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Weber V12 conversion: air filter FIRE!!!

 
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carlv12



Joined: 20 May 2009
Posts: 33

PostPosted: Wed Mar 16, 2011 8:05 pm    Post subject: Weber V12 conversion: air filter FIRE!!! Reply with quote

Hello,

my E Type V12 Roadster is still at my mechanic - we are converting the car to 6 Weber carbs with the "sausage" style foam air filters from Ramflo.
I have tried to follow all experts advices: lowering the engine (engine mountings), putting shims to the hood to gain clearance and AIR under the bonnet. I have changed the "poor working" retard vacuum unit from E Type V12 and fit the advance vacuum unit form XJ-S H.E. together with the DAB113HE distributor conversion kit from SNG Barratt. But the car still missfires sometimes when starting and accelerating. And today happened what I hope would never happen: one carb missfired and its foam air filter fired!! My mechanic immediately could extinguish the fire and we cannot understand how the foam air filter material is NOT fire resistant or incombustible!!!!! Now my mechanic will fit an air mesh filter made of 2 or 3 coatings or layers of a colander or sieve metal material that filters the air, but cannot catch fire. (I hope you understand my english...)
My mechanic wants me to ask the experts or people with experience in Weber V12 conversion how to avoid the miss firing: should we try even more ignition advance? Because at around 30 degrees of advance the missfiring never happens, but so much advance is not normal. Change spark plugs, try with another distributor cap and rotor, even other spark leads? Please give me ideas or advice.
This was a shock for me.....
Thank you and best regards from Valencia
Carlos Crying or Very sad
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PeterCrespin



Joined: 05 Mar 2010
Posts: 1970
Location: Gaithersburg, Maryland.

PostPosted: Thu Mar 17, 2011 10:14 am    Post subject: Re: Weber V12 conversion: air filter FIRE!!! Reply with quote

carlv12 wrote:
But the car still missfires sometimes when starting and accelerating. And today happened what I hope would never happen: [b]one carb missfired and its foam air filter fired!!

This was a shock for me.....


Carlos, you are fitting six new carburettors, right? Without the air filters, is it always the same carb(s) which spit back? With six new carburettors you don't know if they are all functioning correctly, or even all jetted the same, unless your mechanic has spent time checking them all individually, which would make something like 80-90 different jets, tubes, screws etc to check. How has he set them up? What equipment has he used? Synchromesh? Colortune? Gas analyser? If he just took them out of the box and bolted them on, you should not be too surprised at what has happened.

Does it spit back nearly *every* time you run the engine? Are you 110% certain you have the spark plug leads connected up correctly, and then re-checked to make sure? A V12 will start and run fine on ten cylinders with two leads mixed up and will spit and stumble as you describe.

Spitting back could be an air leak. Do you have the flexible rubber mounts? Is anything split or dislodged? A Colortune would show one or more weak chokes.

You must be extra careful now that you have the fuel right next to the plugs and distributor, instead of on the opposite side of the cam cover. It is essential you use the vented distributor cap with the inlet hose positioned well away from the engine and a mild vacuum connection somewhere inside your air cleaner. You do not want petrol fumes anywhere near the distributor, which will happen incredibly easily with your risky set up.

Hopefully this will be the only fire you experience but don't be surprised if it isn't.

_________________
1E75339 66 Zealia D; 1R27190 70 FHC; 79 S2 XJ12L
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Heuer
Administrator


Joined: 01 Mar 2008
Posts: 7672
Location: Nottinghamshire

PostPosted: Sun Mar 20, 2011 4:59 pm    Post subject: Reply with quote

Carlos

There are a couple of very good downloadable Weber guides in our Knowledge Base: http://etypeuk.com/forum/viewtopic.php?t=1664 but correctly setting up those carbs is a huge amount of work especially when you have six!

_________________
David Jones
S1 OTS OSB.; S1 FHC ODB #860294
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Woolfi



Joined: 28 Jan 2010
Posts: 160
Location: Germany

PostPosted: Wed Apr 13, 2011 8:02 am    Post subject: Reply with quote

"A Colortune would show one or more weak chokes."
A colortune can show, how the mixture is when iddling. If there is a hole, where air is comming in and makes this choke running weak, you can see very good with a colortune.
But if you want to check the mixture, when driving, you MUST have something like a LC-1 from innovate. If you can't check the mixture when driving, the chance to have a good mixture above iddling, is VERY low.
I have mounted a 6,0 Liter motor (with strombergs from the 5,3 motor) from a '93 limousine into my EV12 and had to reshape the needles, to reach a good mixture. In the beginning the mixture ws much to weak and the car was faaaaaaar away from divability. I have a LC-1 since 5 years in my car and can check just in time the mixture of 6 cylinders. If you mount the lambda-sensor more nearby the exhaust ports, it would be pssible, to check the mixture of each carb. I have been to lazy, to do like this. In few steps , done this also with my 5,3er motor before, I have been able to grind the needles to a correct shape, that feeds the motor with a correct mixture. Slighly fat at iddle, lean at part throttle, and fat at full throttle. Without a lambda-meter it is NOT possible, to "adjust" the carbs correct.
For me it would have been a bad solution, just to "adjust" the mixture fat, that the car is running okay. Bad smell and a low mileage would be the price of this "tuning-strategy".
Regards Wolfgang Gatza
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