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  #1  
Old May 18th 2003, 09:48
Ron Roberts Ron Roberts is offline
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Tuning Dells

I switched my Kadrons for a pair of Dell 45s. The improvement has been fun. Much better trottle responce, and all around smoother operation. I also gained 2MPG (so far). My only concern is that I am running about 10* hotter on the oil temps and was getting some detonation around 1500 -2000 rpm if I load it. So, I retarded to timing a few which pretty well took care of it. BUT that caused it to cough on decelleration (only when moving not sitting and revving the engine) I am guessing this is beacause of unburned fuel igniting after the cumbustion. I am pretty sure the coughing is from the exhaust and not the carbs. Should I go up a notch on the idle jets and put the timing back where it was? Any recomendations?
2017
8.5 CR
009 now set to 25* full advance was at 29
34 vents
55 idles
150 mains
200 airs

Thanks
Ron

P.S. Next day now. I pulled all the idle jets and cleaned them. Each one seemed to have a slight resistance to passing a jet drill through it (drill had been through before) as if there was some gunk lining the jet. I put them back in and no more coughing. Next time I started up it backfired right at startup and now its coughing again on decelleration. I use the stock fuel filter, and it is new.

Last edited by Ron Roberts; May 18th 2003 at 17:53.
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  #2  
Old May 18th 2003, 22:19
chigger chigger is offline
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Since I just bought a pair of 40mm dells almost new I also invested in a book about them. The Dellorto Superperformance Tech Book is written and available from CB Performance. It goes into great detail about calibrating the carbs and alot of other information about the proper ignition advance, etc. There is also great section on troubleshooting the setup. Hope it helps.
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Old May 19th 2003, 12:08
Ron Roberts Ron Roberts is offline
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I have the Dell book. It has been very helpful. In the trouble shooting section I don't see coughing on decelleration though. Really the carbs need a different engine, and there are no carbs that will really fix my engine. But thats another story and I'm just looking for something that I can do for it today.

I went to 60 on the idles, and moved the timing back up which did take care of the coughing but the detonation is still there. The problem is in the engine, and I think the bigger carbs load the intake charge more. Thats why detonation is triggered by opening the throttle, right? The only other thing I can think of is that the 009 has an advance curve that is out of whack. Thats what it is! My distributor needs more Whack! :silly:

Ron
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  #4  
Old May 19th 2003, 17:21
kdanie kdanie is offline
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Get the Mallory dist.

Dump the 009 and get the Mallory, you don't need the one with vac advance so you will save a few $$. These distributors are really great and tuneable to the advance curve your engine needs. It always amazes me when VW people just slap in an 009 distributor and expect it to run correctly. V8 builders have known for years that every engine requires it's own advance curve for optimal operation. The Mallory is more $$ than a 009 but you will never regret it. I run a stock Mallory on my beater trash bug with an unknown engine and it made a world of difference over an 009 and an old school 019! I bought that distributor for my 2.0l type 4 and just slapped it in my trash bug after taking my 019 out in disgust, now I need to buy another for my type 4!

I know you can get the detonation to stop with the correct advance curve.
ken
ken
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Old May 20th 2003, 00:01
chigger chigger is offline
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Detonation is usually caused by to much advance. Total advance should be around 28 deg. My problem is that the stock distributer clamp keeps slipping. Just recently I took measurements and made one out of billet aluminum. It looks just like the empi or bugpack. It won't work. The stock case stud doesn't stick up enough. The clamp is going to have to be reengineered before I am happy with it.
Slap a vacuum gauge on the motor or spray around the gaskets and throttle plate holes with carb cleaner and see if the idle changes. Well used carbs usually have leaks at the throttle shafts. All four throats should pull the same vacuum and be smooth as the rpms go up.
45 dells are really big for your engine. You might try using the recomended venturies and jets for the 40 sized carb. Hope some of this helps.
Check you valve clearance too and maybe a compression test. You might have a burned or sticking valve.

Last edited by chigger; May 20th 2003 at 00:12.
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Old May 20th 2003, 00:26
Ron Roberts Ron Roberts is offline
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Thanks for the response guys.

Chigger, The carbs are big but I decided to try them because mine came with the 34 vents which are more in line with the 40 carbs. I tried the carb cleaner trick, and I also tried starting fluid. Neither change my engine speed even if I spray it into the carbs intake. At one time when I was obviously lean the spray would pick up the rpms. I went up a step on the idle jets and then it didn't make a difference.

Here is the new findings: The knocking occurs between 32and 40 MPH in 3rd or around 20-25 in 2nd and around 45-55 in 4th, AND I here it on decelleration as well as accelleration. Now I question if this is really knocking, or some other problem. Valves? main bearings? What else would make this sound. Knocking is caused by the piston skirt slapping the side of the cylinder, or so I've been told. Can the piston get sloppy enough to knock on decellaration? I get a bit of blow by at idle but if I rev the engine and open the breather it isn't really putting much out. So, I'm guessing things are tight. This could be a harmonic thing that happens at a certain speed.

Thanks
Ron
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Old May 20th 2003, 08:10
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dgluyas dgluyas is offline
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Talking Tuning Carbs

Dear Ron. I am running a 2332cc with 48mm Webber IDFS
The venturis are 42mm(valve size on intake =40mm)
The mains are 145s
50 idles
200airs
Thing to realise is that 45Dells are not way too big for your motor!
It is important to know how big your valves are .
Your venturis should be about the same size as your valves for medium performance and streetability, and about 2-3mm larger than valve sise for full on race engines.(mine is mostly drag racing)
So my question is ..are you running 37mm intake valves??I doubt you are. So what you need to do is..

1. adjust your valves and check your venturis are about the same size as your valves)
2. synchronise your carb flow
3 .drive it again
remember that up to 3500rpm you are still on idles and above that your' e mains cut in .
You need to reduce your mains in size by 5' until it sputters on acceleration then go up one size.
You need to do the same on idles until it wont cruise below 2500rpm without sputtering.
Remember too rich and it will run but foul plugs
too lean and long term its no good either.
Dont look at what other people run.. even though I have listed my parameters, in the end it only gets you in the ball park. You need to keep changing jets and listen to how its running.(as you are doing) P.S your venturis are still ok if you just adjust your jets to suit . You will have a lot better low down torque with smaller venturis and they are somewhat costly ! Good luck!

David
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Old May 20th 2003, 09:53
Ron Roberts Ron Roberts is offline
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Thanks David, Heads are stock valve size.

When you say go down on the mains until it sputters on accellaration, is that still restricted to 3500 and up, or at lower rpm are you in the main circuit at open throttle?

Ron
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Old May 21st 2003, 04:29
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dgluyas dgluyas is offline
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Thumbs up Tuning carbs

Hi Ron ! Idle circuits work from low rpms up to about 3000rpm , so most of your driving /cruising is done on them. The mains overlap slightly with the idles. They operate somewhere between 2500rpm upwards. Its not exact with these ranges as you would expect. The important factor is constant rpm testing. If you drive it and maintain a constant 2500 rpm you are listening/feeling the idle circuit at work. If you are holding it in gear at 3500 then you are on your mains. Its good to have the window down and a lonely street !! Play with different combos. Its the only way you can really jet it.
Good Luck ! David
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  #10  
Old May 21st 2003, 07:16
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Wally Wally is offline
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Quote:
Originally posted by Ron Roberts

Here is the new findings: The knocking occurs between 32and 40 MPH in 3rd or around 20-25 in 2nd and around 45-55 in 4th, AND I here it on decelleration as well as accelleration. Now I question if this is really knocking, or some other problem. Valves? main bearings? What else would make this sound.
Thanks
Ron
Hi Ron, I had an old 1600 dp engine once that made knocking sounds on both accelleration as decelleration. It proved to be the main bearings: they were very worn. I didn't have an oil pressure gauge at the time, but I suppose oil pressure should be noticebly lower when the bearings are very far gone...
If your tuning of the carbs and ignition doesn't work out, you indeed might have to consider the bearings. (A) bad rod bearing(s) could also be the cause of course. How 'old' is your engine? Oil pressure readings?

Good luck,
Walter
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  #11  
Old May 21st 2003, 09:51
Ron Roberts Ron Roberts is offline
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Hi Wally, The engine is only about 18K old. But it has ran hot. I don't have a pressure guage. It would be a shame if I had to change to a better engine!

Thanks
Ron
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  #12  
Old May 22nd 2003, 20:56
Ron Roberts Ron Roberts is offline
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I am concerned about the bad bearing possibility, so I ordered an oil pressure guage from aircooled.net. The idiot light doesn't tell you anything until too late, and actually mine sometimes doesn't tell me anything at all...I noticed yesterday mine seems to have a bad conection somewhere. When I turn the key on sometimes it doesn't light up and sometimes it does. I guess thats why they call them idiot lights. You're an idiot to rely on them. Anyway on the pressure guage I believe its 25 at idle and 60 psi at speed? Is that right?

Thanks,
Ron
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