1969 gmc 4x4 1500 deluxe

[1972RedNeck]

If you ignore the tranny slipping, to be turning 3500 RPM @ 55 with 33's you have to have around 6.2:1 gears.

http://www.summitracing.com/expertad...tio-calculator

Is your tranny shifting into third? Have you verified your tach and/or speedometer?

Second gear is 1.52:1. 6.2 divided by 1.52 is 4.07 - very close to 4.10's. You may need to look at your transmission.

[davepl]

Undo every underhood modification made by previous owners and return all parts to stock. Carburetor, choke, heat stove, heat riser, crossover, fan, shroud, coil, distributor.

Then undo every suspension modification, lift kit, oversize tires, knobby tires, bags, dubs, lubs, rubs, blings, whatever. None of these help things.

Then a full tune-up to factory specs. You'll probably need more base timing and less mechanical than the original distributor curve.

Make sure you have vacuum advance hooked up. It's for economy and driveability, not emissions. All of your advance should be all in by your cruising rpm.

Then at least you'll get factory gas mileage. Which is about 12. But people (not saying you) butcher these trucks and get 4 mpg and complain. Yeah they're old, but those guys still had engineering degrees and slide rules, so why every shade tree teenager thinks they can improve on the engineering of our trucks by adding Chinese chrome, screwing up the suspension and removing all the driveability features, I'll never know.

And of course I made all of these mistakes along the way, and the fads in my youth were no crazier than the ones today. But that still means they're crazy. And mistakes.