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Sept 30, 2019 15:50:40 GMT
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A bit or reading on the net & I think I need a smaller main jet but combined with a needle with a much smaller tip for W.O.T but retaining the fatter main stem for cruising. This ought to bring the AFR leaner at idle and cruise but let it go richer under power. I need to buy another kit of parts with leaner jets & needles as my current one only has richer parts in it.
is this a carter /edelbrock carb mark ?
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Sept 30, 2019 19:31:38 GMT
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Would it not be worth you having the car set up on a rolling road? One of my friends is one of the top dyno tuners in the UK and he does some evening work monthly at Surrey Rolling Road which isn't far from you? His name is Chris Todd (He owns the Scooby powered mk1 Fiesta that runs 9's) It would, yes. Difficult finding someone who knows V8's and has spares for Edelbrocks mostly. There are a few around but mostly far away. Surrey not far so I'd be interested in knowing more. I'll try to get it close on my own first as I want to understand the carb better and how it affects running but a proper session would be in order in the longer term. |
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Sept 30, 2019 19:33:47 GMT
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Robert, yes it's an Edelbrock AVS thunder series 650 CFM.
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He is in Spain at the minute but I'll ask him when he gets back if he can help or knows who can local to us/you. He specializes in mapping usually but I know he does carbs too.
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96 E320 W210 Wafter - on 18" split Mono's - Sold :-(
10 Kia Ceed Sportwagon - Our new daily
03 Import Forester STi - Sold
98 W140 CL500 AMG - Brutal weekend bruiser! Sold :-(
99 E240 S210 Barge - Now sold
02 Accord 2.0SE - wife's old daily - gone in PX
88 P100 2.9efi Custom - Sold
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Robert, yes it's an Edelbrock AVS thunder series 650 CFM. gotcha , i would do one change at a time , perhaps the smaller main jet and see how that works ,your tickover mix is alright isn't it ? the smaller main may just be enough to bring your cruise into the 16/17's and then you could thin down the needle tip if its not rich enough on full throttle . |
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Smokem - thanks.
Robert,
Yes, I'm running a 92 primary main at present, 89 is recommended in the Carb manual. Needle is currently (I think) .070/.047 fitted with 3in.Hg springs.
Secondaries are .098
I am looking at going to something like .070/.037 needles.
Idle is a bit on the rich side still at about 12.5
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Had the carb apart today and had a good read up of the manual.
Reset the float heights as they were off and set the float stops as I don't think I had done that before?
Then moved on the jets and metering rods. I was running .092 jets with .065/.037 rods.
Reading the manual again the stock carb settings are .095 jets with .068/.047 rods.
So to go 2 steps leaner at idle and cruise but to keep std settings at power I have switched to the recommended .095 jets with .070/.047 rods.
I've not driven it yet but the idle emissions have improved to around 13-13.5 AFR and when I rev it quickly it does now go rich, but more importantly when I back off it goes super lean as I would expect it to do. At a constant 2000 rpm its around 14 AFR in the garage.
So - road testing notwithstanding it looks better.
Which brings me on to the next question - vacuum advance.
With the engine at idle I pulled off the vacuum hose & sucked on it - instant increase in engine speed of 2-300rpm. So vacuum advance in dizzy is working - but not at idle.
EDIT, MSD quote vacuum canister at 10 degrees advance.
Looking at the vacuum take off ports I am using 'timed' vacuum as against manifold vacuum. Edelbrock recommend 'timed' for emission engines and full for non emission or big cam engines.
So which is best? I put the hose on to the full vacuum and had to drop the idle around 300 rpm on the carb idle screw. It idles much more smoothly on full vacuum and the vacuum guage now shows 15" at idle (was a lumpy 13" before).
Any clever tuning people know which one I ought to use as the net is divided on the subject!
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Cant offer any professional advice, but it sounds like its happier how its set now.
Most stuff ive had activates the vac advance at idle as its normally recommended to remove the vac to the dizzy when setting the timing.
I'm sure someone with actual knowledge will advise though.
Sounds like the car is constantly getting better, hope i get to see it at a show sometime.
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Mark where are you taking the vac feed from?
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Pete, if you mean for the vac guage then its full manifold vacuum from the back of the inlet manifold.
Feed for the dizzy is from the 'ported' connector above the throttle plates at present but swapping to 'full' manifold vacuum gives the better idle and aparrently a cooler engine at idle and cruising speeds.
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as i said above mark run the vac at tickover ,so take it off the ported and put it on the non ported. only slight drawback can be when the car is cold it makes a bit less vacuum ,so the vac cannister can be less advanced so your tickover comes down .
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Cheers Robert, will do.
Will this increase the MPG? benefits seem to also include cooler running - which I do have an issue with, so that will be a plus.
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yes better mpg and cooler running at tickover , anytime the port was uncovered it will be the same .
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Noice  |
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This is a question to Mark and Robert I have fitted a Vacuum gauge to the Corsair and it worked before I stripped it but I was never sure of where the take off should be?    Any advise appreciated? |
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Either one will do, they are both full manifold vacuum.
Just add the servo hose wherever it route's best and put the gauge on the other one. As you have it in the photo is correct.
'ported' vacuum is above the throttle plates on the carb, so is only a tiny take off.
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The ported feed (vac advance take off on the carb) is small A on the pic is the servo take off and B is the engine breather take off, I was not sure about the ported take off on the cab and the affect on the vac advance so still unsure which would be best.
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If you're using the carb takeoff for the vacuum advance, I was surprised by mine (Carter twin barrel) that the vacuum advance takeoff hole in the venturi is slightly above the flap at warm idle position.
Thus, at idle there is no vacuum advance at all and the ignition timing should be dead on where it's set static.
Once you open up the throttle a little it engages as the butterfly moves the other side of the hole and vacuum is drawn.
The little digging into this that I did would appear to be quite common because it aids starting (DO NOT PRESS ON THE THROTTLE WHEN CRANKING THE ENGINE in the manual, this appears to be the reason because the timing flails around like crazy if you press on the throttle a little while turning the engine over and it doesn't like to catch).
--Phil
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If you're using the carb takeoff for the vacuum advance, I was surprised by mine (Carter twin barrel) that the vacuum advance takeoff hole in the venturi is slightly above the flap at warm idle position. Thus, at idle there is no vacuum advance at all and the ignition timing should be dead on where it's set static. Once you open up the throttle a little it engages as the butterfly moves the other side of the hole and vacuum is drawn. The little digging into this that I did would appear to be quite common because it aids starting (DO NOT PRESS ON THE THROTTLE WHEN CRANKING THE ENGINE in the manual, this appears to be the reason because the timing flails around like crazy if you press on the throttle a little while turning the engine over and it doesn't like to catch). --Phil Interesting Phil this may apply to all that have vac gauges fitted. |
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Pete,i would put the gauge feed into the servo vacuum line... engine side of the servo one way valve .
if you have it on the engine breather line,with hte breather connected to the engine the vac would be low .
one of the other reasons manufacturers put the ported vacuum on is to create a sudden advance in timing as you ease in the throttle to pull away ...this creates a sudden increase in torque so the car is easier to drive off from a stop .
regards
robert
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