Power is rated in watts. Watts = voltage times current in amps. So, if this is a 12 volt system the 45 amp starter would produce 540 watts and the 20 amp starter would produce 240 watts.
But I don't think any of this is relevant because I've never heard of starters for small block Chevys that would operate at such low current.
'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.
Generators and alternators are rated in amps, I've never seen a starter rated that way. Horsepower and torque would be more relative to a starter rating. SBC starter would draw 150 - 250 amps.
1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy
A 45 amp starter might crank a Briggs & Stratton lawn mower engine, but I doubt it. 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!
Go to Rock Auto. You can look at the specs of each starter that's listed for the year make and model vehicle you're searching for.
1950 Chevrolet 3100 (Ol' Roy) 1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1956 Cadillac Sixty Special Fleetwood (The Godfather) | 1966 Oldsmobile Toronado (The Purple Knif) | 1966 Ford Mustang (Little Red) | 1964 Ford Galaxie 500 coupe | 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
One thing is for sure, real application to the truck and it prefers the 45 amp starter. Truck does not like the 20 amp starter. Dis-liking means intermediate cranking . Rebuilt AC Delco starter sounds like a good option. I actually have one of those. I`d have to test it.
You are kind of on the wrong track with your description of starters. Generators and alternators produce amps. Starters draw amps. I have not seen a starter sold by specifying amps. They have so called heavy duty/high torque and all that jazz and GM spec sheets have some test data. The starter will pull BIG amps. I quess you have a 327. Maybe you have a high compression motor or new rebuilt motor which may be why a certain starter does not perform. Seems the numbers you have are "no load" test Amps. Don't know. Anyway, they are not relatable. Except to show one is higher than another.
You can get some insight from GM testing data shown in yearly spec sheets. Showing how much they draw.
Example from GM: 1953 Chevy Truck with 6 cylinder, 6V Delco starter. Load test: Locked: 525 amps/3.4V No load: 65 amps/5V Torque 12 ft lb RPM 5000
By 1966 they were talking optional "heavy duty" starter. 6 and 8 cylinders got "bigger:. As some 327 were 10.5:1 compression ratio. GM was using words like "High Torque" for everything. The 6 cylinder starter test results were: Delco no load 12V starter: 49A-76A/10.6V RPM: 6200-9400
Thanks man, IDK much about these sort of things. Only I can do the work and do the best I can. With another 1958 with a newly rebuilt 327 the powermaster works fine(3year old starter). Same rewire ,same everything to my knowledge. This other newly rebuilt 327 will not work right (start)with the same rewire same starter. With me and my experience, bad parts and replacement "things" seems to be running rampant. Popsicle stick ignition, bad starters , steering boxes, HEI ign modules.There is more.
Some things work well. I think rebuilding original equitment would be my 1st choice from now on. My next project is a 235 witha 58 panel I will try and keep original. The 235 ran when last used(fingers crossed ,will take the man at his word) I`m sure things will come up. The flywheel is getting turned at the moment. I will clean the engine as best I can and supply new clutch ,pressure plate, carb. I have 2 original 3 speeds. and a warner 3 speed OD transmissions to work with. I am kinda proud of myself lately for fitting a M-22 RC in my 58 step and a M-20 in my 59. Hurst comp + shifter to move it as far forward as possible and shims to move it more to center. Where REVERSE will not hit your leg. It takes 2 handles I plan on taking pics of the "mod" in hopes of helping others with the same thought in mind.
