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New engine intake manifold questions- '66 coupe

920 views 6 replies 4 participants last post by  Gt350HR 
#1 ·
While I'm waiting for my new engine to arrive (302 long block) I've been doing a ton of research on the other parts I'll need to complete the installation. The old engine is going to be rebuilt and used on another project so I'm not going to use many of its parts to finish up the new one. The only things I am planning on using from the old set-up is the carburetor, the valve covers, the alternator and possibly the intake manifold.


My question has to do with the intake manifold. The old motor was hot- high lift, long duration cam, high compression pistons, flowed heads, etc. The new engine is going to be a mild performer- stock compression, mild 'rv' cam- set up for daily driving. The old set-up included an old Edelbrock Torker single plane intake manifold and everything I'm reading points toward that being a poor choice for a stock-ish daily driver type engine.
Can anyone here explain the differences between single- and dual-plane manifolds and what benefits each might offer? I've gotten solid advice here in the forum in the past, I'd like to know what y'all think.
 
#2 ·
Single plane intake manifolds have all 8 intake ports meeting in one central area called the plenum. Because of this the ports are usually short and "tuned" for higher rpm operation.
A dual plane manifold is divided into "two seperate" manifolds that each feed four cylinders , two on each side of the engine. Two accomplish this four ports are at a low level and the other four are at a higher level. This allows a bit more port length and less fuel and air "confusion" below the carburetor. Since carburetors work off of vacuum and the "plenum area is smaller on the dual plane intake , they normally produce more torque than a single plane. There are of course exceptions to this "basic" rule.
Small ports in a single plane help them produce torque but hurt horsepower. Big ports in a dual plane don't suffer quite as much , but do rob a little bottom end. If you are using a very small "rv" cam , "I" would run the factory cast iron intake unless you need the wow factor of an aluminum intake. Not that the torquer is a bad intake , I ran one of the first one Edelbrock made back in the early '70's . It was a race car , not a "driver".
Just My Personal Opinion , it's your car to enjoy . Mine has dual fours but is not a driver in that sense. LOL
Randy
 
#3 ·
A single plane is for high rpm use, at low rpms throttle response is sluggish due to the high volume under the carb and all the runners tied into it that slows the velocity of the air fuel mixture down. A dual plane will have a higher velocity flow through the runners, which will give better throttle response, for a daily driver. Using the stock intake is probably a good idea, as the 4 holes will seal the bottom of the carburetor, some carbs have cavities under them, and using a aftermarket intake with the 2 rectangular bores versus a 4-hole intake can result in vacuum leaks where you don't want them, in those cases a 4-hole adapter plate is needed. My 2 cts. Good luck.
 
#4 ·
Edelbrock had a "streetmaster" line of single plane intakes which had small ports and were not high rpm intakes. They were also not as good as their own dual plane intakes. The Torker is in between the streetmaster and Victor jr power and low end performance wise. Using an intake with a powerband out of your "normal operating range" is useless. "I" would still go with a dual plane.
Randy
 
#5 ·
Another reason to go with dual plane is that single plane ones are generally taller and may result in hood clearance issues. I put a Torker on my '66 289 years ago and had to install a hood scoop to clear the air cleaner. It ran fine most of the time, and even got better gas mileage than the old 2-barrel and stock manifold (as long as I kept my foot off the floor. . .). But keeping it running until it warmed up good on cold damp mornings was a challenge. The manual choke helped. But I've since switched to a dual plane, and plugged the hole in the hood.
 
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