[Fot] head selection.

[Jack W. Drews]

At 01:54 AM 10/26/2007, you wrote:
>FOT
>I am preparing to build a high performance engine for use in my 56 TR3. Not a
>fully tweaked one, but one that I can take to drivers school in the spring and
>begin to campaign in vintage events. (Plans include updating to modified TR4
>front suspension and TR6 brakes as well.)
>I have purchased a bare block and crank sourced from a TR4A to serve as the
>basis for the engine build. Question is, what is the preferred head for my
>application? I plan to do some mild porting and use the larger than stock
>valves.

The heads are virtually identical with the exception of the intake 
port diameter at the manifold face of the head. Both new and old 
heads flow about the same on the flow bench, despite the common 
general opinion that the later small port head flows better. Even 
with significant porting work, the big port head and small port head 
can flow about the same. However, you should use a head late enough 
that it has a flat on the bottom side of the front water outlet to 
clear the water pump housing. The really early heads require a LOT of 
grinding there.

>  I have a set of the short-throated HS6s and a 4A intake manifold I'm
>hoping to use. Does anyone know if this will result in a hood clearance issue?

This combination does not craeate a hood interference. Since the 
carbs are shorter and the manifold longer, the carbs end up in the same place.

>I would like to make an intake plenum with ducted remote filter, though I
>suspect this would not be allowed by most vintage racing sanctioning bodies.

Sanctioning bodies vary in their view of this.

>Additional comments or suggestions would be appreciated.
>Thanks!
>Steve Preiss


Good luck with your project!

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uncle jack 



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