Fan clutch install 72 GMC C15 350 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

huntznsam · 07-24-2019, 08:35 PM

Another post about fan clutches prompted this replay. 2-1/2 months, 1250 miles, 7 fill ups. Old truck mods don’t occur in vacuum, however. I did play with the timing curve, and replaced a bad plug with a full new set. I installed a cheap manual choke conversion. The divorced choke was perfect all winter, but for the life of me I couldn’t get it to perform well in summer. After 2 weeks, I trashed it, bought a good cable, made solid brackets & linkage and it works perfectly.

So anyway, my tank-to-tank mileage has increased consistently, up 10%. Ten trailing is up 5%. My truck does like summer, but it has never shown such a regular increase.

How much is the fan clutch responsible for? Some, but exactly I can’t say. It is irrelevant. The free and easy acceleration and cruising more than compensate. At first, I was really enjoying the throttle, but as mileage increased every fill from 12.5mpg to 13.8 mpg, I’m sure some psychological factor came into play. My commute is consistent, averaging 45mph, anticipating lights for fewest stops possible. The truck is so much more enjoyable, I’d highly recommend the fan clutch conversion.

Stocker – the studs make aligning WP, pulley, and clutch a breeze. We sold them all the time back in the ‘real’ auto parts store. Many pumps even included them. Bolts are a pain in the dupa with limited clearance and a pump & pulley that want to rotate freely.

Minkota – TH350, 3.73 rear, 235/75R/15 Michelin Defender LTX, no tach but by the calculator about 2700 at 60 mph. Without that fan noise, we enjoy the revs coming so easy.

**Ironangel** · 07-25-2019, 01:51 AM

Good info! Thank you for sharing!

**Stocker** · 07-25-2019, 09:29 AM

Quote:

Originally Posted by huntznsam

Stocker – the studs make aligning WP, pulley, and clutch a breeze. We sold them all the time back in the ‘real’ auto parts store. Many pumps even included them. Bolts are a pain in the dupa with limited clearance and a pump & pulley that want to rotate freely.

Agreed, having studs there certainly would make life easier! Maybe I'll remember to get some next time I have to take it apart. Thanks for the tip.

**Grumpy old man** · 07-25-2019, 09:38 AM

O'rielly's has the studs for .79 each

07-24-2019, 08:35 PM	#1
huntznsam Registered User Join Date: Jul 2017 Location: Will Co IL Posts: 30	Re: Fan clutch install 72 GMC C15 350 Another post about fan clutches prompted this replay. 2-1/2 months, 1250 miles, 7 fill ups. Old truck mods don’t occur in vacuum, however. I did play with the timing curve, and replaced a bad plug with a full new set. I installed a cheap manual choke conversion. The divorced choke was perfect all winter, but for the life of me I couldn’t get it to perform well in summer. After 2 weeks, I trashed it, bought a good cable, made solid brackets & linkage and it works perfectly. So anyway, my tank-to-tank mileage has increased consistently, up 10%. Ten trailing is up 5%. My truck does like summer, but it has never shown such a regular increase. How much is the fan clutch responsible for? Some, but exactly I can’t say. It is irrelevant. The free and easy acceleration and cruising more than compensate. At first, I was really enjoying the throttle, but as mileage increased every fill from 12.5mpg to 13.8 mpg, I’m sure some psychological factor came into play. My commute is consistent, averaging 45mph, anticipating lights for fewest stops possible. The truck is so much more enjoyable, I’d highly recommend the fan clutch conversion. Stocker – the studs make aligning WP, pulley, and clutch a breeze. We sold them all the time back in the ‘real’ auto parts store. Many pumps even included them. Bolts are a pain in the dupa with limited clearance and a pump & pulley that want to rotate freely. Minkota – TH350, 3.73 rear, 235/75R/15 Michelin Defender LTX, no tach but by the calculator about 2700 at 60 mph. Without that fan noise, we enjoy the revs coming so easy.

07-25-2019, 01:51 AM	#2
Ironangel Senior Member Join Date: Feb 2010 Location: Falls City, Nebraska "100 Miles From Nowhere" Posts: 2,219	Re: Fan clutch install 72 GMC C15 350 Good info! Thank you for sharing! __________________ Michael of the clan Hill, "Two Seventy Two's" 71 1-ton Dually 350 4-Speed 71 C/50 Grain Truck, 350 Split-Axle 4-Speed 02 3/4 ton Express 14 Indian Chief Vintage 1952 Ford 8N, "Only Ford Allowed On The Property" "Be American, Buy American"

07-25-2019, 09:38 AM	#4
Grumpy old man Senior Member Join Date: Dec 2013 Location: Gods country East,Tn Posts: 8,545	Re: Fan clutch install 72 GMC C15 350 O'rielly's has the studs for .79 each __________________ 1967 Factory short bed - Old school '71 - 350 / 4bolt / 487 heads / Edelbrock C3BX Muncie M-22 4 speed / Hurst Comp plus Factory 12 bolt posi 3.73 / 255-70-15 Smoothed firewall / Factory cowl induction Power disc brakes / power steering / 3.5-5" drop



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