Just curious if these parts interchange?

Doc

I would really doubt it. Demon is not based on the Holley design.

The overall design of the Demon carb is exactly the same as the Holley. It isn't a copy, but very close. Holley tried to sue Barry Grant for that reason, but lost in court. Hoever, thad doesn't mean that all of the parts interchange.

Demon did do a lot of tuning to the design to make their carbs better. Their success is why we now have the Holley HP series.

Are you looking to add the " idlez feature to your Holley .. or just in need of a baseplate and thats whats available ?

I was looking to add the idle eaze feature. I like the adjustability of this vs. drilling a hole in my baseplate that I cant make smaller if I go too large.......

The idle eeze is ok but i have mine all the way open and i have .075 holes in all 4 butterflies to get the thing to idle worth a crap....

My idle Ease dose not seem to make a difference....I never have gotten it to work....I would not waste your money. Drill bits are cheaper anyhow.

racerdoc, that combo looks pretty familiar ;)

You DO NOT need either idle eaze or holes drilled in your butterflies to make it idle.

I suspect you have some other tuning issue going on if you cannot get it to idle properly. Look into the low speed air bleed and IFR combination for your particular carb. I'd also make sure you have enough timing at idle -- should be around 18-20* at idle and 36* total.

Amazing that we have come this far ( 12 - 18 *) in inital timing where not long ago we were setting initial close to factory specs. Not to mention that they dont run better at hi initial. but I guess we have gotten better at running low comp and better cam designs.

Just a comment. I need a couple of replacement parts for my Demon. Closest dealer is over 100 miles. Car is down till I get parts. Holley parts are everywhere and easy to get. I emailed the Demon tech line regarding this with no reply. If they want to be successful seems to me they need to get some parts out in the market place. I was totally satisfied till this happened.

racerdoc, that combo looks pretty familiar ;)

You DO NOT need either idle eaze or holes drilled in your butterflies to make it idle.

I suspect you have some other tuning issue going on if you cannot get it to idle properly. Look into the low speed air bleed and IFR combination for your particular carb. I'd also make sure you have enough timing at idle -- should be around 18-20* at idle and 36* total.



Eric,
Yeah, I noticed that your combo was similar. How long until you fire it? I'll tell you one thing. This motor is twice what my old 350 was.......and it wasnt too bad in my 3600 lb. pig.
Here is my problem. I originally had a 700 DP on my 350. As I was building my new motor I accidentally stripped a bowl screw on the main body of my carb. This had already been helicoiled by someone else and the helicoil was not screwed in far enough. SO.......I chewed up the forward edge of the helicoil and was not able to get it out. I had a proform main body and a billet base plate/metering blocks that I wanted to try so I basically built a new carb. I can get the car to idle fine with this carb but my plugs are black(dry) from idle. I have been playing with IFR's and idle air bleeds trying to clean it up. I have an Innovate LM1 but I havent hooked it up yet. Im sure that will make things much easier. I also need to find a new set of valve covers that will give me room to set up a PCV valve system with my stud girdles in place. I was looking at these http://www.jegs.com/webapp/wcs/stores/servlet/CategoryDisplay?lang=-1&catalogId=10002&storeId=10001&categoryId=30006&searchItemId=123171

or these....
http://www.jegs.com/webapp/wcs/stores/servlet/CategoryDisplay?lang=-1&catalogId=10002&storeId=10001&categoryId=19723

http://www.sallee-chevrolet.com/GM_Valve_Covers/aluminum_competition.html


I have a few things to work out. I havent had alot of time to mess with it yet because of weather and work. Should be killer when I get it tuned right.


Doc

PS- What pistons did you end up using for your combo?

Sorry double post.

Doc,

I used SRP flat tops and the Edelbrock Vic Jr head with 70cc chambers. Makes exactly 11.0:1 compression.

The motor has been fired and I just drove it yesterday. The weather was awesome so I burned out about a half tank of gas on the country roads. It runs GOOD. :D

How far out are your idle mixture adjustment screws? It sounds to me like your mixture is rich at idle, not lean, if your plugs are black. Try setting that idle mixture at idle with a vacuum gauge and go from there. You may have to increase the idle speed to keep it running while you do this.

Doc,

I used SRP flat tops and the Edelbrock Vic Jr head with 70cc chambers. Makes exactly 11.0:1 compression.

The motor has been fired and I just drove it yesterday. The weather was awesome so I burned out about a half tank of gas on the country roads. It runs GOOD. :D

How far out are your idle mixture adjustment screws? It sounds to me like your mixture is rich at idle, not lean, if your plugs are black. Try setting that idle mixture at idle with a vacuum gauge and go from there. You may have to increase the idle speed to keep it running while you do this.

Yes it is rich. This is why I was asking about the idle eaze baseplate. It really seems to want more air at idle. If I open the throttle plates to allow enough air in, then I get into the transfer slots. What carb do you use Eric? Holley 950 HP? Demon? Maybe this is the "Proform" brand that I am fighting here.:(

I am currently using a 750 Speed Demon. I hope to get the Demon 850 with annular boosters soon.

I suspect that you have a size mis-match between the Idle Air Bleed and the Idle Feed Restrictor. They need to be sized correctly to work as a pair. They actually determine the A/F ratio of the idle mixture -- the idle screws actually control the amount of AF mixture the carb gets.

If you are in fact rich when on the idle circuit you can tell because the engine stays rich even when you almost close off the idle mixture screws. When this happens you would want to use a slightly larger idle air bleed or a slightly smaller IFR.

If you are lean when on the idle circuit you would go the opposite way with a larger IFR or a smaller idle air bleed. You would be opening the idle mixtuyre screws a LOT and still not getting enough fuel.

The ratio between the IFR and idle air bleed is more important than actual size of them IMO. If you pieced together a carb there is a good chance for a mismatch because the main body contains the low speed air bleed and the metering block contains the IFR.

Just my opinion.

So what is a normal IFR size and IAB size for a 4 corner idle holley on a carb that flows ~830 cfm? I have .031 IFR's and IAB's are .070.

Doc

On my wife's 383/425, we have the speed demon 750dp. The idle ease does almost nothing. At idle with non-ported spark, there was not enough idle "window" showing according to the pamphlet. (the slot should appear square)
I switched to ported spark and had to increase the idle speed screw to get the idle speed back up, this put the throttle blades in perfect position, the car idles better now too. Maybe not the perfect setup, but it's working good right now.

Doc, that's a good question. I dunno. I would suggest you try an idle air bleed that is a couple thou larger than the ones that are in their now and see if there is any improvement.

Again, how far out are your idle mixture screws?

Right now they are out 1 turn each. I havent had a chance to put a vacuum gauge on the car today but I tuned it this way initially. Will try again when the weather improves.

Doc

Try bringing the idle mix screws in some. I run them on my Speed Demon at 3/4 a turn out all four corners.

i was running into the same problem Doc, one 2 minute call to Patrick at Prosystems and its fixed:p maybe a little more tweaking but not much at all.

Any ways, i went up .010 on the Primary Idol air bleeds, left the secondays the same, lowered the floats just a touch and biased the idol to the secondaries, closing the primaries a little. This helped my Cruise mixture as well.

My plugs were always rich while driving around town till i did this and now they are looking good. Not near as much exaust smell at idol anymore, Cant belive how sensitive those IAB are. I think i'm gonna try going up about .002 on the secondaires, maybe not.

Just a comment. I need a couple of replacement parts for my Demon. Closest dealer is over 100 miles. Car is down till I get parts. Holley parts are everywhere and easy to get. I emailed the Demon tech line regarding this with no reply. If they want to be successful seems to me they need to get some parts out in the market place. I was totally satisfied till this happened.

You should have called, not emailed. E-mail is not a formal method of communication and phone calls are always highest on the priority list. Most tech guys know that it can be almost impossible to answer every single email question, especially since you can answer a question in 5 minutes on the phone to where it takes 20 minutes typing it out.

Give 'em another chance, and call instead!

I don't understand what Demon oarts you need? The Demon is made so the Holley parts all fit. Except of courser for the major components.

I agree -- call 'em

If anybody knows the sizes of the IFR and low speed IAB for an 830 holley DP with 4 cornr idle feel free to chime in. My current sizes are listed above.
Thanks,

Doc

P.S.- Eric, Do you think this new motor will turn a better time than the last one based on what you have felt so far? Also, did you install your cam straight up? Mine is a billet custom without any advance ground into it.

Just a note, but idle air bleeds tend to influence the upper end of the idle range, so, low cruse speeds where you are not getting fuel out of the main venturi's will be affected by the idle air the most.

I just thought of another factor that may be affecting my situation. I was very limited in sparkplug choices due to header clearance. I ended up using Accel 0416s header plugs. If anyony knows of any other brand of shorty plugs I would like to switch these out and see if it makes a difference. My problem is not that I cant get the car to idle, but the plugs keep fouling. Maybe this plug isnt hot enough.... How precise of a heat range can they be if they cross reference to multiple heat ranges by other plug manufacturers?