I have a '72 Camaro, TH350 & 3.08 gears. I have headers w/2-1/2" exhaust w/Magnaflow mufflers. I just got a 5.7 crate w/vortec heads. I want to put a cam in it that sounds good, leaning towards Comp cams XR276HR. I am also leaning towards the Edelbrock RPM intake with a Demon 750. I do plan at some point on putting in aluminum 1.5 rockers w/screw in studs, new valve springs (to accommodate the .500 lift cam), new gears around 3.40's & a new stall converter. Any suggestions/comments??? Thanks in advance

 

I think your set up is spot on with the set up you plan on doing. In the stock form you are making 330hp and 380tq with the crate vortec motor. If its the one in the GM book? Do you plan on doing the cam and head upgrade before you install the motor or run it as shipped for a while. Very interested in how you like and how it performs. I build a lot of these vortec and you sound like you did some home work with your combination.

 

Yes! The only thing I plan on doing later is the rear end gears. I have been reading a lot and was looking for someone to say ya that sounds right. Now let me throw one twist at you. Dual quads? I know they do have some problems and you might give up a little in performance but I'm not racing everyone down the street. Something I've always wanted that's all. If all I give up is a little power, I'd do it. Thanks & any comments?

 

They are not that hard to tune. But they will put a SMILE on your face and any one that sees it. Please do it and post pictures.

 

Yeah that's my opinion too

 

I'd probably go a bit lower on my gear ratio choice, or leave the 3.08 gears. Swwapping to something around 3.40 will probably end up with 3.31 or 3.36, which are the most commonly available ratios near 3.40, and you wont hardly notice a difference. I'd go to something around 3.55 or 3.73, and which depends on how much freeway driving you do. The 3.55 if you do more highway than city driving.
I love dual quads, and have them on two of my cars now. But be sure you get the right carbs! Many of these setups are offered as a package, and include the twin 450 Holley, with mechanical secondary carbs. DO NOT buy that setup! Mechanical secondary carbs are horrible on a dual carb setup that's for the street. Be sure to choose a pair of vacuum secondary carbs, as they will work better together, and secondaries wont open until engine wants the extra volume. I prefer Holley carbs, because I like the fact I can buy a quick change spring kit to adjust secondary opening, and tie the vacuum signals together to time them to open together. But my buddy has twin Edelbrock 500 cfm carbs, and they work excellent on his 350.

 

Thanks for the advice. Love the Austin! What size stall converter does your buddy use?

 

Since he doesn't have a big monster cam, he can handle a low stall converter of about 2000-2200. His car is a heavy '56 Chev, with 350 SBC. The dual carb setup wont determine the stall speed. It's more about what your cam will allow, and the weight of your car. Heavier cars and bigger cams need higher stall speeds. My Austin has a TH350, but is only about 2500 lbs., so even with a little larger cam in the SBC 355, it still does well with a 2500 stall.

 

Thanks. I think I'll be in that 2200 range & I've decided I'm going dual quads, why not you only live once

 

I agree! Anyone who has an urge to try dual carbs, and has the ability to tune them a little, should go for it. As much as I fought the twin 450's on my Austin gasser, I still stayed with it, because I wanted dual carbs. Had I known then that most of the issues I had were because of the mechanical secondaries, and lack of secondary accelerator pumps, I could have saved myself a ton of headaches.
The twin 600 Holley vacuum secondary carbs on my 464 BBC bolted on and just worked right out of the box. I didn't have to make any changes until I took it to the drags, and began to make passes with open headers. When I did plug checks I saw the engine was running very lean with open headers, and I had to make changes to nozzle size, and secondary springs, to richen the mixture up.
When I put the 350 in my buddy's '56 Chevy, and he bought the dual Edelbrock 500's, I warned him we might need to do a lot of tuning. But it fired right off, set the idle, and he's never touched them. They seem to work well on the street or the strip, and plugs look good on the street or strip. I hate to admit they work so well, as I've always been a Holley fan; but they sure do work well!