[MusicMan70]

I copied and pasted this from somewhere; maybe this forum or another, I'm not sure. It does have some specifics about performance changes.



Heres a little about these motors I learedt back in the mid 80's. My grand
father gave me his 1965 GMC 1t 4x4 that came with the gas 351c v6. I rembered
from a kid that this old truck would out pull anthing and never broke down. The
old 351 was getting tired with about 200k on it so i decided to rebuild it and
of coarse hop it up. So I started looking into performance imfo on these motors.
That put me in contact with Babe Erson. He told me about the gas 478M motor and
how with some work the big 478m v6 will easily make more tork and hp than a
mildly built 454bbc. So I bougth a 478m motor from the junk yard and went to
work per Babe's rec's. The first thing was to throw away the stock 4 ring
pistons and masive rods that weight about the same as a complete hemi motor. I
had a crank grinder turn the rod journals down to a much smaller size to fit a
426 hemi rod. I had BRC make some new lighter 3 ring pistons that also raised
the cr up from 6.5 to 9.0. Engine dynamitics lightened the crankshaft alot and
rebalanced every thing for me. Babe made me a special cam and all the vale train
parts. I ported the heads and polished the combustion chambers myself. I also
made a sheetmetal cross ram intake with 1 850cfm Q Jet carb and a set of home
made 1 3/4" headers. Once I got all the tuning done on this motor it was one
tork animal that would rev easily to 5.5k. It broke the transfer case right away
so I put in a beffier transfer case out of a newer ford truck I think then I
blow the old gmc rear end so I upgraded it to a dana 70 with posi. I also
upgraded the old truck 4 speed to a newer 5 speed that could be shifted much
faster. I had put big 38" tires on this truck and could smoke them in 2nd gear.
It did not do to bad on fuel also at about 12 mpg fully loaded with a 10ft
camper and pulling a 30ft enclosed trailer running about 65mph. I wish I know
where this truck (James) is today as I would try to get him back