flathead alt conversion belt help
Cross-Country
Joined: Jul 2003
Posts: 86
Likes: 0
From: Evans,GA
Harley's right, the correct measurement would be from the back of the bracket; that is, the front surface of the intake manifold in the "slot". On mine, with narrow belts, "X" = 3.5". (This is looking down on the bracket from the top) PS, mine has 1-3/8" long spacers like shown on the ad. Y think you would want to make them longer, not shorter, for wide belts?
One thing never discussed is that these really need a brace back to the manifold IMO.
One thing never discussed is that these really need a brace back to the manifold IMO.
Did you see Bobs post where he measured 3.25 inches from intake to center pulley? Hes suppose to have the same bracket as you from CAE, but he has the 5/8's pulleys. I get the same 3.25 on my original set up with the gen. Thats good news, except how does that make any sense? Yours measures longer with more narrow pulleys? If everything is constant except the pulley, then it would seem like ours should be the longer measurement. Then, I just had an another idea. Maybe the center of the pulley was designed to stay constant on either size. But I guess in that case we would all get the same measurement and those co's wouldn't be warning that the bracket wouldn't fit the trucks. I think I'm going to measure one more time.
M Joiner
Update: Just for future reference the correct numbers are: Intake to center orig. pulley is 3 5/16 inches.
Cross-Country
Joined: Jul 2003
Posts: 86
Likes: 0
From: Evans,GA
Mitch J
Senior User
Joined: Dec 2008
Posts: 104
Likes: 1
From: Central Florida
I finally had a chance to install the slingshot on my '49 and am finding the same problem with the belt...too short to go over the pulley. I would like to keep the height as low as possible and stick with the stock belt, did anyone have luck trimming the mount? In the absence of that, what belt size ultimately worked? I'm using the Speedway version.
Ross-you mentioned that the intake "slot" can be fixed. That turned out to be broken on mine too. What is the fix? I still have part of the driver side one holding it in place for now.
Ryan
Ross-you mentioned that the intake "slot" can be fixed. That turned out to be broken on mine too. What is the fix? I still have part of the driver side one holding it in place for now.
Ryan
Fleet Owner
Joined: Jul 2004
Posts: 27,288
Likes: 1,053
From: NM
Is your manifold aluminum or cast iron? I don't recall where I said it could be fixed, but it would be an aluminum manifold I presume. What reallyt matters is the big bolt, the slot is not that important IMO, as long as there is enough to keep the bracket from turning while you're adjusting. ONce that big nut is cranked down, it takes a lot to rotate the bracket. If yours is really bad and is cast iron, and you have the pieces, you could get it brazed back together. By far the easiest thing for a stock cast iron manifold is to just buy another one, they rarely sell for more than $10 (shipping is another matter).
As far as the belt, are you trying to slip the belt over with the alt in place (raised up)? Try putting it in the pulley with the alt as low as it will go, then raising the alt.
As far as the belt, are you trying to slip the belt over with the alt in place (raised up)? Try putting it in the pulley with the alt as low as it will go, then raising the alt.
Senior User
Joined: Dec 2008
Posts: 104
Likes: 1
From: Central Florida
Yes, the intake is cast...didn't realize they were so cheap! I'll look to replace it at some point, but there seems to be enough to hold it while tightening. I wonder how it broke in the first place?
The alternator mount is as far down as it goes in the slot. I think the stock belt is 52" and it appears to be about 2" short. My setup may be a hybrid too as the pulleys on the water pumps seem to be narrow--belt rides pretty high compared to the crank pulley. I will pick up a couple of belts to try I guess...just wondered if anyone had the magic number. It's looking like maybe 55" based on the other posts here.
The alternator mount is as far down as it goes in the slot. I think the stock belt is 52" and it appears to be about 2" short. My setup may be a hybrid too as the pulleys on the water pumps seem to be narrow--belt rides pretty high compared to the crank pulley. I will pick up a couple of belts to try I guess...just wondered if anyone had the magic number. It's looking like maybe 55" based on the other posts here.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Fleet Owner
Joined: Jul 2004
Posts: 27,288
Likes: 1,053
From: NM
They can break from having the shoe cocked in the slot, when tightening the big nut. Especially with fat-fender trucks with generators, it's hard to keep everything in place while leaning way over the fenders. Also from being dropped!
Hotshot
Joined: Oct 2009
Posts: 16,155
Likes: 4,754
From: Burbank, WA
That could be the answer to your problem/question. If you have narrow belt pullies on the water pumps and wide belt pullies on the crank and generator, that will not allow the belt to sit right in the w/p pullies and "use up" potentially a couple of inches. You also won't get good contact at the water pumps, causing possible slipping problems and undue belt wear. If this is the situation, you may want to look into changing water pumps/pullies to the correct, matching type.
Fleet Owner
Joined: Jul 2004
Posts: 27,288
Likes: 1,053
From: NM
That could be the answer to your problem/question. If you have narrow belt pullies on the water pumps and wide belt pullies on the crank and generator, that will not allow the belt to sit right in the w/p pullies and "use up" potentially a couple of inches. You also won't get good contact at the water pumps, causing possible slipping problems and undue belt wear. If this is the situation, you may want to look into changing water pumps/pullies to the correct, matching type.
Senior User
Joined: Dec 2008
Posts: 104
Likes: 1
From: Central Florida
Ok, this is actually a car motor, but it looks like I have the correct truck water pumps and pulleys per the PO installation. I did, however, need a longer belt to make it work. It appears anything from 55" to 57" works safely within the range of the Speedway bracket. I used a 57" because that is all the local parts house had in stock. Next time I'll order one a bit shorter so the alternator wiring harness isn't stretched to the limit. Now I just hope I don't have the "harmonic" vibration issue with it up so high...
Thank you everyone for the help!
Ryan
Thank you everyone for the help!
Ryan
New User
Joined: Apr 2011
Posts: 1
Likes: 0
Alternator Conversion - belt issues
I ran into this discussion this evening, and I know that you have found a solution, but I was having the same problem with my truck (1950 F-1 Flathead V-8). I found a 12V neg ground alternator conversion kit at MAC's Antique Auto Parts (New York), bracket, wide pulley and alternator fit like a charm, but the stock belt didn't fit. I was able to find a longer belt at NAPA (25-22553) that did the trick. Now I just have to find an easy way of tightening the fan belt. 
Lester
----------------------------
1950 Ford F-1 Pickup
(Getting a makeover to 12V)
Lester
----------------------------
1950 Ford F-1 Pickup
(Getting a makeover to 12V)
Fleet Owner
Joined: Jul 2004
Posts: 27,288
Likes: 1,053
From: NM
PS -- welcome to the forum!