Intake and carb choice. Holley or Edelbrock. Stall convertor

[piecesparts]

If you were to spend time running the 750 CFM carb on the street for daily driving, you will probably find that the acceleration to be a little sluggish. That is UNLESS, you are running the RPMs up and then launching the truck. The reason I say this, lends to the weight of the truck compared to something like a Camaro of the same era. The 750 will perform really well on a lighter vehicle and give you a great driving ability in traffic, but on a truck, the 4000 lbs in your truck will tend to load up your carb and make it run different than on a car. ALso, while you are loading up the engine, you are plating out material from the gasoline on your intake valves and making them less efficient.

If you discussed this with any of the carb manufacturers, they would tell you that on a heavier vehicle, the smaller CFM ratings give a faster air charge to the cylinders and thus give you a better low-end torque. Holley/ Edelbrock/Carter/Demon---all of them will talk the same in this area.

Now if it is your plan to run the truck on a track at high speeds, then you could justify the use of the 750, but daily driving, the 650 is a better size choice. I am running a 650 on my 84 GMC SWB/383 stroker/comp roller cam/700R4 tranny/3.73 gears truck and it works fine on the street. It even gives me a decent 15 MPG gas mileage for a heavy truck that when I travel is loaded up in the bed. I had a 750 on it for awhile and I have experienced the lazy/loaded up performance that can come from a bad combination. The Quadrajet design is the best (small primary bores and larger secondary bores) is the best combination of them all. However, the choice is yours. The only real noticeable difference between the 750 and the 650, other than the street driving capability is the top end on your acceleration. The 750 will let you rev the engine higher, where the 650 will limit the acceleration by the amount of air flow. I can tell you that I have seen the point on my speedo, where there is no more numbers and the guy next to me said his speedo was above 125 MPH. So the 650 is good for that much effort. I call that the OH WOW section.

[slomotion]

I have run Holley's and Edelbrocks. I've had good results from both depending on the application, but all things being equal, I prefer the Edelbrock for a couple of reasons; You can change jetting without removing the carb, ( this isn't a huge consideration unless you're doing street/strip duty on a small budget and change them every week end). The clincher for me is there are no gaskets below the fuel level in the bowls.
(My apologies to Gary, and Prostreet!)

[GASoline71]

No sweat yo!

However you most certainly can change Holley jets with the carb on the engine. Do it all the time at the drag strip. My rig isn't a dedicated drag rig either.

Gary

[a_barth]

I don't think its that he couldn't change the jets while on the truck I just don't think he likes the inevitable fuel spill when the bowls are removed.

X's2 on the gaskets below the fuel bowls slomotion

[slomotion]

Originally Posted by a_barth

I don't think its that he couldn't change the jets while on the truck I just don't think he likes the inevitable fuel spill when the bowls are removed.

That's the biggest thing, then pretty much feeling your way around making sure the rear bowl is centered up while reaching across what seems like a long ways with the hood hinges, and hood in the way.

[prostreetC-10]

Originally Posted by piecesparts

The 750 will let you rev the engine higher, where the 650 will limit the acceleration by the amount of air flow.

Only to the extent of the valve train which will give out before the extra cfm is needed in many to most street builds.

As far as the "gaskets below the fuel line". Are there people out there trying to put Holleys together with their eye closed? Do I just get lucky about 300 times a year and don't have fuel bowl leaks? Are there Holley gaskets that I don't know about that are made from recycled panty hose? Bottom line is that when you REALLY want to go fast, you will need to say goodbye to the Eddy. How many Holley based carbs do you see on the motor shot on Pass Time??? 99% unless FI. The Eddys get you TO THE TRACK and the Holleys get you DOWN THE TRACK!!!

Come on Gar......let's suit up!!!! lol

[a_barth]

I'm not opposed to holleys and yes for true performance they are the best design but every carb has its place. I have been happy with edelbrocks and have had good luck with q-jets especially in the offroad world. Traditionally afb's and q-jets have worked better of hillclimbs etc. while the holleys design tends to allow them to flood easier on an incline. I've got a 750 holley on the shelf for a future street project though and am considering it for my 400 in my C30.
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[Jkeith]

Last bit of info. The heads are standard 350 heads. And also I will be running long tube headers
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[prostreetC-10]

Originally Posted by a_barth

Traditionally afb's and q-jets have worked better of hillclimbs etc.
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Holleys suck offroad unless you have the truck avenger. They are one of the best offroad carbs there is. Spring loaded needle and seats control the bounce of the floats and the unique primary annular booster with it's metering can tackle super steep pitches.



JKeith.....350 "stock" heads could be 2.02 fuelie if an LT-1 but not likely. if you have an average mid 70's + motor, those heads are probably small valved and restricted. Be careful with cam and carb choice. Like my wife says "keep it small honey"!!

[a_barth]

Casting numbers would help on the heads.

Originally Posted by prostreetC-10

Like my wife says "keep it small honey"!!

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