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| | | | Joined: Jun 2011 Posts: 21 Wrench Fetcher | | Wrench Fetcher Joined: Jun 2011 Posts: 21 | I am planning to get started on the restoration of my 38 chev truck this coming winter and am looking for comments on a powertrain that is being planned to make a daily driver, (hopefully for speeds of 90 km/hr. I have a set of Coker 6:00 - 16 bias tires from Summit Racing for the front steering axle to match the original tires that came off the truck. I also have a pair of Uniroyal Fleet Master 6:50 - 16LT Type E tires for the drive axle. The diameter for these rear tires is 29 inches. These also match the tires that came off the truck and assume they were installed to give the truck a bit higher highway speed. I am planning on replacing the 216 engine with a rebuilt 235 engine from a 1957 truck, keeping the original 3 speed transmission and torque tube differential as well as original brake system. Can anyone comment on the average expected speed that can be achieved using this combination without running the engine at excessive high RPM numbers. As well, will the original transmission/clutch be reliable with the extra HP from the 235 engine? Thank you in advance: Brian 1938 chev truck replacement wheels/tires | | | | | Joined: Jun 2011 Posts: 5,096 Crusing in the Passing Lane | | Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | What is your diff. ratio?
Ed
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
| | | | | Joined: Jun 2011 Posts: 21 Wrench Fetcher | | Wrench Fetcher Joined: Jun 2011 Posts: 21 | I am not sure what the differential ratio is right now. All I can say at this time is that it is still the original closed tube drive line for a 1938 Chev 1/2 ton truck, I have not removed the differential cover yet to check the gear ratio, but may need to confirm that at some point.
Brian
I just checked the "GM Heritage Center" web site and it lists the differential ratio as 4.11 to 1 for a stock chev 1/2 ton closed torque tube drive line.
Brian
Last edited by 38 chev; 08/10/2017 10:59 AM.
| | | | | Joined: Sep 2001 Posts: 29,270 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,270 | | | | | | Joined: Nov 2009 Posts: 639 'Bolter | | 'Bolter Joined: Nov 2009 Posts: 639 | Try this: http://www.csgnetwork.com/multirpmcalc.html Enter your info under "Transmission Final Gear Ratio Manual Entry" 1.00 three speed 4.11 rear end 29" tires 56mph / 90kmh = 2667 rpm | | | | | Joined: Jun 2011 Posts: 21 Wrench Fetcher | | Wrench Fetcher Joined: Jun 2011 Posts: 21 | Thank you so much for the information, which brings up another question that am sure has been answered many times already. For a rebuilt 235 engine, is 2600- 2800 RPM a reasonable RPM to run consistently, and what RPM does the average gas consumption get excessive with a standard single carburetor?
Brian
I am just getting familiar with the Stovebolt site, so forgive me if I am asking for information that has already been answered. I am trying to read as much as I can absorb on this site, but there is so many topics covered here it is overwhelming. | | | | | Joined: Sep 2001 Posts: 29,270 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,270 | My 235 engines start to decrease in fuel economy after about 2400 RPM (cruising on a relatively flat road - Interstate).
I can easily cruise at 2600 RPM, but gas mileage suffers. | | |
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