Fixing fuel economy on Pinto with 32/36DGAV- dilemma
James - 13/9/12 at 06:10 PM
So, I have a standard 205 Pinto running a Weber 32/36DGAV carb.
I bought it many years ago 'rebuilt' to bolt straight onto my Pinto as I wanted an easy life.
However, even with relatively normal driving (inc' motorway at 70mph) I get little better than 15mpg. This makes the car practically undriveable
for any distance and even any little trip out costs me a tenner! 
I had to abandon the planned trip to France in it- 1200 miles at 15mpg didn't
seem so affordable!
It also needed a *very* helpful MOT tester to get it through the 3rd part of the emissions test (is that lambda, I can't remember?).
I took it for tuning at a friends Triumph restoration business. They spent a lot of time buggering around with it but weren't able to improve
things.
We stripped apart the carb to check all the jets/tubes etc. and they appear about right but then you can't tell if they've been drilled or
anything.
Even with the ali plate intact when we phoned Southern Carburettors they weren't able to identify the specific carb so a rebuild kit is difficult
to identify. They suggested a whole new carb (as did my friends tuning place) which from Southern Carbs is about £250+vat.
Although this will be paid for by the saving in fuel, it's a lot to pay whilst currently unemployed! 
Bob reckons he could get 40mpg out of his Pinto'd Indy on a long motorway run- this seems like a good figure to achieve.
Just want some ideas on best way to proceed really (cheap ones! 
).
Thanks!
James
[Edited on 14/9/12 by James]
snapper - 13/9/12 at 06:16 PM
There are plenty of 32/36 DGV, s on eBay.
I suspect you have an issue with the auto choke, they were thrown away and replaced by manual ones a lot.
My bike carbs give better than that
Xtreme Kermit - 13/9/12 at 06:47 PM
Are you sure your dizzy is working properly and the timing is right?
I used to get 20 from mine with twin 45 dcoes on...
James - 13/9/12 at 06:53 PM
quote:
Originally posted by snapper
There are plenty of 32/36 DGV, s on eBay.
I suspect you have an issue with the auto choke, they were thrown away and replaced by manual ones a lot.
My bike carbs give better than that
Agreed, but new ones on ebay seem to be similar money to what Southern Carbs wanted, and if I go 2nd hand I'm putting myself in the same position
but not knowing what's actually in there! 
The auto choke opens when the car is warm... what else can go wrong with it?
Maybe bike carbs is the answer then? What sort of mpg do you get? What carbs and what manifold are you using?
Cheers,
James
James - 13/9/12 at 06:55 PM
quote:
Originally posted by Xtreme Kermit
Are you sure your dizzy is working properly and the timing is right?
I used to get 20 from mine with twin 45 dcoes on...
It's at 10° which the tuning place said was ok.
snapper - 13/9/12 at 07:05 PM
They were always a problem and did not always work properly causing exactly the problem with fuel consumption you have.
pjay - 13/9/12 at 07:11 PM
What about your vacuum advance (assume it's dizzy based)? 10° sounds like the static advance (set with engine not running).
If your vacuum advance isn't working this will badly affect your fuel consumption (or if you have no way of increasing advance under light load).
chillis - 13/9/12 at 07:21 PM
This sounds more like ignition, don't think your getting any vacuum advance or posibly centrifugal advance has stuck.
With a timing light attached and the vacuum tube removed and dizzy end of the pipe plugged, rev the engine and see how much the advance changes - if
it don't change then the centrifugal has stuck. if all is ok re-connect the vac pipe then see how much more advance you get, if you don't
get any more than when it was plugged then the vac capsule or pipe are leaking.
Carb re-build kits are available for around £30 but many places want to sell you a carb 'cos there's a good mark up on carbs and nothing on
re-build kits!
Unless you have a lot of play/wear in the throttle spindles then a re-build kit shoud sort it out. Check the mains, air correctors and emulsion tubes
are to the spec of a late mk4 cortina or mk5 as they were jetted to be the most economical.
Any decent carb/injection centre should have jet gauges to check if the jets have been drilled or just re-build it with jets of known size and see if
it changes but such poor fuel cons on normal driving suggests either a massive fuel leak into the primary throttle or duff dizzy.
If your running the autochokestill make sure the coolant is going through it, doest the autochoke body seem hot to the touch after a run? (too hot to
hold your hand on it). I've ditched the autochoke on mine as you don't really need it on a kit car.
BTW I see 30mpg on a run - 2.1L 140hp pinto with 38dgs carb so 15mpg on yours is way wrong.
Hope that helps.
[Edited on 13/9/12 by chillis]
Not Anumber - 13/9/12 at 07:22 PM
I suspect that either your 32/36 Weber has very badly wrong jet sizes and emulsion tubes or it has worn around the spindles or the mixture screw
seating is knackered from over enthusiastic tinkering some time in it's life. My Pinto has a 38/38 weber which is currently over jetted and runs
rich but this still deliivers over 25 mpg. 40Mpg on a long run should be achievable with the right setup. These engines weren't bad on fuel
consumption in the Sierras and Capris and are even better when they dont have a ton and a bit of bodywork to lug around.
£ 250 for a brand new carb doesn't sound like an attractive option. Look out for a 2nd hand one on the for sale part of this forum first and then
try Pistonheads, local breakers, on line breakers and then Ebay. Tell the seller it needs to be spot on for what you need it for and get them to
agree to take it back (minus carriage) if it is knackered.
Ive found that most reaonable vendors will agree to this kind of thing if you get them on the phone for a chat and strike up a rapport with them, tell
them what car you are building etc and ifin doubt offer them an extra tenner if they would agree in writing to take it back if it's not right.
Andy S - 13/9/12 at 08:49 PM
it could also be that the power valve is stuck open which is more likely
Andrew
perksy - 13/9/12 at 10:13 PM
Have you checked to see if the carb is badly worn ?
If it is there's not much point in playing with jets etc
It should be getting a lot more than 15mpg in a car as light as a 7
James - 13/9/12 at 11:54 PM
The throttle linkage has a bit of play.
We tested the vacuum advance by sucking on the pipe and you can see the dizzy parts move.
I'm not sure what the "power valve" is. Is this the accelerator pump jet? This was faulty but we got it to work.
I'm at the limit of my knowledge on this subject. Hence the reason I bought a 'rebuilt' carb off an ex-member on here- so it was easy!
Thanks!
James
mcerd1 - 14/9/12 at 07:55 AM
quote:
Originally posted by pjay
10° sounds like the static advance (set with engine not running).
I'd guess thats 10° at tickover using a strobe light on the crank pulley and with the vac hose pulled off the dizzy.... brings back memories of
my old mk1 fiesta - checked and set every 5k, happy days
if you did seriously think about a new carb then it might be worth a look at some bike carb's before you buy a new one for £250
if fuel econnomy is a big issue then a set of smaller bike carbs might be an answer (around the 600cc bike size) they also tend to go for a bit less
money than the bigger bike carbs
in fact with a bit of luck and some effort for £250 you could get bike carb's, a DIY manifold (with a flange from FASTdan) and a megajolt setup
or similar too (TPS on the bike carbs intead of vac advance)
just a thought 
[Edited on 14/9/2012 by mcerd1]
[Edited on 14/9/2012 by mcerd1]
mcerd1 - 14/9/12 at 09:05 AM
well that was good timing:
http://www.locostbuilders.co.uk/viewthread.php?tid=174422
ditchlewis - 14/9/12 at 01:21 PM
used to get similar milage out of my 2.1 pinto with twin 45's (as low as 10mpg). turned out to be a leak in the mecanical fuel pump.
there was no apparant leak and no standing pool of fuel on the floor, but one day i notices a smell and reached down and found one of the soldered
joints on the mechanical pump was weeping when under pressure (engine running) a little more light fiddling caused the pipe fitting to come adrift.
just an idea, a bit off the wall i know but if it is not the obvious problems above it might just be worth a 10 minute investigation.
regards
Ditch
Andy S - 14/9/12 at 04:45 PM
quote:
Originally posted by James
The throttle linkage has a bit of play.
I'm not sure what the "power valve" is. Is this the accelerator pump jet? This was faulty but we got it to work.
I'm at the limit of my knowledge on this subject. Hence the reason I bought a 'rebuilt' carb off an ex-member on here- so it was easy!
Thanks!
James
Not many do or how it works - Timing being out or a vacuum loss is not likely to increase fuel consumption to the degree being indicated here - they
just do not, and nor do air leaks through worn spindles - letting tiny amounts of extra air in does not increase fuel consumption. Good things to
check and keep an eye on though.
The power valve is a direct bypass of the main jets and emulsion tubes that allows neat fuel into through the carb to give high load enrichment - its
like like having two sets of mains jets open when off going full bore. When it goes wrong it massively overfuels. The acceration jet and injector
nozzle push fuel in from idle to the end of progression - when you stand on the pedal to snap open the progressive second choke on the DGAV the power
valve steps in to richen the fuel so that it does not go lean - when failed its on all the time the auxiliary venturi's are in action. i.e
anything over 1/3 throttle. When all it should do is come on at over 2/3 throttle and then only for a short time.
It's not a difficult job to check it out but you need to know the vacuum paths to check for air leaks etc.
Get a DGAS - they dont have the powervalve - trouble is they have to be set over rich to compensate
Andrew
Andy S - 14/9/12 at 05:01 PM
http://www.thelolaregistry.com/DIY/Weber.htm
Have a read and it also shows the valve in a decent detail
If you want to have a chat about what to check PM and I will reply with number
Andrew
[Edited on 14/9/12 by Andy S]
ragindave - 14/9/12 at 06:12 PM
I would look for a fuel leak if you can not find a fuel leak I would then get in touch with fast Dan and get a set of bike carbs
on it asap you will probably double your fuel economy.
James - 14/9/12 at 06:22 PM
quote:
Originally posted by Andy S
The power valve is a direct bypass of the main jets and emulsion tubes that allows neat fuel into through the carb to give high load enrichment - its
like like having two sets of mains jets open when off going full bore. When it goes wrong it massively overfuels.
Andrew
Hmmm, it did have a problem that when flooring it the thing would bog down and nearly stall.
I had to 'double pump' the accelerator at roundabouts etc. to keep the engine running. This seemed to be largely fixed by getting the
accelerator pump jet working though.
Thanks for the link- having a read now.
Cheers,
James
Andy S - 14/9/12 at 09:05 PM
But start with the basics first - did your tuning friend set the float heights correctly and check the needle valve is sealing ?
Not Anumber - 16/9/12 at 11:56 AM
Weber carb for a decent price on this forum, http://www.locostbuilders.co.uk/forum/34/viewthread.php?tid=174422
mcerd1 - 17/9/12 at 08:40 AM
quote:
Originally posted by Andy S
The power valve is a direct bypass of the main jets and emulsion tubes that allows neat fuel into through the carb to give high load enrichment - its
like like having two sets of mains jets open when off going full bore.
sounds like the issue I had with my mk1 fiesta (motorcraft carb) after I decided to fiddle with it.....
found a tinny brass weight on the workshop floor the next day, took me 2 weeks to workout that it had come off the fiesta which was only managing
20mpg for some reason - once it was re-fitted it suddenly went back to 35mpg