CS 3/1 and 6/1 flywheels

[mikenash]

Hi there

I've been playing with a 6/1 and an ST head - just waiting on some workshop time to get the two of them onto a single base and - hopefully - running

I have been looking at belt-drives (Dieselgman Gary and others thanks for your thoughts/recommendations re serpentine pulleys - a great option but expensive over here with freight and the greenback/$NZ elationship)

I recently saw a seized 3/1 for sale cheap and bought it ("My granddad had it running ten years ago" says the owner) it has been outside for many years with an upwards-pointing open section of 2" pipe by way of an air (and rainwater) intake so we'll see what the internals are like . .

It has 2" crankshaft outers/flywheels just like my 6/1

Now I had been thinking of having one flywheel of my 6/1 grooved by a local machine shop to take two B-section belts; but that felt like a bit of a permanent step in possibly a wrong direction from which it would be hard to retreat

Now, that 3/1 will have a smaller (and possibly lighter) piston than mine but I wonder how much flywheel weight difference that would translate to . . .

I was thinking of swapping the flywheels and - if it ran OK - grooving one of them for belts and leaving mine "original"

I wonder if this is a stupid idea?

I guess there will be opinions, and I'd appreciate hearing them

Thanks, Mike

[32 coupe]

Mike,
Several of the guys run v belts on the flat flywheels with no problems.


Gary

[mikenash]

Mike,
Several of the guys run v belts on the flat flywheels with no problems.


Gary

Yeah I have heard differing accounts, Gary.  I suspect it depends on the quality of the alignment in maybe three planes, and the crown or otherwise of the pulley . . . .

It seemed to me, however, that the grooves might maybe double the contact surface?

Thanks for your response

Cheers, Mike

[BruceM]

I did a propane conversion for a neighbor using a DES 8/1.  It drives an air compressor and an ST-3.  We used a single B vee belt to drive the ST-3, running flat on the flywheel.  No problems with that pulling a full load and motor starts.  No alignment issues since there's a vee pulley on the ST-3.  Don't waste your time and money cutting vee grooves, there's plenty of contact area without it.

[mike90045]

until you have a ridiculously loose belt, it will never slip on the big flywheel.  The slip/chirp happens on the smaller alternator pulley, so that is the one to have grooves in .   Flat serpentine automotive/truck belts should be pretty common, and work well

[dieselspanner]

Hi Mike

Should you ever find any difference between the 3/1 and 6/1 flywheels, please would you post it up.

I've just rebuilt a Bitza into a 6/l on what I believe is a 3/1 bottom end, I've swapped the piston from iron to aluminium and this has moved the 'critical point' vibration from around 450 rpm to 660 rpm, thus making it a useful 6/1. I lack the balls to try and rev it to 800.....

As with all projects I've only spent far too much on it and have loads of bits left for the next one, it would be good to know if there is a difference before parting with more cash in the wrong direction!

Cheers Stef