LD340 and Holley 750 on a 360

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Forrest

Forrest

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I just got a hold of an LD340 manifold and a Holley 750cfm Double Pumper with vacuum secondary. Will this do my '77 360 with stock crank, rods, and pistons, any good? I plan on doing some mild head work and a good valve job along with a new cam kit and timing chain. My concern is whether this intake and carb are too much for the mild build of this motor. I'm willing to do what it takes to increase the compression to at least 9:1 with my compression goal being 10:1.
Thanks,
Forrest
 
If you plan on doing all the work you mentioned, it should work ok. The manifold will work well even if you make some of the mods. Are you sure that 750 has vacuum secondaries or does it have mechanicals? Your motor probably has somewhere around 8.5:1 compression as is so you may want to consider that.
 
That LD340 will really wake up your 360, even in its stock configuration. I've been running on of those for 20+ years with an old Carter AFB 625 carb and it's a great combination for a mainly street drive car.
That 750 will be either a Douple Pumper or a vacuum secondary - not both. If you have a standard tranny with stiff rear gears, the DP will work well. If you're running an auto tranny and highway gears, the DP will be probably too much for your combo.
 
The 77 360 will have about 8:1 compression...but it will work fine. I'd probably run a 600 carb just because you won't really get any performance out of running a 750. Just make sure you don't over cam it.

I'm running a 77 360 with magnum heads, the edelbrock air gap intake, and a 600 holley...and the summit k6901 cam and she runs great. The magnum heads up the compression a bit though.
 
[That 750 will be either a Douple Pumper or a vacuum secondary - not both.

I was told it was a double pumper and something about the secondaries(?) and vacuum(?) Sorry, I don't know my carbs. I'll be using a 727 trans with an 8-3/4 rear with 3:55 gears, sure grip. I'm thinking 600 cfm's will be fine, based on what I have read on this site and the fact I want to keep the build mild.
Thanks Again,
Forrest
 
A double pumper will be mechanical secondaries and have a accelerator pump on each bowl. A vacuum secondary 4150 List 3310) will only have a accelerator pump on the front bowl but still have the dual feel (a line to each bowl.)
 
I would recommend a 600-650 carb for a basically stock 360. You will have to have quite a stout build up before you will be able to use the capacity of the 750 and you will give up throttle reponse down in the rpm range where you will be driving on the street. The intake is a good choice.

The two biggest mistakes people make when modifying their cars is too much cam and too much carb for the intended use.
 
If you can bump the compression up a few points that intake and carb(being it has vacuum secondaries) will perform very well on the street,i ran that same combo on a "stock" 340 years ago with great results...
 
I'm with Old Vart and DGC333 on the carb size. You can get a 750 to work well on top, but the smaller carb is a bit snappier.
 
rumblefish360 said:
I'm with Old Vart and DGC333 on the carb size. You can get a 750 to work well on top, but the smaller carb is a bit snappier.
Click to expand...
Thanks y'all for the responses. This build was originally going to be big, mean, and nasty but my mechanic/good friend talked me out of it so now I'm going with the more reserved street build...with some punch of course!
Thanks Again, Forrest
 
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