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I'm building a stroked small block and am using the vintage Edelbrock TR1 tunnel ram set up pictured below. I just realized that there are no vacuum ports on it. I see that new tunnel rams have vacuum ports on them.
Is there any reason I can't drill and tap bungs into the plenum of this intake for vacuum ports? I'm using a Comp 282 Hydraulic roller cam and the carbs are 450 cfm if this info helps.
Can't see any reason why not. IF the casting is thick enough to support a threaded fitting. If not, you could TIG weld a bung in. I'd have to think about putting the port(s) in the bottom side of the plenum. Hide them. I'm like that.
Can't see any reason why not. IF the casting is thick enough to support a threaded fitting. If not, you could TIG weld a bung in. I'd have to think about putting the port(s) in the bottom side of the plenum. Hide them. I'm like that.
Great idea with coming off the bottom! I hadn't thought of that. I was going to come off the back for the brake booster. Coming off the bottom for the other accessories would really clean up the look.
I'm concerned that the amount of vacuum I'd get in such a large plenum wouldn't be enough for the brakes and headlights though.
I myself would not put the vacuum ports in the bottom. Keep the ports at a right angle to the incoming airflow. That air rushing past the port will help increase vacuum. If the port is in the bottom, the incoming air will be blasting right into your drilled port and may not give you any vacuum at all. Look at the vacuum ports in most any carb or intake. They are most always at a right angle to the airflow so that the incoming airflow is rushing past the port and not blowing directly into it.
i drilled and tapped more than one back in the day, id tap the back of the manifold toward the bottom . you can somewhat hide the hoses. if you did the bottom it is possible raw fuel could get in the port and cause a problem. glad to see someone using the old stuff. the better heads available today will help those old manifolds work better than people remember.
I myself would not put the vacuum ports in the bottom. Keep the ports at a right angle to the incoming airflow. That air rushing past the port will help increase vacuum. If the port is in the bottom, the incoming air will be blasting right into your drilled port and may not give you any vacuum at all. Look at the vacuum ports in most any carb or intake. They are most always at a right angle to the airflow so that the incoming airflow is rushing past the port and not blowing directly into it.
Thanks for the replies. One more question. According the Comp Cams dyno sheet, my cam will make the following vacuum on a 355 ci engine. 9" Hg @ 800 RPM & 11.5" Hg @ 1000 RPM w/ no load.
Will my engine being 389ci produce more vacuum and is this enough vacuum for the power brakes and headlights?
03-31-2015, 08:25 PM
Tunnel ram vacuum ports
