Hi David,
What size are the main venturi's? I would be a little concerned that the
40's are a touch small for your engine. You would be fine at the bottom end
but might find that top end suffers if the engine can't get the air Mass
that it needs. Given that you have gone to the effort of porting your head
to increase the VE of the engine, it would be counter productive to restrict
air flow in the carb area.
Ideally, I think you will find that you might be more successful with DCOE
45's with 34 or 36 main venturi's. If you are not racing, go with the 34
as you will have better bottom end torque and vacumn.
If I recall, the DCOE 40's were recommended for the TR6/TR250 engines which
have a smaller displacement.
All this being said, I would not give up on the DCOE 40's (especially if the
price is right). I would just investigate the availability of main
venturi's available for it. You really need a venture of 34mm. Any less
than that and I think you will have some trouble.
Do the Carbs come with intake manifolds?
The suitability of any particular Singe Runner Carbs like Weber is
calculated based upon the displacement of the cylinder it is serving. For
example, the individual cylinder displacement of a 2.9litre engine is 490cc
or about 30 cubic inches......Weber produces a chart that calculates the
main venture size recommended (at peak rpm - 6,000 for the AH). Based
upon this chart, you should have a main venturi of 34mm.
On a side note, you should have a look at the sizes of the jets and air
correctors as they will likely have to be replaced if not suitable for your
car.
There are some good books that address the Weber carbs 1) Weber Carburetors
by Pat Braden 2) How to Build and Power Tune Weber and & Dellorto by Des
Hammill 3) How to Tune and Modify Carburetor Performance by Forbes Aird and
Malcolm Elston.
On the plus side, because your engine is basically stock, the initial setup
will be pretty easy.....Jets, correctors etc are all pretty well identified.
Paul
-----Original Message-----
From: healeys-bounces@autox.team.net [mailto:healeys-bounces@autox.team.net]
On Behalf Of D HALL
Sent: Saturday, November 08, 2008 6:13 AM
To: healeys@autox.team.net
Subject: [Healeys] Weber Carburettors
I read with great interest the thread regarding the use of weber
carburettors
a couple of weeks ago.
The opportunity has arisen to acquireB three 40DCOE,s andB I would like to
hear from anyone who has had the experience of such an installation. The
engine is ported and does run with a standard BJ8 cam.
Regards
David Hall
Healeys@autox.team.net
http://autox.team.net/mailman/listinfo/healeys
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