Rupunzell
Bernice Loui
It turns out the 74' needed an alternator as the one that came with the car was never working.. properly, the lack of an alternator light with the ignition switch on should have been more than a clue as problem.
Resulting in a dead battery.. A quick DVM check with a newly charged battery measured only 12.5V and dropping under load..
So, rather than getting the original Fiam alternator rebuilt or replace it with an later Bosch alternator.. I decided to install a Denso alternator from a Toyota Camry, Avalon, ES300. These are good units, reliable, durable, small, easily availiable and rated at 80 Amps, 14 volts running.
Here is the Denso Alternator next to a Marelli from a 79'.. This alternator is about the same size as the Bosch units used in later EFI cars.. Note the smaller size of the Denso -vs- Marelli.
The Denso pulley is a 6 groove flat belt, the X needs a 3/8" wide Vee belt.. So off came the pulley from the Marelli alternator for a trip on the lathe. The rear of the pulley has been relived similar to the stock Toyota pulley to clear the alternator body and set up the belt alignment. This clearance relief is tapered by 10 degrees from center about 0.10" deep x 1.30" on the ID.
The front pulley nut recess on the stock X pulley is not deep enough, so it is counter bored 0.20" deeper. And, the shaft hole gets enlarged to 0.670" to fit the Denso alternator shaft. Not shown is a 5/8", 0.125" thick SAE washer between the Denso alternator shaft/bearing to space the modified X vee belt pulley to get proper spacing and alternator body clearance.
Next, the stock lower alternator bracket is cut down from 72.3mm to 40mm initially on band saw to "rough in the cut" then finished in a mill. Note the corner re-entrant radius at the corner to prevent a corner crack from starting. The modified bracket is deburred and all sharp edges removed.
Here is the modified bracket painted and compared to a stock bracket. A FIAT twin cam head bolt is proper lenght and thread (M10x1.25) for the Denso alternator mount.
The top bracket consist of a support bar that mounts on the water pump housing and an adjuster bar and block.
The support bar raw made from 2024 aluminum bar stock. It has a 15 degree relief cut into it for the adjuster bar's rod end. The M8 bolt holes are 52mm center to center, M8 socket head bolts are 40mm long.
The adjuster bar is made from a 1/2"x 20tpi left hand threaded 4140 alloy steel threaded rod, ~3.5" long. One end has been drilled for 5/16"x24tpi right hand threaded rod end and the adjuster rod has been drilled from the other end to reduce thread engagement of the rod end side (it also lightens the part, HA!). A 1/2"x20 left hand jam nut held on by a 1/8" dia. x 3/4" long roll pin to allow turning of the adjuster bar. A jam nut lock the adjustment when set.
The block is 1018 steel, 1" x 1.2" x 0.75", The 0.75" side is threaded for 1/2"x20tpi left hand, and a 5/16"x24tpi threaded hole is for the top alternator mounting ear.
Here is the assembly mocked up before paint.
Same parts painted, front side.
The back side showing the 15 degree counter bore for the rod end bolt. This 15 degree counter bore is required to stop any bending force on the rod end bolt & nut.
Denso alternator and brackets installed in the X.. Top view:
Same, bottom view:
Same, end view:
Part two will be wiring up the Denso to the 74' electrical system.
:bla:
Bernice
Resulting in a dead battery.. A quick DVM check with a newly charged battery measured only 12.5V and dropping under load..
So, rather than getting the original Fiam alternator rebuilt or replace it with an later Bosch alternator.. I decided to install a Denso alternator from a Toyota Camry, Avalon, ES300. These are good units, reliable, durable, small, easily availiable and rated at 80 Amps, 14 volts running.
Here is the Denso Alternator next to a Marelli from a 79'.. This alternator is about the same size as the Bosch units used in later EFI cars.. Note the smaller size of the Denso -vs- Marelli.
The Denso pulley is a 6 groove flat belt, the X needs a 3/8" wide Vee belt.. So off came the pulley from the Marelli alternator for a trip on the lathe. The rear of the pulley has been relived similar to the stock Toyota pulley to clear the alternator body and set up the belt alignment. This clearance relief is tapered by 10 degrees from center about 0.10" deep x 1.30" on the ID.
The front pulley nut recess on the stock X pulley is not deep enough, so it is counter bored 0.20" deeper. And, the shaft hole gets enlarged to 0.670" to fit the Denso alternator shaft. Not shown is a 5/8", 0.125" thick SAE washer between the Denso alternator shaft/bearing to space the modified X vee belt pulley to get proper spacing and alternator body clearance.
Next, the stock lower alternator bracket is cut down from 72.3mm to 40mm initially on band saw to "rough in the cut" then finished in a mill. Note the corner re-entrant radius at the corner to prevent a corner crack from starting. The modified bracket is deburred and all sharp edges removed.
Here is the modified bracket painted and compared to a stock bracket. A FIAT twin cam head bolt is proper lenght and thread (M10x1.25) for the Denso alternator mount.
The top bracket consist of a support bar that mounts on the water pump housing and an adjuster bar and block.
The support bar raw made from 2024 aluminum bar stock. It has a 15 degree relief cut into it for the adjuster bar's rod end. The M8 bolt holes are 52mm center to center, M8 socket head bolts are 40mm long.
The adjuster bar is made from a 1/2"x 20tpi left hand threaded 4140 alloy steel threaded rod, ~3.5" long. One end has been drilled for 5/16"x24tpi right hand threaded rod end and the adjuster rod has been drilled from the other end to reduce thread engagement of the rod end side (it also lightens the part, HA!). A 1/2"x20 left hand jam nut held on by a 1/8" dia. x 3/4" long roll pin to allow turning of the adjuster bar. A jam nut lock the adjustment when set.
The block is 1018 steel, 1" x 1.2" x 0.75", The 0.75" side is threaded for 1/2"x20tpi left hand, and a 5/16"x24tpi threaded hole is for the top alternator mounting ear.
Here is the assembly mocked up before paint.
Same parts painted, front side.
The back side showing the 15 degree counter bore for the rod end bolt. This 15 degree counter bore is required to stop any bending force on the rod end bolt & nut.
Denso alternator and brackets installed in the X.. Top view:
Same, bottom view:
Same, end view:
Part two will be wiring up the Denso to the 74' electrical system.
:bla:
Bernice