The Ford Barn

klawockvet · 06-13-2013, 01:29 PM

I see lots of threads and comments on cruising speeds but they usually fail to mention the drive ratios. My question is regarding safe RPM for cruising with a babbitt motor? Is 2200 safe for a long haul? If not what is? I change oil at 500 miles and run an air filter. How long can it run at 2500 without problems, as in passing or getting out of the way? If all this could be found by searching please educate me in how to do that as I have tried a lot of combinations and although I've received some information it took a long time and really didn't address my specific questions. My car, with a B head, cam and carb really wants to run a lot faster than I let it. Its a daily driver and I want it to last. And yes, I'm going to go with an overdrive asap. Thanks in advance for the advice.

johnsor · 06-13-2013, 02:03 PM

If your engine is in good balance (mine is), 2200 RPM is not too high. On flatland, I go more by sound and lack of vibration.

James Rogers · 06-13-2013, 02:51 PM

A good Model A engine should be able to cruse at 55 all day. That is with a 370/1 gear which is normally stock.

Tom Wesenberg · 06-13-2013, 04:12 PM

Sponsored Links (Register now to hide all advertisements)

Without counterweights on the crankshaft, I like to limit my speed to 45 with the 3.70 rear end. For a daily driver and longevity, counterweights and an overdrive would be my first choice. A 5.5 head would also be a good choice.

06-13-2013, 01:29 PM	#1
klawockvet Senior Member Join Date: May 2012 Location: Klawock, AK/Kanab, UT Posts: 301	Sustained RPM & Cruising I see lots of threads and comments on cruising speeds but they usually fail to mention the drive ratios. My question is regarding safe RPM for cruising with a babbitt motor? Is 2200 safe for a long haul? If not what is? I change oil at 500 miles and run an air filter. How long can it run at 2500 without problems, as in passing or getting out of the way? If all this could be found by searching please educate me in how to do that as I have tried a lot of combinations and although I've received some information it took a long time and really didn't address my specific questions. My car, with a B head, cam and carb really wants to run a lot faster than I let it. Its a daily driver and I want it to last. And yes, I'm going to go with an overdrive asap. Thanks in advance for the advice.

06-13-2013, 02:03 PM	#2
johnsor Senior Member Join Date: May 2010 Location: Spooner, Wisconsin Posts: 242	Re: Sustained RPM & Cruising If your engine is in good balance (mine is), 2200 RPM is not too high. On flatland, I go more by sound and lack of vibration.

06-13-2013, 02:51 PM	#3
James Rogers Senior Member Join Date: May 2010 Location: Asheville,NC Posts: 3,104	Re: Sustained RPM & Cruising A good Model A engine should be able to cruse at 55 all day. That is with a 370/1 gear which is normally stock. __________________ http://www.model-a-ford-4bangers.com/

06-13-2013, 04:12 PM	#4
Tom Wesenberg Senior Member Join Date: May 2010 Location: Mpls, MN Posts: 27,582	Re: Sustained RPM & Cruising Sponsored Links (Register now to hide all advertisements) Without counterweights on the crankshaft, I like to limit my speed to 45 with the 3.70 rear end. For a daily driver and longevity, counterweights and an overdrive would be my first choice. A 5.5 head would also be a good choice.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode