45 DCOE

[bobwhittaker]

I have aquired a 45DCOE fitted with 38mm chokes and reputedly jetted to suit an A Series out to 1315cc or so,
( My engine is at plus 40 thou. on the bores. ) There was a manifold as well , 3 1/2 inches between flanges, however
I used my original from the 40DCOE installation which is 5 3/4 inches between flanges and also has provision for
a support bracket to carry some of the cantilevered weight and not just rely on the manifold flange bolts.This also
has port diameters to match the 45 which is fitted with angled upward inlets and the whole set up looks the part
now it is in place with a nice easy sweep to the cylinder head.

I fitted it last week and on Sunday did some 120 miles on a trip to a car show at Ripon Racecourse.The settings/jets
are probably 95% ,with more mid and top end than the 40,however the idle needs sorting.Minisport ,who have a rolling
road and are obvious A Seies exponents, are only some10 miles away so once I have finalised some other items I will
have it set up there.

The show on Sunday was a great success with good weather/good crowd/good display. The Eleven as usual created
a lot of interest and people are surprised to learn it is a copy of a 60 year old car.I had youngsters from 8 or 10
years old upto people even older than me ! ! showing a genuine interest .There were at least two or three serious
enquires as to availability of kits,donor vehicles,build times,required skills and on the road procedures.

In all a good day topped of by a good driving experience.
Bob Whittaker

[Westfield 129]

I'm running a 6" Maniflow with my Weber 45. I have not needed any bracing to keep the manifold from vibrating, or cracking, even after 10 years of use. The total miles on my manifold is more than 40,000, while the last one I installed on the RHD chassis has more than 10,000 on it in less than two years. Both setups have short stacks inside a large K&N air filter, and the one piece anti vibration O ring mount.

BTW, the longer the intake, the more power. 6" is a very good length. Running that long an intake manifold usually requires the very short 1" velocity stacks. All the easier to mount an air filter. This setup you chose is far better than the short intake.

As for your idle jets, you might try the idle jets that is in your old DCOE 40, if they happen to be richer than the ones you have with the '45. An easy swap, and it is easy to re adjust the mix screws.

Just make sure that the tuner has a properly working exhaust gas analyzer. I have had a few problems with webers and tuners that didn't have the right diagnostic setup. Now I just tune using the instantly available data from my own built in "arse' dyno", and a stopwatch.

I am curious as to which emulsion tube, main jet, air corrector and idle jet you are using when you get it all sorted out.

[bobwhittaker]

Have gone back to the 40 DCOE.With the 45 DCOE fitted the " britches arse dyno " definitely indicates more
mid and top end as does the change in induction / exhaust noise ( That in itself was worth the effort ).However
the gains were only really evident if I was on an open road and able to " Press on ".Back on the 40 which, is well
set up, the drive is much smoother and progressive.
I have now aquired a Kent 731 camshaft and my winter project (Still driving weather ) will be to have the engine
and gearbox out to refresh the unit with bearings / oil pump / fit the cam and followers / rings if needed / uprate
the rocker gear and fit a long first gear to the Type 9 gearbox I installed last year.I will then use the 45 DCOE and
have the car set up to suit.

Regards the 731 Cam ,Vizard is a bit disparaging about it's effectiveness,can anyone comment from their own
or someone else's experience

[erictharg]

For "sensible" road use stick with the 40. However, once you have upped the cam and really want the engine to sing at the top end (5k rpm plus), assuming the head can support the flow,
the 45 is better. Again, though, for road use I'd suggest 36 rather than 38 mm chokes. Unless you routinely drive at over 5000 rpm and more than half throttle... on the road??

[Westfield 129]

My own experience is that a 40 is not really the best way to go with a 1275, let alone something from 1300~1380. Even the Weber kits for the 1275 include a 36mm choke 45 DCOE.

A 45 does a better job with small chokes than a 40 with large chokes, given that you have a good jet solution.

As for 38s Vs. 36mm choke, well, that depends on the cam, intake and head preparation. Then the trick is to find a working emulsion tube, idle jet and main jet.

Regardless of which carburetor you choose, the jet solution is going to be the main concern to making it work. The 45 is just easier to set up if you are starting from scratch.

If you are going to build an engine, select a known combination or a built engine from MED or other reputable builder. Cam, head, compression, exhaust header, intake and ignition and the Weber 45. Hopefully, there is much dyno information on the combination, and it will be much easier to arrive at a solution for the carburetor.

I did this with David Anton at APT, and was able to get the carb sorted with only one jet change. The next engines benefitted from David's data and my own, giving me a perfect setup right out of the box on the next engine I built.

As for "sensible" street use (as though the W11 was "sensible" for road use), I have found that the 1380, a Longman race head with the SPVP3 scatter pattern vintage race cam, 45 DCOE with 38mm chokes10.5:1 compression (on 91 octane, amazingly enough), and a 6500 RPM redline makes for a fine street engine, with a solid idle, sharp throttle response (alloy flywheel), excellent mid range acceleration, and a reasonable spread of torque, from 2400 RPM on up. This makes a solid 100 HP at the rear wheels, which is quite exciting on a 1200 lb package. It doesn't like low load, low RPM with small throttle openings much (the cam...), but this doesn't seem to be a problem in our traffic or stop and go driving. Since the W11 is pretty light, and even with a 3.9 final drive and 5.00X15 Dunlop race tires (3600 RPM at 80mph cruise in top gear), it is still able to hit 60 in under 7 seconds. This is essentially a "race" engine, but it is flexible enough for the legendary Los Angeles traffic, and can handle the usual slow SUV in the tighter portions of the canyons without loading up or over heating, even on a 42C day (which is more than can be said for the driver...).

[bobwhittaker]

Gentlemen,
very interesting and conflicting opinions,I will consider both and can see each point of view.My present intention is to
go with the 45 DCOE after the other work.Not much of my driving involves congested urban roads and usualy if I am
out in the Westfield I am going no where in particular and take detours if I encounter any traffic problems.Also ambient
temperatures in excess of 25 C are rare never mind in excess of 35 C so there is some leeway there.

If I can achieve somewhere in the order of 80 BHP at the wheels I will be more than happy,if needed I will go back
to the 40 DCOE. I have said previously Minisport are near to me and they have a rolling road and are obviously very
familiar with "A" Series engines and sorted it last time.

It is still good driving weather so major off the road work is on the back burner for the time being.
Cheers , Bob Whittaker

[allymally]

Hi Bob, what I would like to know is what your engine consists of? does it have a standard head, raised compression, larger valves, balanced, etc.
80 BHP @ flywheel should be easy, probably better on 40 Dcoe.
You may even get to 80 BHP without changing the camshaft but you will need 1. a good head 2. Raised Comp 10.5/11.0 and a good set up.
All the very best Malc.