Intake mod

66shelby

Well-known member
I am putting this here because I think it will apply to boosted and N/A applications.

A while back Linc posted a reply considering an external runner parrallel to the log. By turning the carb "sideways" and feeding the log with one venturi, and the ends with the external runner.

I have been thinking about this since I saw it, and think it could be an excellent approach to better distribution of mixture. I hope I'm not the only one who saw potential in this approach.

I am thinking about an adapter plate and using 1.25 round steel pipe for the runners. If I use a 1.5 tee under the "carb" and reduce to the 1.25 it should help to keep the velocity up.

I am not planning on blocking the log anywhere, and one question is where to dump the outlets. Before or between the outer cylinders? My application will most likely start as N/A but I plan to put a turbo on as soon as it is running well.

Does anyone have any opinions on this approach? If the under carb plenum can be fixed to the log I think brazing the outlets would be strong enough. What about flow characteristics? Would the log take priority by virtue of it's proximity to the runners?

After seeing some of the major mods being done, shaved tops, cut off logs, 3X1 adapters, etc, I think Linc's idea has some merit. And before someone screams NEW HEAD!! I just can't afford one right now. I know this mod can be done for around $40 and a little time. Linc, I'd sure like to know where your thought's went on this.
 
After contemplating the layout I think plumbing the external log directly between ports 1&2 and 5&6 would generate the best intake pulse. The log will have a total capacity of @ 25 cu in under the butterflies. Under boost I doubt it will make a difference, but a N/A motor would want a good draw from that pipe. My concern would be that the factory log would take priority and only be working one side of the two barrell. I have been advised that you should envision flow as the primary characteristic, but there is a difference between vacuum and pressure that may negate any benefits to the distribution.
 
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