MTFCA Forum

I know they exist, I have one that is in another engine. I would like to find a couple (at least two) of .0025" oversize Ford pistons. They are stamped accordingly on the tops. You might not even know you have them until you clean the tops off.

Trying to save my engine the cheapest way possible, vs. buying $150 for aluminum pistons and rings + boring the engine.

Let me know what you have. You can IM me here, or email crazydart400 AT yahoo.com.

I would hate to say how many I have threw away! I will look tomorrow to see if any are in the scrap pile.

You mentioned "a lot of movement" on pistons 1 and 2 on another thread. 2 & 1/2 thousandths oversize will not take up "a lot of movement".

What are the piston diameters now, and what are the cylinder dimensions for diameter, roundness, and taper?

I must be missing something...

No Scott, your not not missing anything. Even .0025" oversize wont fill the hole, but it will help. Your asking all the right questions, and I know all the "proper procedures" for building engines, have all the tooling, and have been building 60's-up V-8 engines for other people for 20+ years. I'm just looking for a suitable temporary fix without engine removal, and turning into a giant ass project that will keep me off the road while I continue to collect parts for the replacement engine to build. Did I mention proper built T engines are NOT cheap?!

In case you need to know, using my dial bore gauge from the bottom side (which means I cant get right on the major / minor thrust sides), I have about .009"-.012" bore difference from the standard 3.750". I'm just looking to take some of the piston knock out of this for a while---a band aid fix.

I'd think that you'd be looking for .005"-over pistons, then, with those numbers. Best of luck on the hunt.

Wasn't aware they made .005" pistons. If anyone is still reading, I am now looking for those also.

Thank You

I have seen some .005 pistons over the years, but don't know if I still have any, or if they are good enough to use. I have a couple that the markings are not eligible, but I know they will not quite work in a nice standard bore. I don't think I have a good way to measure them either.

Putting .0025 or .005 pistons in a worn standard bore is risky if you do not check things very well. The taper and oval of the worn bore can allow the pistons to fit and work very nicely in the top half of the bore, while the bottom half can still be way too tight to actually be run. I did this to myself some years back because I didn't check the fit well enough. The pistons in the engine were bad matches, and a couple were in poor condition. so I replaced them from pistons I had at the time. Apparently one or two of the pistons I tried to use were slightly oversize, and although they went in all the way down, and seemed to work fine cold, when I started and tried to run the engine for a few minutes, it would seize. It could not be cranked over again until the engine cooled down for about a half hour or so. Then It could again be started, run for a couple minutes, and seize again.
A good ridged hone can clean up taper and oval without enlarging the more worn top half. I highly recommend getting one and properly fitting the oversize pistons.
Most common hones today are not ridged hones. They will clean up the bore to help new rings seat for a refresh. But they can not straighten taper or oval. Most common hones today simply follow the bore and will make it look okay, but the taper or oval will still be there.

Bump.

Wayne, I don't want to take it apart until I find some pistons, But I do have all the tools to measure bores and tapers. Based on my experience, the .0025" will drop in no issues, the .005" would definitely have to be checked for the precise issues you state. Im just looking for a band aid fix here.

bump .. Anyone?

You can have your pistons Knurled to expand them.

I had two sets of NOS oversize pistons, one .025 OS the other .005 OS . I sold one set years ago but have the other set still. I paid $100 for each set, I guess Im a pretty generous guy LOL . If you're interested email me and I'll check out which I have.
I may have a set of used OS, I can check that out as well. Let me know if you're interested.

I had .0025 pistons in my 09 when purchased 40yrs ago. When I joined the 2 piece crank club, one got smashed but I still have the other 3. Only trouble is I am in the UK, so the postage cost may be excessive.

Your best shot is having your pistons knurled. .0025” or .005” pistons that are unused are practically extinct. You might find a set but it would be an unlikely find. Used pistons that “look okay”, will have .002” to .005” (or more) wear. The T cylinder has a tendency to have a belly in the middle. The “usual” situation on an engine that has been together for several decades (or many miles) might be an .008”-.010” belly slightly below the middle of the bore, and .004” piston wear. On a T motor with cast iron pistons, the slap noise becomes noticeable at about .008” total clearance. Slap noise is louder and at a smaller clearance with aluminum pistons, usually noticeable at about .006”.

You could also machine a larger oversized piston to the size you need. I imagine you could acquire a set of oversized cast iron pistons very reasonably.