I just got most of the parts I need for the valve job on my 26. All new 1/64" over size stem valves with ream, springs, keepers and pins. My valves back ordered and will be here next week.I have a previous thread on build up around my valves in which it was determined that I had lost the cross hatch on my cylinders which would result in excess oil in the combustion chamber and that my valve guide to valve stem fit could be excessive, again resulting in excessive oil in the combustion chamber which creates heavy carbon build up on the valves themselves. I was talking to Jim at Neway about what I needed to cut the three angle valve seat. He recommended reaming the guide and then measuring the bore to determine which pilot/s I would need. He prefers solid pilots over adjustable since adjustable pilots can flex easier than solids and result in valve to seat concentricity issues. Bear in mind I don't have a concentricity gage or a split ball gage to measure the ID of the hole in the guide. I was hoping to use a telescoping gage to measure the guide ID. In the course of my discussion with Jim, he was asking about valve stem to guide clearance. I didn't know what to tell him. Can one of you advise me on that? I also need to know what the ring end gap needs to be and at what depth in the cylinder to measure it. Is it the same for the compression and oil rings? I am using aluminum 0.020" over size pistons. I will have to hone my cylinders as they have become mirror shiny. Also, I will be reaming the guides by hand. Which direction do you rotate the ream and do you have any advice for starting the ream in the hole and keeping it centered? The ream doesn't have a pilot or a starting taper.
Chester, Before you get started on the valve job look closely at the area from exhaust valve to cylinder to see if there is a crack there. I have found that about 70% of the 26-7 blocks have them, I will not buy a 26-7 block with out pulling the head and looking there been burned to many times. If there is a crack there then it needs sleeved and seated. Not to scare you but if you are going to all this work it is something to look at.
Chester, I am about to do the same to my intakes - new way cutters. Just read the instructions today. Wishing us both luck :-)
Hi: Im confused as to why the mirror finish bothers you. They are supposed to be that way. The cross hatch is only there to help the rings seat. It will wear away to a mirror finish. You need to check the cylinder to piston clearance. The books will show you how to do it. Also make sure to use the manufactures suggested clearance, if you are using new pistons. Aluminumn pistons need more clearance than cast iron. It is better to be a little loose than too tight with aluminumn as aluminumn is more prone to sieze the motor up if to tight. I once had a car that someone before me rebuilt. It had cam issues so I removed the head to check it out. To my supprise there were nice new cross hatch marks. But I also found brand new .060 pistons in .080 holes. No that is not a typo. I figure that the rebuilder bored it .080 and found out that .060 was the biggest he could get. Back then .080 was only offered in the high dome pistons for racers. Anyway I fixed the cam and put it back together. I drove that car for 3 years with no sign of oil pumping, piston slap or any kind of problem. The man I sold it to is still driving it and no problems yet. I would just do a good valve job and if the pistons fit fairly well put some rings in it and go. The major reason for oil pumping is the ring to ring groove clearance. Make sure the rings fit snug in there groove. If loose they move up and down in the groove as the piston is moving up and down. That turns the rings into a "oil pump". We sometimes over restore these old Ts and try to bring them up to modern specifications. They are a lot happier if a little loose. Not sloppy or worn out, just a little to the loose fit. Good luck with the rebuild... Donnie..
I still need to know ring end gap for the aluminum pistons and vale stem to guide clearance. I also still have questions about how to start the oversize ream into the guide so it cuts square to the seat. Here is a link to the event that started me down this road to the valve job. http://www.mtfca.com/discus/messages/331880/386145.html?1378602191
The truck wouldn't pull a hill and was real hard to start. It had been coming on gradually for about the last 1k miles or so but got real bad the last 300 Miles. Low compression on cylinders 2 &# prompted me to pull the head and have a look. I have burned exhaust valves on #2 and #3 and according to the posts, way more carbon on the valves than I should have for 3K miles since putting the engine back together. Two sources of carbon outlined were excess oil from worn valve guides or oil past the piston rings. Some posts suggested the mirror finish and lack of cross hatch on the cylinder walls was contributing to excess oil past the piston. When I clean up the block I will be sure to inspect it for cracks around the valve seats and cylinders.
Here's a 2001 thread regarding ring gap:
Chester, I haven't used the vendor supplied reams for the valve guides but I think they give you the right clearance for the valve as they are not adjustable, someone correct me if I'm wrong, as for ring gap, gas engines, .003-.005 per inch of bore diameter on all rings used on aluminium pistons.
Hi Chester. Do you have the "Red" Engine Book on engine rebuilding from the Model T Ford Club. I think all the vendors have it in there catalogs. If not you need it. It covers most of what you are asking. It shows that the valve stem dia is .3105 to .312 and the valve guide hole is .3125 that translates to a clearance of 1/2 of a thousands of a inch to 2 thousands of a inch. on a new motor. Basically they are saying a nice sliding fit to .002 of a inch. The stem diameter is so small there is very little thermal expansion in the valve guides. Since I personally like a loose engine I would use the .002 measurement. When I say loose I do not mean sloppy or worn out I just mean that I lean toward the loose measurement when I can. As to oil from loose valve guides they are not useally the problem in a valve in block engine. The oil is below the valves. It has a hard time making it to the pistons thru the guides. Mostly oil vapor. The big problem with loose valves and guides is on a more modern overhead. The oil is above the cylinders and can just drain into the cylinders because oil is pumped into the valve covers for the rockers. The big problem with loose guides on our engines is it plays hell with the fuel/air ratio. Which can cause ovrheating problems from a too lean mixture. As more air is allowed to slip past the guides and lean down the fuel/air ratio. As to piston to cylinder clearance it is not as critical on these model Ts. I would use the recomended clearance on the pistons from the manufacture as they can vary depending on type of material, style, and manufacture. The ring gap stated above of .003 to .005 per inch of bore is a good measurement to use. As to the mirror finish I do not see it as a problem. That is what you are striving for. The purpose of honeing and cross hatch is to give a very light "rough" finish to the cylinder walls. It is there so the rings and cylinders can "wear to fit" Cross hatch is only needed if replacing your rings. If you ever reuse rings they "must" go back exactly where they came from. I suspect that you have worn ring grooves in the pistons if you have much oil pumping. What happens is at TDC and as the piston is starting down in the bore the ring moves to the top of the groove. As the piston travels down it scrapes oil from the cylinder wall and partially fills the void below the ring, as the piston reaches bottom and starts back up the ring moves to the bottom of the groove and presses out about 1/2 of the collected oil. The other 1/2 moves behind the ring in the groove. When the piston reaches top again and starts down the ring moves back to the top of the groove and presses the collected oil to the area between the lower ring and second ring. If you repeat this process thousands of time you can see how the oil is "pumped" to the top of the pistons a little at a time. The rings need to be a nice clean fit in the grooves to stop oil pumping. Now back to the valve stem clearance. It can cause some problems if it is excessive. It will cause the valve to not seat true sometimes must "skate" into position to seal. That can cause missing, rough idle, burnt valves, and other problems. A good valve stem clearance is desireable but not necessary to have a good running engine. I am very curious to know what your ring groove condition is. Keep us posted... Donnie...
Chester: I forgot to say that the reamers you buy from the vendors have the clearance figured into them already. You just need to use the proper oversize reamer with its matching oversize valves. As to a guide for the reamer. "Stevens" tool company made a nice one in the day. It is a thick washer type item with a 45 degree taper to the bottom side of the washer/guide that will match up with the angle of the valve seat. The washer/guide has a hole in the center to match the diameter of the reamer stem. They also had a clamp that held the washer/guide in place while in use,that was held by a bolt in a head bolt hole. To use it you inserted the reamer into reaming position, then slid the washer/guide down the reamer stem and centered it in the valve seat. You then clamped the washer/guide into position and then turned the reamer with a wrench to reame out the old valve guide. Remember to "never" turn a reamer backwards to remove it. It will ruin the reamer. Just keep turning it as you did going in and put outward pressure on the reamer to remove it. Also keep it clean with a air hose as you reame. If you want I will try to find a pic of the "Stevens" reamer guide. Donnie...
Here is a link to the photos of this same job as I did it a few years back. Sorry for no running narative as I am going out the door to work. Do clean the crud from the intake areas as can be seen in my pics......
Erich, I noticed your ream has a smooth portion on the end to help start the ream in the hole. Mine doesn't have that. I think I need to see the washer Donnie mentioned above to help me get my ream started in the hole. Erich, did you ream your guides with the lifters still installed? It looked that way from the pictures but I just wanted to confirm.
I forgot to mention that I do have the Red MTFCA engine book and will study it before beginning work. There is a possibility that my valves will arrive today but I'm not going to start till I have all the parts and my Neway cutters.
Chester, not wanting to do more work than needed, I did try to do it that way at first but quickly learned the ream needed to go down into the space occupied by the lifters. They had to come out. That gave me a good reason to look over the whole bottom end of the engine anyway. The engine was in the car and the job was not very hard to do but my back was quite angry with me by the end of it. I did very carefully cover the lifter area and the whole valve galley to avoid getting the shavings into the engine. Go slow and easy. This ream was part of our club tool kit and it did a very true job. The last valve by the firewall I couldn't use the T handle so turned it carefully with a ratchet being aware of not imparting side load as I turned it.
I took full advantage of getting all the caked on crud out of the intake areas of the block. I was amazed at the amount of oil sucked past the worn guides. I would say you might leave the rings alone and do the valves first. It may be all you need. I used the stainless valves and seated them well. I used the double nut lifters and would get the single nut type next time.
Take all the time you need to set the clearances on the valves. With new springs you should note a much happier engine. I am running the stype cam and set my clearances at .010 as suggested. Very happy with the results. Get a nice new copper head gasket and spray it down well with the copper spray. Let us know how it goes.
Hi: I found a pic of the Stevens reamer guide. Its not the same as the one I used to have. The one I had did not have the long guides to support the reamer better. They may have added the long supports on a later version or did away with them . Im not sure. But the pic should give you a idea as to how it works. If you have access to a lathe, a person should be able to fab up something to act as a guide for the reamer that indexes to the valve 45 degree seat. I also thought a person could take an old hand "seat cutter" and remove the handle and drill out the handle hole to the reamer size to make a reamer guide with. Ive never made one that way but may be a cheap way to make a reamer guide.?? Donnie ...
I got my parts yesterday and started experimenting/practicing on a spare block I have. I discovered that the ream does have a starting shank portion at the beginning. What through me off is that it's fluted as well. I'm used to seeing the starting portion smooth. I cur one guide on the spare block to get a feel for how much pressure I needed to exert and how suceptible it could be to side load. I think I can do this with out any additional contrivances if I take my time and position myself square over the top of the block. I plan to take the engine out of the car so access shouldn't be an issue. I did take an old valve that had a good seat but a bad steam and made a ream guide yesterday but I'm not sure I need it. I'll post pictures of it soon. In the picture below, note the groove at the starting end of the ream, it denotes the pilot portion of the ream.
Studied on the "Red Book" last night and made a couple tools based on the article about valve timing and based on some posts here. I will contact Neway Monday now that I have the valves measured and a practice hole cut in the spare block to measure clearance. I know "Jim" at Neway prefers solid pilots for valve seat cutters but I think I need an adjustable pilot. I made the valve spring tension checking tool and used this on my digital bathroom scale to check my new valve springs. They all measured in between 28 and 30 lbs.