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Discussion Starter #1
Hi, I have a gasket/mating surface type of question

First here is what I did during my rebuild:
I needed to remove the remaining gasket on the heads which was a real pain.
I used the permatex gasket remover, let it sit and tried to scrape it with a plastic razor: didn't work at all
I then switched to the CRC gasket remover which was more agressive. With 1 spray can and 3-4 plastic razor blades several attempts later I managed to remove most of it but I still needed to finish the job by soda blasting the heads.
It took me forever and seeing how ineffective it had been on the heads I didn't want to repeat the same process on the block.
I used a razor blade which was somewhat effective but it was insanely difficult to handle the larger blade and I couldn't apply enough force on the thinner one.
I tried placing a wet scotchbrite pad on the surface, waited for it to dry and soften the gasket material in the process, scrubbed with the pad for 20min: nothing.
At this point I was kind of fed up. I had the idea to use my air angle grinder on which I can place scotchbrite discs. I thought I could use the super fine grit (grey silicon material) to reduce the gasket material to dust and once reduced to a super fine layer I could scrub it with a regular pad.

It turned out to be more effective/realistic to use the very fine disc (green scotch write material). I proceeded with care, not at full speed and with very light even pressure. I knew it wasn't the best idea but it was my last hope.
Now I am happy the surfaces are clean but it's a bit too shiny for my taste and I started to wonder if I had in the process "polished" the surfaces.
In that case is there a way to give back some "bite" to the mating surfaces?

(I mean I can think of a solution but I'd rather have a more educated answer)

Also I wonder if anyone has tried to use a silicon type gasket on the other mating surfaces and if silicon is more forgiving than paper/gasket material in this kind of situation?
 

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What you are aiming for is a perfectly flat milled surface, so anything that rounds off edges or scores the surface is less than perfect. Grinding with a soft pad on aluminum is not a good idea in my opinion in that the aluminum could be damaged in the process of getting the gasket off. Chemicals to soften the gasket would be better. Aluminum is incredibly soft compared to steel and it doesn't take much to damage it. I use razor blades but am always nervous doing it, but it works best for me, and yes I have nicked the aluminum more than once doing it. I've thought about getting a large whetstone and trying that with light oil on it but as of yet have not had to resort to that attempt at home milling.
 

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After spending way too much time removing an old head gasket (much like you just did) I asked a friend that is a Honda mechanic how they do it in the shop. He told me he uses a large Olfa type knife to remove the big chunks, then a razor blade for the smaller pieces and once it is down to mostly glue use a sharpening stone that hasn't been used to sharpen blades (you want one that is really flat) or oiled. Dip the stone in water (a small bucket or plastic yogourt tub works well for this) and rub the stone on the mating surface in a circular motion, moving over the whole surface more or less equally and taking care to keep it flat on the surface. When the water looks dirty put the stone back in the water while you wipe off the part with a rag, then repeat until the surface is uniformly smooth & clean.

BTW: I have a toilet paper holder on the wall above the workbench because it has lots of uses in the shop. When I need to clean a cylinder's mating surface I pull off a foot or so of TP and twist it into a rope that I can insert into the water jacket and stuff other pieces of TP into any other openings (just far enough in so the tools don't catch it) to keep bits of gasket and dirty/gritty water out of the engine.
 

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Discussion Starter #4
I've talked to a machinist and a performance engine builder, both said the block was usable. The first one advised me to use copper spray on the gasket (which I would have done anyway) the second one said an ultra thin layer of silicon gasket would help with the imperfections better.

I soda blasted the heads, do you think resurfacing them will help ?
Also the machinist suggested I have the valves cut (even though he didn't see them) , do you believe it's necessary after lapping them ?
 

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Anything less than a perfectly in-plane milled surface means less contact area. But engineering is an art of close enough approximations. If you think you have rounded off or scratched the surface too much then if I were you I would use the oiled whetstone method to bring the surface back to good enough condition. I don't like to take the cheap route with gaskets personally, especially those subject to extreme pressures, so no comment on any goop you use to supplement what I assume will be a high end head gasket.
 

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Not knowing any better, I used silicone believing that's what was referred to as "liquid sealant" in the FSM....then it was pointed out to be a bad idea. As engine was still on bench, I removed the heads and all the silicone had been squashed around the edges of and into the water channels, firmed up, and had I left it would have cracked off and gone into the channels and who knows what. I replaced the gaskets and used copper spray ....Saved a potential disaster.
 

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Silicone is not suitable for use on head gaskets.

Silicone can be used on the other gaskets but only if applied ahead of time in a very thin layer (barely enough to see) and allowed to cure overnight before installation. This will allow the gasket to seal but prevent it from bonding to the mating surfaces so that it can be removed easily the next time. Most non-head gaskets can be used twice if you do this. Ordinary grease works just as well and doesn't have to cure overnight.
 

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I use a big piece of plate glass to which I contact cement a piece of wet/dry 1000-2000 grit paper at the corners. This is the final step after using a gasket scraper and razor blades. By the way use a razor blade holder, make a world of difference.

I started to use the plate glass and paper to level and resurface my big Penn tuna reel drag washers. They get glazed and the steel plate can warp after a drag searing run of a big bluefin tuna. I have even fused the drag plate to the steel plate. Usually this means a broken line in short order.
 

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Discussion Starter #10
I'm probably going to use a stone and copper spray
A Shapton glass stone seems to be the best in term of quality and flatness compared to an average kitchen whetstone
I saw I could also use a diamond bench stone
For those who actually tried this method what grit/product works the best ?
 

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There were a box of stones among the tools &c I inherited from my Dad and I just picked the newest looking one that hadn't been oiled. It lives in the "special tools" part of my tool chest now so nobody decides to sharpen something with it.
 

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Discussion Starter #16
I thought I could restore any damaged edge with something real flat and super fine grit and in a second time use a 280 grit with a piece of glass or gage block or something flat to help with the bite does that make sense ?
I also thought about using copper gaskets
 

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If you are going to finish with 280 why bother with anything finer? It will take a lot longer to make it flat and the result won't be any better than if you start with 280.
 

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Discussion Starter #18
You are right, at first I thought I would have to use an average kitchen knife whetstone because that is all I was able to find. I was worried because most of them are just crap made in china, they deteriorate very quickly and are made of nasty aluminium oxide. Eventually I found a norton oilstone made of silicon carbide (280 grit) and I'm almost sure I can even use the honing oil to deglaze the cylinders. With a diamond lapping plate I shouldn't have to worry about the flatness issue.
Thank you for the tip
 
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