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Edlebrock 750 #1407, junk or not junk?


Guest zfan

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I put a 750 inplace of my old carter 625 when I changed to a rpm airgap manifold, it used to have a performer manifold on it. The problem is it will not get out of its own way so to speak. Have not put a vacuum gauge to it yet. Secondaries looked to not be opening when hitting pedal hard but Edlebrock tech said under no load it will not open up got to drive it to get it to open. Thinking about replacing step up springs. Checked spark plugs and they are not lean or rich, look good to me! Any brite ideas, Im about ready to deep six this piece of s__t!!! Should of listened to my friend and stayed away from Edlebrock carbs.

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I had a problem with this same carb, but my problem was with the idle circuit. It would dump globs of fuel instead of a mist. I baught their tunning kit and changed jets and things, but it didn't help. I ended up buying a Carter.

An airgap manifold will cool the charge, so you may have to change your jetting. Check your air/fuel mix with a vacuum first. I think you do have to be under load for vacuum secondaries to work.

 

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http://members.tripod.com/~SnowSurfer/mikekz1.html

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The Holy war has begun, to Holley or Edlebrock!!! rolleyes.gif

 

Iim going to second what Mike said and believe that the idle circuits are dumping in excess fuel. I don't believe it would be a problem with the secondaries. If it's dogging off the line, it's more than likely getting choked up with more fuel than it needs. An engine will run a lot better with less gas, than with more. Besides, an engine doesn't really need the secondaries opened, until it's well into it's own power range.

 

Therefore, "lugging" carbs are typically a result of over richness. But then, you did say the plugs looked fine. I don't know? confused.gif The only other thing I can think of is that, maybe, your carb linkage has slipped and the pedal is no longer fully opening the carb. This happens to me all the time (nobody makes a good holley braket with a TV cable attachment frown.gif ).

 

Once you get everything figured out, let us know how that air gap works out. It sound good in theory, just haven't heard any street stories yet to back up it's claims.

 

-Andy

 

------------------

"But I don't sit idly by,

I'm planning a big surprise."

 

Andrew's Land of Z and Honey

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Guest Tom Scala

About 1 year after Edelbrock released their line of carbs Summit Racing had a sale on "factory rebuilt" Edelbrock carbs. There was a display on the Summit showroom floor stacked 7ft. high with these rebuilds. Why would a significant amount of 1 year old carbs need "rebuilt"? Hmmmm

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Are you running an AOD trans or Standard(?); if AOD, could the TV cable be misadjusted & effecting your shift on a rolling WOT?

 

I'm not familiar w/the RPM Cam's profile; what is the Lift/Duration & Lobe Separation Angle? What Pistons are you running w/the RPM set up? Sounds like the new setup at low rpm's isnt comparable to your previous set up! Dont get frustrated...even tho it is frustrating/sounds like tuning issues, didnt the carb come w/instructions on tuning? Their tech line has "NOTHING" to suggest-what good are they if they cant help you thru this? Sounds like a huge let down in Quality Control if their "Tech-Line" cant help!

 

A 7' floor display of 1year old rebuilt carbs is highly suspect(?).

 

Just throwing this out there; you mentioned the plugs look fine. Are you running a "Hot" ignition(?); if your ignition is hot-could the hot spark actually be keeping your plugs clean-even tho you're actually running too rich? A bogging issue sounds like too much fuel!

 

If it were a Holley-I'ld also suggest changing the jets/possibly the Vac.Sec.Spring! If the Edlebrock Carb/Pkg didnt come w/tuning instructions...have their tech line send you their "Flow-Chart" for diagnosing your carb...or suggest to their "Tech-Line" you're gonna be forced to dump their carb & go w/one of their competitors!!! I know Edelbrock is a customer oriented company...they'ld have to be after all these years/remind them that you have a lot of "Hot-Rod" friends that you have confided in.....including @ 670 of us HybridZ bro's who have read & processed your problems into our Memory Banks & as a result (If Your Problem Isnt Solved) WE WILL NOT BUY NOR CONSIDER BUYING AN EDELBROCK CARB!" And remind them that we have friends that we will talk to; and so on; and so on/and so on!

 

You get the idea/The Consumer does have rights! You payed your money/now where are the results they promissed you?

 

Kevin,

(Yes,Still an Inliner)

 

 

 

[This message has been edited by Kevin Shasteen (edited April 05, 2001).]

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Off the line it is just ok, but when your rolling and you get on it it just seems to behave nothing to offer. Ive got the fuel pressure set to 5.5 as they recommend. Running holley blue electric pump with regulator and 3/8" return. Have not touched jets or step up springs. Could be vacuum but Ive even installed a crane vacuum canister as I am running the rpm cam and matching heads. My old v8 cast heads with performer manifold, carter 625 and stout cam would stomp the s__t out of this puppy. Sometimes I think alot of mods can be a waste of money. Mike

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  • 2 weeks later...

quote:

Originally posted by zfan:

I put a 750 inplace of my old carter 625 when I changed to a rpm airgap manifold, it used to have a performer manifold on it. The problem is it will not get out of its own way so to speak. .

 

 

ZFAN, we need more info and you need to do some more investigating. I'll address some of your q's and others points.

-idle circuit is fully independent, if you can stumple your idle by turning each idle screw in separately they are responsive and you do not have an 'numb' idle condition/set idle appropriately and it will not affect any other circuit at all

-what is your vaccuum reading and cam being used?

-you won't activate your vaccuum secondaries sitting still.....needs airflow and vaccuum change that you wont' get blipping your throttle sitting still

-you can hear vaccuum secondaries when they open as well....did you notice this with your 625? do you hear it now?

-have you checked for vaccuum leaks?

-get a tuning kit for that carb, you can't discern these types of problems without making alterations

-if your on the throttle is 'sluggish' is your timing set perfectly? you mentioned a crane vac. cannister, they give some 20+ degrees unaltered and can really nix things...(36 total timing/14 initial is fine starting point)

-using edelbrock's great tuning chart and approach time your 2500-5500 WOT in 2nd for ie., then richen your WOT circuit (needle change)and retry, if worse or no better step back leaner than original and progress from their

-the springs only control your transition to WOT and back to cruise, not your true WOT so don't alter them unless it's only a transition your chasing

-the performer carb series is one of the easiest if not THE easiest to tune IMO (not saying they're the fastest/best in the world) and their guide is great/one can go a ways beyond their guide in needle/jet combos as well

-many step from a 650 (1406) to a 750 and can't get it quite as sharp so step back to their 650 setup, work fine on anything including high 400hp stroker's on the strip to street's, the 650 is not a limitation to anything but a v. wild motor

-their are some duds, my first had a numb idle screw, but that's a rather simple/easy defect IMO, my plugs have been consistent and its very easy for me to swap to my sniffer test state of tune as well

-I've chased WOT transition stumbles and found they were mostly timing related (14 at least initial), a little acc. pump related, and mildly those stepup springs you mentioned....the stepup springs can radically affect mpg so do alter them on an 'as needed' basis

-I agree fully that a lot of aftermarket parts $ is wasted, I bought the crane adj. vac. kit and it was nothing but trouble...JB weld and a $5 spring kit were a lot more effective for me

-I ran my V8 on an illtuned Qjet for 4 years and wish I'd boughten my 1406 initially.....free carb feeding my $$$$ efforts! something wrong their!

-no reason the RPM air gap isn't a fine manifold/RPM is proven/works great and Vic. Jr. works great so marrying the designs as they did cannot be a bad thing IMO, IMO more V8Z's should step straight to a Victor Jr, I finally did last spring and will never go back smile.gif

 

 

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Of all the things I've lost, I miss my mind the most.

 

[This message has been edited by Ross C (edited April 17, 2001).]

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Good news! Finally debugged carb problem. Guys at Compitition Machine of Plano looked over carb and symptoms. Results were as follows vacuum leak due to carb warpage and nice mist from passenger side venteries but gas just seeping in at high volume on drivers side primary venturies. Called shop that sold me carb six months before and they said bring it in no questions asked.

 

Replaced 750 and fired up with no problems!!

Changed step up springs to yellows from orange, little richer. Thanks for all imput guys. Mike

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I was secretly wanting you to blow out your carb for $20, which I would have gladly paid...until you said it was warped. Did they say why it warped or what caused this to happen?

 

David

 

[ April 23, 2001: Message edited by: DavyZ ]

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Davey, no they did not say what caused it but those carbs are aluminum. Who knows? Ross, Yes it appears car is running great, Knock on wood!! Buy the way the Guys at CMP who did the testing etc on my car say thats the first Edlebrock they have seen in a long time thats had problems. Usually pretty sturdy they say, not as finicky as Holley.

 

Mike icon_biggrin.gif

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I personally like Edelbrock stuff too; I've never used their carb's but have heard only good things about them; that's what stumped me when it was said that their Tech Line had nothing to suggest in the way of a solution.

 

Glad to hear the provlem was solved & they took care of you-that's what a customer oriented company is suppose to do, "Take the Customer out of the Middle!"

 

Kevin,

(Yea,Still an Inliner)

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