StewartG Posted December 26, 2002 Share Posted December 26, 2002 I've a Vauxhall engine running on DCOE 45s and Webber alpha 3D ignition. The engine runs well, starts well, good tickover, revs cleanly to 7000rpm with no flat spots etc. The only problem I would like to cure is a hesitation when going off and back onto the throttle. I feel the jets are ok as they were done by webcon and the carbs have 5 progression holes so that cured the just above idle hesitation.Anyone got any ideas? Link to comment Share on other sites More sharing options...
Joe 90 Posted December 27, 2002 Share Posted December 27, 2002 Leave it alone 🤔 If you do change things, keep track of your current settings as they sound very good. If the hesitation is at relatively small throttle openings then you may want to look at the accelerator pump circuit. 99,000 miles so far Link to comment Share on other sites More sharing options...
DAVID L Posted December 27, 2002 Share Posted December 27, 2002 Hi Stewart, Same type of engine (HPC), same carbs, same problems but often fairly severe, with quite a bit of hesitancy. Just explain to me what the words "webcon" and "five progression holes" mean as I would like to feed off your experiences! Thanks, David Link to comment Share on other sites More sharing options...
Graham Perry Posted December 27, 2002 Share Posted December 27, 2002 Have a look in the archive I think this was discussed a while back and Roger King explained the progression hole problem and the fix Link to comment Share on other sites More sharing options...
Bilbo Posted December 27, 2002 Share Posted December 27, 2002 Hi Stewart Well mine also runs on DCOE 45s and Webber alpha 3D ignition set up by RK two years ago. Well it could be just the throttle cable sticking just a bit. This mostly gives throttle sticking open but can give mild hesitation on throttle as well. My first one lasted years but lately I seem to need a new one every year. Think the first one did not have a plastic coated inner cable the later ones do. If you take an old one apart the plastic coating on the inner cable wares where it bend back up to the carbs. Other problems the one I had last year was the Butterfly Spinal sticking as they are not centred in the barrels. This is normally a close throttle problem but I suppose it can be both. Still not perfect its going to Roger in the new year for a good look over. Not that he knows this yet Sticking throttle pumps normally mean nothing foot goes down more then more then its massive. Had that when the car was new.... scary .... if it happens pulling out into a main road then the back ends up at 90 deg. I managed this pulling out left on to the main road leaving Caterham. 'Can you hear me running' ......... OH YES and its music to my ears 😬 😬 😬 1988 200 bhp, 146 ft lbs, 1700cc Cosworth BD? on Weber's with Brooklands and Clamshell wings, Freestyle Motorsport suspension. Q 979 CGY Edited by - Bilbo on 27 Dec 2002 18:55:10 Link to comment Share on other sites More sharing options...
captain chaos Posted December 27, 2002 Share Posted December 27, 2002 I've just come off carbs and onto TB's hopefully to eliminate all of the inaccuracies I used to get with carbs. I put up with it because i felt it added character, but after a wet track day with minimal grip earlier this year I have given up. The problems you descibe I could never get rid of. i think it's just one of those things you have to put up with. the rest of the set up sounds excellent for carbs. Link to comment Share on other sites More sharing options...
StewartG Posted December 27, 2002 Author Share Posted December 27, 2002 Captain you could well be right, it's just that with patience, mine and skill, not mine, the carbs just get better and better although the fuel consumption is an insummountable problem. This is the last glitch to be cured. David L, Webcon are the webber importers and concessionaires and 5 progression holes are the extra drillings in the carb throats to richen up the mixture as the carb progresses from the idle circuit to the main one. Originally 45s fitted to xflows and the like had 3 progression holes but with the advent of 16v engines like the Vauxhall and especially the Zetec which flow much more air at small throttle openings webber added extra progression holes to help with flat spots caused by a lean mixture just above idle, in the 1000-2000 rpm region. Link to comment Share on other sites More sharing options...
captain chaos Posted December 27, 2002 Share Posted December 27, 2002 My local dyno/webber man also made additional progression holes, this seems quite a common exercise. I just got to the position where we had exhausted all the tweeks that could be done. My motor was also running hotter cams with a freer flowing SBD exhaust system. This new system, whilst giving me more mid range and top end, also removed some of the back pressure which was previously helping the car at low revs. Between 2k & 3.5k revs the car became awful. Everyone I spoke to kept saying get TB's, eventually I gave in. Link to comment Share on other sites More sharing options...
StewartG Posted December 28, 2002 Author Share Posted December 28, 2002 And has the fuel injection completely cured all this? Link to comment Share on other sites More sharing options...
Swiss_Tony Posted December 28, 2002 Share Posted December 28, 2002 I have got carbs on my vx. Its got pretty big cams etc and after a bit of tweaking I reckon it runs great. No flat spots etc and pulls cleanly through 8500 rpm. Throttle response seems to be as good as injected engines. I personally think that most driveability problems could probably be ironed out unless the cams etc are really silly. My 7 does about 30 mpg on the road including a heavy right foot. I personally dont see how injection could improve greatly on this or driveability considering the costs involved. Also I prefer carbs so if it runs ok with the big cams I am fitting this winter then I will stick with them James Link to comment Share on other sites More sharing options...
Paul McKenzie Posted December 28, 2002 Share Posted December 28, 2002 James, Can you give us more info about your set-up...cams, other mods, carb size and jets, chokes, ecu etc. You seem to me to have found the holy grail with your VX setup Thanks, Paul Link to comment Share on other sites More sharing options...
Budjuggler Posted December 28, 2002 Share Posted December 28, 2002 Someone call 🤔 R770 VOM Anniversary (with cycle wings) and starter button Link to comment Share on other sites More sharing options...
Swiss_Tony Posted December 28, 2002 Share Posted December 28, 2002 Paul I forgot to add that my carbs are 48's not 45's.Obviously the jet sizes would not be comparable. Personally I reckon that 45's are a much better bet unless the engine is really silly. iirc its got 42mm chokes. The cams were not too big.Not sure about lift/duration etc. DTA mapped ignition which I noticed a big difference over the standard type. It went well enough to get a quicker 0-60 than K2RUM at Brooklands Hopefully the new setup will be as driveable but I doubt it ☹️ James Link to comment Share on other sites More sharing options...
Swiss_Tony Posted December 28, 2002 Share Posted December 28, 2002 Forgot to say that imho a decent dyno/rolling road would be able to get most things right. The only thing I had to sort with mine was a bit of a hesitation at lower revs.The idle jets and pump jets sorted it. After this it was great. James Link to comment Share on other sites More sharing options...
StewartG Posted December 28, 2002 Author Share Posted December 28, 2002 James, I'm amazed your engine runs cleanly on 48s, must be the diferent cams or something as when mine had 48s Roger King did his best to tune it to pull cleanly through the midrange but said it never would run well for the road with those carbs, gave loads of top end once past the flat spot though. Link to comment Share on other sites More sharing options...
Paul McKenzie Posted December 28, 2002 Share Posted December 28, 2002 Thanks, James..very interesting. Regarding the 48's the VX racers run very well on those with IIRC an otherwise standard engine. Paul Link to comment Share on other sites More sharing options...
Swiss_Tony Posted December 28, 2002 Share Posted December 28, 2002 Stewart/Paul Quite a few people said that the 48's are unsuitable for road use and decent throttle response and general driveability. Not sure if it makes any differences but I have got oversize wasted stem valves and lots of headwork (coscast head) similar spec I guess as SBD's 290bhp kit which I was reading about the other day *tongue*Maybe this helps? From what a few people have said about the vx's the exhaust makes a lot of difference. ie the standard system gives a midrange flatspot. What exhaust are you using? James Link to comment Share on other sites More sharing options...
captain chaos Posted December 28, 2002 Share Posted December 28, 2002 By the way, my car was on 48's aswell. James, you have definately found the holy grail! My car would just not pull through 3K revs cleanly and almost not at all if you came off the throttle and back on again at about that point. I had 3d lumenition fitted and could just not get it set up right. I used 2 different dyno people with the same results. Stewart, your remarks about 48's mirror my experiences. I have not finished the installation of TB's yet so I can't tell what it drives like. But I have high hopes. My SBD exhaust gave an additional 16bhp at between 6k & 6500 but only 5 at peak. James, Can you give an accurate BHP figure for your engine? Link to comment Share on other sites More sharing options...
Doug phillips Posted December 30, 2002 Share Posted December 30, 2002 I dont think that anybody will get the BHP figure from james about his se7en 😬, I know that he knows. Lets just say that its B***Y fast , as James said it's faster than K2RUM *thumbup* *thumbup* Su77on Se7ens Link to comment Share on other sites More sharing options...
Swiss_Tony Posted December 31, 2002 Share Posted December 31, 2002 Thanks Doug At present my engine produces 0 bhp and 0 lb/ft of torque ☹️this is very even across the whole rev range with no horrible flat spots etc. In the new year I am hoping this to increase considerably 😬. Not sure what the output will be but it should be somewhere between 200 and 400 bhp See I told you i would spill the beans 😳 James Link to comment Share on other sites More sharing options...
millsn Posted January 3, 2003 Share Posted January 3, 2003 Consider your pump jets. If it hesistates as you squeeze the throttle it may be that they could be improved. Speak to Roger K. for advice / sales! Don't know how easy they are to swap though as he did mine for me. Nigel Mills - 2.0 Zetec carbs Link to comment Share on other sites More sharing options...
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