Hello everyone! I drive my 55 second series daily. I just put in a 3 speed muncie 318 tranny that came in a 1064 car I have 235/80/16 tires and 3.90 rear end. At 55 mph my tach says 2600 rpm's. I am running a 235 and after reading this forum I believe that is a safe running speed for my engine. Everything is stock on the truck and I would like to run 60 mph. Any thoughts please?
Last edited by Gdads51; 04/16/20241:48 PM. Reason: edit title and text to make it a separate thread
As long as you don't have a bunch of loose rod bearings and/or low oil pressure, your 235 will live happily ever after at any RPM below 3K, and it won't self destruct at 3200 for short spurts. Most of the engine noise people obsess about with an old stovebolt when it's wound up is coming from the fan. Just for grins, pull the fan blade off and make a highway run. You'll be amazed at how much less noise you hear, at road speeds you wouldn't even think about running otherwise. 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!
Assuming 235/80/16 tires are 30.8" diameter (that is the spec I found online), 2600 rpm should yield 61 mph with a 3.90 rear gear, not 55 mph. The tach and/or the speedo is off. Try it with a GPS speedo function on a smartphone to determine which.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
Thank Jerry. I don't have any noise from bearings or lifters and oil pressure is a little over 30 lbs at idle of 700 rpm's and around 35 lbs while driving. Just went out and @ 63 mph the RPMs were 2700 very happy with the ole girl.
Hi again Bill what do think would be the rear end equivalent running the size of tire on the rear? Would it be around a 3.40 or is there a website that I could search for myself. I noticed a big difference in starting out and also pulling a trailer. Thanks in advance for any help. Also if there is already a post about this please put me in the rifgt direction.
I use a home brew Microsoft Excel file. It looks like shown below. You fill in the green boxes and it does the rest. Send me a PM with your email address and I'll send you a copy.
By the way, the simple formula is Mph x gear ratio ÷ tire diameter in inches ÷ .002975 = rpm.
Last edited by Bill Hanlon; 04/17/20243:18 AM.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
Mods- - - -You might want to poof that email address on the open forum- - - -no telling what kind of unwanted attention that might attract. (Done!-Modertor edit ) Mike- - - -now that you have made at least 5 posts, you have access to the "private message" function of the website. It's the small "envelope" icon at the upper right of every page beside your username. You can share priveleged information with other forum members privately by clicking on their username and selecting the "private message" option on the drop down menu. Welcome to the forum- - - -where the inmates have free run of the asylum! Jerry
Last edited by Peggy M; 04/17/20242:58 PM. Reason: edit for mission accomplished
"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!
... is there a website that I could search for myself. ....
This rang a bell for me. We have a good Tech Tip, Calculating RPM, axle ratios & tire size, and in there at the bottom of the page, it gives a link to THIS WEBSITE: "Welcome to OnlineConversion.com." That is a interactive page where you can plug in numbers.
Does this help?
And HRL, we'll fix the email mentioned. Most of the Bolters have their email in their profile, which is accessible to Members Only, and not guests.
~ Peggy M 1949 Chevrolet 3804 "Charlie" - The Stovebolt Flagship In the Gallery "We make a living by what we get; we make a life by what we give." -- Winston Churchill
email with spreadsheet sent to your email address Mike.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
To find the speed vs. RPM in each gear, just divide the speed from that formula by the individual gear ratio (2.75:1, etc.). The usual formula for safe maximum cruising speed is 2500 ft per minute. It's 3,810 RPM for the 235 & 261.
1955 235 engines are factory HP rated at either 3800 or 4200 RPM, depending on the specific application. Any speed below those numbers will be "safe" for a good condition engine with proper connecting rod bearing clearance. Very few stovebolters ever rev their engines that fast, so "safe" rpm suggestions are usually a solution in search of a problem. 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!
Good info here. Thanks for sharing the calculators
Craig
My '50 Chevy 3100 5 window, '62-235cu, 3:55 rear My truck ....... Respect The Rust If I'm not working on my truck, '65 m00stang or VW camper, I'm fishing with the wife or smoking Salmon.
