I just took apart a spare engine. It has iron pistons in it and everything thing looks good. I am thinking of just honing the cylinders and installing new rings for the pistons. The crank and rods move nice and smooth.
If I finally get around to building another Speedster, this is where the engine will go. Many of you still use your old iron pistons and as long as they are still good, why switch to aluminum? Save a couple bucks? Be happy in knowing this is the way Henry built it, so keep it that way? I want to use coils and not a dizzy when I finally get it together, too.
Positive comments please.
Go for it.I have one engine I did that way.
I also would like to know about iron pistons. I have a bunch.
I think, IF you can afford it, that all real advantages and disadvantages considered, GOOD aluminum pistons are worth the cost. The cylinder wear is less, the stress on the crankshaft (especially at higher speeds or at that dangerous low middle ground where you begin to lug the engine) is less and therefore less likely to eventually result in a two-piece crankshaft.
At average speeds, or if you get one of those bad sets of thick (and therefore heavy) aluminum pistons, there isn't enough advantage to warrant the extra cost. Especially if you are on a tight budget. Some years ago, I did have a set of aluminum pistons that were heavier than the original cast iron pistons. I often run cast iron pistons. So far, no trouble from them.
Drive carefully, and enjoy, W2
Go for it. Henry made 15,000,000 of them with cast iron pistons. They work just fine for a stock Model T.
However, if you are interested in better performance than a stock T, then aluminum pistons is the way to go. Murray Fahnestock compared cast iron pistons to heavy horseshoes on a plow horse, and lightweight horseshoes on a race horse.
I like to run aluminum pistons, Chaffin's touring cam (or your favorite high lift performance cam), and a Z head. Everything still looks stock, but the car performs with a little more oomph. I run Ruckstells with 3:1 gears in my 1915 runabout and my 1919 touring. Next time I have the Ruckstell apart from the touring, I will put in 3.25:1 gears as the 3:1 ratio is just a little tall.
: ^ )
Dave, I say go for the iron pistons also, but be sure to balance them and the rods also. It's amazing how much difference there is in the weight of these components.
Below is a table showing the weights in grams for a recent engine rebuild I did. The total weight difference is over 6 lbs of reciprocating weight. Certainly would be a kindness for your old crank.
PS Doesn't drive or sound any different.
New Aluminum Pistons (Lang's) .030 over
Cylinder 1 2 3 4
New (Al) 576g 578g 580g, 582g (5.1 lbs)
Old (steel) 1134g, 1132g, 1502, 1474g (11.5 lbs)
I wonder if the real issue with CI pistons isn't the weight so much as the unbalance.
I refer to the pistons, not the drivers.
You may very well be right, or it may be a combination of the two.
Maximum difference for the Al is 6 grams! For the cast iron 370 grams.
Of course it's possible that those 4 iron pistons didn't start out in the same engine. I wonder whether Ford made any attempt to sort components such as pistons and/or rods by weight when assembling the engines originally?
I like the extra low end torque you get with cast iron pistons. It's kind of like a heavier flywheel. I wouldn't put them in a car you want to drive on the highway a lot for the reasons others have stated.
I know that many will disagree, but the iron pistons can work very well. Some will say that they are harder on the crank and babbitt, and I would agree. However, I don't think that anyone has gone through the work to show just how much of a difference it makes over aluminum. It could be very small, or maybe not.
The problem is that your cylinders may be worn significantly. If they are, then your best bet is to get the block bored to the next size and get aluminum pistons accordingly.
In the end, if you want to build an engine with original iron pistons, I'd say go for it! Just make sure that they are balanced and that your cylinders are in good shape, and then all should be well.
Any time you can make factory original parts work is something to be proud of. Go for it.
Ford did weigh and sort the pistons for assembly.
From the encyclopedia
FORD PISTONS AND PINS
The finished weights of Ford pistons vary, maximum, about six ounces. Each piston is weighed and marked on the head by a heavy center-punch used without a hammer, with one, two, three, or four center marks, dividing the pistons into four weight classes, maximum weight variations in each class three-quarters of an ounce. After inspection, the inspector places the assemblies on one or another of four shelves, according to center marks on the piston head, and the pistons are paired for weight on opposed crank-throws by the motor assembler.
Cast Iron pistons add a lot to the demise of a crank as far as the weight goes.
Yes, balance also, but weight is a very big factor.
Dave, you may want to check the crank for cracks.
I would respectfully disagree that you get more low-end torque with iron pistons because, unlike a flywheel that benefits from inertia, a piston has to start from a dead stop, speed up, slow down, stop, reverse direction and speed up, etc. That reciprocating action prevents an iron piston from "storing" energy like a flywheel. According to the late brass-car guru, Harold Sharon, the ideal weight for pistons is zero.
Here is a link to a thread where we really got into the cast-iron piston question.
Wow!!! I am impressed. My car with cast iron pistons seems to have more momentum and less likely for the engine to kill at lower speeds. Maybe that is not low-end torque. Just what I have noticed in driving it.
Two of my 3 Ts have CI pistons and both run wonderfully. The 3rd is a restoration project and came with aluminum pistions. It ran well when last run prior to body being rebuilt. It seemed that the tow with old CI pistons run smoother and quieter than the one rebuild with aluminum pistons.
Cast iron pistons should be saved for the scrap bin. If the engine is running great, why did you take it apart? If it is apart, now is the time to put in lighter pistons. There's no negative to lighter pistons. Engines with aluminum pistons accelerate better, have less imbalance, and are smoother as a result.
If your engine runs good with cast iron pistons you can change to aluminum pistons and you will notice an immediate improvement in power and a much smoother engine, with no other changes.
I think that any dubious gains to be had from cast-iron pistons are surely offset by the disadvantages.
The chief positive for using cast-iron pistons that I can see is that they are cheap.
Some of the negatives (assuming the iron pistons are heavier, which they almost always are):
Higher crankshaft and bearing loads
Rings don't tend to seal as well
I feel the need to point out that a true FORD fan would keep any old parts regardless if they will be used again. I have 3 sets of iron pistons on the shelf and have no idea why.
I did what you're considering. I kept the iron pistons. It runs just fine and I'm happy with it. Each to his own, I guess.
One more comment intended to be helpful: If you're going to go so far as rings, shouldn't you also do the valves?
the engine with aluminum pistons was a rebuild of unknown origin and vintage prior to my purchase. I would not rebuild an engine and use Cast Iron pistons, I'd use aluminum for reasons mentioned in this thread. Alternately, I am not inclined to remove Cast Iron pistons from a smooth running but worn engine and risk non-seating of rings and accompanying noise from loose pistons in worn bores. The original engines will stay original until they need attention.
Your point on better performance, though, is noted and I agree.
This is out of the Model T Ford Owner.
This is one of the biggest reasons for lighter parts!
Out of Fast Ford Handbook
If you do decide to use aluminum pistons - don't throw the old cast iron pistons away.
Myself and three friends now have great pen / pencil holders for our shops. Clean them up, invert them and give to your buddies.
Not everyone can say they have a hundred year old pencil holder!
"use it up, wear it out, make it do, or do without"
PS If you have more than three good buddies, you'll have to restore a V8! ;o)