Rebuild almost done! Head question

[db454]

I had the machine shop do what they thought needed to be done on the 8n engine. Being this was my first rebuild, they had way more experience than i did. I figured i would have them put the new sleeves in and a couple new valve seats that looked pitted. I walked out a week later with sleeves installed, all new valve seats, crank polished, pistons all put together, top of block milled .030 and head milled .025. I'm glad they did all of it except for the milling. It seems to be alot taken off just for a few minor scratches in both the head and block. The head had been ground on by someone that needed a little more space to fit the pistons.(They did a pretty bad job at it). I dont want to take any more out in that area, so what are my options. The machinest told me they make a shim in different thicknesses to bring the head up enough. I have also heard of people using 2 head gaskets. The shim is about $80 and head gasket is around $30. I have $1100 in this rebuild so far, dont want to loose all that by cutting corners now. Any advise is welcome.

 

[Cush Al]

There are posts on this site addressing this problem. Something to the affect of applying grease to the top of the piston and slowly turning the engine by hand (with head gasket, no torque) grind accordingly! My opinion...has worked for me for 20 plus years...2 gaskets with copper spray between each contact point?

 

[Cush Al]

Again.. never ever use the solid gasket! Collapsa ble will outlast your rebuild without leaks

 

[db454]

Cush al, you are saying use 2 collapsible head gaskets to get enough clearance.? I have the gasket that came with the rebuild which is metal on both sides with a fiber in between. Machine shop tells me to set head on without gasket and spin crank. If head lifts, measure how high off the block it rises and buy shim or use 2 gaskets. I tried it and its about .050, but hard to be very accurate when head rises different at various spots. Tried it with 1 head gasket on but not tightened down and head didn't move at all. I don't know if it will hit when tightened down or not. Hate to waste head gasket trying it out. Might just have to try it!

 

[Bob]

You might want to use the terminology he will encounter at the store when buying a gasket... composite vs. metal-faced/laminated.

If he asks for a "collapsible gasket" they will REALLY scratch their heads!

 

[Bob]

Are you SURE they really took off .055" between the block and head???? I've never heard of such a thing unless someone is deliberately trying to remove as much as possible to raise the compression ratio!

Set head on and see if it lifts when the engine is turned over. If so, you can make a ring of paint around the pistons with a paint marker, then try again, marking the spots of interference.

Then use a die grinder with a stone or a carbide burr to relieve the trouble spots on the head and provide clearance.

You can use modeling clay (PlaDoh) to determine actual clearance.

This is GREATLY preferred over stacking gaskets or shims and will do nothing but GOOD for this low-compression engine.

Lots of guys can't seem to get ONE gasket to seal. and using two DOUBLES the chance of failure!

 

[R Geiger]

(quoted from post at 11:47:02 08/30/11) I had the machine shop do what they thought needed to be done on the 8n engine. Being this was my first rebuild, they had way more experience than i did. I figured i would have them put the new sleeves in and a couple new valve seats that looked pitted. I walked out a week later with sleeves installed, all new valve seats, crank polished, pistons all put together, top of block milled .030 and head milled .025. I'm glad they did all of it except for the milling. It seems to be alot taken off just for a few minor scratches in both the head and block. The head had been ground on by someone that needed a little more space to fit the pistons.(They did a pretty bad job at it). I dont want to take any more out in that area, so what are my options. The machinest told me they make a shim in different thicknesses to bring the head up enough. I have also heard of people using 2 head gaskets. The shim is about $80 and head gasket is around $30. I have $1100 in this rebuild so far, dont want to loose all that by cutting corners now. Any advise is welcome.

I overhauled an 8n engine last winter and had the block decked and the head resurfaced. With no gaskete the pistons hit the head and would lift. I used grease on the pistons and turned over engine by hand and marked where it was hitting. I used a carbite burr in an air grinder to remove enough material off the head so that it no longer hit. Worked out real good for me.

 

[elmersooner]

187 for a new head on this site.... how much is your time worth. seems like the machine shop went a little overboard with the clearance. sad part is, even with new head the block has been milled enough that you still might have to use some southern engineering.

 

[Bob]

If he can relieve the head a bit and make it work it is BETTER than getting a new head, as he will gain a little compression with his milled head. NOTH'IN wrong with spending a few minutes with a die grinder and then savoring the satisfaction of a job well done!

NO reason to throw away a QUALITY 60-year-old casting for a likely imported piece of questionable quality!

 

[elmersooner]

agree with you, but when you start putting shims and double gaskets is where I would not like it.

 

[Hobo,NC]

No Doubt a new replacement head will resolve your issue are

http://ytforums.ytmag.com/viewtopic...postorder=asc&highlight=mark&start=15

I am not doubling up a gasket are using a shim least not yet. If I did not have the balls to grind away I would buy a new head. The new head I have on the shelf they relieved it so it fitz all and should clear just find...

 

[db454]

Thanks to all who posted with your comments. Yes they really took off .055 off head and block. Seems like a lot to me but what do I know. I'm going to head out and try the paint marker or grease trick and see what the results are. Does the head gasket compress much when torqued down. I will probably take off just a little extra for that. Thanks again for all the help

 

[BillM (OH)]

With a total of 55 thou milled off, it'll take a lot more time with a die grinder than minutes - might get there in a few hours. Grind - check, grind - check several times!!!!