Anybody use a Holley 750 street HP on a SBC?

[Mrturner1]

Truck is a 1970 C10 LWB, 10-1 355 with RHS 170cc heads and comp 280H cam (.480"/.480" and 230 @ .050", Edelbrock performer RPM intake and Edelbrock 650avs carb currently.

I over tightened my current carb and cracked right where the bolt goes through the hole, hangin on somehow, still runs but will need to be welded once I remove it as I'm sure that corner will fall right off, and there's possibly a vacuum leak now.

I don't think my current setup really NEEDS a 750 street HP, but I'm building a pretty roudy 383 right now that will replace the old 355 and I don't want to buy two carbs. I like the 4 corner idle adjustment, and the Dominator bowl. Will this run ok on my current setup for a year or so until I am ready for the 383 to go in?

Another side note, it's more than likely getting boost referenced for the 383 because I really really really want to try a blower or turbo

Truck is driven purely for fun, and will go to the drag strip when it gets to a point where the brakes and suspension are safe enough to go 100+ mph

[68Gold/white]

It would be best to have a lot of gear, 3.73-4.10 for best drive-ability, might need a 50cc acc pump in front...yes front...

[Mrturner1]

Originally Posted by 68Gold/white

It would be best to have a lot of gear, 3.73-4.10 for best drive-ability, might need a 50cc acc pump in front...yes front...

It's a 3.73 mini spool. I'm not fluent with carbs yet, what kind of ac pump do they come with? And are there front and rear acc pumps?

[68Stepbed]

NO!!! Get a 650 QuickFuel. My buddy has a rowdy 650hp(dyno proven) 383 that has a 650 QF carb on it. 750 is always overkill on a small block.

[summitflier]

It's what I run on my 383. I think for a stock 350 it might be a little too much.
But a 600 wasn't keeping up with mine. I'd rather have a little too much
than not enough.

[cypressbog]

I also hear others say a 750 is too much for a small block, even a 400 punched out to a 406 (I ran a 650 on my IMCA stock car with a 406), but I'm sure it can be jetted down to work.

[burnin oil]

All depends on the cam and heads. I run a 830dp from quick fuel on my 400. With the roundy round cam and good heads she will drink it all. When I dropped the cam back to a 268 solid that was a different story. Another part of the equation is the intake manifold. Dual planes will let you run a larger carb than a single plane. Another option is to buy the carb based on the throttle blade size then switch the mainbody. A couple manufacturers sell the main casting for a little over $100. The only down side is the choke tower is lost if you need the choke.

[Mrturner1]

I have also looked at the Holley Ultra Street Avenger 670. Looks like a nice peice and definetly a better compromise for both engines that will use it.

As long as I don't LOOSE power with the Holley Street HP 750 than I think I'd rather get that, because the 383 will surely like that better than the street avenger 670

[74Corvette]

The 750 is probably too big for your 355 SB especially if you go with the mechanical secondary variant of the street HP. You probably can get it to run OK on the 355 with jet modifications at mid-high rpm, but most likely the problem will be lower rpm drivability. With the smaller motor at lower rpm you won’t get a good primary venturi signal and will go lean when you open the throttle. To compensate for this you will have to try different accelerator pump nozzles and maybe cams. You might even need to go to a 50cc pump on the primary side. If this is a truck that you cruise around with but take to track occasionally I would also recommend going with a vacuum secondary carb and get the secondary spring kit. I have always had a lot more success with a vacuum secondary carb setup that can be street able and still perform at the track over the mechanical type.

[davepl]

In 1969 on the base 350 you had two options - 2bbl or 4bbl.

With the 2bbl, it made 250hp.
With the 4bbl, it made 255hp.

And that's a 750cfm Q-jet. The 2bbl maxes out around 265hp whereas the Q-het is good up until about 400 maybe.

As you can see from the factory example, once you have "enough" carb, "more" isn't better. I actually had that motor and stuck a 44bl on it and saw no improvement, which is how I know (I could have read the specs, but I was 17).

If you want a giant carb, by all means, put a giant carb on it. You just have no NEED for a giant carb.

[KY_GMC]

Why don't you find a used Quadrajet, call Cliff Ruggles at Cliffs High Performance and give him your engine and carb specs. He will sell you a rebuild kit and the proper jets for your current application. Buy his rebuild book also, it will be very helpful understanding and rebuilding the carb. Rebuild the carb and fine tune it to your current engine. Then, when you get to that 383 monster you want to build, call him back and get the carb re-jetted for your new application.

When I build my 383 (it is milder than what you are planning), I gave him my engine build specs and he supplied me with a good rebuild kit and up sized the jets. After some fine tuning of the carb and engine, this engine screams at WOT and is a pleasure to putter around town.

[AnotherWs6]

Engine RPM and Cubic Inches are the main two things to consider, not just the cubes. Volumetric efficiency is also important but much more difficult to measure.

A 650 will run well and feed a l lot of cubes if it's revving to 5,500 rpm. a 750 on 6,500rpm 383, that's probably about right but still not necessary. On a 5,500 350 its way too much.

[Grumpy old man]

Buy a Camaro , Chevelle , vett, Malibu and build your race engine for it , building one for a long bed truck is well .......