Weber DCOE help?

[eschneider]

I'm trying to set up a SINGLE Weber 40DCOE-2 on a Cortina 1500 motor. I don't know what the compression or cam specs are.

I arrived at some initial settings to get started, with the aid of my ex-weber vendor, who isn't answering my emails since I purchased the parts from him. Not gonna throw names around - my point is I'm on my own now.

I'm generally pretty Weber-saavy, but this is the first time I've set up a DCOE from scratch. I know the "idle" (misnomer) jets are the first item to tune, but I'm having a hard time isolating the idle and pump jet function as my first problem.

I attached a photo of the carb along with a chart of the methodology to date. Any help is appreciated!

 

[DrEntropy]

All my Weber reference lit is 50 miles away ATM, but it seems to me the venturi at 30 is a bit too small. Feeding a 1500 on a single DCOE...

 

[eschneider]

All my Weber reference lit is 50 miles away ATM, but it seems to me the venturi at 30 is a bit too small. Feeding a 1500 on a single DCOE...

Should have mentioned that this car is being set up for lower RPM town driving. For more power and high rev use a dual setup with 32 or 34 chokes would be more appropriate, I agree.

This was an upgrade from a single barel zenith downdraft.

A comment on another forum suggested that the initial setup seemed have been derived assuming 2 DCOE's, not 1, and that the problems are the result of the main jets being too small as a result......

I have time on this one. The car is an hour away.

 

[coldplugs]

I've had good luck using Des Hammill's Weber book. He has no listing for your particular setup & usage but shows the following for a hotted up 1600cc Ford crossflow head & single carb:

34mm chokes with 4.5 secondaries
140 main jets
F16 emulsion tubes
210 air correctors
40 accelerator pump jets
45 F8 idle jets
7.5mm float level
15mm "full droop" setting on the float
Idle adjustment out about 1 1/8 turns

 

[RonMacPherson]

Agree, 30's is waaaaay too small for a single feeding dohc 4 banger.

Now have you searched the teglerizer.com website?

He does have quite a bit of info on the Webers and setup so might save you a book purchase.

 

[eschneider]

Now have you searched the teglerizer.com website?

Yeppers. Read his info before the initial setup.

30's is waaaaay too small for a single feeding dohc 4 banger.

OK. But I thought venturi size was determined by CFM, and CFM was a function of volume and RPM?

 

[RonMacPherson]

SUGGESTED venturi size is mainly determined using CFM as the main input. But it is not the bible.. Especially with a fairly quick revving good breathing engine.

30's might be fine for a VW type I 1500 cc single port head that you're going to cruise around town in. But recommend 34's for a dohc 1500 that you are trying to accelerate in.

Somewhere on one of the Z websites there was a dissertation presentation by one of the (he stated he was) a former Weber employee who engineered setups. I can't remember it right now but if you do a search for Z cars and Weber setups you might find it. He goes into some depth on the selection of Venturis, auxiliary chokes and carb body sizes...

 

[coldplugs]

SUGGESTED venturi size is mainly determined using CFM as the main input. But it is not the bible.. ...

And air velocity??

 

[RonMacPherson]

is factored by the engine speed, throttle opening and auxiliary choke/secondary venturi..

 

[coldplugs]

is factored by the engine speed, throttle opening and auxiliary choke/secondary venturi..

Indeed. My poorly made point was that I look at velocity as the critical factor for street use & then swag the choke & venturi sizes needed to keep this up to a reasonable level at low to medium speeds.

I agree that 30mm is too small & more suited for a smaller engine like an A-series.

(Help me on this: Is this really a DOHC engine?)

 

[DrEntropy]

I doubt it's a DOHC, John. 1500 Ford pushrod from what I can see of the head.

 

[coldplugs]

I doubt it's a DOHC, John. 1500 Ford pushrod from what I can see of the head.

Kinda' what I thought, Mr. Doctor.

 

[RonMacPherson]

hth a little

https://forums.hybridz.org/showthread.php?t=93343

 

[eschneider]

Help me on this: Is this really a DOHC engine?

Definitely not. Cortina 1500. Not even a crossflow head. Doubtful its even a GT head.

Sorry to be absent lately. Ill post more later as I get caught up from being under the weather for a few days.....

 

[DrEntropy]

Know th' feelin' Eric. Been barkin' like a seal cub bein' bludgeoned...

All upper resp and no respite.


I ~HATE~ winter!

 

[RonMacPherson]

Doc, something that works for me, my girl. Airborne. Got two tubes of it at Costco around 14dollars. Any time I feel a sore throat, stuffiness, or any other symptom of cold, allergy I pop one. works quite well....

 

[coldplugs]

You guys are joking about "Winter", right?

(Currently 21 deg & breezy).

Irish coffee is all you need...

 

[DrEntropy]

Any progress on the Weber, Eric?

 

[eschneider]

Any progress on the Weber, Eric?

Nope. It's in the customers garage an hour north. He was in a rush to have it stored in his shop, so I guess we'll take it apart when the driving season starts.

Gives me time to read up on theorey and practice.

This week's headache is a Morgan with the dreaded "Malvern Dance" -- front end vibration severe enough to snap the radiator stay rods off the rad. Common with Mogs, but this one's being a booger.

Why do I always get the weird ones?

 

[DrEntropy]

Ah. Late April for "round two" then.

With the weather and ice youse-guys have had this past week, how th' heck do you check the Moggie for improvement after you change or set something up?!?

Why do I always get the weird ones?

Somebody let th' cat outta th' bag that you just don't give up?

...just a thought. :smirk: