New Demon is here.....

[Orangecrush]

Well, my new Speed Demon 650 cfm arrived. I'll bolt it on and see if all my problems miraculously go away (stumble, terrible idle, stumble/surge at cruise...all that fun stuff). The one I am taking off is a 525 Road Demon Jr.

We'll see. I am hopefull that the carb was causing all of the problems; but, I don't feel confident about it. I am willing to bet the ignition setup is not the way it should be.

If this works enough to drive the rig, I'll take it to my tuner and have a full MSD system installed. [-o<

 

[Broncoholics]

I doubt its weak spark but you never know; I tried the MSD system. It helped the engine run slightly smoother but it was still rough. I've never heard of Speed Demon carbs are they suposed to be good?

Did it run any better or worse with this new carb? Did you try and tune it a bit?

On my 68 after thinking I had a dead cylinder, bad spark, etc etc. I did a compression test and it came out fine. Then I did a air leak down test it would hold at T.D.C. and I could hear the air leaking into the upper engine galley.

I found it had leaking valves in the heads when I pulled it apart.

When gas dropped the lead out of it and went to unleaded our old style heads do not have case hardened valve seats and end up recessing up in the heads causing bad leaks. This is due to higher heat. After I reinstalled everything with new valve seats it ran like a new engine! Might look into that.

 

[BLADE262US]

If you can istall a carb you will have no problem installing an MSD system I can walk you through it if you like all 6 of my trucks have MSD ignitions most I have wired with MSD 6 OFFROAD box , Rev limiter , MSD timing computer , and MSD distributor . Very very easy to hook up just follow the directions . /emoticons/[email protected] 2x" width="20" height="20" />

 

[Orangecrush]

Okay, new speed Demon (yes, it's supposed to be good....$450.00 plus another $80 for the hard fuel lines) is on. I had trouble with getting the fuel lines sealed correctly. I had to do it twice and use extra teflon. It seems fine now. Anyway, with much anticipation I fired it up in the garage.......sounds VERY nice and VERY smooth. It's really too early to tell, but I think that may have been it. After some REAL quick "tuning" ( I don't know what I'm doing really), I got it to idle on it's own. I was then able to shut it off, wait 30 seconds and turn the key to fire it right back up with no throttle. It fired and idled fine.

Problems remaining:

1) Rich idle- well, at least it's the oposite of what it was before....Now, I can see black smoke coming out of the exhaust pipes (slightly) at idle. Also, within 30 seconds of letting it idle in the garage, you can't hardly take the fumes. My eyes were burning terribly. I think this would sort of indicate too rich?

2) It has yet to be tested under load. I don't want to do it tonight as it's getting late and I don't want to bug neighbors. I'll test it out in the AM and report back. [-o< [-o< [-o<

Tuning- It's 4-corner idle adjustment type, so, I want to start about 1 1/2 turns out from full IN (all four corners). Then, I want to lean it out (IN) about 1/4 turn increments at the four corners until I get peak RPM. Then, richen it up from that point by about 1/4 turn on each corner. Is that about right for getting the idle mixture close to correct??

On the cylinder heads- I'm supposed to be having Victory Sr's installed next month. I may hold off it it really runs well. I'm holding my breath though on the drive test. [-o< [-o<

Thanks guys!

 

[Orangecrush]

Okay, new speed Demon (yes, it's supposed to be good....$450.00 plus another $80 for the hard fuel lines) is on.  I had trouble with getting the fuel lines sealed correctly.  I had to do it twice and use extra teflon.  It seems fine now.  Anyway, with much anticipation I fired it up in the garage.......sounds VERY nice and VERY smooth.  It's really too early to tell, but I think that may have been it.    After some REAL quick "tuning"  ( I don't know what I'm doing really), I got it to idle on it's own.  I was then able to shut it off, wait 30 seconds and turn the key to fire it right back up with no throttle.  It fired and idled fine.
Problems remaining:

1)  Rich idle-  well, at least it's the oposite of what it was before....Now, I can see black smoke coming out of the exhaust pipes (slightly) at idle.  Also, within 30 seconds of letting it idle in the garage, you can't hardly take the fumes.  My eyes were burning terribly.  I think this would sort of indicate too rich?

2)  It has yet to be tested under load.  I don't want to do it tonight as it's getting late and I don't want to bug neighbors.  I'll test it out in the AM and report back. [-o<   [-o<   [-o<

Tuning-  It's 4-corner idle adjustment type, so, I want to start about 1 1/2 turns out from full IN (all four corners).  Then, I want to lean it out (IN) about 1/4 turn increments at the four corners until I get peak RPM.  Then, richen it up from that point by about 1/4 turn on each corner.  Is that about right for getting the idle mixture close to correct??

On the cylinder heads-  I'm supposed to be having Victory Sr's installed next month.  I may hold off it it really runs well.  I'm holding my breath though on the drive test.  [-o<   [-o<

Thanks guys!

21560[/snapback]

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YEA!!! I finally took it out this afternoon. I had a real hard time with the air cleaner base fitting over the both of the huge float areas. In fact, it's pretty rigged up right now. I'll work on that later.

It runs SMOOOOOOTH and strong! Idles like a champ at 900rpm and drops right to 650 in gear. No stumble at light to moderate throttle. It's a little rich with some black smoke when you hit it; but, that can be tweeked.

YES! ) )

NEXT:

* New Heads

* Complete inspection of the drive shaft (7" lift and I suspect this is going to

create problems with the drive shaft due to the angles) and modify as needed.

Drive it and enjoy!

 

[Bandit]

Well, my new Speed Demon 650 cfm arrived.  I'll bolt it on and see if all my problems miraculously go away (stumble, terrible idle, stumble/surge at cruise...all that fun stuff).  The one I am taking off is a 525 Road Demon Jr. 
We'll see.  I am hopefull that the carb was causing all of the problems; but, I don't feel confident about it.  I am willing to bet the ignition setup is not the way it should be.

If this works enough to drive the rig, I'll take it to my tuner and have a full MSD system installed. [-o<

21495[/snapback]

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Im no expert,but I thought it out and made alot of calls to Holley,Edelbrock,and Summit.For the horse power range of my basically stock 302,on my '73,with MSD box,and pro billet distributer,I fought the urge to go big and got a 470cfm,holley truck avenger carb.So far it runs super no hesitation whatsoever.I had a 600 cfm on there and had to jet it way down and never got it to run right.The holley runs great and I just jetted it to the 6000 foot elevation.

good luck;

BANDIT