Re: Looking for a lonely 300 head

["James J." <m1garand@speakeasy.net>]

All,
   The problem with uneven surfaces in a combustion chamber is that you 
don't get uniform heating of the surface, and the peaks often become 
hot-spots which cause pre-ignition and dieseling.  It also promotes 
carbon build-up too, so it is more than cosmetic.  This is pitted enough 
around the stock valve seats that it has undercut the edges a bit.  
Also, does anyone know what that little keystone shaped protuberence 
behind the spark-plug hole is?  I think it has to do with flame-front 
propagation.  Regardless, it's pretty eaten up too.
   Since I wrote the original post, I went at the chamber with an 
abrasive wheel on a high-speed drill.  This is a black sponge-like 
material that is impregnated with abrasive.  It took out the small pits, 
but the deep ones (and there's alot of them!!) remained.  I was doing 
some basic porting too, with a carbide tool designed for aluminum.  If 
you use the tip, it barely removes any material.  I used that and got 
out most of the big pits in the open areas and then hit the surface 
again with the drill abrasive.  To the naked eye, the chamber doesn't 
look any different than the rest, but it still looked like a bunch of 
aluminum chips went flying earlier.  Unfortunately, I can't get to the 
areas where the valves are closest to the edge of the CC, and also 
around the (formerly) sharp edges of the keystone thingy.
I'll have to cc the CCs (measure the volume of the combustion chambers) 
to see how much damage I did.

As far as finding a single head, I was hoping that somewhere out there, 
somebody had experienced similar problems, bought another pair of heads, 
and kept the single good one from the original pair out in the barn, and 
would be willing to sell it to Sgt. Pepper's Lonely Heads Club Block.  
But I can see what the shop says about this one in the meantime.

Thanks for all the inputs,
James J.

David Kernberger wrote:

> James et al.
>
> 	A single Buick 300 head is probably going to be hard to find.  Do
> you really think you need it?  Others may want to add their comments to
> mine, but I think the damage you describe is more cosmetic than functional,
> unless something is broken or cracked.  What do others think about this?
> I'll bet that a basic smoothup of any really high spots with a small hand
> grinder would be perfectly OK.  Not enough to remove much metal, so CR will
> not be affected much.  Nobody's going to see inside the engine after it is
> assembled, so the only real question is if it will cause problems in
> operation.  That's my 2 cents worth.
>
> Regards,
> David Kernberger
>
> -------------------------------------------------------
>
>  
> > All,
> > Anyone have a single, aluminum Buick 300 head they want to get rid of?  I
> > was cleaning all the carbon off of my heads and then bead blasting them, and
> > one combustion chamber is so heavily pitted, that I don't think I can use it
> > It really looks like the dark side of the moon.  I guess that the whole
> > chamber could be ground (polished) down to virgin aluminum, but I'd then
> > have to do it to all CCs, plus the corresponding loss of compression.
> > Thanks,
> > James Jewell
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