04-27-2020, 12:47 AM | #1 |
Still Green but learning
Join Date: Nov 2004
Location: Central NC
Posts: 1,895
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Horsepower estimate
I think we got the back firing squared away today. I had a friend come over and help. First I took the carb off sprayed it out real good to make sure that the pin valve wasn't dirty or the ports. then put it back on the engine my buddy came over and we adjusted the timing to 14 btdc run smooth now pulls really well so my next question is what kind of horsepower do you think I'm getting? Its a 350 with a 3 speed on the column, long headers going to 2 and 1/4 inch pipes with flowmaster 40. Oh yeah and HEI, that's the reason the timing was messed up. when I put in hei I did not redo the timing. Anyway, how many horses would you guys guess I am putting out?
Thx
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-- Cory 71 Cheyenne 10 - SWB, 350, "3 on the tree" AC cab 07 Suburban LTZ 4x4 2010 Acura TL 98 Mastercraft "FrankenStar" 225 27253 UPS/USPS IIOY....nope never was |
04-27-2020, 08:01 AM | #2 |
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Join Date: Feb 2011
Location: Parkville, MD
Posts: 1,024
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Re: Horsepower estimate
Assuming this is the original engine on the 71. Factory horsepower would be about 255 gross / 195 net. Realize this would be closer to 165 HP at the wheels.
If the only modifications are exhaust, HEI, and timing, don't think that it will be making much power power than stock. At MOST, I would say 30 HP over stock, but I would be surprised to see more than that. All those gains would be on the top end, as the factory exhaust would be sufficient at lower RPM, but not flow enough at higher RPM. HEI is more of a reliability mod, it is not going to make more power than properly adjusted points.
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1970 C20 Custom Camper - 350, TH350 1997 GMC Suburban 1994 Acura Integra GSR 1987 Dodge Daytona Shelby Z |
04-27-2020, 08:13 AM | #3 |
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Join Date: Nov 2004
Location: Mt Airy, MD
Posts: 85,851
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Re: Horsepower estimate
I'd estimate it could be less than rated depending on tune or if tuned and timed to optimum it could be 10-15hp more in higher RPMs. I agree, basically still stock.
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"BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~ |
04-27-2020, 08:47 AM | #4 |
Still Green but learning
Join Date: Nov 2004
Location: Central NC
Posts: 1,895
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Re: Horsepower estimate
Thanks guys, I never knew my original HP so this is helpful. I figured it wasn't a lot as we didn't make large changes (cam. Etc...)
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-- Cory 71 Cheyenne 10 - SWB, 350, "3 on the tree" AC cab 07 Suburban LTZ 4x4 2010 Acura TL 98 Mastercraft "FrankenStar" 225 27253 UPS/USPS IIOY....nope never was |
04-27-2020, 09:35 AM | #5 |
Registered User
Join Date: Jul 2014
Location: South East Ohio
Posts: 644
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Re: Horsepower estimate
Torque/horsepower increases are more significantly made in the bottom end (stroke/displacement) and at the cam. Though carburation (or fuel system) coupled with intake and headers CAN produce more power, it's generally a result of something being left on the table from the manufacturer. That's not to diminish the potential of a good set of heads but as they say, "there's no replacement for displacement".
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