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Old 02-26-2009, 12:46 AM
GMCfive-0V6 GMCfive-0V6 is offline
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fabricating performance parts for a 305 GMC V6

first, i guess i should have a small introduction. i'm currently a college student studying to be an auto tech and welder (duel major) and working on a 1961 gmc with a 305 v6 engine. OK... now I've done some searching and haven't found any real definitive stuff on fabbing a sheet metal intake(mostly leave it to the pros...). now i know this engine is not going to have massive HP but i would like some performance gains and i would really like an upgrade form the one barrel holly carb that is on it now.

now from the little i have gathered the flanges seem to be the hardest parts to get a hold of, lucky me my school has a sweet machining course with a CNC mill as well as an excellent auto cad program, so i have had the flanges made (used the new intake gaskets as a template). i have also used the old intake manifold to make a jig. im going to be using mild steel and MIGing it:
1. because i have access to the welder
2. its easier
3. weight is not a factor
4. its not a bleeding edge, need to milk out another 5hp project
5. they don't make after market performance parts for a 305 V6
6. it looks wicked cool

that all being said how can i net the most gain from this, i am thinking about a cross flow design the only considerations i have are the total height with a carb and air cleaner and the width of the plenum since it has the plugs in the valley. i would like to be able to change them without pulling the intake.

now what considerations should i take in regards to the runner length?
can the be too long?
too short?
i will most likely be running a 2 or 4 barrel carb but nothing too radical, recommendations(low profile will probably be necessary)?
is there such a thing as to much flow?
i'm probably going have the manifold powder or ceramic coated once i have it finished, any preference or performance issues i should take into account?

im looking for a net of ~20hp but anything over stock will be awesome
also i want to eventually convert it over to EFI should i make considerations for the placement of the injector bungs?

i have looked at and they did give me some info but i was wondering if any one here had anything more. also i have used as basically my bible concerning this engine/truck combo

now i know this is rather jumbled but im just trying to see if i have overlooked or have completely missed something due to ignorance

thank you in advance
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