Conversation Between ceetwarrior and eclectix

a couple of possibilities-- (1) the engine needs another 1500 miles of break in time. i dunno. (2) needs a taller gear ratio, eg 5.6:1. seems wrong to me. (3) some kind of simple throttle linkage problem. me: maybe. the problem seems there although less so at lower speed shift points.

any thoughts welcome. what is your max speed if i may ask, and do you rev it above 3500 RPM before shifting from 4th to 5th? maybe i don't rev high enough in 4th, dunno.

cheers

steve
northern california

i have a 1968 f250 with a newly rebuilt 390, rv cam, edelbrock 4 barrel carb, tri-y headers, nv4500, 4:10 gears, 33" tires, 2" lift, a flatbed, and a 20' pipe rack out of 2"x2" steel. I figure with just me driving and no passenger, i might be about 500 lbs over stock weight (not great but hopefully not too bad).

the best speed i can get so far (only started experimenting) in 5th gear is about 75mph at about 2100 rpm. at this speed, i can maintain it on a flat freeway, but i cannot accelerate-- if i push the accelerator all the way, the speed remains at 75mph. the rebuilt engine has about 400 miles on it.

any ideas? i am a software engineer. i don't know anything about this stuff.

i have sent an inquiry to the rebuilders. it is still under warranty. i am still waiting for a response from them.