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Discussion Starter · #1 ·
Ok, help me understand this a little better. I've got a 302/350 hp engine from the Engine Factory with the standard 650 thunder series Edelbrock Carb. If I'm reading the Holley specs right, I should be using mechanical secondaries because of my car's low weight combined with 3.73 rear end and low first gear gearing. The Ed carb on the engine has vacuum secondaries. It wants to die on sudden stops and hard cornering. Have checked the float levels and all is fine. Timing right on 15 initial, 36 total. It also pauses/sputters momentarily on flooring the throttle in first gear. I want to smooth this thing out and am not opposed to chucking the Ed and getting a Holley 670 Avenger or any other carb to eliminate the stumbling. Will mechanical secondaries solve the sputtering issue? Or should I just keep tinkering with this carb? Would prefer to take one out of the box and not have to tear it apart and tune every circuit. Or am I missing something on the Ed carb?
 

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BLUBLUR
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If you pay yourself a mechanic's wage for the time you will spend troubleshooting and setting up your Edel carb for performance to match your performance engine, you will earn more than enough for a Holley DP or Demon, either one will require minimal set up and seat of the pants difference will be priceless.
Some had good success wiht the street avenger, the key word however is "Street". I had the Holley street avenger 670 on my FMS 302 it just wasn't right. Street driving was fine and made good MPG. But performance and Dyno data don't lie. I replaced it with a Speed Demon 650 with mech secondaries, out of the box, got 26 more TQ and 15 more HP and the performance difference is night and day. Just my personal experience.
 

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650 DP Holley looks great, easy to operate and set up, sure wakes up the 302. Good luck. I am sure enjoying mine. Face hurts from smiling! Bud
 

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Discussion Starter · #5 ·
Thanks Lex. I followed that thread but it got too complicated for me when he started showing his A/F graphs. I just want to be able to bolt it on, adjust the idle mixtures a bit and drive off. Preferably at WOT!
 

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I've done several different carbs ie>Edl,Holley, Vac sec vs mech and on my Cobra the best running is what I have now. A 650 Double Pumper. This is on a bone stock engine and it flat kicks the pants off everything I tried.
 

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BLUBLUR
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yup yup a Double Pumper baby! Holley or Demon.
 

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Discussion Starter · #8 ·
What about the choke on a DP. Are you guys using manual chokes? Dp only comes with a manual choke, right?
 

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They come manual but you can buy an electric conversion for about 40.00.
 

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sorry if i've just hi-jack'ed this thread...

Which exact holley 650 is recommended? there seems to be a few different Holley models that are 650 DP with mech secondaries.

i'm hoping someone can post the model/part number.
 

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Discussion Starter · #11 ·
If I go with the Holley DP 650, is it a simple swap or am I looking at replacing the manifold as well?
 

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Bolt on swap. Edl & Holley are the same base pattern.
 

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SCracer, I run a model 4777
 

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Discussion Starter · #14 ·
Do any of you guys run chokeless? I live in So. Cal by the beach where it never gets very cold. Have no problem using my foot to moderate the idle for a few minutes.
 

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BLUBLUR
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I don't have a choke on my Speed Demon 650. Just gotta pump the gas pedal a couple of times to fire up when cold, hold the RPM for a minute and drive off. It may stall a time or two until warmed up. I live near the beach. I love this carb and I will be getting another one with the blue coated bowls so it will be going on sale soon along with the Holley 670 street avenger. Anyone interested, lemme know.
 

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I'm chokeless
 

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Shade Tree Mechanic
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jhv48,
There's a thread I started about 2-3 weeks ago with a bunch of good info on stumbling carb, also an even better link to another post that tells exactly how to tune these things. I also have an Edelbrock and finally got it dialed in with zero stumbling. It's an 1806 Thunder AVS. I'm running mech secondaries (MSD) This is a good carb but the BG DP will make more HP. I went down to 8% lean and tweaked the secondaries to get it to quit stumbling. In doing so I'm almost sure I cut a few horses out, but I don't really care, since this thing's got so much power and torque. I also used the silver springs that came with my metering rod kit. I did not re-jet though. My issue was stumbling and horrible mileage. If my mileage doesn't improve dramatically I'm getting my $ back on the Edel and going with a Holley 4150 or BG. I never built this car thinking of mileage but as long as my mileage sucks I may as well have a decent carb. Just search on my handle and you'll see the post.
 

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Shade Tree Mechanic
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My first double post :rolleyes:

[ October 10, 2007, 10:40 PM: Message edited by: Scalded Dog ]
 

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Discussion Starter · #19 ·
I'm going to try loosening the spring on the secondaries one more time. If that doesn't help, then it's a Holley DP.
 

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Discussion Starter · #20 ·
Scalded Dog, how did you switch the Thunder Series to Mechanical Secondaries? Mine has vacuum secondaries.
 
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