View Full Version : Jets for webber 40s.
I have twin 40s but they are jetted for a 1.8 ford.
There is a list here for the different jets, do I need to get all of them? i.e. will the choke jets etc be used on track driving or can some be let as they are?
1400cc
Choke size: 27mm
Main Jets: 110
Emulsion Tubes: F11/F15/F9/F16
Air Correctors: 160
Idle Jets: 40/F9
Pump Jets: 30/35
Auxiliary Venturis: 4.0
Just trying to see if I can cut any costs as buying all the jets seems to be quite expensive.
Also, I have no trumpets, does this cause running problems? Can I attempt to make trumpets (not worried about how they look)?
Thanks
they need setting up by somebody decent, as in some old school engine tuner with a cupboard full of weber bits & a stack of knowledge.
What these guys dont know about carb's isnt worth knowing...
http://www.aldonauto.co.uk/shop/
BRoadGhost
10-06-12, 09:49 PM
Shame you're not down south, I know a chap that jets by turning them out by hand using a drill bit ;o
Shame you're not down south, I know a chap that jets by turning them out by hand using a drill bit ;o
I'll send them down!!!!
gearbox90
10-06-12, 10:11 PM
Shame you're not down south, I know a chap that jets by turning them out by hand using a drill bit ;o
Glad i`m not down south then .
Glad i`m not down south then .
Im guessing youve never had engine work done by proper old skool boys then.
gearbox90
10-06-12, 10:20 PM
yes mate i have had work done by PROPER old school boys
gearbox... if you'd read any really old CCC magazine tuning articles, you'd know that drilling out jets with proper accurate drill bits was standard practice for decades....
the amount of knowledge that is rapidly dying out is quite frightening
Well I assume my jets couldn't be drilled out as I am going from what ran 1800 ford to 1400 vauxhall.
Should I use filler to make them smaller? (clearly joking!!!!)
in the same CCC magazine articles, brazing up the holes & redrilling them was also mentioned, as a last ditch method to sort out the car...
gearbox... if you'd read any really old CCC magazine tuning articles, you'd know that drilling out jets with proper accurate drill bits was standard practice for decades....
the amount of knowledge that is rapidly dying out is quite frightening
Whilst my knowledge is basic, I know what you mean about actual mechanics knowledge. I once had to set the ignition timing on a mechanics car because he didn't know what I was talking about. He was very pleased that his car ran better. When I buy points I always get asked "what?"
I think it is ecu controlled injection systems and manufacturers ethos of making things unsuitable for diy that means that most of the last 20 years worth of cars are not as straightforward and therefore as you had said prevuously, soem mechanics are more fitters than skilled mechanics.
gearbox90
10-06-12, 10:31 PM
i am quite aware of what used to happen , but always was and still is reguarded as bad form to drill out jets for the reason that marc69 has put `Well I assume my jets couldn't be drilled out` .Then people come on a forum like this and quote what jets they have and `experts` tell them what they should be running or they should go up 2 on the mains or whatever to get rid of flat spots when the real base line was never known because someone drilled the jets out but left the numbers on them .
in the same CCC magazine articles, brazing up the holes & redrilling them was also mentioned, as a last ditch method to sort out the car...
Well here is ignorance, I'll need to do a search to see what brazing up actually means.
Thanks for that though, if it does look too expensive I may ask for a scan of the articles and invest in some very precise drill bits.
i have suffered this for the last 25 odd years... first off i had people who couldn't understand the concept that the autodata book was wrong because unleaded fuel had appeared, so timing engines had altered...
then i got my e16se & couldn't find anyone to wire it in, in the words of a leading auto electrician 'i don't do injection' so i advised him to find a new career, and worked it out myself
then i run into people with not the first clue how to repair anything from first principles, as in pressing bearings in, seating seals, shimming, and even the use of feeler gauges... they find it completely foreign to them...
Well if it's non professionals like me doing something wrong, fair enough but a mechanic who doesn't know what a feeler gauge is....
Timing, even on my 1.0 which is supposed to be prepped for unleaded. When it is timed with the strobe, it still has to be retarded a hairline otherwise it gives a little pink. This is through experience.
yes mate i have had work done by PROPER old school boys
If this is the case then youd know that using 0.1mm incriment drill bits to increase jet size was common place, and at some places (Bogg Bros for example) still is. Doesnt help the situation the OP is in as they need to downsize but ethos still remains the same.
However, what the OP needs to do is disasemble what hes got, check sizes of what hes got compared to that of what he needs for a 1400cc & simply buy accordingly. ANY company with detailed knowledge of carbs will be able to help out. And IMO Aldon are the grandads of carbs & ALWAYS have massive stocks of parts on site everytime Ive been there & they supply Demon Tweeks, so I cant see them NOT having either the info you need or the parts.
gearbox90
10-06-12, 10:42 PM
ye mate i done my appenticeship over 20 years ago . I was trained by the old boys you talk off , where we fixed the broken part not replaced it . I have been around people building rally cars since i was in nappys. But if i was paying someone to jet my car then i would be too happy with them drilling out jets and brazing up old ones . But if we are talking about old bill who is tuning up his own car then that is a different thing .
Yes i agree aldon know there stuff , and what normally would happen is they change your jets for the correct ones and keep your old ones.
Thanks, I have sent them a message so we will see what they say.
If this is the case then youd know that using 0.1mm incriment drill bits to increase jet size was common place, and at some places (Bogg Bros for example) still is. Doesnt help the situation the OP is in as they need to downsize but ethos still remains the same.
However, what the OP needs to do is disasemble what hes got, check sizes of what hes got compared to that of what he needs for a 1400cc & simply buy accordingly. ANY company with detailed knowledge of carbs will be able to help out. And IMO Aldon are the grandads of carbs & ALWAYS have massive stocks of parts on site everytime Ive been there & they supply Demon Tweeks, so I cant see them NOT having either the info you need or the parts.
I was trained by the old boys you talk off , where we fixed the broken part not replaced it.
You said it not me.... so I cant really see why your qeustioning using a lathe & set of drill bits as your old skool guys still do it to this day if parts are not avaible.
Personally Id never braze & redrill but if needs must then so be it.
gearbox90
10-06-12, 10:47 PM
if parts are not avaible.
gearbox90
10-06-12, 11:11 PM
Agreed :-)
But none of the ones available on the aftermarket lol
BRoadGhost
11-06-12, 11:27 PM
Listen, "correct" jetting is so subjective it could vary on any given day due just one thing, such as air temperature. Then there's what the cams are lifting, the chokes / venturi / trumpets are flowing, along with the head, how recently you filled up with petrol; what ron you put in, where the ignition timing's at...
Don't knock someone turning out a brass jet by hand with a drill bit after the exhaust gases have been analysed on a rolling road; it will be perfectly accurate should the operator know the dance.
I phoned a specialist today race carbs, the guy on the phone asked what my jets etc were, he reckined the car would run on those and I should try this then get new jets for improvements. He said the most improtant thing to do was to balance them first.
So today I removed the peirberg setup, for an initial setting I set both carbs on the manifold on the bench and set them so the gap on the throttle butterfly was the same according to my feeler gauge.
Put the whole lot on the car, got it running and up to temp. Well it went just the same as before, coughing etc, the more you open the throttle the worse it gets. I tried by adjusting the balance a 1/4 screw turn minus umpteen times and then did the reverse and moved it 1/4 turns plus etc.
It runs exactly the sema no matter what!
I'll remove the spark plugs tomorrow to see just how sooted up they are, a little frustrated to say the least.
Bit more successful today, a friend said he thought he had jets that his 1.3 went on many years ago.
Cleaned them and put them in and went for a spin.....
It goes reasonably well but doesn't feel that fast but i will need to do road testing. There seems to be a little miss when the foot goes down flat at low revs so i preobably haven't got them balanced exactly yet and trumpets may help?
At least I have an initial setting. It's pouring here as always so I couldn't be bothered any more tonight. hopefully proper road testing at the weekend, also an assistant with a watchclock is handy too.
I know people have recommeneded getting a specialist to do a rolling road set up but, Aberdeen is unbeleivably expensive for living costs/labour. The oil people here cause everyone else to hike thier prices up to a ridiculous level therfore leaving us non oil based workers way short. I know how different Aberdeen is as I have lived In glasgow and Northern England in the past, massive difference! A good example was when the ignition system failed, I went to a recommended local firm to ask if they could tell me whether it was my coil/distributor or the thing below the coil whoch had packed up. "I'll have to charge you for looking up the old books etc to get the exact details before I begin testing, probably 3-4 hours labour in total", yes at £72 an hour!!! I replaced it with a whole different system funnily enough.
The point of that is, the cost to get it set up by a specialist would probably be way more than just going for a bigger engine. It's just a track car for a bit of fun and I am skint so, it's all on a very tight budget. If settinbg these carbs does turn out to be way beyond me, I mat just go back to the peirberg but I am going to give it a go, the only cost should be different sized jets etc and the fuel for road testing.
But...any advice form anyone here who has balanced them and set them up would be much appreciated.
Have you got or got acess to a carb balancing tool? If not you really need to invest in one & they'll be a doddle to setup. EDIT: Providing your running the right sized jets.
http://www.ebay.co.uk/itm/Dellorto-Weber-synchrometer-carb-balancer-tool-made-in-Germany-not-China-/290682796527?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item43ae0b79ef
I dont quite know how the hell youve managed to do any kind of "setup" without one of these?
By ear.....and then drive up the street, how even is it, turn the balance screw a quarter turn one way etc. Got it going but it doesn't feel faster than the pierbergs yet.
I have set up single webers (1.0) many times, they are easy and had to do some work on the pierberg to get more out of it which worked a treat.
Thanks for the link to the carb tool, I'll have a look into it.
Have you got or got acess to a carb balancing tool? If not you really need to invest in one & they'll be a doddle to setup. EDIT: Providing your running the right sized jets.
http://www.ebay.co.uk/itm/Dellorto-Weber-synchrometer-carb-balancer-tool-made-in-Germany-not-China-/290682796527?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item43ae0b79ef
I dont quite know how the hell youve managed to do any kind of "setup" without one of these?
The set up tool, in simplistic terms is it as easy as this;
get the car on a fast idle by using the throttle screw, use the airflow meter to check the balance between cylinder 2 and 3, use the balance screw until these are the same, seems easy....?
womble sri
21-06-12, 09:31 PM
Got it going but it doesn't feel faster than the pierbergs yet.
T40's set up by an amateur (not doubting you ability) and no other mods probably will not be much faster. You'll certainly need a decent camshaft and some mods to make it flow better (such as an exhaust manifold and some head work) to see any decent gain 40's alone even if set up right won't give you that great an improvement of performance.
Trumpets will totally change the airflow into them and increase it by probably 5-10% as the air doesn't like the sharp edge at entry. (Although 5-10% is based on flowbenching heads with and without a shaped entry made up, might be a bit less on a carb but I'd expect similar)
It's most likely missing when you boot it due to the pump setup being for a 1.8, it's probably washing it with fuel, it's also probably then running lean as hell on the 1.3 setup.
Get it set up properly, save yourself hours of hassle and never have to think about it for the near future.
C612DNM
22-06-12, 07:56 AM
The only way (as has been mentioned before) to set up carbs properly is on either a static dyno, or a rolling road. No amount of "tweak and drive" will do. A good RR operator will do the biz.
With no trumpets, you will suffer "stand off" where the pulsations in the inlet tract cause the carb to "burp" fuel-air mix out of the carb. This can (and has) led to engine bay fires. It also reduces performance. You see it as wet fuel deposits on your bulkhead (if you're not running filters - which is a no-no), or fuel soaked filters!
There are many trumpet designs, but the best of them can't be used on a Nova because there isn't room. Ideally you want something like a 60mm rull radius ram pipe (these are the ones that have a big rounded edge, not the short sharp jobs). Dave Vizard, a god among engine tuners, published a lot of his work in this field, and he developed a number of designs that worked exceptionally well, though some of them were impractical for use on car installations, but his findings showed the benefit of rull radius pipes over conventional abrupt ending ones.
Don't forget you need filters on there too. The best solution is to build an air box, plumbed to a large flat panel filter for maximum flow of clean air without interfering with the area immediately around the inlets. This means that the best length of ram pipes is going to be about 40mm to allow for bulkhead clearance, and that will allow an airbox to be fitted. I found that pipes of less than 25mm didn't stop the stand-off sufficiently.
The 60mm figure came from Vizard's formulas which take inlet tract length, distance from throttle butterfly, cylinder capacity, stroke, revs, and some magic constants, and is taken as the idea.
The longer the pipe, the larger improvement in mid-range torque.
Moving on - balancing. If your ears work, get a length of hose. Listen to each inlet either side of the balancer. You will notice when they are in balance - they will sound the same. That's old school balancing.
I spoke to Ricky Gauld this morning who is apparently considered a bit of a god for tuning up north. He reckoned I'd get about 2 seconds difference (0-60) times going from standard carb to twin 40s tuned and running properly. I explained to him what I have done with the pierberg and that I am getting (0-60) between 1.5 and 2 seconds faster with the modifications. He said that I probably would get very little more out of the webers with the 1.4 block without a lot of head work/piston work etc.
So I'm off to remove the webers and put my pierberg back on!!!
Thanks everyone for the advice etc though
had to do some work on the pierberg to get more out of it which worked a treat.
Interested to know what you did to the Pierburg to get more out of it.
changed the jets to ones from an unknown pierberg (think it was an astra?) I had lying at the back of the garage.
Made sure all the vacuums work, did my pen test to see if the second barrel opens when it should and the fuel goes through it.
Nearly blew the engine up doing this once when idling as the carb stuck with the 2nd barrel open at way out of the range for the rev counter...how a valve at least wasn't bent is a miracle.
Put a physically bigger vacuum thing on the 2nd barrel (again from the donor carb) and the vacuum thing at the back was also replaced.
Cleaned it etc,
Took the advance pipe for the distributor and put it on the 2nd barrel vacuum to give an earlier opening.
Adapted a K and N air filter to fit.
Basically now at 3500rpm with the foot flat in any gear the 2nd barrel opens, not just a bit but completely and throws fuel in the wee pipe bit above. You can tell the differenc ein every gear. 0-60 (on the speedo) moved form 10.3 as standard to 8.3-8.8 in our test runs, depending on my driving!!!!
But even with a consistentish 8.8, not too bad for a 1.4 although it was one of the slowest cars on the track but I think no-one else hafd anywhere near as small an engine.
The pierberg still is ok for normal driving but...is very thirsty when driven hard. Although any type of 2nd barrel/2nd carb would be thirsty I expect anyway.
That's what I did, not sure if it should be recommended though and not sure how long it will last.
Although i have taken the 40s off for the moment, I had to take brackets form other carbs and adapt them etc for the speedo cable during the last few days. Pic 1 shows what it was like before and pic 2 is what I have adapted it too, does this look ok? It was certainly easier to pedal and seemed more secure.
You never know, I may be putting them back on in the future......
http://i988.photobucket.com/albums/af5/69marc/Photo410.jpg
http://i988.photobucket.com/albums/af5/69marc/Photo409.jpg
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