I've been a member here for a couple (or more) years , but since my son had my truck ... Rojo Grande is an '86 GMC 1500 , 305 with a TH700R4 . The problems started when I let my son "borrow" it ... but that's another story for another day .
Today , the story is that it ran out of oil and nearly seized - not his fault , broken oil pressure sensor dumped the oil . I've got the motor stripped some but still in the truck , and piston #1 is bumping the head but that's also not what I wanted to ask .
This is the "H" motor , supposed to be 9:1 compression with the 1.840 intake/1.5 exhaust valves and closed chambers . The Chilton manual sez this motor makes 165 Hp @ 4400 ... stock . I'm planning on an .030 overbore with stock .110 dished pistons , an Elgin E-922-P CAM (.444"/288° intake, .465"/298° ex) with an Edelbrock Performer or Torker intake , 1.25" diameter long tube headers and the stock Quadrajet . I'm also stripping most of what's left of the emissions plumbing and running some fairly quiet mufflers .
My real question is how much can I reasonably expect to gain horsepower-wise from these mods ? Am I too optimistic to expect around 220 or so ? I'll also be swapping the original 2.73 rear axle gears for a set of 3.42's , which I expect will also add a little snap off the line without hurting mileage much - I'll be turning around 1750 at 60 MPH .