Re: 305E Intake mod.
 

The 2 barrel intake will require some welding when opened up, and I would highly recommend using a milling machine. Here is an album of one of those intakes opened up:

http://6066gmcclub.com/album.php?albumid=51

Re: 305E Intake mod.
 

So if I get my hands on a magnum manifold, which of you gurus can I send it to to open it up for me? Seems intimidating for a rookie like me.:helpsign::teehee:

Re: 305E Intake mod.
 

If you wanted to send it over here I'd have no problem doing one. It'd be exactly like mine though and not professional but very functional.

Re: 305E Intake mod.
 

TJ, glad to see you volunteer to do one of these manifolds for one of the members, I had a feeling you just might. I've done three myself and still quite not done with the third but it'd close:ahhhh:

Re: 305E Intake mod.
 

Thanks Pete, I did mine with a manual mill so it took me a good 6 hours to machine mine. haha But I didn't exactly know what I was doing then either. :teehee:

Re: 305E Intake mod.
 

TJ - I have been away for a while. Just stumbled on your youtube videos on this topic and reminded me about it. Life has been BUSY. Anyway, how hard are the Magnum intakes to find? What is a reasonable cost in your opinion?
Thanks!

Re: 305E Intake mod.
 

I haven't ran across one since that day to be honest. They pop up on Ebay once in a great while but the prices are becoming outrageous. $50 is what I paid for mine and would do it again for $200 now in a heart beat.

Re: 305E Intake mod.
 

I paid $100 shipped for one a few months ago. It was on ebay listed as a 1961 GMC 305 V6 2bbl manifold but it's magnum intake. It has the larger carb flange and no divider in the big port.

Re: 305E Intake mod.
 

There would be no such thing as a Magnum manifold before 1966:pullinghairout: and especially one without a divider.:ahhhh: 1960-65 401 and 1962-65 478 small port heads engines used a semi hi-rise manifold that used the larger Bendix-Stromberg carburetor, this is actually an excellent upgrade for a 305 V6 if you were to go with the Holley 500 with a trapezoid adapter. If you plan on converting one to a 4bbl then you need the 1966 on up Magnum manifold which has the divider. Included are some pics of converted Magnum manifolds to 4bbl

Re: 305E Intake mod.
 

The intake I picked up was cast in 68, has the trapezoidal carb flange, a divider in the plenum, and no divider in the 1-3, 4-6 intake ports.

I have a trans-dapt trapezoidal to holley 2bbl adapter that I thought about using with a GM TBI adapter, but it looks like a great source for vacuum leaks. I was planning to use your idea and mill the top of the intake flat and add a single 4bbl to TBI adapter.


Your saying there are small port trapezoidal carb flange intakes which would have a divider in the 1-3, 4-6 intake ports for the small port heads. This would be perfect for a 305 and not require the larger intake gaskets.