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| | | | Joined: Nov 2019 Posts: 36 Tbone | | Tbone Joined: Nov 2019 Posts: 36 | I have a 1949 3600 with a 216 engine. My mechanic skills and knowledge is limited so I'm looking for advice on ways I might achieve more top-end speed. I live in Renton, WA.and would like to be able to drive my truck to Portland, OR. and the Oregon coast where I have family. Top end with my truck is about 45-50 ... 50 feels like the engine is straining. Would going to a 235 engine help my top end speed? Ideally, I'd like to be able to hit 55-60mph without over-burdening the engine. Would I need to upgrade or modify the transmission and/or gear ratio. The 1949 with 216 has the three speed manual + granny low first gear. Thanks for any help and input. | | | | | Joined: Feb 2004 Posts: 29,811 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,811 | Installing a 235 will help with pulling power, but not top end in any measurable way. The problem is the rear axle ratio. Most 3600's (3/4 ton) have a 4.56:1 rear end gear. There is a very scarce 4.11 center section that was used in a similar application in the mid-1960's that's a bolt-in swap, but they're scarce and expensive when you find one. Nobody makes replacement gears for that housing with a higher ratio than 4.11. You could either install a different rear end with a better selection of ratios, such as the GM corporate 14 bolt, or install a 5 speed overdrive trans, but that requires some pretty extensive modifications. If you go too high on the rear end ratio, you'll get out of the torque band of the 216, and bog down on every hill.
Once you get the truck up to highway speed, then you need to consider a few other little details- - - -like steering and stopping. At the very least, you'll need to bring the steering, suspension, and brakes back to brand new original condition. Otherwise, you're going to have a rolling deathtrap on your hands that's a hazard to your safety, and that of everybody who shares the road with you. Good luck!
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: May 2001 Posts: 1,904 'Bolter | | 'Bolter Joined: May 2001 Posts: 1,904 | I like the 4.10 I installed in my 3/4-ton but I still am comfortable with only 45-50 MPH. Driving the back roads to Portland might be OK and fun but I'd be scared with I-5.
I occasionally drive I-90 in MT at 50 MPH (speed limit 80, actual >>80) but I hang a blaze orange triangle in the back, turn on the flashers and spend most my time looking in the rear view mirror ready to dive to the right. What a guy doesn't do to get to his fishing spot.
1948 3/4-Ton 5-Window Flatbed Chevrolet 34 Years. Now with a '61 261, 848 head, Rochester Monojet carb, SM420 4-speed, 4.10 rear, dual reservoir MC, Bendix up front, 235/85R16 tires, 12-volt w/alternator, electric wipers and a modern radio in the glove box.
| | | | | Joined: Nov 2019 Posts: 36 Tbone | | Tbone Joined: Nov 2019 Posts: 36 | Jerry and others, thanks for the reminder to pay attention to my running gears IF I were able to increase the speed. Going through the steering, suspension and brakes is absolutely on my list to restore. When I've gotten her up to top end of 45-50 mph, I experience notable vibration and shaking. Her sweet rolling speed in 45 or lower. | | | | | Joined: Jan 2013 Posts: 2,234 Moderator: Interiors, Texas Bolters, Name that Part | | Moderator: Interiors, Texas Bolters, Name that Part Joined: Jan 2013 Posts: 2,234 | TGILL,
Once the front end was aligned, anti-roll (anti-sway) bar in place, and 3.55 gears, I can cruise comfortably at 65mph. The anti-roll bar was probably the best thing I upgraded on my truck. Well worth the money!
Before the anti-roll bar, I could go 50 mph with out breaking a sweat trying to keep her on the road.
Chris | | |
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