reg Posted May 8, 2005 Share Posted May 8, 2005 Drove my unregistered 20. zetec / 54 dcoe equipped sdv for the first time on friday to a "pre sva pre m.o.t". Loved the super fast 6 mile blast there and back but couldn't not notice the huge flat spot / complete dead spot at around 1500 r.p.m when the throttle was stamped to the floor. I've heard of this reported before and understand its difficult to cure. Is it cureable? Quote Link to comment Share on other sites More sharing options...
Blatman Posted May 8, 2005 Share Posted May 8, 2005 No and yes. Seach for progression using the search function, as I suspect that's the problem. The solution and much discussion is all there for the reading... Quote Link to comment Share on other sites More sharing options...
reg Posted May 8, 2005 Author Share Posted May 8, 2005 I seem to remember that the instructions tht came with the ECU "omex" there was talk of the possibility of some additional progression holes needed to be drilled. Is that the fix? Quote Link to comment Share on other sites More sharing options...
Blatman Posted May 8, 2005 Share Posted May 8, 2005 Maybe. First you need to make sure that you actually have both sets of butterflies working in perfect unison. Received wisdom says that *lots* of builders overlook this very important check. If the butterflies aren't synchronised, it won't matter how many progression holes you have, they'll still be being uncovered incorrectly so it'll still run like a bag of spanners... Quote Link to comment Share on other sites More sharing options...
ROC Posted May 8, 2005 Share Posted May 8, 2005 After Chaz told me that Webcon are still doing the progression drillings, (you need 5 for your Zetec) got mine done a few weeks ago and it has transformed the running low down in the revs. They charge £100 plus VAT to do it. Cheers, Rich. Quote Link to comment Share on other sites More sharing options...
reg Posted May 8, 2005 Author Share Posted May 8, 2005 I brought myself a "very basic" gunsons carbalancer to set the balance between carbs to set them up roughly.So I don't think that balance is the problem. Once I get past the dead spot it appears to be jet propelled. Quote Link to comment Share on other sites More sharing options...
Blatman Posted May 8, 2005 Share Posted May 8, 2005 Balance is distinctly different from progression. As you press the throttle, the butterflies move. As the butterflies move they uncover little holes in the roof of each choke tube that allow ever increasing amounts of fuel in. If the butterflies on the front carb aren't perfectlyl aligned with each other and the butterflies on the rear carb, then the holes are being uncovered at different times, so each cylinder is getting a different amount of fuel. So it runs like a bag of spanners. Adding holes without addressing the fundamental set up will just mean that you have more holes to uncover badly... Quote Link to comment Share on other sites More sharing options...
reg Posted May 8, 2005 Author Share Posted May 8, 2005 I brought the carbs brand new so hoped such things could be relied upon to be pretty much perfect. The flat spot is more like a dead spot than some rough running (its just like turning the ignition key off). Quote Link to comment Share on other sites More sharing options...
Blatman Posted May 8, 2005 Share Posted May 8, 2005 Never rely on anything to work straight out the box. Webers used to come with an anti corrosive substance covering them. If it wasn't cleaned off before fitting, it would block jets and cause all sorts of troubles. Most people thought the mere act of filling the carbs with fuel would be enough... Then there's the issue of ECU's and base maps. A base map is NOT the map your car will need for it's life. A base map is simply good enough to get the car running, just. Once you know it works, get it to the rollers to be properly mapped. Anything else will risk serious, and possibly terminal damage to your engine... Now, progression... Have a read of this thread, where the following phrases are used; The engine is reconditioned and pick up at low revs isn't very good. If the advance is too little you may be having to open the butterfilies a little to get the idle correct, so you are then starting on the progression stage early within the carbs, thus giving you a flat-spot just off idle.... and Progression will be wrong. As ever. Sound familiar? Quote Link to comment Share on other sites More sharing options...
Blatman Posted May 8, 2005 Share Posted May 8, 2005 Then there's this. It's a bit long, but if you pick the bones out of it, again you'll find some familiar reading. Then there's this thread which is pretty comprehensive too. Quote Link to comment Share on other sites More sharing options...
reg Posted May 8, 2005 Author Share Posted May 8, 2005 Well you're obviously an expert. About 15 miles from me is a webcon dealer complete with roling road, Do you think an afternoon and some adjustment will cure it or do I have to part with my brand new carbs for a month to get it fixed? You see that now I'm ready for SVA my other half is telling everyone that "its finished and now he can start decorating the kitchen" ! Quote Link to comment Share on other sites More sharing options...
Blatman Posted May 8, 2005 Share Posted May 8, 2005 I think you should make sure they are properly adjusted before deciding to send them off and spend money that may not need to be spent. Mind you, I'd rather spend money on carbs than Dulux eggshell paint... Quote Link to comment Share on other sites More sharing options...
reg Posted May 8, 2005 Author Share Posted May 8, 2005 Reading the chat tonight I don't think It'll ever be finished! Quote Link to comment Share on other sites More sharing options...
StuartMackay Posted May 9, 2005 Share Posted May 9, 2005 Which Idle Jets do you have fitted, 45F9? Quote Link to comment Share on other sites More sharing options...
Blatman Posted May 9, 2005 Share Posted May 9, 2005 Reading the chat tonight I don't think It'll ever be finished! The car or the kitchen? I'm having the same feelings about my sprint car right now, and this is the 3rd season in a row that the winter rebuild had been badly delayed by things outside of my control, so you aren't alone... Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.