Weber 45DCOE152

[R2D2]

I have a Lotus Twin cam engined 7 with about 160bhp and it is fitted "Spanish"45DCOE152 Webers. I bought the carbs new about 12 months ago.

 

The engine was set up on a dyno and the jetting seems OK apart from the idle which has never been particularly stable around idle.

 

I have heard that the 2 litre Zetec conversions using these carbs suffers from the same problem.

 

It seems that the Spanish carbs only have three progression drillings for the idle jet and according to my local Weber Agent/Rolling Road it can be almost impossible to set the idle correctly without having a fourth progression hole drilled. It seems that Dunnell Engines do this mod for the Zetec with some success.

 

It seems that the only way to make the car idle with the 152s is to slightly over-richen the idle mixture which then makes the car "fluff" slightly on initial pickup.

 

Does any one have any experience of the 152s before and after this mod?

 

I want to solve the problem and I don't know if I should buy some new Delorto's find some Italian Webers, which are said to have better progression of have the carbs modified £100.

 

Any information/advice would be welcome.

[Roger King]

It is impossible to be absolutely certain without seeing the car, but yes, the current 45s do often suffer from a driveability problem on very light throttle.

 

Usually, the actual idle is no problem and nor is moderate throttle. It is just the bit in between where the idle screw cannot provide enough fuel and the first progression hole has not yet come into operation. Generally, the solution is to machine an additional hole, but £100 sounds a bit steep.

 

This can transform driveability and suddenly the car becomes a pleasure to live with.

 

As an aside, I bet your pump jets are too big as well. This can lead to fluffy response on initial acceleration.

[oilyhands]

The progression hole problem is a common one, especially with 4 valve engines, setting the throttle plates slightly differently can improve matters as can a small flat filed on the outside top of the throttle plate in the right position that causes the initial progression drilling to become uncovered slightly earlier in the throttle plates movement. A bit of trial an erro is called for here. The proper solution is to re-drill and with the correct tooling its a simple operation. I've seen it done for £15 per carb so £100 seems a little expensive.

 

Oily

[stevefoster]

What sort of fuel pressure / pump do you have.

 

See my thread on HPC 45's and idle problems when hot....

[R2D2]

I have a weber/Alpha Fuel pump and a Purolator Regulator set on 3. I think that float heights are OK.

[stevefoster]

I have the Weber alpha fuel pump and have noticed the improvements when the pressure reg is set to 2.5.

You could try that.

[ian balson]

Chris,

 

I have a pair of "Spanish" 45DCOE152 Webers on a standard tune HPC Vx. Mine have 4 progression holes. The car was built in 93 and I've owned it for the last 2 years, so I can't say if the carbs were modified from new.

 

James Whiting has been looking at a problem I currently have where I can't get the idle to drop below 1400 revs. It looks like I'm heading for a carb refurb to resolve the problem.

 

Back to the progression holes, James said to me that even with 4 progression holes you have a choice of a smooth idle with a fluffy pickup or set the idle mixture at higher revs to "smudge" the fluffy area which gives you a lumpy idle but a cleaner pickup.

 

Check with James, but I believe he also said that the after market Weber conversion kit for the Zetec engine has a 5th progression hole.

 

I don't want to put words into James mouth, so please check with him that I've got this right.

 

Good luck

Ian.

 

 

 

[R2D2]

I have an old pair of Italian Webers and I will check the progression holes to see how many there are but I am worried about general condition.

 

I have also spoken to Delorto and theyn have some new/old stock 45DHLAs from the 2 and 2.2 litre engines and these carbs have 6 progression holes, but they cost £420 +VAT

 

I have tried to speak to Webcon on several occasions but without success. The last time they kept me holding for about 20mins and then told me that they couldn't transfer the call because the 'phone was faulty.

 

Any one know who else can modify my existing Webers?

 

Thanks to everyone for the help/advice.

[oilyhands]

Phegre engineering in Hartley Witney, Hants used to do them, as did Aldon (Brierley hill), Oselli (Oxford) and Auto - Technique (Luton). Tom Airey(New Cheriton) may well have a contact who can do them.

 

Oily

[Steve W]

Well I can't comment on the tech issue's here but I do know that Roger King tuned my Zetec last year on 45's. I remember him saying something about the progression holes but I don't know exactly what was done. Now the car is fantastic,smoooth idle and a great pickup.