Holley Question

[70c10stepside]

I am wondering rather not a 750 vacuum secondary will be to big for my motor. The 600 we had on it is just to small, and for the price there is no in between. I am on a strict high school budget.
Motor specs
355, cam is 508 lift 313 duration. Heads are 327 double hump heads 64cc. Flat top pistons, Should be close to 9:5 compression.. Supposed to have a close to stock crank and rods. It is bore .30 over. Edelbrock Torker II intake. Arp rockers, its a Hydralic setup. The motor will ping like crazy with a 600, if it isnt getting premium fuel. I''ve had the motor rev to a little over 6k, with out a sweat. We are running a turbo 400 with 4.11 rear gears. It has black jack heads, straight back to flowmasters. What i believe to be a classic 40 series.

Sounds ok? The 600 is going back tomorrow, and a 750 will probably go in its place...

I did post this in another forum on here, just you guys reply a lot quicker.. This is not a dd, just a weekend driver

[Fldawg]

600 should be fine on that motor, i'm running a 650 double pumper on my 383 and could use more, the pinging your having could be timing too advanced, back the timing off and see if that fixes your probelm, that engine should run good on regular unlead because it's not over 10:5 to 1 compression, a carb won't cause one to ping hope this has helped

[bubbaj]

I've got a 750 vaccum secondary on my stock 350 and its not to big
Posted via Mobile Device

[70c10stepside]

We've tuned the thing the best we could, holley said themselves its way to small. Bubbaj, hows it run?? And how stock?? Does it run rich?? Just, all that good stuff?

[69GWC]

You could also use a 670 Street avenger series Holley carb, might be a better fit. Sure the 750 would work though.
Posted via Mobile Device

[bubbaj]

It is completely stock I took the oe quadrabog off and used an adapter to bolt the 750 up it has 67 main jets a 31 squirter and 36 degrees of timing idle mixture screws are out 2 turns starts first touch everytime
Posted via Mobile Device

[70c10stepside]

Originally Posted by 69GWC

You could also use a 670 Street avenger series Holley carb, might be a better fit. Sure the 750 would work though.
Posted via Mobile Device

This is what I really want/need. Just, its about 100 dollars more

[bubbaj]

That motor is big enough to carry a 750 double pumper if you wanted to
Posted via Mobile Device

[70c10stepside]

Originally Posted by bubbaj

It is completely stock I took the oe quadrabog off and used an adapter to bolt the 750 up it has 67 main jets a 31 squirter and 36 degrees of timing idle mixture screws are out 2 turns starts first touch everytime
Posted via Mobile Device

Sweet. Not killing plugs, anything? Its probably what I'll be stuck going with.. The price is just, yeah.. Cheap lol And, I have to go Holley, because thats the only brand my dad will trust.. And, its a father/son thing. Its been his truck for many many years, and is my first

[70c10stepside]

Originally Posted by bubbaj

That motor is big enough to carry a 750 double pumper if you wanted to
Posted via Mobile Device

Money though.... lol Plus, its an auto.

[bubbaj]

I can't stand an edelbrick carburetor they are a pain to have you will be very happy you should go ahead and get one with an electric choke then you will be set
Posted via Mobile Device

[70c10stepside]

Thanks for the help, man!

[bubbaj]

All we use on customers cars are holley 600 for the mild motors and 750 for the noise makers we have bought about 15 in the last 6 months from holley and they are great out of the box you can almost adjust your idle rpm screw and let it be but the perfectionist I'm me will never do that of course
Posted via Mobile Device

[70c10stepside]

lol So you build motors?? So, what all do they normally need? Just floats adjusted and stuff?? I am still new with this.

[bubbaj]

The floats are pre set from holley all I normally adjust are the two idle mixture screws located on the front metering block and the idle rpm screw. The easiest way to adjust the idle mix screws are to run them in til they stop and back them out counting half turns of the screwdriver. I usually end up between 1 full round and 2 full rounds out be very gentle with the screws. If you happen to have a vaccum gauge hook it to a manifold vaccum source(one of the small ports on the carbs base plate works best and adjust your mix screws to get optimum vaccum and then adjust your rpm and your set.( clear as mud)
Posted via Mobile Device and yes we build motors and can do anything else needed on any make and model

[70c10stepside]

Ah, Gotcha. Normally, thats all that needs touched, correct? Thats all we ever do lol
Posted via Mobile Device

[70c10stepside]

Also,the motor you put these on. What is normally done to them? I know you said you have one on your stock 350, but curious lol this one is fairly built, imo. Im sure im for getting lots of specs, when it gets wound up, its mean. But, the 600 has gave me so much limitations. And what hp would you believe its at with the 750 vs 600?
Posted via Mobile Device

[bubbaj]

We run 750s on all types of motors. We have a 750 double pumper that has been converted to alcohol that is on the drag car it has a 383sbc in it making about 700 hp the center section is the same as the vaccum secondary version I just built a 355 street motor that has a 482/482 lift cam in it and put it in a 71 chevelle it makes about 350hp and my stock 70 c10 motor has a earth shattering 150 hp on a good day. We put 1 on a 53 f**d with a 454 bbc in it and that motor loves the carb you will love the drivability gains of the 750 over the 600
Posted via Mobile Device

[70c10stepside]

Wow!! Didn't realize the range. Ive always looked at things as the more cfm, the more motor. I guess is away to put it. And will this affect mpg?? Right now its at about 13 mpg on a really slow day lol
Posted via Mobile Device

[chopped68]

it also depends what 600 it is.there is a couple of different versions.the smog version is horrible for even a mild 350.the 1850s can be modified to work but will run out of air between 5500-6000 rpm.it sounds like you were leaning out with the 600 anyway.4.11 gears are going to affect your mileage more than the carburetor unless you are running a tall rear tire.

[70c10stepside]

we had the non adjustable float version. After 5k, it was just, done lol It'd rev higher, but power wise. Nope. And yeah lol 4.11 doesn't help much. Dont know to much about it, its a 12 bolt. Its been on it for I think dad said 24 or so years. Never had a problem. Never broke an axle, anything. In the truck, its had 305s to 454s. Dad use to build a motor every week or so. Until, I came along
Posted via Mobile Device

[70c10stepside]

Sir. I was asking opinions. Simply opinions. My father can tune a Chevy motor just fine, my motor should be able to easily produce6500 rpm. What the cam calls for. I just like asking on a spread board to pick up different info. My dads done this stuff for years, what he does for a living. Just, he dont always answer my question completely. So, I come here. And gather more info
Posted via Mobile Device

[70c10stepside]

Also, Holley said the 750 is fine. That the 600 is to small. Yes, on back roads at normal speeds I'd like ok mpg. Never underrated anyone ever. The manifold has been on the motor since before I was born, and dont have extra cash although I'd like to go with somethin different.. Your post was kinda, uncalled for . On both my threads. First member on here to do that lol
Posted via Mobile Device

[70c10stepside]

Also, look in my statistics, go to a recent thread called 'opinions'. I was fed different opinions there. I just like hearing what people have to say, I have respect for everyone on here lol
Posted via Mobile Device

[eldogg]

I love a tuned up 750 vac sec. I have built at least 50 in the last 10 years and they just flat work. 3310 is the most universal carb Holley every made. Works great on a mild- to hot small block and warmed up big block. I did one for my 355/700r4/3:73 el camino and it got just over 18mpg and went 13.20 @ 108. The idle circuit is a little rich for today's cam profiles but bolt it on and ride.
Posted via Mobile Device