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Ignition advance with Weber DCOE

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J

jgrewe

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So I'm hanging a DCOE on the 1275 in my B.E. while its getting its refresh. What do people do for advance with no port vacuum signal? Is there enough mechanical advance available in the stock dizzy?

I've been reading about the Crane ignition here to get rid of the points and also somebody that can 'lay hands' on it and excercise all the demons.("Jeff")?

What are my options? Rebuild stock dizzy and recurve, Flamethrower, or do I ditch all the 100+ year old tech and Megasquirt it so I can tune it with my laptop? lol
 
I have a Crane ignition and a Weber DCOE 45 on my Bugeye.I had Jeff at Advanced Distributors recurve my dizzi. My static timing is now 16 degrees BTDC.The Weber has a hard time coming off idle and will bog down when you least need it to. Like pulling out into traffic. The fairly radical advance eliminates that problem. My max advance is about 36 degrees.
 
The crane ignition is great. Just get the XR700, it works just fine, good to 8500 rpms.I use them on all my sprites, street and race cars. Don't use a high voltage coil. You only need 30,000 volts.(Bosch blue coil work great) More than that will blow through the rotor cap. Ask me how I know.
I have no problem using 34 degrees full advance with the vacuum disconnected. just make sure you dial in the timing while the engine is spinning around 3 grand just to make sure you get the advance right. Do not try and set timing advance by ear. You will end up with 40 or more degrees...this is not good.
Using a 45 on a sprite is tricky. Most are over carbed and as a rule they can be a bit sloppy. Even in the best situations Webers tend to dump fuel out the vent into the air cleaner on hard turns and the shaky nature of a tuned A-series doesn't help.
 
jollyroger and bugi, what size chokes do you have think would be best on a 1275 with a mild cam, LCB header and the ports just cleaned up a little?

kind of hi-jacked my own thread...
 
Depends on the build and rev range. 32/34 maybe would be a good start for a mild unit and up to a 38 for something pretty wicked. I have a number of webers on a shelf in my shop. This is because I went back to S.U.'s. I have found that for me a set of properly built 1.4 or 1.5 S.U. carbs work great.(I have only S.U. carbs on all my race cars and street cars)
I was successful in jetting the webers, in fact folks still bring cars for me to jet. The webers offer a bit more power off idle and off a corner due to having an accelerator pump. The down side is they are very sloppy and always seem to dump fuel out the bowl vent on hard cornering and as a result always smell like leaking fuel. I know folks sell all sorts of devices designed to keep the fuel in the bowl. I have not found any that worked perfectly. This is tough on a rough idling A-series engine.
You can open a can of worms when jetting a weber. There are a number of variables that can get expensive,chokes, emulsion tubes, idle jets and mains. I have a box of chokes, jets, mains and emulsion tubes that all cost money used in search that really good setup. Guys who sell webers for sprites can get you kinda sorta close. They like to sell webers because they know you will likely be buying more parts. It's the gift that keeps on giving. I could get you kinda sorta close but in the end you will either except what someones says will work and try to drive with it or you will end up owning a box of weber chokes, jets, emulsion tubes and idle jets like me.
I own a book about tuning webers. The beginning of the book has very good instructions with graphs and calculations that helped me learn this art. It is still in print and if you read it carefully and do the math you too can get pretty close at first try.
I always try and talk guys out of webers unless of course they came on the car from the factory, then they get to read the book or learn or pay someone like me to do it. It is hard to beat a fresh proper set of S.U. carbs.
 
I may end up looking at the SU's that I have and go that route. I have a few sets that I don't even know what they are and I saw a spotters guide somewhere here. If it runs into too much money between the dizzy and carb rebuilds this thing may end up fuel infected after all. I do have a box of Weber parts already from tuning rotaries but I also have a couple Megasquirts, a bunch of injectors, fuel pumps etc etc.

I just hung the engine in the car yesterday. Man, its a game of millimeters with the Rivergate conversion.
 
Use a set of carbs that have been rebuilt properly. Make sure the throttle shafts are tight. If you are running a 276 or smaller cam you likely only need a 1.25 carb set. Likely use a red damper spring and #5 needle. The number five is a bit rich at high rpms but it seems to work for me. I have found that these engines like a rich mixture at high rpms and tend to make hp and don't detonate. Your results may vary.
 
I have 38mm chokes in my Weber. Probably 36 mm woulb be enough. I also have about $200.00 worth of assorted jets,tubes, etc. getting that sucker set up. Now that it is working the car goes like stink. My engine has a Kent 276 cam.
 
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