Carb questions WEbber DCOE40

[pinballking2]

Hi all,

finally got my Purple Seven running, and have questions as to the carbs. We are running WEBBER DCOE 40's with 45 idle jets. 115 mains, 30 mm venturis, and are getting lot of sputtering and backwash of raw gas in the two rear carb. Carbs (generally)don't respond to fuel mixture adjustment? We installed gas pressure regulator as per Dave Bean and have set at 2.5 PSI? All new floats and valve seat sets from the same. What do you experts? reccomend?

We have static timed at 10 degrees BTDC as per DB? Any and all solutions will be appreciated as it is 60 degrees here in NY and will be *0 on Monday? Thanks To all. Best new is it's now longer stuck in the Bronx. Thanks for all your help. Andy in New York

[bsimon]

Everything you did or didn't want to know about DCOEs. Here

[Croc]

Hi Andy - good to hear that you and the seven escaped the Bronx. Which shop did you find for helping you out with this work?

[bball7754]

From my reading, changing jets, etc. on Webers is a steep, slippery slope.

 

Float level is important. Did you check/adjust it when you installed the new floats?

 

Carb's also have to be synced.

 

Welcome to the brotherhood of the Xflow.

 

Steve

[lowflyer]

Famous quote: "90% of all carb problems are electrical".

 

Besides the normal carb stuff look at the spark plugs to see if they are firing. Are the plug wires for #3 and #4 crossed? Valve adjustment?

 

Normal carb stuff, blocked idle jets, vacuum leak, float level, etc.?

 

The idle jets, BTW, control the running from idle up to about 1300-1500 rpm.

[pinballking2]

Just so you know. no affiliation... CROC and CO. my car was brought to Intermecanica, 511 center Avanue, Mamaroneck, NY 10543, Tel 914 381-3614, email intermecanic@gmail.com, where Lotus Whiz Waldir Zangiacomi, rebuilt all the mechanicals, pisons, ring, valves,bearings and is a great Loti resource for members in the Tir-State area.

Can anyone put us in touch with some knowledgable Webber experts, that can help us sort our the Webber DCOE condundrum? I'll post up some shots, when I figure out how to?

The bottom line is I had, thanks to Waldir and Co. at Intermecanica (Father Son operation) the most rewarding and first ride in my Seven last Saturday. I bought it sight unseen in California based on pictures and discussion in Feburary, and My first ride was a BLAST !!! The one thing I will relate to you as observed by my 16 year old son, was the LOOK on Poeples faces as we rolled BY! If I had a camera it would have been one for You tube. Now mind you, where I live people see the cream of the crop as far as cars go, but if a couple didn't stumble off the curb watching us go by, I don't know what happened. What a rewarding experience... Thanks to all who keep the candle lit..Andy in New York

[JohnCh]

When you write “backwash of raw gas in the two rear carb” do you mean spitting back through that one carb? If so, that is usually caused by a weak mixture misfire. As others have suggested, make sure your ignition system is working correctly. If is it, then check the following basics, most of which were also recommended earlier:

• Check for air leaks around that carb. Any leak will lean out the mixture and cause spitting back.
  
• Ensure the carbs, as well as the barrels within the same carb, are properly synced.
  
• Check the butterflies on the spindle to confirm there is no slop and the position is the same in both barrels.
  
• Look over the various internal bits to ensure no fuel residue that is gumming up the works.
  
• Check the float levels. I don’t recall what they should be, but if the front carb is working fine, ensure the rear float level is the same.
  

-John

[pinballking2]

Thanks John. This car has only 2,200 miles since new in 1997, and I don't doubt that it has never run corectly, and as such, that's why so low milage. First owners Father to Son) were not car people and as such probably were not aware it was running poorly. The important thing is to get it right and back on the road.

Just for the Record, This is a Bob Yarwood assembled(kit originally sold and assembled by himin 1997) 1700cc Crossflow Supersprint Engine.

Could that be some of the reason we are having problems?

It was just reassembled and static timed, has electronic ignition, and from what I gather, The two Webbers were new just before it left California? Don't want to have to switch the carbs? Others must have had the same teething problems. Let me know what yopu think. Andy

[JohnCh]

I didn't realize you had a Westfield. I had one of Yarwood's engines, and although it didn't make the claimed power, it was a great little engine and there were no issues with the carb jetting as supplied by him. Of course that doesn’t mean someone didn’t mess around with the jetting over the years and screw things up. I would go through the various items people have identified in this thread and see what turns up.

 

BTW Blatchat is a great resource for crossflow tuning info and worth a search to confirm jetting and timing basics. For reference, Yarwood’s 1700 engine used 9.8:1 pistons, Kent 234 cam, and stock valves.

 

-John

[pinballking2]

Thanks john, Although everyone is calling it the Purple Seven and my dopey friend sent me a fake NY tag that says Barney7, The real color is Lilac , and although frightfully bright, a very rare color indeed. According to the original owner, His son and him went to the Westfield Factory and the Demo they drove was Lilac, so they went with it. I would have to say any Seven reguardless of color is better than no seven at all...

It seems that the rear carb does not respond to the mixture screws. For example you can screw one all the way in and no effect at all on running or RPM 's?

I will check out Blatchat as Croc had reccomended them early on in this adventure.

BUT, knowing what I know now, I still wopuld have purchased the Westfield. Very tight and responsive and a unique driving experience. A

[mac w]

Be careful with the Yarwood era car probably not set up for unleaded gas and could have very high compression and not 1700 more like 1630 use octane booster/ lead substitute and check your ignition timing more than 36degrees can give problems welcome to the Westfield world great car enjoy.

[20Vx]

Blatchat calling - thouhg not a real Weber expert. 2.5 p.s.i. COULD possibly overcome the float valve if it is in poor condition. Spitting back IS a sign of weakness of mixture as JohnCh says. I have a 5 hr layover in JFK this Sunday 8th May and can bring you a workshop manual on Webers if you fancy it - seriously (also have a set of twin 40's in the garage jetted for a 1700 s/sprint but I don't think US Customs woould be happy if I brought those). Will try and dig out my jetting info and post back or e-mail. Dave

[20Vx]

I was going to send you the DVA info on Webers until I noticed that BSIMON had put a link in to it.

Also - check the sealing of teh rear carb onto inlet manifold. Potential leak in the "o"-ring (or misab is you have those fitted instead) could also cause the symptoms you mention.

Go to Blatchat, search on Tech talk using a Boolean search, say for (weber)and(jetting) and see what comes up. Try this link http://blatchat.com/t.asp?id=50855 (sorry, can't do linky thing on this forum yet).