>IMO, if you're looking for a better carburetion setup, get the HS6 carbs
>and curved intake manifold from a later TR4A. They will work better
>than Webers (on a near-stock engine), at 1/10 the cost.
I agree. Hard to beat a good set of HS6's on a stock or near stock
engine. Way easier to tune. Way cheaper to obtain and set up. Better
fuel milage almost guaranteed. The DCOEs are for masochists who NEED the
looks of DCOEs on their TR.
>Note that, for the reason mentioned above, the Webers suffer a great
>deal of reversion, some of the intake air goes backwards through the
>carb when each intake valve closes, and then forward through the carb
>again when the valve opens. On some engines, this problem is so bad
>that the air cleaner becomes wet with fuel. And IMO, the reversion is
>part of the reason it's so hard to get Webers tuned to match an engine
>throughout the throttle and rpm ranges.
This is why TRs running Webers tend to need more initial advance than TRs
running SUs. 8 degrees BTDC is a good starting point when tuning with
Webers on the four cylinder TR.
>As far as restriction, the TR3A-early 4A heads already have very large
>intake passages (relative to engine displacement), larger than many
>American V8s ! Large passages are not conducive to mid-range power
>(which is usually more important on the street), which is why the late
>TR4A heads actually have smaller head passages and manifold runners.
A little known secret on the high port TR heads is that they really all
have 1-1/2 inch dia intake ports. On all but the last TR4A heads, A ball
mill was inserted into the head intake passages about 1/4" to assure that
the production intake manifold ports lined up with the production head
intake ports. So these heads have intake ports that measure 1-5/8ths
dia. All because of a 1/8th larger dia ball mill to overcome
manufacturing slop. I picked up this gem of data directly from Kas
Kastner.
The advantage of the late head is that it does not have this step & short
bulge to induce turbulence as the mixture enters the head.
TeriAnn Wakeman Marigold Ltd.
Santa Cruz, California Web design, site updating, testing
webmaster@overlander.net search engine optimization, graphics
and more
http://www.overlander.net/Marigold/index.html
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