I am ready to install the pistons in my 59 ab block. Which direction does the squirter hole go? Also, I've heard that three rings work better than four. Can you use three rings on a four ring piston?
It is better to run a three ring piston than run a four without the lower oil control ring. The skirt will be slightly less stable. Having said that, I have built many flatheads and left of the lower ring set. Ford had oil control problems and hired some former Olds to cure the consumption problem. Their solution was the four ring configuration. That cured the oil consumption problem but caused a new problem of causing the top compresszionring to run too dry and overheating. Anyone that has torn down a later flathead and seen the top ring broken and segmented crawling over bits of each other an attest to the dry ring damage. Leave of the bottom ring and live with the miniscule piston rock and oil consumption and not cook the top ring. I learned all this from a couple of old Ford mechanics when I was just startingout in the early 60's. Believe me the pluses far out weigh the minus'. Or if you haven't purchased pistons yet, get three pistons to start with.
Not a method I would endorse, but back in the 50s, an older friend built his own engines for oval racing, dirt and asphalt, same car back then. He would take a hacksaw, and using the 4th ring groove as a guide, he cut that part of the piston off.
Thanks. The pistons I have are like new, but I may check on some three ringers. I'm running an Isky Max-1 cam, Offy heads and deuce intake. What do you think about scrapping the fiber cam gear and going with aluminum ?
Pistons are designed to have back and side clearance in the grooves. Rings do not stabilize the skirts. they are free floating in the grooves.
What finn said. I have pulled down lots of flatties with the bottom oil rings omitted. Pretty much standard procedure among old pro mechanics around here. Sawing the pistons off would raise balance issues, I would think. Hard to get them all the same.
I didn't say I agreed with sawng off the pistons at the 4th groove, just that this was his tactic when he was too broke to buy a set of 3 ring solid skirt pistons. Balance? man this was back in the day when everybody was bucks down and a balanced rotating assy was out of reach for most all of the guys. I actually encountered this same guy late one night in the post office lobby with a set of pistons and a file, using the small set of beam scales mounted to the lobby table for weighing letters and packages in order to follow the weight/price chart on the wall!
The 4 ring piston was also used by the English and I saw a lot of those growing up. PArt of the idea was when an engine was reconditioned 4 ring pistons would be supplied. On the initial install you used 3 rings and left the 4th one out cause it scrapped too much oil away from the top three rings. However as the engine wore and you would do the old rings bearing and valve job you would slip the 4th set of rings in to help with the oil consumption. And once they wore out and you were tight on money you would take those pistons and get them micro-peened up inside the skirts to expand them to reduce the bore to piston measurement and reduce/eliminate piston slap. The next trick after that was to drill a hole in the skirts and compress an expander ring into the back of the skirts to keep the piston under tension and to keep that bore/skirt clearance minimal. All this was done to make the piston last as long as possible because we could not get new parts at a good price. Any one old enough on here to remember NZ in the 50's through to the early eighties will recall there were fierce import restriction left over from WW2. Rootes group cars were supplied new with 4 ring pistons which had the bottom 4th set slipped in once the engine used to burn oil
That's a lot of good info. Have you had any problems with ring gap? I have stock 3-3/16 bores and had bought stock rings, the problem is, I have about 0.030 end gap at the top and bottom of the cylinders. It looks like it has new sleeves installed. Could I get 0.020 over rings and file the gaps?
Yes you can take .020 rings and file the ends to suit. It would be better to use say .o1o rings but they would be like rocking horse manure to obtain
Something isn't right here, either with the rings or the bore diameter. And also if the bore is 3-3/16, and it has sleeves, then somebody sleeved it, as I never saw a 3-3/16 bore block with OEM sleeves. Unless you've checked the ID of these cylinders yourself, then you need to check them, or if you don't have the proper tools to do so, then get it checked by someone you know and trust.
I'll measure them again. This engine appears to have been rebuilt and not run very much at all. But it had set in the car for a long time. At some point it had moisture in a couple cylinders that stained the bores but had not pitted. I checked the top of the bores with a vernier caliper and read 3.187" I have mics and telescope gauges I can double check.
Here are a couple pics. You can see the sleeve line on top of the block. I measured again and it may be closer to.3.192". I thought I had 4" Mics, but mine only go up to 3".
Appears that you have a block someone has bored, sleeved and bored back to stock bore. They may have added a few thou. for extra clearance. Maybe for solid skirt racing pistons?????? And with the circumference increasing by a factor of 3. 142, this would account for a lot of your excess ring gap. On edit: I think I would get hold of a 4" mic somewhere and check both the bore and the skirt diameter 90* from the wristpin bore and about 1/2-3/4" above bottom of skirt. Are you planning on split skirt or solid skirt pistons?
Appears to be a split skirt piston, 4 ring, and I hope somebody here has some idea what clearance to run these and you find a 4 inch mic to check things.
I wish I could find the original rings I took off. I may have to get.020 over rings and fit them. I will get some Mics tomorrow at the shop.
Well, I got a good measurement on the cylinders and pistons. The bores are 3.193 and the pistons are 3.187 at the skirt. 0.006" different. I remember having the bores power honed. But if a standard bore is 3.188 then these pistons seem too large. I can't find any specs on piston diameter.
You now have .006" clearance, and I'm not at all sure what it should be, as I have no good idea what those pistons are, except your pic seems to show a split skirt 4 ring piston. I haven't built a flathead in about 55-60 years and I no longer have any books or specs for the piston clearance, but if my memory serves me correctly that may be a little loose, as in pistons if they are split skirt, a little small for the cylinder bore, not too large, however, again IIRC that would be about right for a solid skirt piston, in an engine pushed hard in competition. If you have access to any flathead manuals, or diy books on flatheads try to figger out what type of pistons those are for sure, or maybe on Ford Barn. But I'll bet with a 4th ring groove they are split skirt. .006 is a little loose, at least in what I can recall but I'm sure there were many, many engines reringed with piston clearances larger than what you have related.
Dirty old man. I have assembled many flatheads using the hack saw on the 4th ring. I have also on race engine's not installed any oil rings. This was good for 100 to 150 laps of racing. Most of the timeon race engines I left the old oil rings and installed compression rings. But that was over 50 years ago when you could buy very good running flatheads for 25 dollars. Very few people wanted them. every body was installing overhead engines in their hot rods.
K9, you do go back a ways also, back to the time when flathead stock blocks, cranks, etc. didn't bring much more than scrap price, LOL! Am I correct in thinking you had to use more piston clearance for solid skirt pistons vs split skirt "stock type"? Do you remem,ber the clearances recommended? And do the pistons GMiller shows in his pic look like split skirts to you also? Gard to be absolutelt sure with just that one pic, but I don't recall ever seeing a 4 ring solid skirt flathead piston.
Here ya go guys. They look like solid skirt pistons. And they are also knurled. I ordered a set of 030" over rings today from Midwest Early Ford. I am going to try and fit them. The only thing, they only have one oil ring.
Question: Are you measuring piston dia. on those knurls? That's why they are knurled, to exp;and them and take up some excess clearance. Comment: That sure looks to be a split skirt piston Wild ass guess: Being a retied 40+year general machinist who spent the last 24 years of working career in aircraft jet engine repair, and knowing quite well also of the quality of the work coming out of many, but thank god not all, automotive machine shops and the length some so called machinists will do to try to cover up a fuck up before it leaves the shop and work long enough before failing that maybe they can blame it on something other than their work being not in tolerance specs. So slick bored the block for the sleeves, pressed them in, and somehow bored/honed for the pistons, but got them too big. So then to get it to run long enough to throw off the blame, the piston skirts were knurled to tighten things up for awhile, the present condition being the final result. Way in the back of my mind,and way back further than I put absolute trust in my memory, lurks figures kinda like .003-.004 clearance for flathead split skirt stock type pistons, and .006-.008 for solid skit racing pistons. This part I'm fairly safe on. Now where I'm getting way back in the dark corners: Seems that I remember that stock type pistons were sized for proper clearance with a dead on bore ID. IOW: for proper clearance on stock type 3&3/16" bore, the bore would measure 3.1875 and the pistons would measure 3.1845. But for a set of solid skirt aftermarket pistons the piston OD was on size at 3.1875 and you honed to around 3.192-3.194 for your clearance. Then along comes someone trying to use split skirt stock type 4 ring pistons, so they knurl the skirts to try to tighten things up. Or either someone has taken stuff from 2 different engines to try to assemble one. All just theory, mind you.
That sir, makes a lot of sense. I tried to measure the skirt on the smooth surface. And yes I agree on your theory about how this thing was thrown together. That's probably why all of the specs don't add up. And so I'm faced with a decision to put it together like the last knuckle head, or make it right. This is the part of this hobby that I enjoy most! Thanks for the thoughts, I'm going to do some thinking about this today.
The Jalopy Journal
