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Weber 40DCOE with which cam ?


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Hello,

for street use I am interested installing 3 Weber 40DCOE carburators. Is there any rule or recommendation regarding camshaft duration which fits best with Weber?

Currently I have a Kent 270° (TH12-6) installed. I am hoping not having to change to a 280°.

Jochem

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Hi Jochem,

 

I know of no such rule regarding Webers and duration. I currently have (2) Webered engines in service, one with 292 degrees / 12.75mm valve lift and the other with the CP cam. I previously ran a Kent TH-2 with 295 degrees duration. The Webers satisfy all these cams quite well in my experience.

 

I see no reason to change your cam as it has a good amount more lift than the CP. Tuning in the mid range will probably be easier due to better vacuum than a longer duration cam will give. I believe it should have 9.5:1 c/r or better to benefit from the Webers, however.

 

With 30mm chokes and optimum jetting I would expect at least 15 BHP more than the (2) ZS carbs give on the same engine.

 

Regards,

Tom

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Hi Tom,

I appreciate your input...

c/r runs between 9.5 and 10...so I should be good to go. Currently I have about 140 BHP so we will see what happens....

In the mean time I learned that for street use it is advisable to stay below 280°. Just as you said due to tuning mid range.

Regards

Jochem

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Hi Jochem with six individual runners and six throttle plates you can go hotter

with the cam with less negative behaviour but you do not have to.

 

Agree there is no such rule and agree with the 15+ HP expectation where

I would like to add that there is no negative thing along with individual runners

like a hotter cam that takes more fuel and has its benefit on higher revs.

On the other hand its fun with the sound and reving till hell with that engine that has both.

We are here on 290 degrees BASTUCK and Newman PH3 300 degrees.

 

That is why modern cars have individual runners and sporty engines additionally

six throttle plates like BMWs 3 litre compared with the 6 cylinder M engine.

 

The benefit of six throttle plates starts around the 270degree cam and some people got even 290

degrees tamed with a single throttle plate or twin carbs. But that is far away from perfect

and a lot of work to bring that together. Part throttle and idle will be better with six plates.

 

I learned that our six cylinders often got problems with twin carbs and the hotter cam

around 2000rpm and part throttle. You can expect idle and part throttle benefit already

with the DCOE and your 270.

 

Anyway, that was not the question. DCOE is nice for TR6 but I would envisage them

only if I have them at hand, otherwise I would take the PI equipment and go for EFI.

That can be a fit and forget solution with same performance like DCOE but cheaper

and very reliable.

 

There will be people in the South that work on that project but not come up any longer

at our Freunde Forum because that is no fun.

Maybe you will find a clubmember there to do an EFI project together.

Ernst is phoning from time to time informing me about his progress.

Peter will finish EFI in some weeks...... He does a very good job.

 

Maybe good idea to contact them by PN before investing in DCOE.

Its not the DCOE system alone, I invested in a small little box to have the most needed items

for setup at hand and it is beyond 2000 Euros!

If you take help of a professional like IOZs Annette it will be also over 1000 Euros.

EFI setup can be done without that!

 

The benfit of EFI against DCOE is that you do not have cooking fuel from the Weber over the exhaust.

I always had these problems with boiling when I used Weber in the past.

They are fine for touring and open roads or motorsports but can be a pain crossing Siena on a warm day

during the Mille Miglia........

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Hello Andreas,

thank you for your reply. I have been thinking and deciding between Weber and EFI. Recently even Dellorto was an option. I know there are many advantages regarding EFI. However, I have decided to remain loyal to the carburator. Yes, with the money I could go either way. IOZ will do this project. Date is already set. It costs, but I am sure it will be worth it. In my opinion....the Weber have a great performance, sound and look great and are sexy :)

Jochem

Edited by JochemsTR
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