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Discussion Starter · #1 ·
I'm in the market for a new carb. What do you guys suggest?
I am running a 0.020" over 1986 302, D0OE 302 heads, 1.94/1.60, e-303 cam, Weiand Stealth intake, 9.1:1 compression SpeedPro hypereutectic pistons, SpeedPro moly file-fit rings, rebuilt stock rods & crank, Ignitor I & coil, hi-po header manifolds w/2 1/4" exhaust, AOD trans w/wide ratio gearing, TransGo shift kit, 3.25 rear diff gears, 215/70/14 tires. Has anyone built a similar set-up? What size & brand/model seems to work best? I have an old Carter 625 carb now, but it doesn't seem to hold a tune well. I've already checked for vacuum leaks & have repaired them(undertorqued intake manifold). When it's tuned up well, it pulls almost 13-14 inHg at 12-14 BTDC. About 30 deg total timing. Does that sound about right? I recently disconnected the vacuum advance & it seems to run a little better. When it is tuned, it runs great, nice & torquey on the street & pulls well on the highway. The tune seems to degrade within a week or so. Any other ideas?? I really appreciate any help. Thanks-Mike
BTW-do you think it would be worth puting a set on heads on this motor. Has to be 58cc. I'm thinking about the World Jr cast iron heads.Anyone run these?-Mike
 

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Look at a 500-600cfm carb. A Holley or Holley clone 600CFM vacuum secondary carb would work well and be streetable. Here are some to look at:

Demon 525 Road Demon
Holley Street Avenger 570CFM
Proform Street Series 600CFM vac sec (this is on the high side - both size and budget)

In the non-Holley style the Edelbrock Performer 600cfm would work.

This to keep in mind is the intended use of the engine. These are all performance street carbs and have a basic tune for a broad range of engines. You may need to make adjustments to make it work well for your engine combo.

The cfm selection is based on engine size and max rpm desired. A 302 at 6000rpm needs 525cfm. Some manufacturers fudge their numbers a bit. For example; Demon carbs tend to flow more than the rated CFM.

Your compression ratio may work better with some nice iron heads. Aluminum heads have a more efficient heat dissipation property that may cause the heads to run too cool and not have efficient combustion. World Products has 58cc iron head for SBF with a 180cc intake runner that would probably work well.

_________________
Patrick Brown

62 Falcon - 331 stroker - C4

<font size=-1>[ This Message was edited by: pbrown on 1/3/07 9:46am ]</font>
 

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Discussion Starter · #3 ·
I've always liked the Demon carbs, but have heard that they have alot of problems. Even Summit stopped carrying them due to massive returns. Have they fixed the problems? This is a street car, but I run it hard sometimes. These are all the exact carbs I've been looking at, but don't know which one to pick. The Holley street avenger looks real nic(570) as do the Road Demons (525 & 625). I don't plan on running it past 5,500rpms, and very seldom at that. It usually runs between 1,500 - 4,000. Thanks-Mike
 

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Demons have had a bad rap for 2 reasons: One was the fact that many people found all kinds of machining trash inside.

The other was that they are not tuned like a Holley and many people just didn't want to take the time to learn how to tune them.

As far as the heads go, if you're going to stick with iron take a look at some Thumper E7 heads. Price is decent and so is the flow.

http://thumperoforangepark.com/

I'm going to put some on my 5.0 in a few months.
 

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Discussion Starter · #6 ·
I just purchased the Holley Street Avenger w.elect choke. Hope it runs good. I'll have to get a tune kit too. Thanks for the help-Mike
 

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Avenger 570. What plugs, wires do you have and how much gap. This can make a big difference. Electronic systems like about .045-054" gap with good wires. Weak wires will hurt you fast.
 

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On 2007-01-02 19:43, mstngjoe wrote:
BTW, if you get a Demon let me know. I've got some very good tuning files on them.
I dig Demon Carbs. They kick ass. I built 4 motors and they all run Demon Carbs. I started with Edelbrock then Holley and on to Demon. They are worth the money and time to tune. Can you send me some of the literature you have on tuning Demon Carbs? I am always up for new tricks and tips.

I'll send a PM with my email address.

Thanks in advance...
 

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My 575 Annular Demmon is the best carb I have ever owned. I currently own and have tried a 650 and 750 Doble pumper, and a 750 Edlebrock all on the same engine. Then went to a 575 Anular Mighty Demon, and it is by far the best carb ever.

My spark plugs are like brand new clean, (except the normal light brown fuzz)best idle ever ( not even using the ez-edle) low end tourque is un-touched by the other carbs, and no more unburnt gas in the exhaust. My mileage went from 9 MPG to 17 MPG, and picked up a lot of speed... have not been to the track with this one yet, but no question it is a faster car now.

However, all the hype about machining trash is TRUE!!!! If you buy one, plan on taking the entire carb apart for de-burring all the alluminum out of it... it is everywhere, even the places you can not see. The base plate was miss-allighned to the main body, and jetted from the factory about 8 sizes too small front and rear.

Worse place was inside the idle mixture screw bosses.....and at the bottom of the squirter bosses.

In my opinion, Barry Grant would be very well if he shipped a free carb rebuild kit with each unit. I bought mine 5 months ago, complained about all the crap I found in it, and they sent me a free $30.00 value rebuild kit for it.

Another bennifit is larger fuel bowls, for more fuel reserve for a 1/4 mile run, just incase you fuel system can not deliver long enough to get down the track.
 

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PS, your timing sounds too low... 32 - 36 is where you should be.....(no vacuum can)

The most important timing is your 3000 RPM timing... so set that correctly, and do not worry about where your initial is.... Initial timing spec is for factory setups, with a fixed advance dizzy. Don't let the books or folks that recite the books fool you.

Your initial should be a little higher, near 18 - 20 ( no vacuum can) But you must be able to taylor your total advance. Many dizzys can not be adjusted lower then 14 degrees mechanical, and mine needed to be at 12- 13 degrees.

My engine, tranni, 3000 stall converter, and gear setup is very close to yours, you would also do every well with a 1 inch 4 hole spacer, not an open hole spacer.

<font size=-1>[ This Message was edited by: Mikes66 on 1/3/07 7:16pm ]</font>
 

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holley street avenger 570 elec choke will give you a no problems run everyday carb. run a couple of street avengers they are pretty good for street everyday driving
 

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Discussion Starter · #12 ·
I'm running Taylor 8mm wires. Isn't that gap a little wide for the Ignitor setup?.. I'll try bumping up the timing too. Should i get a set of advance springs & if so, how would I adjust it correctly for my application? Should I be using the vacuum advance? I did have a phenolic 4-hole 1" spacer at one time, but removed it in my search for a vacuum leak as a potential source, just never reinstalled it. Forgot to mention I also have a B&M torkmaster street converter. 2,000rpm stall. I'm running just stock plugs. Should I be using something else? Thanks for all you help-Mike
 

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Mike, For a car as lite as yours.... "(if you do have a 65 Fairlane???) You have a light car and would do much better with a converter near the 2800 - 3500 stall range.

Vacuum advance is great for increasing your gas milage and that is all it will do... maybe smooth out your part throttle cruise, highway speed a little bit too.... but it should be the last thing you should worry about. Get everything else working first, then when all is great, then install your vacuum can line. Keep it blocked off for now.

If your going with aftermarket heads, the head MFG will tell you what plug works best. Your heads 1.94 / 1.60 iron are great heads, and with a little love (grinding and shaping) they will work very well for you. Not sure what plugs are best. Factory specs are useless, cause the gas is much different then it used to be.

Your dizzy springs... if you have stiff springs in their now, you would also do better with lighter springs. But that is also considered fine tuning, and a matter for later. My timing is a very fast curve. 20 degrees initial timing on mine @ 800 RRM's and 34 degrees at 2400 RPM's. Stock you probably don't get full advance till 3000 rpms... that is a bit too slow for a light car.

Yes, .045 and higher is going to be too much gap for you. .035 is a great place to start. .040 max. Use a wire gauge to set your gap. Usually the gap from the plug factory is correct, so you should just verify they are all the same.

I am not sure what Taylor wires are, but as long as they are surpessor core, you will be fine. Never run solid core wires.
 

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Discussion Starter · #14 ·
I do have a 65 Fairlane S/C 4spd car, but the one I'm working on right now is the '64 Fairlane S/C. Weight should be around the same, 3200 lbs or so. I have Taylor Pro series solid core 8mm wires installed. Why should I not use solid core? I don't have any radio interference problems or any sensitive equipment on board.-Mike
 

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Solid core wires put a lot of stress on all of the high voltage components of a system. The cap, rotor, coil plugs and wires too. A surpressor core wire limits the current flow in an electrical discharge. Once the gap of the plug has been breached by the high voltage, a solid core wire will then instantly discharge the entire contents of the coil in a single high current pulse, could be instantanious of thousands of amps.... this is how it wares down all the electrical properties of the high voltage system. Also your spark duration will be significantly shorter.

A resistive core wire, slows down this current discharge and actually makes a better spark because the coil can now create a longer duration spark of much lower current without burning out everything in the path.

Also with a very high current discharge of solid core wires, you create a lot of IONs inside the rotor cap, that fly around. Ionized air inside the cap can actually cause cross fire for other plugs that are not supposed to be firing, because the ionized air creates a current path to the other spark plugs.

It will only take one plug firing at the wrong instant to cause detonation in your engine. There is really not a good reason to use solid core wire, and many reasons to use use resistive core wire.

Hope this information is usefull to you. Best.... Mike
 

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Discussion Starter · #16 ·
Thanks for the info. I've always used solid core just because I figured the least resistance is best, & real metal wire has to be better than resistor core wire. I think I might order a new set soon. What type do you suggest? I have always used Taylor because they are not too expensive & have very well made boots that seal well & are easy to grab onto & remove. BTW, why are solid core wires even sold if it's so bad to use them?-Mike
 

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Gimics.... High voltage coils too... You don't need anything over 35,000 volts for a spark, but I bet every coil MFG says a higher voltage spark is better, just to sell a product.

When actually the higher the voltage the faster your wires dielectric will break down. I am sorry, but I don't have a recommedation for a set of wires. I buy off the shelf accell. Pretty looking wires is an option that is worth it.

Another gimic is metal sheilding (braiding) over the wires, or running the wires through metal tubes.... that actually hurts the spark a lot, because the meatle container over the wires causes a capacitve reactance, and takes a lot of energy away from the spark.
 
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