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| | | | Joined: Apr 2007 Posts: 30 Apprentice | | Apprentice Joined: Apr 2007 Posts: 30 | I have a 1951, 80 mph speedometer that is very rusty, don't know if it works. I also have a 1953, 90 mph speedometer, in very nice shape (don't yet know if it works though). Is there any differences between these two speedometers in calibration, gearing, etc. such that I wouldn't want to use the the 90 mph speedometer? I would think that the transmissions and rpms would be the same for those two years. Any thoughts? Thanks for the help! | | | | | Joined: Aug 2000 Posts: 587 Shop Shark | | Shop Shark Joined: Aug 2000 Posts: 587 | I bet they are probably the same, but my master parts catalog is a 1950 edition, so cannot say for sure. Earlier years the gearing in the tranny was different, but same speedo. | | | | | Joined: Oct 2006 Posts: 9,671 'Bolter | | 'Bolter Joined: Oct 2006 Posts: 9,671 | Same speedo, just a little higher calibration of the head, shouldn't be any differance in the trans gears. I'm of the belief that it was just sales hype because there taint no way one of these could be driven at 80 or 90 mph. with the gear that was in them.
They also changed the temp gauges from 212 to 220 but I think that was for a practicle reason since they started using a 4lb cap.
Denny G
Denny G
Sandwich, IL
| | | | | Joined: Jun 2004 Posts: 8,597 Riding in the Passing Lane | | Riding in the Passing Lane Joined: Jun 2004 Posts: 8,597 | All speedometers are calibrated for 1000 revs pr mile. It should be the same reading regardless of the maximin speed of the head. This was true up into the 1980,s. I,m not shure after that or Imports.
They say money can't buy happiness. It can buy old Chevy trucks though. Same thing. 1972 Chevy c10 Cheyenne SuperIn the Gallery Forum | | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | Different gearing of the transmission (if that is the case) should not cause an incorrect reading, if the speedometer drive gear is on the transmission output shaft (I think it is).
In what year did the temperature gauge change to 220? In what year did the light truck thermostat (sorry, radiator cap) change to 4 psi (1954?)? | | | | | Joined: Oct 2006 Posts: 9,671 'Bolter | | 'Bolter Joined: Oct 2006 Posts: 9,671 | Sure ya meant a 4 psi cap not stat Tim. Not sure there, my latest Chevy parts book shows '53 up to '55 using a 5 1/2lb.,RC-2 cap. However, my Stant V338 catalog is a little more generic and calls out a zero for 1937-52 then a change to 4lb from 1953-55 early. 1955 late to 1966 used a 7lb.
As far as the gauge goes, one of my books doesn't show anything before 1956 and the other doesn't show anything after 1950. Gonna have to look it up at tocmp.com that manual covers up to 1954 I believe.
I was just applying a little common sense to the gauge. Stands to reason that when they started running the system under pressure that they could run higher temps with out it boiling. Therefore till I hear different I’d have to think they changed them in 1953.
I know one thing, I bought a new one from Chevy Duty this summer to replace mine in my 1950, 3604 and they sent me a 220°. I’m just so darn sick of having to fight for the right parts that I just stuck it in till I can get my original gauge repaired.
Denny Graham
Sandwich, IL
Denny G
Sandwich, IL
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