Piston Removal and Install

Dick Deegan

Dick Deegan

Well-known member
With the crankshaft out of the engine, is there any reason why I can't pull the pistons out from the bottom of the engine and reinstall them that way? I have a piston ring compressor. I want to do this to avoid having to remove the ridge at the top of the cylinders.

Any downside other than the pistons will be more difficult to reinstall from the bottom?

Dick
 
You can't just stick in new rings. You need to run a hone lightly and make a new cross-hatch pattern for the rings to seat correctly. That requires running the tool past both the top and bottom of the bore. You won't be taking off much metal, perhaps a few tenths. If you re-ring without honing you will have a nasty oil-burner with poor compression. Don't forget to measure and set the ring end gaps.
 
I agree with the other comments and will add.

The one thing not mentioned yet is what gets in the way... The main bearings extend past the bulkheads and prevent you from getting the pistons out. It's not a clear shot straight down.
 
If you try to pull the pistons out from the bottom you will be in a BIG mess. When the 2 bottom rings clear the bottom of the bore and the piston hits the main boss you won't be able to pull it any further or push the piston back up without compressing the rings and they are extremely hard to access from the bottom.
 
Thanks All; I will remove the pistons from the top. I don't have access to a ridge reamer, so can I hone the ridge off - or will I not live long enough to see it done?? I do have a cylinder hone.

Dick
 
Dick, if the ridge is bad enough to keep the piston from coming out with little effort, you will need to pull the engine and have it bored. Sounds like you are ready for a rebuild unstead of a freshen up.
 
Honing the ridge off won't work. I have seen pretty nasty ridges removed by hand with a set of machinist's scrapers, but that takes practiced skill. If you have a true cylinder hone with followers that hones to a set size as you crank out the tension, you will end up chewing up both the stones and followers as you cross the ridge. If your hone is only a spring stone deglazing hone you'll end up with a big radiused top edge trying to remove the ridge.

If you do buy a ridge reamer, there are two fairly low-priced ones out there- I have tried both. The KD, about $55 USD is a real piece of junk and will chatter, chew, and dull fast. The Lisle roller action reamer, about $60 follows the condition of the present bore (usually slightly out of round) and gets the job done without gouging. That said, I personally have an old Snap-on model 30.
 
When I was a teenager,a mechanic loaned me a spare bearing scraper & I used it to remove the cyl ridges on my 1st A & it worked very well.The ridge reamer I use is the type that has avery fine thread center shaft & as the cutter is turned,it advances up the ridge one thread at a time.Others styles seem to chatter quite a bit.Ive overhauled many engines that needed the ridge removed to get the pistons out with out breaking the ring lands & have rerung them & still got 50,000+ miles out of them before they started burning oil.Obviously,if the ridge is real bad,then a rebore is necessary.
 
If you buy a ridge reamer, make sure it it has a spring loaded cutter that will follow the shape of the bore per Mike K above, otherwise things will be all screwed up. Look at it before you buy it. You have no clue of the details like this if you buy it over the internet. And check it out if you buy it at a local parts shop. I say this because it seems to me that most parts and service dealers today have no clue what they are selling unless you have an "application number."
It is sort of fun at first to say the application is a 1930 Ford and the guy at the parts counter thumbs the book and says they do not have it, then you have to teach him that other "applications" may apply. That is why I buy locally, to see what I am getting (and it helps local business), or only buy internet from the Model A suppliers for Model A goods, or for things that have universal applications that are not Model A specific.
Basic rule of thumb for sloppy work, if the ridge is .010 or so, then get .010 over rings, measure the ring gap at the bottom of the bore to be sure there is is suitable gap, and it will work if you deglaze the cylinders. If you want quality work, bore out to the next oversize or whatever oversize gives you a consistent bore. If you use the reamer, you can let the reamer ride up to the top of the cylinder and put a small (1/16"") champher on the top of the cylinder and it helps burn off the end gases and inhibits detonation.
 
Last edited:
fordgarage said:
Cast iron ridges will cut easy, and you can use a quality high speed carbide router bit with end bearing to trim the ridge flush with the worn bore. . . . . . I have used a 1/2 inch Porter-Cable router.
Click to expand...

Max cutting speed for C.I. with uncoated carbide is about 400 F.P.M. A 1/2" cutter reaches that at 3056 rpm. That must be one slow router! Variable speed? My wood router only goes 21,000 rpm. But, if it works. . .
 
Dick - how bad is that ridge ?

I've got the heads off three A engines - one with 62,000 miles, one with 88,000 miles, and the third unknown mileage, but all three are still stock bore, with original factory pistons... there is a slight ridge at the tops of the bores ( barely enough to catch the edge of a fingernail dragged-across), and the pistons / rings come right-on out...

You might luck-out ?

SC Frank
 
Once again, thanks to everyone who responded to my questions about piston removal. I feel sort of stupid in asking the question about removal from the bottom. A quick look makes it apparent that this is impossible.

The ridge reamer that I would purchase, if I need to, would probably be the Lisle 36500 suggested by Bruce. However, I am also interested in the router solution. I have a number of routers and carbide bits and am quite used to using a router.

Before I do anything I will examine the ridge more closely. There is a lot of carbon on the ridge as well. I will remove the carbon and see just how big the ridge is and try to remove the pistons before doing anything further.

Once again thanks for all of the info. I will report back in a couple of days.

Dick
 
Whoa!!!!

The idea is to remove the ridge FIRST, so you don't damage the ring lands. I've seen them broken by removing the pistons before removing the ridge. If the rings don't slip past the ridge easily, DON'T force them.
 
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