DCOE tuning questions...

BrettM

BrettM

1981 RHD X1/9
I have the DCOE carbs installed and plan to drive a little and do some tuning as I go. What is the best jetting for my set-up? I will be running a 40/80 Faza cam, adjustable cam gear, 10:1, ported head, header and electromotive ignition. With this set up, any suggestions what jetting to use?

6696_1195315523707_1253028430_537324_2403009_n.jpg


I am not finished with the instal yet. The whole thing comes out this fall and I am going to redo the linkage with proper material and detail everything up really nice.
 
Balancing them would be the first step. Do you have one of these?
d046_1.JPG

It'll come in very handy.

This is where I bought mine.
http://www.carburetion.com/books.asp

Every car is different and what I'm finding out with my DCNF set-up is that dyno time is the only way to do it right. Any recommended jetting will only get you in a "ball park" or what worked for someone else's set-up. A base line pull on the dyno that has a wide band O2 sensor will tell you exactly where your rich or lean, then you can buy jets accordingly. Then test it again, and again, and again until perfect. :laugh:

Looks like you'll have a very nice running X when it's done.
 
Thanks...

I have a Haynes Weber book and a syncrometer. The car runs great, better than it did with the DCNFs. I have not done any dyno time yet but seat of the pants tells me that there is an improvement. I wanted to do this upgrade in stages so we could tune on the dyno and compare the differences. My old DCNF setup had 89.7 hp and all I have changed thus far is the carbs. I will run it and see what it shows, then start adding the new head and other goodies.

Does anyone have a stash of jets and such that they might want to rent out? I would of course add to the collection if someone had such a collection. I would like to have different size jets on hand when doing the dyno if possible.

Brett
 
Brett...

What are the specs of the motor right now? Would be interesting to know since you have actual dyno numbers.

Thanks,

///Mike
 
Here is a starting point

I don't look on the site much so I missed this earlier. I would have figured you would have pm'd me on this one based on what you are looking for; not many folks running DCOEs.

This is the tune I got 97whp with, it was really rich at the low end so it is only a start:
Choke = 32mm
Idle = F9 55
Main = 125
Air = 180
Emul Tube = F15
Pump = 40

I found the F11 to have better drivability

I have more power now but am fighting a really rich shot when I trounce the pedal (9.5 afr)
Choke = 34
Idle = F9 50
Main = 130
Air = 190
Emul Tube = F11
Pump = 35
**Make sure the float level is correct; look at the innovate site

It is still rich but I am getting a flatter afr profile with the F11. It is a difficult trade off throughout the range: idle, low, and high rpm but that is the result from my engine configuration; combustion chamber design, intake manifold blend, and cam. Your engine may be easier to tune. I was hoping to have dyno numbers by now but I am continuously fighting the POS IAP header with fatigue cracks etc.

CR = 10.5/1
CAM = 40/80
Valve Cut = 30/45/60
PBS Big Valve
Header = Modified IAP, length 30"
Lightened Flywheel
Adjustable Cam Gear (Piper)
DCOEEmulsionTubeComparison.jpg
 
Thanks...

I was actually going to get with you but wanted to see what else was out there as well. I am currently driving the car and seeing how things go so far. I am going to do a dyno run like it is, then put the new head and Electromotive stuff in and see what gains I get. If I see the other side of 100hp, I will be happy. My DCNF set up was 89.7hp so I am hoping for some gains. I will be sure to keep you posted and most likely will be calling at some point.
Brett
 
Thanks Brett

I was really asking DallaraX19, but I'm still curious about the specs of your current motor. Is this the same configuration as the one you dynoed a few years back, only with sidedrafts?

I'm trying to get a sense of what kind of power one can expect with various configurations so it's nice to know the engine specs and type of fuel when looking at dyno charts.

Cheers,

///Mike
 
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