As the ***le says...I wanna swap pistons and I have a question for those who have been building 235 or just motors in general for longer than I have. My 235 is a '51, therefore it has iron pistons. I want to know if I can swap in ONLY aluminum pistons? My compression, oil pressure, timing gears, lifters, bearings and even gaskets are good so I don't want to strip this engine down completely. What I'm wondering is, if I pull the pistons out and replace them with aluminum pistons, as long as I put the rings back in the cylinders exactly as they came out will there be any issues? If I hone the cylinder I'll get metal shavings everywhere inside, I don't want that. The car runs fine now, I cruise at just above 50 which according to my tach is just over 2000 rpm, I just want to make it a little easier on the ole motor.
If it was me I would not do that without having it bored for a new fresh bore with the proper size piston. You will be glad you did.
I definitely know that's the preferable way to do it but then that pretty much leads to a full rebuild and unfortunately I'm not in a position to do that. My thinking is, and I may be completely off on this, that if I'm just replacing the pistons but not the rings than everything measurement, clearance and wear wise should stay exactly the same as it is now. I don't "have" to swap pistons, I just figured it would stretch out having to do that full rebuild for a few more years.
Like they say, "If it ain't broke, don't fix it." What is the problem with your stock pistons? What will you do if you break some rings?
I never thought about the rings breaking due to being old as s#@t. This is exactly why I asked this on here...in my mind it was a simple swap with no danger of anything going wrong. I needed other people's thoughts on it so I thank you all for your input. OK so when a ring job is done, is the crank taken out or is it left in place? If I'm going to essentially end up doing a full rebuild, it's going to be on a full pressure motor. The goal is to keep this as inexpensive as possible.
No need do this at all to this unless you are doing a complete rebuild or at least prepared to do a complete rebuild. These little Chevys used a combination of splash and pressure oiling. The rods were oiled by dippers that dipped oil and slung it into a tube that was aimed at the rod bearings. (due to brevity I may have some of the details wrong). Any way when you pull the pan on a "babbit rod six" extreme care must be taken not to malign these aimed tubes. The best thing to accomplish your needs is a higher rear gear ratio. Stock Chevys were low so upping the gear will make 60-65 so much easier on the engine.
Haha yeah it does sound like a ridiculous question now that the rings breaking are on my mind. The only motors I've ever done are small block chevy that were much, much newer and they all came apart without any breakage. If I end up doing anything with this motor, I will definitely have someone do the honing. The ***embling is easy enough but like I said, I was going for quick, easy and as non invasive to the other parts of the motor as possible. I'll just find a full pressure motor to replace this one when it dies
Unfortunately I have the powerglide so my rear end ratio is already as high as it can get (with the closed driveline). I do however still have most of the parts for the t5 swap I planned to do on my '54 (all but the Trans of course). As soon as I have the money, I'll be heading to the junkyard to grab all the factory 3 speed parts (well, most of them anyway) so I can lose the auto. That'll of course tone down the rpms quite a bit but I was thinking I'd have the best of both worlds. I suppose like was said above, if it's not broke...don't fix it
Most over haul jobs keep the pistons, clean them and install new rings. With a fresh hone crosshatch pattern. Use a dingle ball hone with oil and the resulting mess will not be hard to clean up. The particles are fine and suspend in the oil, not fly around like grinding or sawdust. I like the dingle ball hone for a over haul because it follows the contour and gets an even pattern. A 3 stone hone for an overhaul will try to true up cylinders removing material from the high spots and that will make the pistons sloppy by the time a uniform pattern is established. If I were taking the rings off, I'd be using new ones.
I want to know how you are going to change pistons without tearing the engine down. you will have to remove the head and the pan at the very least. I wasn't aware that GM built a 235 with iron pistons either. learn something new everyday.
I was planning on pulling the head and pan. What I meant was the motor, water pump, balancer, timing cover, oil pump and crank.
You are aware that if you swap aluminum pistons for iron ones you will throw the balance of your engine off correct? Are you sure that the engine that you have has cast iron pistons? if that is the case you will have to change the bore as you will no doubt want different cylinder wall clearance. Aluminum has a different expansion rate that cast iron. I am not doubting you I am just asking questions here that need to be asked to help you achieve your final goal.
Pretty much my plan was to, in this order...pull the head, pull the pan, remove the main caps making sure to keep the correct shims in the correct places, pop out the pistons, take off the rings, put on the aluminum pistons and re***emble in reverse order. Now of course this was ***uming there wasn't a ridge at the top of the cylinders so the pistons could in fact be removed. Instead, I'll find a '53 up 235 (or a 261...like that'll happen) that runs well and keep it on the back burner for when things go bad. I drove my '54 on the highway at 60 and I have full intentions on doing the same with this car. If it's not snowing, I'm driving it. From what I've read on here and the other site is not to drive babbitt motors at higher rpms for any length of time. Well, that kinda limits things to around town since at 60 I'm right about 2700 rpm and the motor let's me know it. The aluminum piston ides was to make the rotating ***embly lighter and therefore easier on the **** babbit.
No I definitely appreciate your responses (all of you guys) which is why I posted before tearing stuff apart haha. I thought about the balance issue and did a bit of research on it and apparently it isn't affected by the change. As far as I know (again this is just what I've read) all the dipper motors had iron pistons. As far as expansion rates are concerned, I never even thought about that until you said something
Babbit will take more of a beating than 2700 RPM, actually what knocks them out the quickest is idling too slow. That is not to say that you should scream it @ 4K for an hour and expect it to hold together.
As long as I can go 60 I'm good to go. I've just been afraid to push it past 2100 rpm for any longer than 30 or 40 seconds due to the stories of motors coming apart. If I knew I could ride at 3000 or less without any negative affects this thought of pistons would've never even crossed my mind. I guess what I'll do is try and get the t5 in first. On the gearing calc I used, it has my rpms at just about 2000 at 60 with the 27.something inch tires and 3.70 rear I'll be using.
i'm a flathead guy, but here's something to consider. there are the "steel section" or "multipiece steel" piston rings that are for a ring job on an older engine. i see them on ebay all the time. no hone is necessary with them, but my shop manual says they're better in an engine with cylinder taper in the range of .006 to .015. cast iron rings are for slightly worn or new cylinders and spring-backed rings good up to .006 taper, but both kinds need a hone. and your worry about highway speeds--we used to say you could drive a chevy with cast iron pistons 69 mph all day long, but they'd blow up after 5 minutes at 70!
When that car was built the speed limit was the same as it is today. I may be mistaken but I believe that you are running a pressurized oil system on yours and not dippers. On a dipper motors were bad to not oil as well but even those held together as long as they were not getting severe abuse. On a long ride it doesn't hurt to let off once in a while to **** oil to your top end. When those cars wee built the interstate highway system was not yet a reality and they were built to run what we would consider to be back roads today. On those old twisty roads you had to let off once in a while and so the engines were designed with that in mind.
I keep writing about the use of a ridge reamer. Nobody listens. Before you remove the pistons you should use a ridge reamer to remove the ridge that has built up in the cylinders above the top ring. I believe you could do that by using rags and grease to catch the chips in the cylinder. That should keep you from breaking the rings removing the pistons. But I just can't believe it would be a good choice to save that small an amount of money by reusing rings or gaskets.
I will not tell you what to do with that car and engine but if it were mine, I would drive the wheels off of it. If I wanted to go 70 I would simply mash the accelerator! I would not tear into it for little or no gain.....I'm shooting blanks here but I do know Powerglide engines got the best parts so it may have aluminum pistons in it already. Even if it does not, is there any real gain in swapping them out especially if it is a trouble free good running engine? A cam swap for higher end peforamnce? Yeah, I can see that. Dual carbs Yeah. Headers..split exhausts Yeah. Rebuilding a knocking smoking engine? Sure. It needs it. Swapping out pistons for (simply put) the hell of it? Nope. A lot of the "babbit" engines blowing up is BS. Many of the blown up up engines were on life support anyway. Most of these tales were trucks with low gear and were running much much faster than 60. In Californial Bills Chevy six book, they ran these engines 100-120mph with babbit rods. 2700 RPM personally I would not be concerned until 3500 or more. These engines are and were tougher than many give credit. Heck it's still running fine in your car. Again if it were mine I would drive the fire out of it as is.
You should be able to get the chips out prior to piston removal with a shop vac. here is something that Rich and myself probably never think much about but is a good warning on a ridge reamer. Don't go too deep. Until you get used to using one go a little bit at a time and only take the ridge and not the cylinder wall. I have torn motors apart that had been overhauled and were using a little oil only to find the cylinders pretty straight and within tolerance (albeit loose) except that the rebuilder got too heavy handed with the ridge reamer and the only recourse was to overbore.
I plan on driving it just as I drove the '54. I'm OK with staying at 60. Hell, between my old cj7, my old cherokee, my old '54 and my new to me cj7, I haven't seen anything above 60 (on 4 wheels) in about 15 years haha. I plan to drive to Carlisle, Hershey and even to ink and iron in Tennessee so anything slower than 60 won't cut it. Thanks everyone, I truly do appreciate all of your time. My car thanks you even more for keeping me from ripping it apart
I wonder if it would be a good idea to pull the spark plugs and run one piston up. Take a magnet on a expandable rod that they sell for picking up stuff. See if it sticks to the piston. If you have iron pistons you should be able to tell.
The reason I wanted to reuse the rings was so I didn't have to hone and get metal shavings in all the crevices. I was definitely going to use new gaskets however
Yes, but. 1953 was 62 years ago. Things may have changed in that time. 62 is a long time and those old motors got rebuilt well before 100,000 miles.
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