Briggs and Stratton Intek Plus 18.5HP How Flat does the head need to be for copper gasket?

[nillvurt]

Hi everyone,

I have the standard B&S head gasket blow by between the piston and the rod chamber. I ordered a new copper gasket from Lani at CGI hoping that it would hold up better than the graphite POS, and was wondering how flat the head needs to be?

The engine block is dead flat, but the head has some minor out of flatness. I cleaned it down to the mill marks. It is totally flat where the gasket blew out, but on the opposite side of the cylinder it seems a little cupped. If I put a straight edge across the full width of the head, I can fit a 0.0025" feeler gauge under. If I just measure across the area where the gasket goes (it only extends 1/2" or so on the outside of the cylinder bore), I can fit a 0.0015" feeler gauge under.

Do I have to flatten that head? Since the copper gasket is reusable I can give it a try and see how it works, then if I have a leak, I could pull it apart again and flatten head…?

Any experiences or advice is appreciated!

 

[bertsmobile1]

Flat yes
Remove all of the mill marks no
They actually hold the gasket in place just so long as there is no continous "tunnel" to allow the gasses to escape .

 

[sgkent]

put a magic marker all over the mating surface and lay it on a thick piece of glass with like 2000 grit on it. Wiggle it a little and see what you are actually looking at as to the pattern. You can try sliding thin blades from a feeler gauge set on the areas where the sharpie still exists to see how badly it is warped.

 

[nbpt100]

OK...how much out of flatness is acceptale with a Briggs head gasket? Every thing has a tolerance.

 

[nillvurt]

I decided to sand the head on sandpaper on glass, but probably should have left it! I managed to make the edges lower, one side is 0.004" lower. I'll slap it together and hope for the best! I remember having the problem before when I tried to sand the head of a Subaru. It seems like I am not quite steady enough with my hand when I move the head back and forth and it grabs the edges more than the middle. Any suggestions for the future?

 

[bertsmobile1]

B & S Say 0.002"
There are two different things that get conflaited
Flatness & smoothness
B & S Heads are flat
But they are not smooth because they are fly cut to make them flat
The grooves left by the cutter hold the paper gasket tight

The copper gasket will need to be annealed before you fit it
IF it is full soft you can leave a crescent shaped indent by rolling your thumb nail hard on it .

 

[sgkent]

Next time sand in an X. then flip it 90 degrees and sand in a circle, the flip it 90 more degrees and sand in an X or a +, vary the pattern as you flip it 90 degrees each couple sanding movements. If you have to take that much off it so one side is low now, the head was pretty warped. You would not have been able to get a good seal with out surfacing it.

 

[nillvurt]

Thanks for all your replies and advice!

The gasket is annealed and the manufacturer recommends copper spray a gasket on each side of the gasket. I'll stick it on today and give it a try. The valve cover gasket is still in the mail, arriving tomorrow, so I should get it started up tomorrow afternoon, if all goes well.

 

[bertsmobile1]

Double check the gasket
I get a lot of gaskets from Lanni and most of them are not fully soft
I think he lazer cuts them which means he can use commercial soft sheet but that is still not full soft
You can do it with a propane torch or a BBQ burner

 

[nillvurt]

hmm, when I talked to him he said I didn't need to anneal it and all I needed to do was clean it and spray it with copper spray a gasket. He specifically wrote annealed copper by hand on the packaging, so I hope it is fine

In any case, it is in there. The low point I made is on the head the thin bit on the far side of the valve rod bay and it may be leaking a tiny bit of oil, but I'll have to run it longer to see if that is the case. It did fix the blowing out oil of the oil pump along with all the white smoke.

When I changed the oil after running it for a few minutes, there were a lot of copper colored particles in the oil. What could that be? Is something deteriorating from having a bad head gasket or fuel in the oil? What is made of copper or brass in the engine?

Thanks again