78 liquifire The saga continues

[skoalmint]

Well the saga continues.I was having trouble getting good pistons for my 78 liquifire .The top ring in all the after market pistons would not seat properly.So i finally decided to sand the inside of the ring so it would seat properly.Well 3 hrs later that was done.( I know that sounds stupid having to take sandpaper to a brand new set of rings ,to make them fit the piston that they came with !) I wasnt totally happy with it but it was as good as i could do with what i had to work with.So now i am finally getting a tad bit excited, I am going to get my motor together YE HA.The motor went great going together.It looks brand new(with a little more shine than new).I called Dustin told him i was going to try to put the motor in tonite, He said he will be down to help.I think he wants to hear it run more than I do!So him and I work till 3 oclock in the morning.get everything all mounted its just about ready .All but blowing out the muffler,I sandblasted it so i was kinda worried that some sand may have got in the pipe,even though i taped all the openings you know how that sand is,it get everywhere.So we give her a shot of eather, a shot of fire, i think we got her blowed out.And a few laughs as well!Mounted the pipe we are ready.About five pull of the rope,She is running.Its running a little rough but dont sound to bad.Then it starts to load up real bad.Then i start to see some liquidy looking oil blowing by the exhaust manifold.So we shut her down, pop out a plug ,STEAM not good.Now this motor ran fine when it was taken apart. No head gasket issues.It was just a little tired.So now it is 4:30 in the morning.We are sick! So we tear her all down.Sure enough antifreeze everwhere.NOS head gasket looked like it was really seated in nice.So today i put a straight edge on the head and it looks like it has a slight warp in it. What I cant figure is how it ran fine before.But now that i disasembled it and put it back together its warped.If there would have been a issue i would have thought to check the head.So my ? is has anyone had good result milling these heads down?It doesnt look like it needs much taken off.What is your experience with this matter?I took a head off of a spare motor and it is the same way,Its like the straight edge is touching on the sides of the head,and as you pull it torwad the front of the engine it planes back out.If anyone has any insight it would be greatly appreciated.Thanks Brock.

[nick80lf]

If it's not very much you could "surface plate" it.

This is done using:

Steel plate that has been surface ground
Fine wet dry sand paper (like 600 and finer)
Something like kerosene for lubrication

Lay the sand paper on the surface plate, Squirt with Kerosene; gently polish the sealing surface of the head until flat. You can check the flatness by applying a thin layer prussian blue (sometimes called hi spot bluing) to the surface plate using one of those flat fuzzy paintbrushes. Gently rub the head surface in the bluing. The high spots will be blue.

In the past I've seen small granite surface plate on ebay for cheap, shipping is not though. Also I've been told that a thick piece of glass will also work, but I question the flatness of glass and I've seen glass flex so I'd be cautious about that.

[lwb140]

my thoughts are that as many head bolts as there are around the cylinders for clamping id check for a little nick in the head or jug or a peice of old gasket or something like that causing the gap those heads and jugs for that matter are puny die cast up against the head studs id think a little warp wouldnt be an issue just my thoughts wade

[JDT]

It may have been warped before and did not leak because it was over torqued on the hi spots.

A 1/4" piece of plate glass works well for the truing the surface.

Check the threads on all the studs as some may have been stretched if it was overtorqued.

[JD_Sledder68]

I used 1/4" glass to true the heads on my Kawa 440 this past summer. The trick is have the glass lay on as true of a surface as you can find and to not press down too hard on the glass. I checked my glass sheet with a straight edge to make sure it didn't have any waves to it.

I machined sheet of surface ground tool steel would be great, but that is hard to come by unless you have a buddy who does surface grinding.

I am trying to get my brother to make me a sheet of 3/8" tool steel with spring loaded clamps at each end so I can just clamp a full sheet of 600 3m wet-or-dry onto the steel.

[skoalmint]

Thanks guys for the info. I had the head spotless ,none of the studs were stretched,all the bolts threaded down the same,all the old gaskets were gone.Looked like a NOS head.My thoughts are if the head is warped like this ,the jug could be the same way.I checked the jug it has a slight warp as well! I think I will take it to a machine shop and have it checked out.Thanks for your input.Brock