HD cooling question
July 13th, 2019, 07:34 AM
#2
Old(s) Fart
Join Date: Mar 2007
Location: Northern VA
Posts: 47,300
Yes, HD cooling was optionally available without A/C. W-cars got it. Cars with higher numerical axles typically got it. Depending on the year and model, the water pump length may or may not be different.
July 13th, 2019, 08:34 AM
#5
Randy C.
Join Date: Feb 2009
Location: Albany, OR
Posts: 3,245
My niece has that same car, tranny and differential as well. Hers is regular cooling - 3 core radiator. HOWEVER, your car still could have come with the heavy duty cooling option (Y72) (has a 4-core radiator). See if you have a 3-core or 4-core radiator.
Randy C.
Randy C.
July 13th, 2019, 08:36 AM
#6
Old(s) Fart
Join Date: Mar 2007
Location: Northern VA
Posts: 47,300
In 1968 RPO M21 required RPO V01 HD radiator. If you have stardard cooling, the alternator pulley is P/N 1949357, which is 2 3/4" in diameter. With HD cooling the alternator pulley is P/N 1949355, which is 2 23/32" in diameter. In addition, standard cooling cars got the 5.1" water pump, HD cooling cars got the 5.6" water pump.
July 13th, 2019, 02:04 PM
#7
Randy C.
Join Date: Feb 2009
Location: Albany, OR
Posts: 3,245
I thought the V01 option was required only for the 3.91 or 4.33 differentials. My niece's car (400 engine, M-21 transmission & 3.42 anti-spin differential and we know at least the engine and transmission are original to the car) has the 398681 water pump and 1100767 37amp alternator and not the 400269 water pump/1100777 55amp alternator set-up. I thought the 400269 water pump was the longer one for A/C and/or HD cooling and the 398681 water pump was the shorter unit for cars w/o HD cooling.
Randy C.
Randy C.
July 13th, 2019, 07:22 PM
#8
Old(s) Fart
Join Date: Mar 2007
Location: Northern VA
Posts: 47,300
I thought the V01 option was required only for the 3.91 or 4.33 differentials. My niece's car (400 engine, M-21 transmission & 3.42 anti-spin differential and we know at least the engine and transmission are original to the car) has the 398681 water pump and 1100767 37amp alternator and not the 400269 water pump/1100777 55amp alternator set-up. I thought the 400269 water pump was the longer one for A/C and/or HD cooling and the 398681 water pump was the shorter unit for cars w/o HD cooling.
Randy C.
Randy C.
Here's the page from the 1968 SPECS booklet. For M21 it says "V01 and G88 or G92 required". Note that G92 (3.42) also says "V01 required".
July 14th, 2019, 05:45 AM
#10
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Location: Fredonia,Wisconsin
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July 14th, 2019, 05:48 AM
#11
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I do have a alternator already on it but so much of this has been hacked that I am trying to start from basics. I have two part numbers to choose from but before I buy one off eBay I need to know type cooling as it determines the part number and amps needed for non AC cars like mine.
July 14th, 2019, 05:57 AM
#12
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Join Date: Apr 2019
Location: Fredonia,Wisconsin
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In 1968 RPO M21 required RPO V01 HD radiator. If you have stardard cooling, the alternator pulley is P/N 1949357, which is 2 3/4" in diameter. With HD cooling the alternator pulley is P/N 1949355, which is 2 23/32" in diameter. In addition, standard cooling cars got the 5.1" water pump, HD cooling cars got the 5.6" water pump.
to really determine this I may have to just go from the rear end gearing...?!
The rear I know is original that’s a given as it has never been monkeyed with and is worn to pieces,
gears are 3.42!
this being said car should have the m20 or m22 tranny. I know I said I have the m21 but past comments on this sight have told me m21 should be with higher gear rears this marking this a incorrect geared tranny for the car.
If this is correct I should not have the VO1 or the G codes for HD cooling.
thus that should tell me that I would use the lower amp Alternator sound right????? Or am I over thinking this?
July 14th, 2019, 06:07 AM
#13
Old(s) Fart
Join Date: Mar 2007
Location: Northern VA
Posts: 47,300
I think you are correct this would make sense now. Now every one ready this see if I am correct as this car is a mess.
to really determine this I may have to just go from the rear end gearing...?!
The rear I know is original that’s a given as it has never been monkeyed with and is worn to pieces,
gears are 3.42!
this being said car should have the m20 or m22 tranny. I know I said I have the m21 but past comments on this sight have told me m21 should be with higher gear rears this marking this a incorrect geared tranny for the car.
If this is correct I should not have the VO1 or the G codes for HD cooling.
thus that should tell me that I would use the lower amp Alternator sound right????? Or am I over thinking this?
to really determine this I may have to just go from the rear end gearing...?!
The rear I know is original that’s a given as it has never been monkeyed with and is worn to pieces,
gears are 3.42!
this being said car should have the m20 or m22 tranny. I know I said I have the m21 but past comments on this sight have told me m21 should be with higher gear rears this marking this a incorrect geared tranny for the car.
If this is correct I should not have the VO1 or the G codes for HD cooling.
thus that should tell me that I would use the lower amp Alternator sound right????? Or am I over thinking this?
First, the M22 trans was not offered in 1968.
Second, both the M21 and M22 have the same 2.20:1 first gear anyway.
Third, as the SPECS booklet shows, 3.42:1 rear gears were one of the mandatory gear ratios dictated by the M21 option. Of course, while M21 meant you needed at least 3.42 gears, the fact that you have 3.42 gears does not mean that the car necessarily came with M21.
And finally, the alternator amperage rating has nothing to do with the trans or gears. Cars with lots of options (A/C, power windows, etc) got the 55 amp or 63 amp alternator. Other cars got the 37 amp alternator. This has nothing to do with the HD cooling issue. All that did was dictate the size of the pulley on the alternator. HD cooling cars got a different diameter fan pulley than did normal cooling cars. The alternator pulley diameter needed to change to match.
July 14th, 2019, 12:25 PM
#14
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Join Date: May 2012
Location: New Westminster B.C.
Posts: 451
The offset of the water pump pulley was one of the big changes from standard cooling to HD cooling. It was done to allow the belts to line up with the longer shaft water pump.
I am not as familiar with the 1968 model year but V01 in 1970 was a 4 core radiator.
Also a 3:42 gear W30 would not have gotten a 4 core automatically in 1970.
Hope this helps.
I am not as familiar with the 1968 model year but V01 in 1970 was a 4 core radiator.
Also a 3:42 gear W30 would not have gotten a 4 core automatically in 1970.
Hope this helps.
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