2.0 zetec 45 dcoe "flat spot"

[chalky]

Buy a power boost regulator a lot of zetec's come with a flat spot .Talk to burton's:D

[chazpowerslide]

If your carbs have less than 5 progression drillings per barrel you definatly need to send them off to Webcon to have the additional holes drilled.

The extra drillings in the carbs transformed the way my 2lt Zetec behaved on light throttle openings (don't forget that the idle jets don't just control the idle, they also control the fueling as the carbs come onto the main jets as well and that could be as high as 3K rpm)

Provided that the electrics (map/timing/sensors ect) are all ok, as a minimum I'd buy a propper carb balancer (about £40) so you can then properly set the balance.

Have the progression mods done (if required) it really is the best £100 you'll spend to make the engine behave.

If the problem persists then a RR session to sort it out would be in order (re-jetting the carbs)

As a rule of thumb you can roughly tell if the idle jets are about right as the idle mixture screws will be set between 2 and 3 turns out (2 and a half turns out is rekoned to be ideal) and 1/4 of a turn each way should see the tickover drop off a bit as the mixture moves away from ideal.

If the mixture screws are over 3 turns out the idles jets are too lean and under 2 turns out too rich.

Many RR tuners set the idle mixture deliberatly rich to overcome the progression issues but this is not a cure, your'e only masking the problem.

There are many other related factors that will cause flat spots on the DCOE carbs such as pump jet sizes and and accelerator pump stroke length which can all be fiddled with to optimise the carbs however IMO the most common causes seem to be related to progression holes (Zetec in particular) and idle jet size.

HTH.

Chaz.

[perksy]

Check spec' of carb's on Dave Andrews website.

Have 5 progression holes in my 45's.

[markcoopers]

Chaz is right, I've a "masked set up" on mine. I've early 45's and only 2 progresion drillings. The "fix" was bigger pump jets and massive idel jets. This runs rich at idle before leaning off as it goes onto the main curcuit, to be about right from 3000rpm.

This is definately a bodge to the problem, and ultimately will see me engine expiring. Although perfectly driveable, with no real limitations, it is not the solution, drillings will be done by an expert soon (too old for Webcon to touch)

[reg]

Sounds like I need some more progression drillings then!

Thanks to all for the exellent advice.

[bill shurvinton]

'May Need'.

More than one way to skin the cat.

[Blatman]

I'm sure I said that earlier...