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BB w/4 speed whats ur cruising RPM
Hey All,
Not sure if I should have posted this in the FE section, transmission section or ALL talk section. I wouldlike to know what you cruise at on the highway with having a BB and a toploader / 4speed. I am know the final gear plays a role in all of this but wanted to know if you were crusing on the highway do you keep you RPMs between 2500 - 3000 and forget about the speed your traveling at? Or , do you turn up the RPMs to reach your desired speed lets say 80 mph puts around 3500 rpm. I am looking to possible do a 30 mile stretch and wanted to know if I should be concerned with the RPMS. |
I simply keep up with the flow of traffic. Most recent long trip was from the bay area to Redding. 70-75, generally a bit over 3,000 rpm as I recall. I didn't worry about it at all. FE's are pretty rugged actually, a cruise rpm range in excess of 3,000 is not a problem in my opinion.
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Excaliber,
What rear gear are you running, just curious |
3:31 with 26.5" tires, top loader. From that you could calculate the exact rpm for 70-75-80 mph. Typically I DO NOT exceed the posted speed limit by more than 5 mph. Well OK, maybe for short bursts of speed in carefully selected areas, but not while "cruising" on a trip. Don't need a ticket.
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I run a 427 in my Galaxie with a close ratio toploader and see 3300 rpm at 70 mph on the interstate and haven`t had any problems in the 5 or 6 years I`ve been doing that . Actually , sounds good at that speed .
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Here are a couple of calculators that might be of interest:
http://wahiduddin.net/calc/calc_speed_rpm.htm (note: this calculator uses tire radius, not diameter. First time I tried it, the estimated cruising speed for the numbers I used, was 140 MPH :eek:) http://www.4lo.com/4LoCalc.htm |
I am running a 427 C.O. with 3.50 rear gears and a toploader wtih 26.5" tires and at 70-75 mph I am tuning about 3800 RPM. Higher than I like but the ole engine is good for over 6800 RPM without hurting anything. May drop my rear gears to 3.08 soon.
Clois |
482ci with a wide ratio toploader, 3.31 rear and 26.5" Billboards. Doing approx 3,000rpm at 70mph. I'm playing with speedo gears to make sure I'm close to the right mph, but should be right there. In my case, the cam and carb seem to like to ride right there. If step on it, I'm gone!:cool:
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Other than using a "weak" overdrive toploader, all of the 4-speeds have 1:1 4th gear, so cruising rpm's will depend upon rear gears and tire OD.
If you want cruising capability with a 4-speed, then get a wide ratio toploader, and run 3.07 rears, maybe going to 2.88's, but I'd stick with 3.07's. If you want to run a close ratio toploader, then you pretty much need to run a 3.50 rear or close to that. With a 3.07 rear, starting in 1st, or reverse, is too hard fo regular use. |
One reason I'm going with a TKO .8 over drive and giving up on the top loader is because I've grown tired of "dealing with" the ultra high first gear ratio of my close ratio trans combined with a 3:31 rear gear.
For instance, since I've recently gone with slicks I've noticed the clutch is now slipping under extremely hard accelleration. I believe that is a direct result of the tall gearing, all though OK, the clutch does have about 8,000 hard miles on it. HARD miles because of the tall dam gearing for the most part. :) I thought about changing the gear set in the top loader to a wide ratio and doing a complete rebuild and then decided to just bite the bullet and go with a 5 speed. |
I run a Doug Nash 5 spd with a 1:1 5th gear. So, I am running a 2:36 in the rear and I can cruise as fast as I want to on the highway at 2100 to 2500 rpms.
The car gets moving easily with the 3:27 1st gear. Lots or torque always helps. |
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