Carb tuning my 1971 XKE Coupe

[Magoo]

New guy here,
I bought a 1971 Coupe last year and would be driving it still except it was blowing lots of BLACK smoke. Since this is indicative of overly rich mixture I stopped driving it until I can adjust the twin Stromberg carbs. Have a book on SUs are the adjustments the same? ie How is mixture adjusted on Strombergs?


------------------
Bill Magee
1971 Jaguar XKE Coupe

 

[Jeb]

Bill,
There are a couple of things that could be causing your problems.....

First, check and make sure that the chokes are disengaging.....the cables and the pivot arms on the choke mechanisms get sticky and bind....

Also over time, the floats get perforated and/or saturated and affect the float level..

Third, these carbs have the emissions needles and sometimes the split pin or the crimp in the needle holder go missing, allowing the needle to retreat up into the piston and that will cause it to run rich as well....

Hope this helps....

Jeb

 

[Basil]

Jeb,
Do strombergs have a mixture adjustment? I didn't think they did, but not 100 percent sure. More familiar with the SUs.

 

[kcadams2]

Bill,
You didn't state whether your E-coupe was a six or twelve. '71 was the year they came with both engines, so we must know which. Please repost !!
Come to think of it the inital tests will be the same for both engines. Still might need to know in the end.
Fuel pressure should be between 2&4 psi. should be no evidence of flooding,(look down the throat while running, there should be only be a fine spray from each jet and about equal on both or all four, 6 or 12) Remove the dome from each carb and inspect the diaphragm for tears and be sure the pistons move up and down freely when reassembled.
let me know what you find.

Thanks,
Ken

 

[Basil]

Originally posted by kcadams2:
Bill,
You didn't state whether your E-coupe was a six or twelve. '71 was the year they came with both engines, so we must know which. Please repost !!
Come to think of it the inital tests will be the same for both engines. Still might need to know in the end.
Fuel pressure should be between 2&4 psi. should be no evidence of flooding,(look down the throat while running, there should be only be a fine spray from each jet and about equal on both or all four, 6 or 12) Remove the dome from each carb and inspect the diaphragm for tears and be sure the pistons move up and down freely when reassembled.
let me know what you find.

Thanks,
Ken

Since I know Bill, I can tell you it's a 6.

 

[Jeb]

Originally posted by Basil:
Jeb,
Do strombergs have a mixture adjustment? I didn't think they did, but not 100 percent sure. More familiar with the SUs.

Yes, the early CDs had a jet holder on the bottom of the carbs....

The CD 2s have a little adjustment down through the center of the piston that you use a 3mm long allen wrench to adjust....

You can't really adjust them enough to get into trouble, but you can fine tune the mixture if all else is right...

Cheers,

Jeb

 

[kcadams2]

Jeb,
The adjustment you refer to at the bottom of the piston guide/resivor is not present on all Strombergs. If there is no hex for your allen wrench to go into, you are out of luck. I beleive the E-Types didn't have it, and relied on a trim screw on the side which didn't do much of anything!! However sometimes you can cheat a little by loosening the needle holder clamping screw at the bottom (oposite the alignment groove of the piston) and reposition the needle and holder assy. Also if you are really brave you could move the jet head in the carburator body (but just a bit!!)
He is still probably working with a basic problem, and not adjustments.
see ya,
Ken

 

[kcadams2]

Jeb,
I re-read your last post about the Strombergs and realized that I mis-interpeted your intent about the mixture adjustment. Sorry! I had already sent it and couldn't take it back. I had thought you were refering to the E-Type carbs. Again my apologies. I don't want it to sound like I was correcting you.
Thanks so much,
Ken

 

[Basil]

Originally posted by kcadams2:
Jeb,
<snip> I had already sent it and couldn't take it back.

Au Contraire, Ken. One of the neat things about this UBB software I use for the forum is that users can edit or delete their own posts. In the header of your post, you will see several Icons (Profile, Reply with Quote, etc.) On of them (the one that looks like a paper with a pencil)

is the edit/delet function. With this, you can either edit a post you make, or delete it all together. Isn't technology great!

Cheers,
Basil

See! It says below that I edited this very post (had to correct a typo)

[This message has been edited by Basil (edited 01-30-2001).]

 

[Jeb]

Originally posted by kcadams2:
Bill,
You didn't state whether your E-coupe was a six or twelve. '71 was the year they came with both engines, so we must know which. Please repost !!
<snip>

Well, at risk of being accused of being a smart-ass, he did say coupe and the Series III cars were 2+2s.....8> )

Cheers,

Jeb

 

[Basil]

Originally posted by Jeb:

Originally posted by kcadams2:
Bill,
You didn't state whether your E-coupe was a six or twelve. '71 was the year they came with both engines, so we must know which. Please repost !!
<snip>

Well, at risk of being accused of being a smart-ass, he did say coupe and the Series III cars were 2+2s.....8> )

Cheers,

Jeb

 

[Basil]

Ok now Magoo - you have had some answers, now get back on here and reply or we shall visit you in the small hours and put a bat up your night dress

Basil

[This message has been edited by Basil (edited 02-05-2001).]

 

[Gene]

All the Strombergs I have dealt with, including the four on my 74 12 cylinder have a mixture adjustment down through the top. However, this is for minor fine tuning - probably not the problem if black smoke is present. There is tool made just for this adjustment which is important because it holds in a notch in the piston while the incorporated hex wrench turns the adjustment. Otherwise, with a hex wrench alone, you are likely to tear the diaphram.

 

[Magoo]

Sorry Guys,
I got too busy with other stuff here at work and couldn't find time even for short replies. Thanks you all for your good words; I'll be cruising the Sonic by Easter.

Magoo