Re: Tuning a road demon 625 cfm carb
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Re: Tuning a road demon 625 cfm carb




Bad milage--- my first guess would be the choke plate partly closed all the time or too big on the primary jet size.

If a Demon bowls are like a Holley-- I take a pop can and cut it into. Lay a rag under the bowl to catch any gas spill- take out one of the lower bowl screws and catch the gas that drains out the hole into the pop can. . You can do this on the back bowl too...................MO


{Steve Mick}
http://stevemick.shutterfly.com/pictures#Part%202
----- Original Message ----- From: "Brian Safford" <hzf9vv@xxxxxxxxx>
To: <1962to1965mopars@xxxxxxxxxx>
Sent: Thursday, July 29, 2010 5:14 AM
Subject: Re: Tuning a road demon 625 cfm carb


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No, my mileage is terrible *all* the time.  Don't think I've ever
witnessed a backfire.

The video I have of a guy taking a Demon carb apart and checking
everything indicates jets in the secondaries.

Since I have vacuum-operated secondaries, I've always been concerned
that they're not opening due to low vacuum.

The BG guy said 14 at idle was pretty low, so I was wondering if the
other vacuum stuff ( brakes, PCV ) was getting in the way.

Can I use the vacuum connection for the heater to do that WOT test?

And I presume that removing the bowls to even look at stuff should be
done with the carb off the car so as to not have fuel spill all over
the place ...

Thanks,
Brian

On Wed, Jul 28, 2010 at 10:58 PM, 65 <65Val@xxxxxxxxx> wrote:

Brian...are you getting reasonable mileage when just cruising around? If so,
then your primary jets are probably pretty close. I would suspect the
secondaries are a bit rich. Does the carb have a secondary metering block,
or metering plate? If its a block, you can change the jets in the
secondaries. they are the same as Holley jets. Vacuum could very well be
below 6.5 at WOT. Easy way to check...plumb in a vacuum gauge with a hose
through the firewall, and take her for a ride. Floor it and check the gauge.
I will bet its closer to 0 than 6.5 . The power valve could be blown as
well. This is caused by a backfire.

Just my thoughts...


Darwin/Victoria BC/Canada
'65 Cdn. Valiant Custom 100 'vert
--225/A833...in a million pieces...SOLD
'67 Dart GT 'vert
--273/904...in "enjoying" condition

Check'em out... http://s41.photobucket.com/albums/e285/65val/

----- Original Message ----- From: "Brian Safford" <hzf9vv@xxxxxxxxx>
To: <1962to1965mopars@xxxxxxxxxx>
Sent: Wednesday, July 28, 2010 7:41 PM
Subject: Tuning a road demon 625 cfm carb



Am re-posting as I did this first from my cell phone and am not sure
it posted properly ...

I talked to a tech at Barry Grant about tuning my 625 cfm road demon
on my poly 318. I get black smoke whenever I floor it. He asked me
three things - timing at idle, vacuum at idle and cam duration at .050

Timing is 12 degrees btdc, vacuum was around 14 and my Daytona cam
has 218 at 50.

He suggested I switch to a 4-hole spacer rather than the open one I'm
currently using, and also thought I should move the timing to 14 or
15. He also wondered if I had good hot spark. Not sure how to check
that.

I asked about the power valve and he said it probably isn't even
opening as the vacuum would have to drop below 6.5 for that to happen.

I have power steering that uses vacuum as well as a pcv valve - do
those use up too much of the available vacuum?

I don't want to risk damaging my engine - are any of his suggestions
potential problems?

Thanks as always,
Brian Safford
62 Dart / Poly 318


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----
Please address private mail -- mail of interest to only one person --
directly to that person. I.e., send parts/car transactions and negotiations
as well as other personal messages only to the intended recipient, not to
the Clubhouse public address. This practice will protect your privacy,
reduce the total volume of mail and fine tune the content signal to Mopar
topic. Thanks!

1962 to 1965 Mopar Clubhouse Discussion Guidelines:
http://www.1962to1965mopar.ornocar.org/mletiq.html and
http://www.1962to1965mopar.ornocar.com/general_disclaimer.html.




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----
Please address private mail -- mail of interest to only one person -- directly to that person. I.e., send parts/car transactions and negotiations as well as other personal messages only to the intended recipient, not to the Clubhouse public address. This practice will protect your privacy, reduce the total volume of mail and fine tune the content signal to Mopar topic. Thanks!

1962 to 1965 Mopar Clubhouse Discussion Guidelines:
http://www.1962to1965mopar.ornocar.org/mletiq.html and http://www.1962to1965mopar.ornocar.com/general_disclaimer.html.


----
Please address private mail -- mail of interest to only one person -- directly to that person.  I.e., send parts/car transactions and negotiations as well as other personal messages only to the intended recipient, not to the Clubhouse public address. This practice will protect your privacy, reduce the total volume of mail and fine tune the content signal to Mopar topic.  Thanks!

1962 to 1965 Mopar Clubhouse Discussion Guidelines:
http://www.1962to1965mopar.ornocar.org/mletiq.html and http://www.1962to1965mopar.ornocar.com/general_disclaimer.html.












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