triumphs
[Top] [All Lists]

Re: Head modification(casting #'s?)

To: Randall <ryoung@navcomtech.com>, "Triumphs (E-mail)" <triumphs@autox.team.net>
Subject: Re: Head modification(casting #'s?)
From: Michael Thompson <miket@urgrgcc.edu>
Date: Tue, 18 Apr 2000 13:31:36 -0400
User-agent: Microsoft-Outlook-Express-Macintosh-Edition/5.02.2022
Randall,
How do you know which heads you have? Did the have casting numbers as
american cars do or do you just measure from the port to the block?
Thanks,
Mike

> From: "Randall" <ryoung@navcomtech.com>
> Reply-To: "Randall" <ryoung@navcomtech.com>
> Date: Tue, 18 Apr 2000 10:28:29 -0700
> To: "Triumphs (E-mail)" <triumphs@autox.team.net>
> Subject: RE: Head modification
> 
> 
> Michael :
> 
> I think I saw a post saying you were talking about a TR3...
> 
> There are actually about a half-dozen different head castings, Kastner's
> warning applies primarily to the very early "low port" heads (at least 2
> different castings of these).  If you have one of these, and want some
> performance, my suggestion would be to find a later head and intake
> manifold.  The TR4A head, curved tube intake manifold, and HS6 carbs
> (required to make it all fit between the fenders on a TR3) are supposed to
> be good for 5-10 mid-range horsepower all by themselves, even with the lower
> CR ...
> 
> According to an article written by Ken Gillanders at BFE, the stock
> high-port heads measure between 3.325" and 3.330" from the valve cover
> surface to the head gasket surface.  He says to never remove more than .150"
> from these heads.
> 
> However, well before you go that far, you will need higher octane gas than
> you can buy at the pump.  My suggestion would be to only take .080" or .090"
> off the head, then use one of the thin .020" head gaskets available from
> BFE, Moss, etc.  That way, if you find your CR is too high, you can go back
> to the .060" stock head gasket.  Note that a change in head gasket thickness
> has a bigger effect on CR than shaving the head, because the area of the
> opening is larger.  You should also grind the edges of the combustion
> chamber out to match the head gasket, as shown in Kastner's book, as
> otherwise the exposed sharp edge will increase the tendency to knock.
> 
> I assume you're putting in hardened exhaust seats all around, another
> worthwhile modification is to switch to the later exhaust valves with the
> smaller stem.  There are special "changeover" valve guides available to do
> this.
> 
> Don't forget to check that the head still clears the water pump housing, and
> the intake manifold still clears the edge of the block, after milling the
> head.
> 
> Randall
> 
> Michael Thompson wrote :
>> 
>> Hello all,
>> I have burnt an exhaust valve seat and while the head is off
>> I would like
>> to do a little work on it, primarily shaving it down to increase the
>> compression. I have two heads, so I'm not too worried about
>> not being able
>> to go back to stock.
>> I have a good fast road cam installed and 87mm liners and
>> pistons. Both
>> heads I think are earlier versions. My main question is how
>> can I tell how
>> far to go with the plainer? Kastner's prep manual warns of
>> making the water
>> jacket weak on the earlier heads. Where can I measure this?
> 
> 


<Prev in Thread] Current Thread [Next in Thread>
  • Re: Head modification(casting #'s?), Michael Thompson <=