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  #16 (permalink)  
Old 12-27-2003, 10:42 AM
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This is a discussion I usually try to avoid, but since I saw some incorrect information towards the Holleys I thought I would give my $.02

Double Vision and lluciano are both correct. Holleys are SO tuneable that people get themselves in trouble. Once you know how to tune it or have someone tune it that knows holleys you should not have to touch it again. Edelbrock/Carter/Weber carbs are good for beginers, you bolt them on and tune the idle mixture screws and you're off and running (just not as good as you would be with a Holley).


There is a reason every fast N/A car at the track and on the street has a Holley on it. There is a reason companies made copies of holleys. If you are after performance you can't beat a Holley. If you just want to cruise around town then a Edelbrock/Carter/Weber will do fine. You are just leaving a little performance on the table.

I am not going to argue which carb is better I have run both styles and Holleys just plain out perform the Carter type carbs.

There are a lot of different types of Holleys so make sure you have the right one for your application.

If you don't know how o tune a Holley and aren't willing to learn then buy an Edelbrock/Carter/Weber. They are more user friendly, just less tune-able.

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  #17 (permalink)  
Old 12-27-2003, 11:44 AM
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I liked my predator carb a whole lot more than the holley 750 double pumper. the predators going back on as soon as the 400s ready to go in.
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Old 12-27-2003, 03:51 PM
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Most have you have said "learn to tune your carb", but everyone has failed to mention how he's supposed to learn how to do this? lol .. Does anyone have a website about this, or do Holley's come with a book on this ?
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Old 12-27-2003, 07:46 PM
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well i didnt get to go get the edlebrock today i spent the day messing with this holley.CHeck the acc,pump ,power vavle try a diffrent jet, adjusted the air fuel and know the thing still runs like junk, still got a hesitation to it and backfiring a little.It acts like it flooding in a way but i check the floats and there right according to holley, im at my wits end with this thing.


Any ideals
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  #20 (permalink)  
Old 12-27-2003, 08:34 PM
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Keep trying. You need to start with the recommended jet size. Then try the other things. If your float level is okay and your mixture is set with a vacuum gauge, the next thing to do is make sure you have instant pump shot. Turn the throttle shaft by hand. There should be gas coming out of the accelerator pump nozzles immediately. That should get you closer.

What is your vacuum at idle? What powervalve are you using? Maybe the powervalve you are using is blown. Are your spark plugs fouled?

If you want to own and drive a Hot Rod, you are going to need more patience and knowhow. Otherwise you might as well buy a grocery getter. An Edelbrock tunes using the same basic methods as a Holley, or Carter. If you aren't getting it with a Holley, going to an Edelbrock with out of the box tuning is not the answer. Don't be so quick to blame the carb. Once you do those things that I mentioned, if there is still a problem, you might want to check that your timing and distributor are adjusted correctly.
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Old 12-27-2003, 11:13 PM
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There are books out there on Holley carbs. " How to tune", "How to rebuild", etc..

lluciano is right, you can throw any carb on there that you want and until it is tuned properly you will not have the performance that the car is capapble of. I am willing to bet you can stick the Edelbrock on there and the car will run better out of the box than it will with the un-tuned Holley. That still doesn't prove the Holley is bad, it just proves that it wasn't tuned right. There are so many parts availabe for the Holleys I don't think one is ever beyond repair/tune.

If you have no desire to learn to tune (which takes patience, practice and time), then I suggest putting the Edelbrock on, out of the box just adjust the mixture screws (the two on the front) to get maximum vacuum (or highest idle speed, if you don't have a vacuum gauge). This will make your car drivable and will run decent.

You are the only one that knows your goals, If maximum performance doesn't matter or if you just want the car driveable then there is nothing wrong with swapping the carb.
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Old 12-27-2003, 11:46 PM
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I have read every thing i could find about tunning a holley and ive messed with it for a year and a half now.Ive been able to get it to run great for a while but then its back to working on it again.
This time it has fouled my plugs, i took some sand paper to them tonight and that got it running im going to get some new ones tommorow.The vaccum gauge i have showed 10 pounds in park and only around 2 and ahalf in gear.Ive got a 3.5 power vavle in it right now that was all auto zone had the other day.But your suspose to get on 2 points lower than you vaccum so what do ya do.Ive alwas heard not to plug it off so im kinda stumped on that one.Maybe my gauge is wrong.I adjusted the acc,pump today to.15 on the filler gauge thats where holley said to put it.I just dont know guys.I would really like to keep the holley because i do feel when one runs right they are the best but know i would settle for less power just to beable to get in my chevelle and drive it with out having to fittle with it.
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Old 12-28-2003, 01:39 AM
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Any aftermarket carb will need to be tuned to your specific vehicle, motor,trans and gearing for optimal performance,like the guys above said take the time to dial a holley in and you never will buy a carter/edel carb.Holleys are much more tuneable than the competition.
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  #24 (permalink)  
Old 12-28-2003, 12:32 PM
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If you only have 2" of vacuum and have a 3.5 power valve then the power valve is opening and loading up the engine. More importantly though, I think you should have more than 2" of vacuum unless you have a killer cam in there. I would suggest checking the timing. Can you let us know what you engine combo is. If you have a very aggressive cam, like 242@50 and up you can drill small holes in the butterflies to help with the idle. By the sounds of it, you may be idling on the main circuit as opposed to the idle circuit by having the idle set too high and uncovering the idle slots. If its a double pumper you can also adjust the secondary throttle blades open slightly to help with the idle. You can advance the timing which will bring the idle up and then back off the idle screw to set the idle. We really need to know what the set up is.

Steve
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Old 12-28-2003, 01:10 PM
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2" of vacuum is way too low. What size cam are you running?

That 3.5 powervalve is always open. There is your stumble.

Don't adjust the accelerator pump to .015" on the feeler gauge. Do what I said and verify instant pump shot. Instant pump shot is very important. That feeler gauge measurement isn't always accurate.
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Old 12-28-2003, 01:34 PM
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Ive run many of both,but hands down,a dialed in holley has my vote.Beware of cheezy rebuild parts,they'll turn your hair gray. You might consider a demon carb,but whatever you choose,you'll just be lucky if you bolt it on and its wright,holley carbs are crudely casted and Ive had to trash a couple because of porosity,but,they are a good design, thats why I now run demons. good luck.
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Old 12-28-2003, 06:02 PM
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Ok guys ive got it better today still got the hesitation though but not as bad.Maybe i need a bigger acc, pump.Maybe drill the holes in there cause the cam is large.Here is the run down on the engine.327 30 over, domed pistons,camle hump heads,roller rockes,preformer RPM intake,heads are ported and polished, hei
dist,and here are the cam specs, INTAKE EXHAUST
255 266
Lobe lift 3600 3560

Lobe sep, 106
This is a solid lifter and cam.Thats about all i know about it folks thats the way it was when i bought it.Im running a 700r4 and 373 gears.
So any ideals ,what size jets would you all start out with in the primary it has 72 in it right know?Hey i just want to think everyone who is taking the time to help me here
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  #28 (permalink)  
Old 12-28-2003, 06:05 PM
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Chevellenut, what size carb is it ? is it mech. or vac. secondary ? just curious
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Old 12-28-2003, 06:08 PM
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sorry i guess that would help,Its a 750 dual line vac secondary
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  #30 (permalink)  
Old 12-28-2003, 06:52 PM
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Do you know what the intial timing is set at, I'm still concerned about the low vacuum. That is a huge cam for a 327, almost too big. To me it sounds like a miss matched combo from the start. It wont make power till 4500-5000 rpm and will be tough to tune at low rpm's. I would set timing at 16-18 degrees initial, drill the holes in the butterflys (1/8"). You would probably want a 72-74 main jet, 34-36 shooter and start from there. What convertor are you running and what does the engine idle at?
Just some suggestions.

Steve
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