WAAAY too rough.

Perhaps 250 for a starting pass and then 500 or 600 grit wet sand paper for a finish.

250 will leave big gouged scratches in the head.

#19 Uberoo

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Posted 14 July 2009 - 09:24 PM

Thanks everyone for all the talk and tips of how to mill your own heads.Unfortunatly, I pulled the motor today and took the heads off.I am glad I didnt order headgaskets. Every single piston wasnt centered in there bore. The bores themselves don't even look straight. not to mention that at least 2 cylinders have collapsed rings.
While I could rebuild the engine, it isnt worth the effort when I was planning to put a ej22 in there. So I suppose I try my best to get the "engine" down to just aluminum.

one more EA81 engine gone from the world...at least it isnt the EA81 body:-\

anyone need the the alternator, the crank,the valve train,etc, anything not aluminum?PM me.

Edited by Uberoo, 14 July 2009 - 09:29 PM.


#20 Log1call

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Posted 14 July 2009 - 09:59 PM

250 grit is fine. I have been using it for years and it gives a much smoother finish that the grinding stones do. Any finer and you will be there all day getting nowhere if there are pits to remove.

#21 Uberoo

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Posted 15 July 2009 - 10:30 AM

I just relaized that i have a parts car that the engine is just sitting in the engine bay,already pulled. No idea whats wrong with it.I suppose I can pull the oilpan and check the bearings,if those are good I could see what the heads look like.It might need new headgaskets or something minor...

for those who care, both of my old heads where cracked between the valves. the driver side head had some pretty big cracks, the passenger head the cracks might not have done anything.

#22 GeneralDisorder

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Posted 15 July 2009 - 10:57 AM

The bearings are not accesible with the oil pan removed. Only way to check them is by splitting the block.

Just pull a head from this parts car engine and use it. Cracks between the valves are not an issue unless they extend into a water jacket.

GD




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