My RDJr is jetted up to 61’s in the primary side.  And mine also came with 58’s originally.  The upping of the jet sizes cost me a ~½ mile to the gallon in overall fuel economy but cruises much nicer and runs harder when I put my foot into the throttle.  Spark plug readings are perfect at this point.  The stock #65 power valve is in place.  If I wanted to mess with it further, I would drill out the PCVR channels in the metering block out a little larger and try the 58 jets again.

 

A #75 power valve will open sooner than a #65 power valve.  Opening positions are 7½”Hg and 6½”Hg respectively.  A #65 power valve will take more throttle opening or a reduced amount of engine vacuum to open it as opposed to what’s required for the #75 powervalve.

Lorena, Texas (South of Waco)

Well strangely enough, it wouldn't run w/o chugging like it had a full race cam with the 6.5 power valve.. It read 5 in of vac. on the gauge with that setup...  I pinched the fuel line with vise grips to empty the fuel from the bowls before removing the primary, & when the fuel level was about a quarter inch below the sight glass it cleaned up & the vac. reading jumped up to 13.

I need to play with the timing more, but I only pull about 10 in. of vac at idle. 

In theory the 6.5 power valve should be better...

Your idle mixture was probably too rich. Set the fuel back to the proper level and tune the idle mixture screws for the best vacuum.

Make sure to change only one thing at a time.


Lawrenceville, GA

Ok, put in fresh plugs, drove it & they are white as a ghost!

In the spirit of only changing one thing at a time I jetted up to 64's.(need to get a read on the plugs)

Runs much better. 

Having most of the idle issues due to the secondary idle & the initial amount that the secondary's are propped open by the set screw.  I always made sure my secondary's were tight as a drum on my 4100's years ago... The 4 corner Idle calls for seeing a small amount of the transfer slot when viewing from below the plates... I have closed it 98%, will most likely close it the rest next tune session.

Need to change back to the 65 power valve, since I still only pull 10 inches of vac.

I may also open up the valve lash on the e-4 from .015 to .017 to help the vac, & idle quality & tunability.

I

I think the Demon four corner idle feature is best used with one of the "open plenum" manifold arrangements - not a "Cross H" like we've got to work with. Like I believe you are thinking too - I shut down the whole seondary idle arrangement - did all my idle mixture tuning at the front.

The adjustment they suggest for the front idle transfer slot (adjust blade closed till the remaining opening looks square when viewed from under the carb) worked OK on the primary. Then I adjusted the stop screw for the rear throttle plate to keep the engine running - so I didn't have to alter the primary position. Used the front bowl level to set the total mixture up and down - centered the rear in the glass. The Demon is way more responsive to this move (or at least it seems to be) than any of the Holley's I've tuned.

The newest carb I got - the Road Demon Jr. - had a sticky needle and seat that drove me crazy  - until I changed them both to steel. Everything would seem to be working OK - and without warning - garbage mixture.

 
 Steve Metzger       Tucson, Arizona

Beginning to regret the road demon....



Have swapped to a new 6.5 powervalve, done several attempts to get the idle to work....



I get comments on how great it sounds, trouble is I know that it sounds that way because the carb is running incorrectly, & not that it has the 3/4 cam that it sounds like.



I have jetted up to 67's... I still have flat spots when accelerating gently. It reminds me of when I tried an autolite 4100 from a big block 390... Too much venturi to keep pulling the fuel down at low speeds.



Interestingly I drove it a while, popped the plugs, stark white. Made some minor idle adjustments & let it idle while doing so, (15 mins or so) then pulled the plugs. The 4 rear plugs remained white. The front were progressively geting black. I think the pcv at the rear is the biggest issue. I am going to drill & tap my 1" spacer for a nipple. I will drill two smaller holes into each of the primary bores within that hole just as they did on the factory manifold to reach both planes.



The thing is, this may cure the idle issue within some degree. I don't think the air bleeds on this carb are suited for the small 301. I know they rate it to 265 cubes, but this isn't working right.



I am curious if any of you guys running the road demon Jr. have experienced any of the venturiitis that i seem to get?



I am going to most likely end up shipping this thing back after positivlely identifiing that I can't fix it...



If I can get the Jr, & not have these issues I will probably be happy... This thing pulls hard once it finds the fuel...



If the Jr doesn't work, I am going to order a 465 holley I guess...

Does the Jr not have a pcv port?


Lawrenceville, GA

I'm running the 465 right now, luv it....except it doesn't have a PCV port.....I'll swap bases with another holley this winter. Gary

       

Gary, 55 Vicky, St. Germain, Wisconsin

 

The Road Demon has a pcv port. It is on the back side though, & draws more from one side than another..



I used to have a similar problem with the small-block autolite when used with the rear vac tap on the very back of the 9425B. I ended up fabing up a downdraft tube in the rear for a while, but scrapped that idea after a few years and nearly every gasket started to leak! Maybe coincidence, but all that pressure from winding it up couldn't have helped.



I am going to call Demon & see what their tech guys say.. I am sure they will suggest going to the Jr, but who knows..

I really liked having the quick change vac secondary feature, & the center hung bowls never hang up no matter how hard or at what angle you hit a driveway & jostle things.. I can't say that for standard side hung holleys, & even the 4100 for that matter.



Looks like after a few jet changes on the bench late last night I have the Eddy ready to step in for another stint... Will be good to verify that I don't have a vac leak going on since I am paranoid of that at this time.

Do you have the Road Demon or Road Demon Jr. as the tuning requirements for each do differ.  For the carbs with four idle circuits, I’ll make it a point to insure that all four throttle blades are equally open at idle and the four corresponding idle mixture screws are also set the same.

But it still sounds like a vacuum leak on your end.  Depending upon the carb spacer you’re using, carb gaskets are suspect either from a poor match to the spacer or just not sealing due to irregularities in the surface.  The ‘B’ manifold is already sensitive to carb spacer issues if the carb flange has not been milled flat.  Double check that the intake bolts are still tight also.  Just running lean on the back cylinders makes the intake manifold gasket suspect or a vacuum leak associated with the rear manifold vacuum port.

Lorena, Texas (South of Waco)