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sbf hi ram tunnel ram

12K views 9 replies 6 participants last post by  Johan Lokander 
#1 ·
hi im looking into building a ford 302 and my dads friend has a weiand hi ram tunnel ram intake but he said they run like *****, so i was wondering since the intake is big and open on the inside could i run a small cam to get good vacuum or would that not work with the open plane style intake? oh i would match it up with a set of junk yard GT-40p heads and and 30over bore and 450cfm holley carbs.
 
#2 ·
The problem with those things is they are designed for WOT drag racing. The huge plenum is there to isolate the runners from the carburetor. By providing a big volume for the individual runners to interact with, they perform similar to fuel injector tubes. Unfortunately for a street driven car, carburetors must interact with the runners to perform at their best. They can be run on the street but you pay performance penalties to do so. Cam isn't as important as carb size for these things. I recommend you run the smallest carb you can - Holley 390s? - especially since it sounds like you are building a fairly mild engine otherwise.
 
#6 ·
I have 2 390s on my Vette. It doesn't wake up until after 3000 RPMs. Most of my street driving is done between 1500 and 3000 so most of the time I don't use it to its fullest. But when I get on it and wind it out its a blast.
This is my DD so I will have to change it sooner or later.
 
#7 · (Edited)
It depends the rear gears you are using. Your 302 will not produce the low end torque you will need. You will need at list 370 or more gears in order for the tunnel ram to work. A pair of 390's will do the job. Make sure you have a balance vacuum line connected to the vacuum secondary. It will make the secondary open in uniform. You will have to buy vacuum secondary balance tops from holley in order to connect the line.

http://www.hotrodders.com/gallery/showphoto.php/photo/36900/IMG
 
#10 ·
Jake_Dragon said:
You can also get the 390s with mechanical secondaries so you don't have to worry about low vacuum and the carbs not performing.

I wonder how the tunnel ram would work with a couple of throttle body injectors. I guess thats a question for another thread.

I did that on my Chevy 355".Wanted a tunnel ram for the looks but woldent lose driveabilyty.Used a Weland hi ram whith 2xPredators as trottel bodys, welded and drilled the manifold for injektors and used a VEMS ems for both fuel and ignition.Worked well, but the Predators dident even work good as trottel boddys...Culdent gett the RPMs low enuf even whith the trottels kompletly closed, so i change them fore 2xRochesters...
 
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