Topic: fan belt adjustment

coupeman    -- 03-10-2017 @ 10:50 AM
  Anybody have suggestions on how to adjust fan belt slop with engine in the car. I have a 48 flathead v8 and I need to adjust both the generator and fan assy belts, as you know the generator is heavy and awkward to hold in place while you tighten bolts, fan assy is not heavy but is also awkward to hold in place while you tighten bolts. I would like know what method could be used to help me since this is a one man(old guy) operation.

carcrazy    -- 03-10-2017 @ 11:31 AM
  To adjust the generator belt, loosen the large nut on the bracket that holds the generator to the intake manifold, place a crowbar or length of 2X4 between the bottom of the generator and the top of the intake manifold, lift up on tool you are using to gain the correct belt tension while tightening the nut. To adjust the fan belt, loosen the two bolts that retain the fan assembly to the generator bracket and pull up on the fan assembly by hand to obtain the correct belt tension while tightening the two bolts. Check your belts tensions after the adjustments have been made and readjust if required.

This message was edited by carcrazy on 3-10-17 @ 11:32 AM

cliftford    -- 03-10-2017 @ 3:12 PM
  I do this in much the same way, but I use a screw type valve spring compressor, the curved type, to hold the generator up while I tighten the gen nut. I just stick it under the gen. and tighten the hand wheel till I get the proper tension on the belt. Then I adjust the fan.

This message was edited by cliftford on 3-10-17 @ 9:35 PM

deluxe40    -- 03-10-2017 @ 7:16 PM
  I got a piece of 3/4" x 1/8" steel strap about 14" long, a piece of 5/16 x 18 threaded rod about 10" long and two nuts the same size. I drilled a hole in the 3/4" piece of steel about 4" from one end and put a slight bend upward at about 5" from the same end. I threaded the hole in the strap to fit the rod and locked the two nuts together on one end of the rod. I put the short end of the strap under the generator from the passenger side with the hole above the blank hole on the same side of the intake manifold. I screw the rod into the threaded hole aiming it to fit into the blank hole in the intake manifold. As I screw down the rod (with a short handled ratchet) it bottoms out in the hole and lifts the strap up along with the generator. I hold the long end of the strap in my left hand to adjust the generator while I test the belt with my right hand and then tighten the bolts. On my '40 the fan is on the crank and doesn't have a belt. On my '51 there is no blank hole in the intake manifold so I drilled a slight indent into the top of one of the manifold bolts to locate the rod. Once the generator is solid, the fan is easier to handle. I did this about 10 years ago and the tool has served me ever since. I think I read about it in the V-8 Times.

39 Ken    -- 03-11-2017 @ 4:40 AM
As deluxe 40 said, the belt adjustment bar can be found in the JAN/FEB 2006 issue on page 18. The tool was made by Chuck Ferencz from Ohio. The article, also written by him showed that he made the tool using aluminum bar stock 1/2" thick by 1 & 1/2" and 17 1/2" long. Chuck drilled and tapped a hole (3/8-16) 4 1/2" from one end and used a 3/8" carriage bolt for the adjustable fulcrum. Good tool. Works great and lasts a long time.

deluxe40    -- 03-11-2017 @ 10:02 AM
  39 Ken: Thanks for the correct reference. It would have taken me a long time to find it. And, thanks to Chuck Ferencz for publishing the directions.

coupeman    -- 03-11-2017 @ 6:45 PM
  Thanks for all your inputs, I 'll busy making a tool from the ideas.

Drbrown    -- 03-12-2017 @ 9:12 PM
  Maybe my '47 is different ..... From the passenger side, I stick my socket extension shaft underneath, nest the end of it on the coil bracket that's bolted to the top of the driver's side head, and lift until the gen/water pump belt can only be depressed about a 1/2 inch. Next I use a pry bar on the water pump housing to tighten the fan belt.

This message was edited by Drbrown on 3-12-17 @ 9:17 PM

len47merc    -- 03-13-2017 @ 5:50 AM
  It should be the same Drbrown. These custom tools are 'nice to haves' but an extension or pry bar is all you really need as you say. I use a 12 1/4" long heavy shaft Craftsman screwdriver and it works fine, using the top front of the manifold under the generator as the fulcrum.


TomO    -- 03-13-2017 @ 7:07 AM
  Drbrown, you are adjusting your belt too tight, and it may damage the generator bearing or the water pump bushings. The correct adjustment is 1" of deflection half way between the water pump and generator. See your Operator's Manual.


Old Henry    -- 03-13-2017 @ 7:43 AM
  I use the handle of my large crescent wrench under the generator right against the front generator bracket on top of the manifold. See picture.

len47merc    -- 03-13-2017 @ 11:04 AM
  Same as Old Henry - just with a screwdriver for me.

Regarding the belt deflection specification/tightness, I too always adjust mine as TomO states and have never had a problem or prematurely worn belt; however, Fig. 11 on Page P-4 of the 1942-1948 SHOP MANUAL shows 1/2" FREE MOVEMENT as the tightness setting. I typically tighten just to the point there is no excess belt movement at rpm which equates to approximately 1" deflection. You be the judge of what works best for you.


6lucky13    -- 03-13-2017 @ 2:47 PM
  I agree with Tom and Steve's recommendations. I damaged the front bearing on the generator by overtightening the fan belt. After replacing the generator eventualy one of the water pumps froze up. After installing new water pumps, I tightened to 1" deflection. Runs fine now.


Drbrown    -- 03-13-2017 @ 8:38 PM
  TomO, len47merc, 6lucky13 .... regarding belt tightness adjustment: I should have described my adjustment of my belt deflection in a more detailed manner. I tighten both belts as stated in the Ford "Service Manual" for 1946-1948 Fords, Chapter VI, Section 365, page 174 P365.a.(2) which says for gen and fan have approximately 1/2 inch movement EACH WAY (fig.113)". The Operators Manual I have is silent on the issue. So I have been using the 1/2 inch deflection, from the belt's static position, according to the Ford Service Manual which results in a total deflection of 1 inch. This appears to be a common spec. I have the wide belt and so far have not had any problems with pump bushings and bearings.

TomO    -- 03-14-2017 @ 9:03 AM
  Drbrown, I did not realize that there was a change from 1940 to 1942 and later. The 1940 Mercury Reference Book, (owners manual) states "permits 1 inch inward or outward movement of the belt" and the 1946 Service manual staets a 1/2 inch movement in each direction, as you said.

This change was probably made due to the smaller generator pulley and the higher amperage generators used in the later cars.


supereal    -- 03-16-2017 @ 12:52 PM
  I have been using an old tire iron for years to tension both belts. Be aware that old Fords require a difference width and pitch than modern vee belts. They are best sourced from a reputable dealer in vintage parts. It is important to observe the correct "give" when the belts are tightened, or the generator and water pump bushings will be damaged, as will the fan with the builtin oil reservoir. Ford used belts that gain traction from the sides of the belt so they didn't have to be overtightened to prevent slippage. If you have belts that must ride at the bottom of the pulley groove, you have the wrong type.

This message was edited by supereal on 3-16-17 @ 12:55 PM

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