Hey everyone. I have a SY1 manifold which I am about to fit to a SBC (290HP) crate engine. I am going to run an Edelbrock 600cfm carburettor, HEI distributor. The trans is a TH400, differential gears are 2.92. What issues am I facing here with low idle performance? I have read a bit here and there and most articles say that it was designed for SBC 302 running above 3500 rpms and other say that there is not too much of a problem. If all else fails, I may have to sell it, but I am not keen on that due to the rareness of the manifod-mine is in excellent condition too. Is there anything I can do inside the plenum chamber to reduce the overall size of the cavity to increase direct fuel flow? Any help would be appreciated! Cheers
Are you really asking how to re-engineer something Smokey Yunick did? Personally, I wouldn't go sticking epoxy in anybody's manifold without a bunch of flowbench and dyno time that's not realistic for the average enthusiast. There's cheaper ways to find horsepower if you're paying by the hour for either of those services. Good luck either way
Don't know a fix but I do know that low end drive ability will be a problem, and if you are running an automatic behind it it will be even worse. That intake wasn't made to run on the street but they are cool and I would probably run it anyway. Thats me though. The 6 deuce set up on my 283 is not going to be easy to drive on the street either, but its way cooler than anything else so I will work with it. Good luck.
The biggest issue you will face with that intake is the lack of throttle response, due to the massive plenum. It was designed as a steady-state, high rpm manifold, with a limited rpm variance...in other words, for speedway-type circle track racing. At the time it worked reasonably well in so far as it improved volumetric efficiency over conventional designs of the day. About the best way to get one to work decently on the street is to use a very large accelerator pump shot...which an E-brock is not going to provide. You can certainly try it out....but the few that I've dealt with that actually WORKED WELL used a Holley DP, generally with the larger REO pumps. However, at the same time, you want to keep the carb fairly small...which may mean using the 4150 series 600 cfm, or similar, & converting it to the larger pumps. You will also need to play with the nozzle size & cam profile to see what's best...and use the larger volume nozzle screw as well. You may find that you don't go up in nozzle size a whole lot, even with the big pumps, in order to drag out the pump shot as long as possible. A couple of other things...you will need to play with the advance curve right along with the carb....those high rear end gears will be tough to deal with...a manual trans makes life with this intake a whole lot easier...they work better with a 383 or 406 than it will with that 350...and... due to the plenum volume...backfires are a problem. A big problem. I STRONGLY suggest that you: A) leave the hood off for a while during the sorting out; B) if the engine is brand new, and it sounds as if it is, use a different intake during the initial start up, cam break-in, & debugging. You'll be much happier when you do. Once everything seems reliable, THEN try it out.
Even Smokey had problems,with wet flow on those manifolds. Definately intended for full race motors. I love the design,but probably wouldn't run it on the street. They are very valuable to some,and not in production IIRC. Mild motor,heavy car,short gears,low rpm: you would most likely be happier with a dual plane intake.
Ive had one. Try it if you are going for the look. It will be lazier than some but will work no different than a tunnel ram on a small/stock motor which alot of people do anyway. It is problably the best single 4 intake ever for racing with a little work. If intrested pm me and I could tell you where to put the fuel dams.
I'm sure there are newer manifolds that may improve upon it, but the Edelbrock Torquer manifold was a such a strong street manifold design. You will find that a broad power range and good low to middle range torque will really make your car a driver.
i have one i ran on a 350 LT1 back almost 30 years ago, i ran it in a 57 chevy, M22 and 4.10 posi, the carb was an 850 double pumper, could of used larger accelerator pumps, i started a plate to run 2 carbs but never finished it, as for how it ran well you had to keep it revved up, but once it took the fuel it screamed, the solid lifters and a good set of springs helped, i could smoke those 14" 70 series polyglass tires in every gear. heres the intake today.
Those 2.92 gears are a killer for your planning. You need to lose those before doing much of anything with cam or carburetion. It would be expensive, but going to much lower gears and a transmission with an overdrive would do more for performance than anything you do to the engine, AND it would allow you to play with more radical engine mods.
.... stick a big cam in it and a big stahl or a manual, put some race heads on it and bump up the compression and go racing !
I had one a few years ago, it looked cool, had internal cool water lines running through it to cool down the air inside the manifold, but I talked to a few friends in the racing world and decided against using it for street use, good luck, let us know how it goes....
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