Home » Public Forums » GMCnet » Big increase in power in my 1977 403ci engine (A mechanic increased my engine power, significantly, in 2 simple ways)
| Big increase in power in my 1977 403ci engine [message #318327] |
Thu, 01 June 2017 13:27  |
DavidJForjan
Messages: 65
Registered: August 2016
Location: Tularosa New Mexico
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Hey everyone. This is an FYI post only. No questions. This info may be very helpful to others because a genius mechanic increased my horsepower considerably; very considerably. And he did this without any new parts. It's quite amazing actually. But it's true. I now have ALOT more power from my 403ci engine. Here's what he did (keep in mind this guy restores and services race cars). First he changed the arrangement/hookup of the vacuum hoses. He didn't add any, he just rerouted them. He said "Dave I want to connect the vacuum hoses the way we used to connect them. The other mechanic connected them the way people do nowadays. If you want I'll re-route them and you'll get more horsepower". And I did, just by him hooking up the vacuum hoses differently. I don't know how he changed them, but maybe one of you reading this post will understand and explain.
The second thing he did is adjust my timing differently. This was a wild experience. He had me start the engine, with the emergency brake on, and told me to hold down tight on the foot brakes, and put the transmission in drive. Then HE revved the engine with the throttle in the engine compartment, and revved it really really high. I had all I could handle just standing on the brakes to keep the motorhome from lunging forward. Picture this, he's revving the engine all the way up, while it's in Drive, the emergency brake on, me all but standing on the foot brakes, so the motorhome is trying so hard to lunge forward, but it can't, and with all these opposing forces fighting each other, the motorhome started shaking - violently. I almost lost it once and the motorhome almost got away from me the thing was trying so hard to go forward. And at this point of maximum forces, THAT'S when he set the timing.
I'm not a mechanic so I don't understand all that's involved. The mechanic before him was a young guy and he tuned and timed the engine when he put in new plugs and wires. Rick, the genius (he's about 55), changed the vacuum hoses and set the timing as I described above - and sure enough I have alot more power from that 403ci engine now.
Maybe all this is common knowledge and you all will understand what I've said. But this was all new to me and I have alot alot more power now. Even sounds different. Almost like a jet engine.
FYI to those who understand or want to understand. I look forward to comments from all you experienced folks out there.
Be well. Thanks for listening
david
David J. Forjan, 1977 403 26' Palm Beach, glad to have the 3.70 Final Drive and pork chop for level front end, Tularosa New Mexico
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