Crankshaft pulley - cast iron, steel or aluminum

[Paul Bjarnason]

The crank pulley on my freshly rebuilt ($10K) motor is cast iron and I have heard that the cast iron ones can break, which would be inconvenient when on the road. I see that "Secrets of Speed" offers a billet steel pulley that is the stock size, but they are out of stock. Someone else told me that modern repro cast iron pulleys are "very good". So, what should I do - shall I leave the cast iron pulley on that came with my $10K motor or get the billet steel pulley? Call me paranoid but I want this to be right the first time.

[J Franklin]

I would leave it alone, trust the builder and drive your car.

[CWPASADENA]

I have many of tens of thousands miles driving Model A's with cast iron pulleys without a problem.

You are correct, there are currently available very good quality cast iron pulleys.

Chris W.

[alexiskai]

Reports of broken crankshaft pulleys on this board are probably less than 10 over the last 7 years, and none of those were on a fresh rebuild. Extremely low probability of failure.

[old31]

I have to ask. What was done to your engine to bring it up to 10k?

I know it can easily be done, just curious.

[Jack Shaft]

Sponsored Links (Register now to hide all advertisements)

The reason two piece replacements are available in part is due to the pulley cracking from torsional vibration. The harmonic balancer relieves torsional vibration, a leading cause of center main bearing failure.

[nkaminar]

I second the dampener.

[BRENT in 10-uh-C]

Originally Posted by old31

I have to ask. What was done to your engine to bring it up to 10k?

I know it can easily be done, just curious.

While I am not Paul to answer specifically, -as as engine rebuilder I can say that as you stated, it can be done if it is completely rebuilt with everything being returned to factory specifications. Add in a new C/W crankshaft, new connecting rods, flywheel mods, etc., and then have the peripherals restored where it can be run-in by the rebuilder so that it is a drop-in deal, and you are there.

[Big hammer]

Originally Posted by old31

I have to ask. What was done to your engine to bring it up to 10k?

I know it can easily be done, just curious.

I too was wondering, if new accessories, rebuild trans, etc $$$ adds up!

[Paul Bjarnason]

Here you go:


P.O. No.

Terms

Project

Quantity

Description

Rate

Amount

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

28-31 Rebuilt Model A Long Block with Inserts and Full Oil Pressure 6:1 Cylinder Head
Insert Mains
Modern Rear Main Seal
New Connecting Rods with Inserts for Full Pressure Balance Engine Components - Crank, Rods, Pistons Total Seal Gapless 2nd Ring
Counterbalanced Crankshaft Drill Crank for Full Pressure Performance Intake Valves
Lightened Flywheel/V8 Pressure Plate (Balanced as an assembly)
Touring Grind Camshaft Aluminum Cam Gear Upgrade Cam Plunger Limiter
Side and Front Timing Gear Cover Bolts
Install Cam Bearings
Machine for Oversize Tappets
Internal Plumbing Modifications for Oiling System Custom Valve Cover Machined for Bulk Head Valve Cover Bolts and Gasket
External Oil Filter, Fittings and Bracket
Oil Pump Drive Gear Assembly for Full Pressure New High Volume Oil Pump
Adjustable Oil Pressure Relief Valve Flywheel Housing
Engine Stand Core Charge
Credit: Hershey Show Special- No Core Charge PA State Sales Tax

3,495.00

325.00

800.00

210.00

375.00

225.00

125.00

495.00

250.00

275.00

425.00

95.00

20.00

75.00

10.50

495.00

95.00

450.00

55.00

5.50

189.00

65.00

395.00

48.00

250.00

50.00

880.00

-880.00

6.00%

3,495.00T

325.00T

800.00T

210.00T

375.00T

225.00T

125.00T

495.00T

250.00T

275.00T

425.00T

95.00T

20.00T

75.00T

10.50T

495.00T

95.00T

450.00T

55.00T

5.50T

189.00T

65.00T

395.00T

48.00T

250.00T

50.00T

880.00T

-880.00

610.68

Total $9,908.68

[Paul Bjarnason]

I apologize my cut 'n paste was so messed up. But, you get the idea, anyway.

[hardtimes]

Originally Posted by Paul Bjarnason

The crank pulley on my freshly rebuilt ($10K) motor is cast iron and I have heard that the cast iron ones can break, which would be inconvenient when on the road. I see that "Secrets of Speed" offers a billet steel pulley that is the stock size, but they are out of stock. Someone else told me that modern repro cast iron pulleys are "very good". So, what should I do - shall I leave the cast iron pulley on that came with my $10K motor or get the billet steel pulley? Call me paranoid but I want this to be right the first time.

Hey Paul,
Sounds like you are not concerned with stock. Good , IMO, as you have good options, eh!

I have two perfect condition stock pullies. Both came off B engines. I’ve looked them over closely... as to how you could break them. My conclusion... very abusive treatment... like dropping engine on pavement, using abusing pry bar and smashing with hammer.
If you engage in abusive style, I’d say carry extra equipment.

I personally have used the billet STEEL, and like them... bullet proof !
And, different sizes to achieve different goals.
Choice is good... and you have choices.

[CarlG]

Bill Stipe makes a billet steel pulley.

[Paul Bjarnason]

Thanks for all the input, gentlemen. As good as everyone says the modern cast iron reproduction pulleys are, today, I decided to eliminate all chance and ordered a stock-sized steel billet pulley. I'm just sure that if I had a cast iron pulley on my motor, mine would be the one in 10,000 that breaks while out on the road hundreds of miles from home.

[redmodelt]

Read the description;
https://www.snydersantiqueauto.com/P...shaft-camshaft
or
https://www.snydersantiqueauto.com/P...earchByKeyword

or the Riley type
https://www.snydersantiqueauto.com/P...earchByKeyword

[Jim Brierley]

Cast pulley's usually only break while installing or removing the engine from the car. Having said that, a steel or aluminum pulley is a good idea. A slightly smaller than stock pulley makes it easier to change the belt when needed. A damper is by far the best way to go, but not really necessary.

[Jack Shaft]

2500.00 a hole...phew,its just a model A..

[kawagumby]

Originally Posted by Jim Brierley

Cast pulley's usually only break while installing or removing the engine from the car. Having said that, a steel or aluminum pulley is a good idea. A slightly smaller than stock pulley makes it easier to change the belt when needed. A damper is by far the best way to go, but not really necessary.

Are you talking about a two-piece aluminum pulley with a steel collar? If not, I cannot imagine an aluminum collar holding a seal very long with either the packing type or neoprene type of seal. I own several high-end dirt bikes which are designed with overall lightness in mind...titanium, magnesium and aluminum are everywhere, yet, you will never find an aluminum collar & seal combo, always a steel collar. Perhaps a nickle or other electro-fused coating could help, but even then, the lifespan would be a fraction of a steel collar.

Originally Posted by Jack Shaft

2500.00 a hole...phew,its just a model A..

I have to agree, there's a lot of good stuff an extra $5000 will buy!

[Jim Brierley]

kawagumby, One piece. They hold up OK with the dog turd, maybe not so good with a lip-seal???

[Chuck Sea/Tac]

If it’s full pressure, then it should have the modern seal which goes on a polished pulley shaft. If you change pulleys, no warranty.