Thread: 1977 c20 454

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Problem. My 77 454 lacks power on long steep climbs with the 5th wheel on. Starting out at 60 or 65 on flat ground at the peak of hill maybe be down to 40, and hoping it will make it. These were not real steep climbs like you get down south in the Smokies just rolling type here in the upper half of the lower part of MI. I'm not looking for 500hp but the advertised 230 is not getting it. Engine has 100230 mi. on it 400 trans. 3.21 rear. I think all I need is a bit more hp

3.21 rear gear?????????? The 84 I had had 4.11-----------cruised 70 mph at 3300 rpm (IIRC)
What size ties you got on it? 4x4 or 2 wheel drive? Weight of traler? does it stick way up in air stream over cab like many I have seen?

Yeah, you're probably due for some upgrades. Cam and intake I'm sure would help it out. Those were pretty gutless and if it does have 3.21 gears that doesn't help at speed. I have a 4.10 geared 14 bolt full floater I'd make you a deal on if you get to that point. That would help it I'm sure.

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Originally Posted by jerry clayton

3.21 rear gear?????????? The 84 I had had 4.11-----------cruised 70 mph at 3300 rpm (IIRC)
What size ties you got on it? 4x4 or 2 wheel drive? Weight of traler? does it stick way up in air stream over cab like many I have seen?

it is a 3.21 rear tires are 265/75/R16 Same OD as stock 16.5 that came with it. Yes it does stick up over the cab (Pic) and weights 8K.

Originally Posted by 40FordDeluxe

Yeah, you're probably due for some upgrades. Cam and intake I'm sure would help it out. Those were pretty gutless and if it does have 3.21 gears that doesn't help at speed. I have a 4.10 geared 14 bolt full floater I'd make you a deal on if you get to that point. That would help it I'm sure.

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I was thinking cam and maybe intake. Just not real sure where I want to go I just want pulling power not for drag racing. I went with bigger cam and intake and fancy heads on my 350 to pull it (and that worked) but it's only a 1500 and the trailer over rides it.

Nice looking truck! It’s amazing that those smog era 454s barely made over 200hp and most modern V6s easily make that today. A cam, intake, and headers will probably easily put you over 300.

Turn the air cleaner top upside down so more fresh air can enter-------check the advance mech in the distributor to make sure advance is working-on several older GM dist I have found that the shafts were bound up and advance wouldn't retard so on tune up the timing would get set back and then even with advance it wouldn't be correct.

Are you 100% positive that you have a 3.21 rear gear???????
back in those days there were air dams made to mount on top of cabs to help air flow over trailers

If you have a q jet carb, I would replace it (and manifold) for a 850 or 900 cfm Holley------yes I know all the formulas for carb sizes will disagree-------but, it will give you a better mid range airflow without getting into the seconaries which would then get you into an over rich af and lose power-----------

3.21 gears got to go--------find a 3.73 or 4.11

move out of the hills??????????

3.21 I know but that's what it says

Charlie,
If you elect to go the cam/intake/header route suggested by falcon, selecting a good mid-range rpm cam for towing then replace your rear gears to put you in the sweet spot on rpm's at your cruising speed while towing. Once you've done that, a Gear Vendors unit will double your gear selection options, splitting each gear to let you pick & choose to stay in your power band easier. I know that John Norton used one on his bus, and I believe he'll say it's a good option for maximizing your power band with heavier loads.

Originally Posted by rspears

Charlie,
Once you've done that, a Gear Vendors unit will double your gear selection options, splitting each gear to let you pick & choose to stay in your power band easier. I know that John Norton used one on his bus, and I believe he'll say it's a good option for maximizing your power band with heavier loads.

Yep.
The difference without and with the Gear Vendor unit was amazing.
I can now stay in the sweet spot in my power band no matter what the incline or load.
It made driving it just so much more flexible; I've now got an applicable ratio for all conditions I meet.

Johnboy------what is the rear axle ratio and tire size?????

Originally Posted by jerry clayton

Johnboy------what is the rear axle ratio and tire size?????

3.21 950/16.5

sorry Charlie-I was asking Johnboy what gear and tires on his bus with the gearvenders overdrive-------

JB, thinking about your terrain on the North Island, you definitely put that GV unit through it's paces!! I don't hardly remember a dead level spot anywhere we went, except maybe in the towns. God's Own is hill after hill after hill in my memory! Bet you could make a great Gear Vendors commercial!! A fresh haircut, a clean chambray shirt (rolled sleeves, of course), a ciggy hanging from your lip and a bus load of buxom NZ lassies laughing & squealing as you thrash gears through the countryside!

Don't spend $3000 for an overdrive when your gear ratios are already too high--you need a lower gear in the rear----------now don't forget that the term higher ratio is commonly looked at as a higher number where also lower speeds for rpm