What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Alternator to fit on Lycoming 0-360 vacuum pump drive drive

scottjohnsontampa

I'm New Here
I am replacing my vacuum AI & DG with Garmin g5's so I can rip out my vacuum system. There are two alternators by B&C that fit the vacuum pump drive. They are 1.) B&C BC410-H SD ALTERNATOR 20-30 AMP
2.) B&C BC462-H ALTERNATOR 35-45 amps. Does anyone know if the larger alternator that produces 35-45 amps will fit on a lycoming 0-360 vacuum pump drive mounted on an RV-6A? Also, are there any other options for a vacuum pump drive alternator I should consider? I do have a primary alternator from Vans, but desire to have a second one after I have pulled out the vacuum system.
 
I have used a B and C 8 amp with second battery in the past, and am doing the same in my current build.
 
I am replacing my vacuum AI & DG with Garmin g5's so I can rip out my vacuum system. There are two alternators by B&C that fit the vacuum pump drive. They are 1.) B&C BC410-H SD ALTERNATOR 20-30 AMP
2.) B&C BC462-H ALTERNATOR 35-45 amps. Does anyone know if the larger alternator that produces 35-45 amps will fit on a lycoming 0-360 vacuum pump drive mounted on an RV-6A? Also, are there any other options for a vacuum pump drive alternator I should consider? I do have a primary alternator from Vans, but desire to have a second one after I have pulled out the vacuum system.

I used the B&C 20 Amp on the vac pad on my 7. The electrical is set up as per the Aeroelectric plan with an E-Buss. In the event of a main alt failure the BU can be turned on and run minimum electrics, if required, on the E-Buss. In my situation with 1 EFIS & radio, LED lighting, transponder & 496 BU GPS the BU will run it all with no problem without switching to the E-Buss.
 
Question from Osh

I asked this question of B&C at Oshkosh 2019. They said the smaller one fits no problem. The larger one will fit, but it seems to cover the mechanical tach drive on the 0320/360 Lycomings. But for a Garmin panel, from what i understand, the mech tach drive is not used, rather the G3X gets the tach signal from the mag.

There is a post a few years ago about this ( using the vac paid as the prime alternator).

One thing to note is I think the vac drive RPM ratio is 1.3:1, so the alt rpm is lower than a standard belt drive alt. This will be OK for my all-Garmin system with LED lights, but for others the alt may not put out enough juice.

This is my plan for my 9A. I have no knowledge about anything RV-6, so i am only speaking for the Lycoming compatibility. YMMV. JMHO.
 
Last edited:
Answers on B&C for 360

FWIW the little SD8 on my RV3 does a great job. How much backup juice do you really need.

The 462 WILL clear the oil filter ( Lycoming/Superior adapter) and the tach drive casting. B&C has been advised with pics that filter clearance is about 1/16 inch.

As noted above, the 1.3 drive ratio inly puts out 30 amps at say 2400 cruise RPM.
 
The B&C 20 amp alternator is a superior product, and when used with the B&C standby voltage regulator, normal installation has it running in parallel with your primary alternator. The standby alternator output is zero if the primary alternator is operating. In other words, if your primary alternator fails the 20 amp standby alternator automatically picks up the load - no pilot action. You will know this happened by two indications:
- Bus voltage will go from your normal (~14.1vdc) to the whatever you set the standby alternator at (~13.5vdc).
- The nice little yellow LED provided with the standby voltage regulator will come on.

This is about as simple as it gets.
Carl
 
Back
Top