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Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
Lots of work on Brad's part ... pure enjoyment (and references) for you!
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| | | | Joined: Jan 2002 Posts: 28 Junior Member | | Junior Member Joined: Jan 2002 Posts: 28 | I am running a 55 270 CI in my 50 GMC 100. Motor is rebuilt, bored, shaved head, howard 240 cam, aluminum intake w/manafold heat, holly 390 cfm w/vacume secondaries, cast iron fenton headers, smithy mufflers, and a s-10 style HEI.
I converted the column shift to the old truck 4 speed floor style, kept the enclosed drivshaft, and updated the rear with patricks 3:55s.
The tranny is probably the biggest set back in the system. Maybe a T-5 down the road will help.
I usually shift around 3,000 and often up to 3,500 RPM. It was recomemended that I set 5000 as my red line. The other night I got to 6000 RPM in a hurry. Don't notice any problems, yet.
I get beleiveable performance up to 3,000 RPM. Once I pass that, the truck just keeps taking the throttle and doesn't slow down fo nothin'!
Just wondering what you guys are experiencing with similar set ups?
Grant in Albuquerque | | | | | Joined: Dec 2004 Posts: 1,897 Shop Shark | | Shop Shark Joined: Dec 2004 Posts: 1,897 | Sweet! Did I see that correct? 6000 RPM  I'm hoping my 302 Jimmy will drop my jaw too! Congrats!  | | | | | Joined: May 2001 Posts: 7,438 Extreme Gabster | | Extreme Gabster Joined: May 2001 Posts: 7,438 | Sounds great. I plan to put a 4bbl on my '54. How is yours oriented? | | | | | Joined: Oct 2003 Posts: 5,152 Cruising in the Passing Lane | | Cruising in the Passing Lane Joined: Oct 2003 Posts: 5,152 | Mine runs great, but its still stock and I've never turned it nearly that fast...
1955 1st GMC Suburban | 1954 GMC 250 trailer puller project | 1954 GMC 250 Hydra-Matic | 1954 Chevy 3100 . 1947 Chevy COE | and more...
It's true. I really don't do anything but browse the Internet looking for trouble... | | | | | Joined: Jan 2002 Posts: 28 Junior Member | | Junior Member Joined: Jan 2002 Posts: 28 | The carb sits with the primaries towards the head, secondaries outboard towards the left fender.
The drive gear, in the 4 spd, for the speedo is shot. So much for the transmission guy telling me it was "all OK as far as I can tell." So, I use the tach for a speedo. OK when steady throttle but not very accurate when accelerating. | | |
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