congorobot Posted March 1, 2005 Share Posted March 1, 2005 Since buying my westfield I have not been entirely pleased with its performance. I understood when I bought it that there would be a few things to put right before it came good. I have had to buy a new altinator & starter, coil, points and battery so far. I have not been to have the carbs professionally set up yet but have fiddled with the idle screws and the timming myself. Dont see the point of paying for carb set up until I have got air filters fitted and changed the distributor. The dist that is on the engine at the moment is the vaccume advance type. Could this be the sole reason for my crap performance? Would a mismatch between a vaccume dist, (disconnected), and a kent fast road cam cause such poor performance? I was out-dragged by a 1.2 nova last night! I have been looking at the competition vaccumeless dists and also the ones that are triggered magneticaly. Does anyone have experience of using both, and how much performance difference there is between the two types? Quote Link to comment Share on other sites More sharing options...
Blatman Posted March 1, 2005 Share Posted March 1, 2005 Could this be the sole reason for my crap performance? Would a mismatch between a vaccume dist, (disconnected), and a kent fast road cam cause such poor performance? I was out-dragged by a 1.2 nova last night! I have been looking at the competition vaccumeless dists and also the ones that are triggered magneticaly. Does anyone have experience of using both, and how much performance difference there is between the two types? Yup. The vac advance advances the timing. No vac, no timing changes as the car is under load, hence p*** poor performance. If the condenser is playing up, this won't be helping either, so put a new one of those in while you're under the bonnet. Also "fiddling with the idle screws" is no way to make things better, unless you *know* what you are doing. If you do know what you'e doing, then fine. If you don't then you almost certainly haven't helped matters. Lose to a Nova again, and I'll apply to have your membership revoked... Fix it by getting a non vac dizzy, and fit Lumenition Magnetronic to it. Solves lots of problems... Quote Link to comment Share on other sites More sharing options...
congorobot Posted March 1, 2005 Author Share Posted March 1, 2005 I have been reading des hammill's book on how to "build & power tune carbs", and have only made small adjustments of the idle screws. The car at least runs now which is better than when I bought it! Will take your advice and fit magnetronic and vaccumless dist. Would you recommend changing the coil? The one that was on failed and I went to halfords and bought a Lucas one. Dont know if its up to the job? Once I have this sorted out im going to scour the streets of Edinburgh and settle the score with the nova! Quote Link to comment Share on other sites More sharing options...
Blatman Posted March 1, 2005 Share Posted March 1, 2005 Make sure you have the right spec coil. Some are for use with ballasted ignition systems, some for use on non ballasted systems. I can't remember what spec coil is right for a X-flow, so hopefully a X-flow expert will be along in a moment... Quote Link to comment Share on other sites More sharing options...
chazpowerslide Posted March 1, 2005 Share Posted March 1, 2005 Erm, what engine, what engine spec and what are you intending to use the car for? It's difficult to make a (probhable) diagnosis without all the relavent info. The vac advance can be seen as an extra economy device and would allow the standard engine to run a little leaner with a bit more advance at part throttle. When in cruze mode ie 70MPH on the motorway the throttle is only open a bit, say anything up to 10-20%, the manifold vaccume (throttle butterfly to valve) is high as atmopheric pressure is trying to force the air into the motor through the restriction that is the throttle butterfly. The engine is trying to consume the air faster than atmospheric pressure can force it in so you get a higher vaccume downstream of the throttle butterfly. When the motor is under load (say 40% to wide open throttle) the the vac advance will in actual fact retard the ignition as there is no little or no vaccume in the manifold to act on the vaccume advance unit to advance the ignition. At this point the motor is spinning fast enough for the machanical advance to advancve the ignition past where the vaccume advance started backing off when the manifold vaccume dropped. As you (probhably) have 40 or 45 DCOE Webers and are not going for economy a dizzy without a vaccume advance is probhably what you need. This dizzy (Aldon make them) has all it's advance controlled by bob weights and springs (known as mechanical advance) and is more suited to a high performance motor on twin 40/45 Webers. A good electronic ignition system (Optronic/Magnatronic/ Aldon Ignitor) is a really good idea but it won't make up for other parts of the ignition that are not up to par as all this type of ignition does is take over the switching of the coil from the points (and condensor) Is the timing right? Have you done a compression test? Are all the other ignition consumables in good order? Does the distributer shaft have any sideways play in it's bearings? If it has you'll never get consistant opening and shutting of the contact breakers and thus poor coil charging and a resultant poor quality spark. Are there any air leaks into the inlet manifold (maybe around the carb "O" rings or the manifold gasget)? Are the carbs calibrated remotly near what the engine needs? Start at one end on one system (mechanical/engine, fuel, ignition) and logically work through each correcting the defects you find. Let us know how you get on. Chaz. Quote Link to comment Share on other sites More sharing options...
stu999 Posted March 1, 2005 Share Posted March 1, 2005 Could this be the sole reason for my crap performance? Would a mismatch between a vaccume dist, (disconnected), and a kent fast road cam cause such poor performance? I was out-dragged by a 1.2 nova last night! I have been looking at the competition vaccumeless dists and also the ones that are triggered magneticaly. Does anyone have experience of using both, and how much performance difference there is between the two types? Yup. The vac advance advances the timing. No vac, no timing changes as the car is under load, hence p*** poor performance. Not *strictly* true... The vac advance mechanism makes absolutely NO difference to the performance of the car when the throttle is mashed to the floor. It does exactly what it says on the tin, in that it advances the ignition timing when there is a vacuum sensed in the inlet manifold, and in theory at least, there will be little or no vacuum present in the manifold when the throttle is flat out. However, it is possible that the vac advance is affecting the performance (or at least, not helping) - more in a second... The mismatch *might* be that you have a distributor that has a completely incorrect mechanical advance curve for your engine. This is determined by the bobweights and springs in the bottom of the dizzy - the adjustment of which is best left to the specialists. Although it is worth bearing in mind that even with a horrendously incorrect advance curve, the timing could be adjusted to give exactly the same 'flat out' performance as an 'ideally suited' distributor, but with probable losses elsewhere in the rev range. Back to the vac advance. traditionally, race engines with distributors very rarely have a vacuum advance. So naturally, it tends to be assumed that if an engine is tuned, that it is best to get rid of it. Trouble is, very few people appreciate exactly why they are getting rid of it... The main reason is because the vac advance is connected to the distributor baseplate, which is designed to move according to how much vacuum is sensed, moving the points which are attached to the plate and in so doing altering the timing accordingly. Trouble is, at high revs this 'moving' baseplate can start vibrating due to the points opening and closing, which causes havoc with the timing and the power of the ignition spark -at exactly the point when the engine really wants the timing and spark to be spot on. This *can* seriously degrade power, according to revs, dizzy design etc. Non-vac dizzys have a one piece baseplate, which cures the problem. As the vac advance only works at idle/part throttle/overrun, which a race engine rarely sees, the benefits far outweigh the pitfalls. For a road engine, realistically the engine is rarely at full throttle, so it might not be such a benefit. Nowadays, we have technology on our side. If a vacuum advance dizzy has the points replaced with an electronic ignition system, little or no 'vibration' will occur, and the timing 'scatter' problem is solved. Short of a fully programmable electronic ignition system, IMHO the way to go would be to replace the points with an electronic system, and re-connect the vacuum advance (it can be done, and fairly easily too). Finally, before any of the above is considered, I would strongly recommend a fundamental 'health check' of the engine (compressions and tappets etc), before worrying about timing, mixture etc. HTH Stu. Quote Link to comment Share on other sites More sharing options...
chazpowerslide Posted March 1, 2005 Share Posted March 1, 2005 Hi Stu. You type faster than me Great we said the same thing Chaz. Quote Link to comment Share on other sites More sharing options...
stu999 Posted March 1, 2005 Share Posted March 1, 2005 Hi Chaz. I had typed all that out once, but the 'pooter crashed as I was correcting a few typo's... Lessons learned from tinkering with Mini's as well mate? Quote Link to comment Share on other sites More sharing options...
chazpowerslide Posted March 2, 2005 Share Posted March 2, 2005 Mainly from messing around with the odd Mini or three yes. Interesting to note that on some of the later North South A+ Serise engine installations BL removed the vac advance to stop a rumbling noise coming from the mains. You'd have an engine running in the workshop sounding as if the mains were shot and then you'd pull off the vac line to the dizzy, block the vaccume and hey presto the rumbling would dissappear Anyways back to the plot Chaz. Quote Link to comment Share on other sites More sharing options...
congorobot Posted March 2, 2005 Author Share Posted March 2, 2005 Hi there, in answer to your question the engine is a 711m 'Kent' 1700cc 'rallytune' engine. It has a Westfield shallow baffled sump, HP oil pump, H/D vandelvell bearings, crank tuftrided and balanced, high compression pistions, big valve head, Kent fast road camshaft, twin 40 Dellorto's, 40mm chokes, AP clutch, lightened steel flywheel, and a Jan Speed 'hi' flow manifold. There was a recipt in the paperwork for the carbs being stripped, cleaned out and rebuilt with new mixture screws, needle valves and 'o' rings for idle jet holders. The work was carried out by Robinson Tuning in Glasgow. The car will be used for the most part on the road with the occassional track day. I have not yet carried out a compression test but will do so. I would have thought that it should be fine since the engine only has 3k miles on it since being rebuilt. At the moment the car will not do much more than 70. It is faster at lower speeds, and has little or no pull in 4th and 5th. To do 70 foot is flat to the floor. I have checked the timming and the fuel pressure. Have tried connecting the vaccume advance but without much joy. It improved the innitial accelleration a little but drastically worsened the idle. A friend told me that connecting the vaccume advance would not work properly as it is connected to the intake manifold of one cylinder instead of all four!?! Have just disconnected it. Have seen a distributor with magnetic trigger and electronic control supplied with coil for £140. Details are... Bestek Ford X-Flow Race Distributor & Ignition Kit. The advance on this distributor is set to suit tuned engines with multiple Carbs, higher compression & race / rally camshaft. The advance starts @14 degrees at 1000 RPM & peaks at 34 degrees at 4000 RPM. The amplifier is very high power with a lifetime guarantee. The Distributor is a Lucas electronic unit using an original Lucas pick up. This kit will increase bottom end driveability & top end power substantially. Many improvements are made to the original Lucas design & it is shorter than any standard X-Flow distributor, all units come with a right angle cap & rotor arm. Bestek are an Ignition system manufacturer established in 1986, Supplying only to the trade, race teams & mostly engine builders. We are specialists in advance curves always updating specs at dyno sessions. Has anyone had any experience of this product? It seems great value and very tempting! what engine, what engine spec and what are you intending to use the car for? Quote Link to comment Share on other sites More sharing options...
stu999 Posted March 2, 2005 Share Posted March 2, 2005 The first thing I have noticed there is the size of the chokes - 40mm is *far* too big for the rest of the engine spec - at a guess, 32/34mm would be far more suitable. However, 40mm chokes would also suggest that the carbs are at least 45's, which again are also too big for the engine. Sadly, bigger doesnt necessarily mean better - as an example I have 36mm chokes fitted to a 2.0 16v VX engine. 40mm chokes would be oversized even for the VX. Fitting carbs that are too big generally means that the engine is a pig to set up for low engine revs, and loses out on midrange torque, for no gian at the top end. It seems that the carbs have been jetted to suit another, bigger engine, and it is quite likely that the mixture is way off the mark. Please do carry out a compression test. It is wrong to assume that *just* because it has done 3K miles, that everything is tickidy-boo. It really does sound like the car wants a session at the rolling road, ideally after obtaining some suitably sized carbs. I certainly wouldn't advise ragging the car until it has been looked at. If it really is as bad as you say, there is something wrong 'major league' - and severe engine damage is likely. Tip: if they are 45's, they are worth a small fortune on Ebay Otherwise, you may find someone that is willing to exchange some suitable 40's for your 45's... The vacuum advance can be connected, but you will need to 'T' into all four inlet tracts ideally. But I really do think vac advance/dizzy's are the least of your worries at the moment... HTH Stu. Quote Link to comment Share on other sites More sharing options...
YouMustBeJoking Posted March 2, 2005 Share Posted March 2, 2005 It does sound as though there is something seriously wrong. Before buying a new distributor I would check your existing one with a strobe. I have seen a distributor with jammed weights which didn't provide any additional advance as the revs increased. Engine performance was very poor. At a track day I came across a cateringvan lapping Goodwood at about 70mph. The throttle linkage had vibrated loose and as a consequence flooring the throttle did not open the butterflies the full amount. I think you are going to have to work systematically through the fuel and ignition system until you find the fault. Quote Link to comment Share on other sites More sharing options...
congorobot Posted March 2, 2005 Author Share Posted March 2, 2005 Im 99.99% certain that the carbs are 40s and not 45s. I have noticed that in Des Hamiltons book, "How to build and powertune weber and dellorto", he gives jetting and setting examples at the end of the book. In this he mentions a x-flow 1760cc with 45mm dellortos. Is he wrong? He does mention that it uses 36mm chokes. Earlier in the book in the chapter entitled "Choosing the components for your carbs", he suggests that for 40s using 28, 30, 32, or 34mm chokes. Think that I will go out and double check the size fitted to the car! Quote Link to comment Share on other sites More sharing options...
YouMustBeJoking Posted March 2, 2005 Share Posted March 2, 2005 Also worth bearing in mind that for less money than the distributor you mention you could get a 3D mapped dizzyless ignition kit from Bill Shurvinton. Quote Link to comment Share on other sites More sharing options...
congorobot Posted March 2, 2005 Author Share Posted March 2, 2005 The plot thickens! I have up until now been taking it for granted that the info in the documentation present when I bought the car was correct! The carbs are Dellorto dlha 40e, and the chokes are 35 mm. Not as the previous owner and Robinson Tuning have listed them! Quote Link to comment Share on other sites More sharing options...
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