73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Performance => Topic started by: Snag on November 27, 2021, 06:01:23 pm
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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 .
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There will be some brainiac here that will help you do the math. It won't be me though 8)
Curious if you know the stroke specs of a 305 vs a 350. Longer strokes get their torque/HP at lower RPM's which it looks like your going to be at 60.
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Do not use a Torker II intake. Why bother with the 305 though, especially if it is in the condition you describe? Find a 350 and be happy.
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i think the E-922-P cam would be a good choice-----won't give up too much bottom end while should get you over 200hp on the top end. Might still be able to use the stock converter here?
i would use an edlebrock performer rpm if you're going to continue using the q-jet.
But really, switching to 3.42 from 2.73 alone, i think, will make a big enough difference.
Now, remember, i'm not an engine person and my "advice" is free.......
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As already stated above, get a 350 and dump the 305. I have an H 305 in my Camaro. I rebuilt it .030 over, better cam, edelbrock intake and carb and put together a good tune. Basically what you are considering. I'm certain it is less than 200hp. I had good reasons for it at the time (trying to keep car original). I later regretted it and now I'm trying to wear it out so I can justify building a 350 for it.
Edit: I just realized this thread started in November of last year. Hope the OP got things worked out.
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I don't know about a stock converter....
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