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Discussion Starter #1
I had been planning to just buy an Edelbrock 750 because of the great street manners and tune-it-and-forget-it qualities, but now I'm leaning towards a Holley Street Avenger carb instead. I've read that it's a great carb for a street car and I can buy one almost as cheap as the Edelbrock. Here's the details on my motor:

383ci on 4-bolt block
stock cast crank
5.7" Scat I-beam rods w/ 7/16" capscrews
SRP forged flat top pistons
AFR 195 heads (#1036)
Comp XR282HR (ground on billet core w/ 111LSA)
Comp retro-roller lifters
Comp Pro-Magnum 1.5 roller rockers
Air Gap RPM intake
Will be mated to a TKO-600 5spd.
3.42 gears

With this combo, would I better off with the 670 Street Avenger or the 770 Street Avenger? Or should I stick with my original choice of an Edelbrock 1407 750cfm? If the Holley Street Avenger can be as streetable as the Edelbrock then I think I would rather have the Holley.

Please help!
 

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Actually, with your setup, I wouldn't go with anything less than a 750 double pumper. It sounds like it should be a pretty hot setup, You will give up some performance with the VS carb, even a properly setup one. Keep your foot out of it and you can still get decent milage, if that is a concern. I got over 18 MPG in my wagon running a 650DP on a long highway trip and that was at 65mph.
 

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JTW that combination sounds wicked.
Holley DP 100% is the best for what you want. The AFR heads want big draw at low lift, and the DP is the way to go.
I had a speed demon 750 on mine for 3 years, and finally after an agonizing 10 plus jet changes, finally fed up, changed to a Holley DP.
I bit the bullet and order a custom carb from Patrick James www.pro-system.com a 950 XE HP he custom made for my engine/trans/gear/manifold/cam etc. He gets into the nitty gritty. We bolted the thing on while on the rear wheel dyno. It cranked to fill the bowls, started, idled like it was always on. And once warm ran up to 6,600 RPM with the flatest cleanest A/F ratio that the dyno operator has ever seen. You want to talk 100% different motor, crisp, snappy throttle responce like I have never seen before.
Patrick makes the carb specific for your engine, like I had said, even down to the rear gear he wants to know the details.
The best bucks I have ever spent, other than the Tremec, and the Brodix heads.
I would call Mike Lewis at www.lewisracingengines.com Phone: 707-984-6103
FAX: 707-984-6103
and he will get the carb for you after Patrick compiles the spec, at a real deal price, not much more than a good stock DP.
Mike is a big dealer for him, and very good to deal with, the best.
I ended up talking direct to Patrick after the carb purchase, but he usually only will sell through his dealers. I called to thank him.
 

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Discussion Starter #6
Grandpa - That's a pretty convincing argument for the custom 750DP. I hadn't really considered a 750DP because I thought that would be too much carb on low-end and that it would be temperamental to drive on the street, but I suppose these generalizations about DP's are not true when you're talking about such a custom-spec'ed carb such as yours. This engine build has snowballed into a much more performance-oriented motor than I had originally planned; it started out as just refreshing my old stock-iron headed 383, so I hadn't given much thought to a real performance carb. Streetability is still my top priority, since that's all this car will see. This car is a weekend street cruiser complete with A/C so I wouldn't trade good street manners for an extra 15HP, but from what you described your car ran much smoother with the DP. I suppose the DP's get a bad rep a street carb since so few of them are properly tuned and sized for the application like yours.

BTW, I've spoken with Mike Lewis before and he was a really nice, helpful guy. He didn't know me from a hole in the ground but talked to me for at least a half-hour. It's a wonder he gets any work done with guys like me calling. :)

Considering that I'm approaching the end of my build budget at an alarming rate I knew I couldn't spend much on the carb at this point, so I actually gave in today and bought the Street Avenger 770. At $275 brand new it was hard to pass up. But I'm sure within a year I'll be looking for more power, so it's nice to know that a simple carb swap could change the engine so drastically.
 

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My 750DP has pretty decent street manners even on my little 307. Doesn't like the cold much though.

Kev
 

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novaboy009 said:
My 750DP has pretty decent street manners even on my little 307. Doesn't like the cold much though.

Kev

would that not be more a choke issue than a DP issue?(just wondering is all):)
 

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those new proform carbs are very nice..we run two of them on my friend's camaro and they work real well...just another option
 

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The 750 really drags the idle speed down compared to the 500 Eddy that was on it. The motor doesn't like the stock stall, little motor and big carb. It's a mismatch issue (getting ready for the PW350 and 3000 stall) more than anything else. It's just tough to get it to drop into gear and stay alive when it's freezing out.

It did pick up a tenth going to the DP. Just jetted it down a little bit and it runs real well in the high rpms. It's a little rich at idle (to keep it going) but good from off idle up.

Kev
 

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Discussion Starter #11
68SSGrandpa said:
JTW that combination sounds wicked. Holley DP 100% is the best for what you want...I bit the bullet and order a custom carb from Patrick James www.pro-system.com a 950 XE HP he custom made for my engine/trans/gear/manifold/cam etc. He gets into the nitty gritty.
Well Grandpa, what you said really got me thinking. I really liked the idea of a custom-prepped carb and I hated the idea of not getting the most out of this motor that's been pretty expensive to build. SO... I called and cancelled the Street Avenger 770 that I had already ordered, then called Patrick as you suggested and bought one of his carbs. He's building me an XC series HP double pumper, and said it'll probably end up being in the 760-780 REAL cfm range. I was able to order directly from him, which made the whole thing even easier. It should ship by next Tuesday.

Thanks everyone for your input, and to those who suggested I buy a 750 DP thanks for causing me to spend a whole lot of money! :eek: :D
 

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JTW
You made the right choice.
The carb Patrick built for me was built with street manners taken into consideration, with my Vintage Air II.
Also, the requirement called for me to pass our VERY strict AirCare smog rules here. Can you imagine passing smog with a 950HP DP, I do, and pass with flying colors. You, once a year run on a rear wheel dyno sniffer to get your insurance.
There are a couple of easy tweeks to help pass the sniffer, but the carb stays on for the test. My cam is a solid roller 244in 250ex at .050 gross lift .618 and .613, passes aircare??? I just pulled Patricks work order on my carb 78 primary jets and 88 secondary, draw or CFM 902.

In Aircare mode ready for the smog test, dual high flow cats and mufflers on we made 389HP and 422TQ at the wheels on a Dyno-jet.
Not bad for the smogger motor tune .
Non smog tune is a bit more fun to drive.:D
 
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