Highway RPM's
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Highway RPM's
I am getting ready to install a tach on my 79 with a 351m/C6 and was wondering what RPM's I should expect to see at 55-60mph. I'm not sure what rear I have as I cant find the tag. It's all original/stock setup that doesn't seem to mind cruising at 55 for 30 -45 min trips.
More Turbo
Joined: Sep 2003
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Guess.
I am getting ready to install a tach on my 79 with a 351m/C6 and was wondering what RPM's I should expect to see at 55-60mph. I'm not sure what rear I have as I cant find the tag. It's all original/stock setup that doesn't seem to mind cruising at 55 for 30 -45 min trips.
I'm guessing your axle is 3.00 to one, that's what my '77 with a 400 has. 235-75 x 15s are 698 revs per mile, Should be about 2100rpm at 60. If your truck won't go 80 (2800 rpm) all day long there's something wrong with it.
R.
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Thanks guys, I just found my axle tag but it’s almost completely hidden under muck. Still have to clean it off. I also just realized I forgot to add my main question. What is a “safe” rpm with this setup for extended trips? I have yet to venture past 45 min because I haven’t figured out what my 60mph rpm is. I’ve been nervous about pushing it too hard since it’s all original. I’ll go try and clean the tag to get my ratio. The passenger side sticker must have been removed at some point.
Ho ho ho. You have a sticker in the passenger side door opening that lists such things as transmission and rear end. The rear end is a code that tells you what it is. The C6 has a 1:1 Third gear.
I'm guessing your axle is 3.00 to one, that's what my '77 with a 400 has. 235-75 x 15s are 698 revs per mile, Should be about 2100rpm at 60. If your truck won't go 80 (2800 rpm) all day long there's something wrong with it.
R.
I'm guessing your axle is 3.00 to one, that's what my '77 with a 400 has. 235-75 x 15s are 698 revs per mile, Should be about 2100rpm at 60. If your truck won't go 80 (2800 rpm) all day long there's something wrong with it.
R.
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Joined: Oct 2004
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From: Richmond
From this calculator, you should be able to do 70 mph at around 2100 RPM's, which won't put any strain at all on that 351.
https://spicerparts.com/calculators/...rpm-calculator
https://spicerparts.com/calculators/...rpm-calculator
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