RPM goal?

BigSky
BigSky Senior Contributor
in HUDSON
I’m looking at getting different rear tires for my 37 Coupe with original 212ci engine & transmission but has a Ford rear with 3.45 gears.  I’m wondering what is an RPM range one would suggest at say 60mph?  I ran an online calculator for rpm based on original set up & here’s what I found.  


So appropriately 2820 rpm on original setup.  My current tires are 225/75r15 & would give me this:


Not having driven the coupe yet, I’m wondering what those who have experience driving these old cars might recommend as an rpm which isn’t too high or too low & kills take off.

Comments

  • terraplane8
    terraplane8 Senior Contributor
    I guess whether you are in flat or hilly terrain makes a difference. The stock 4.11 with standard tyres is too low geared for moderately flat terrain that's for sure especially with high compression!
  • BigSky
    BigSky Senior Contributor
    Anyone have anymore suggestions?
  • 50C8DAN
    50C8DAN Senior Contributor
    Do you have OD?  If not you should add it.
  • BigSky
    BigSky Senior Contributor
    Hahaha.... have you got one?  

    I’d love to add one but haven’t found one for sale!
  • Geoff
    Geoff Senior Contributor
    You haven't driven the car yet.  Why are you worrying about this?  You have a high geared non original  back end already,  so why not just see  how it goes first.  
  • bob ward
    bob ward Senior Contributor
    edited May 2020
    To me any car with a 4.11 rear end is only a 50-55mph car, Sure you can drive at 60-65mph but you are being unkind to an elderly engine. The 212 is a lugger it will pull up hills from low RPM, depending on where you live you may need to go back to 2nd gear more often with the 3.45 rear end.
    To help this discussion along, are torque/HP curves available for the splasher 6 and 8?
  • BigSky
    BigSky Senior Contributor
    If I had 2 tires for the rear I would definitely just drive it!  Unfortunately a couple years ago one of the 16+ year old tires failed on the sidewall.  I took the trailer spare tire/wheel & put it on the coupe since the bolt pattern matched but it’s a different size than the other tire.  Since I can’t locate another used 225/75r15 tire, I wanted to see if there was a common target rpm at a specific speed & then I could apply that to my situation.  

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