RobBrown
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| posted on 19/10/06 at 11:23 AM |
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Pinto with Dellortos - Bad emissions
I have just failed my SVA on the emissions test only. 
I am running a 2lt Pinto, with twin DHLA40 and a fast road cam.
The limits were 3.5% CO and 1200 HC, but my readings were 10% CO  and 700 HC, however when I turned in the idle adjustment screws the CO came down
to around 6% but HC shot right up to 3000.
I had recently had the carbs balanced and tuned at a rolling road, and ended up with :
160 main jets
size 12 main emulsion tube
200 Air corrector
60 idle jets
It goes really well 
Any suggestions to get the readings down.
I'm also getting a bang after the ignition is cut, and really high fuel consumption, which would indicate too much fuel (too big main and idle
jets??). Unspent fuel in the exhaust headers??
Regards
Rob
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greggors84
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| posted on 19/10/06 at 11:28 AM |
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I had a similar problem with a fast road cam and weber 45s
I took it to a rolling road and asked them to tune it to pass the emissions. At my first SVA it failed on emissions by a long way, so I took it back
to the rolling road and they did it again for free. They reckoned something might have been sticking in the carbs.
Chris
The Magnificent 7!
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jos
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| posted on 19/10/06 at 11:48 AM |
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see if anyone local to you has a standard carb you can use just for sva, get it thorugh on that and then have the dellortos tuned for best road
performance
.: Motorsport / motor racing circuit / track wall art Apex Traxs :.
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greggors84
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| posted on 19/10/06 at 11:51 AM |
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I was going to go back to standard carb, but it meant cutting another hole in the bonnet for the filter!
Chris
The Magnificent 7!
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PeterW
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| posted on 19/10/06 at 12:00 PM |
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quote:
Originally posted by RobBrown
I have just failed my SVA on the emissions test only.
I am running a 2lt Pinto, with twin DHLA40 and a fast road cam.
The limits were 3.5% CO and 1200 HC, but my readings were 10% CO and 700 HC, however when I turned in the idle adjustment screws the CO came down
to around 6% but HC shot right up to 3000.
I had recently had the carbs balanced and tuned at a rolling road, and ended up with :
160 main jets
size 12 main emulsion tube
200 Air corrector
60 idle jets
It goes really well
Any suggestions to get the readings down.
I'm also getting a bang after the ignition is cut, and really high fuel consumption, which would indicate too much fuel (too big main and idle
jets??). Unspent fuel in the exhaust headers??
Regards
Rob
Rob
That sounds a bit high...! Sounds like drastic over fuelling - on a modified Pinto, Dell'orto 40 should be something like
chokes 34
Main jet 162
emulsion tube 11
air corrector 200
idle jet 62
pump jet 42
needle valve 150
Thats for a single, and giving up to 145bhp. (and taken from my very manky Dell'Orto guide..!)
It doesn't list the twins, but you can recon that the main needs coming down a 135 or somewhere similar.
Cheers
Peter
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jos
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| posted on 19/10/06 at 12:05 PM |
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i dont have a hole in my bonnet as i dont have an air filter and i didnt have one at sva either. as youre only thinking of doing it for sva I wouldnt
cut a hole in my bonnet either just for this purpose.
im envious of the bangs although if its too loud it might be doing more harm than a comical little pop or bang
.: Motorsport / motor racing circuit / track wall art Apex Traxs :.
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mookaloid
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| posted on 19/10/06 at 01:05 PM |
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lots of unburnt fuel in the exhaust and banging on over run and after you switch off can also be lack of ignition advance.
Cheers
Mark
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RobBrown
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| posted on 19/10/06 at 06:09 PM |
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Thanks,
I don't really want to fit a different carb as this is likely to mean adjusting the cam timing again. Also my engine sits quite high in the
chassis so would need a hole in the bonnet even without the filter.
The bang is quite loud, flames from exhaust have been seen.
I have a fair selection of jets and tubes, from my endless tinkering. Now that the timing and balance has been set, is a matter of just playing with
the jets and mixture screws to get it idling smoothly with smaller idle and Main jetsemulsion tubes?
Is there anyone near me that has one of those portable exhaust gas analysers, that I could borrow, so that I can see the CO reduce, without having to
keep taking it down to a garage, who shut at 12 on a Saturday?
I'm struggling to get any more time off work over the next few weeks, to be able to take it back to the rolling road and have only got weekends
to tinker. 
Any advice appreciated
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Andy S
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| posted on 19/10/06 at 06:22 PM |
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The speedpro rebuild book recommends for a Pinto on 40DHLA's
34mm chokes
140 mains
180 air correctors
7772.10 emulsions
55 idles with the fixed DHLA (H) non adjustable idle jet type
Otherwise use the 7850.1 idle jet holder
From the book - the mains you have are for a 650cc cylinder and the idles 560-630
Hope this helps
Andrew
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RobBrown
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| posted on 19/10/06 at 06:33 PM |
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Thanks Andy,
That's pretty much what I had fitted before it went to the rolling road for tuning.
The RR tune also sorted out the cam timing, ignition advance and balance. I was just wondering whether changing all the jets back to how I had them
before would need me to change the advance or balance. I would be reluctant to do this having spent £250 on the rolling road session (3 days).
Rob
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Andy S
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| posted on 19/10/06 at 07:39 PM |
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I am suprised the RR left the idle in such a poor state - surely they would know it would be an immeadiate fail at any MoT unless the car is Q plated
or pre '71 and even then 10% CO is just plain ridiculous.
Its running way too rich so first thing I would do is drop the idles down to the 55's and check the idle air corrector circuits and holders - It
will make no difference to the maximum power as on full power the idle circuits are redundant.
However, surely you have to wonder at the rest of the settings if the RR was happy with 10% CO at idle.
Did the RR leave you with any info on power and CO readings at max power etc. to confirm the jet selections.
Cheers
Andrew
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RobBrown
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| posted on 19/10/06 at 08:08 PM |
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I have no evidence to suggest they even did an emissions test. When I asked them about emissions they said "it would be OK"!
The only printouts I have from them is the power/speed /torque graph from the RR itself, indicating:
Engine Power - 101.5hp @ 5131 rpm
Wheel Power - 82.1hp
Torque - 119lbs/ft @3167rpm
I'll give them a ring to see if they can correct it. Otherwise I'll change the jets at the weekend. My only issue is being able to
confirm the CO and HC readings are OK before spending another £30 on an SVA retest.
Rob
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flak monkey
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| posted on 19/10/06 at 08:16 PM |
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Is that all? The std 2 litre pinto was quoted at 103bhp in a sierra, on std carbs and cam....
I would agree with the others, those jets do seem a tad on the large size....
David
Sera
http://www.motosera.com
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Chippy
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| posted on 19/10/06 at 10:40 PM |
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Taking the results quoted by your RR, I would be very worried about there competance. Sounds to me like it's well over fueling. With a fast road
cam and twin carbs would have thought that the figures were well down on what you should expect. Regards Ray
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