Inliners International Forums General Discussion Engines Sleeeving a 261

You posted this over at stovebolt and I wanted to say a little more over there but just was not possible. Here is my take on this. It is possible to run that block to .100. You would want to sonic check the bores. I have a 261 in the back of my garage that I had checked and it would theoretically go to .100. Needed .030 to clean it up. Got to .030, started to see rust staining on the fresh bore from the cylinder itself. That was it, that block would need sleeves to go any further. Myself, I do not like to go any further then .080 which is where you are now. So just from this point, you could bore to .100 and get new pistons, or install three sleeves and use your .080 pistons.

Yes, you can sleave the entire block back to standard. It’s expensive no doubt but it is not an unusual procedure. You would be what they call dry sleeving (overboring the cylinder and installing a sleeve within the overbored cylinder) as opposed to wet sleeving (essentially removing the old cylinder and replacing). No issues in my mind except for the cost. Once done, you have nice round strong correctly machined cylinders with plenty of meat for another couple of rebuilds. I might go for that my self because I agree those blocks can be a bit of a pain to come by but the cost vs. replacement may not balance.

The deal breaker for me is the misalignment issue you apparently have with the mains. These 235/261 motors have their peculiarities. One of which is the fact that each of the mains is a different size. So in order to do the job, you have to set the block up on center, machine some material from each cap, and then machine each main saddle individuallly, hoping that you can take as little material from the block side of the main saddle as possible. The time for set up and machine work is expensive. If the block is in really bad shape, a pretty good amount of metal from the block side will have to be removed. Now, that in it self is not unusual for a lot of other motors but with theses motors it presents a few little issues.

As you know there is no timing chain on these motors, just what Isky used to call immaculate timing, gear to gear. When the crank gets moved more into to the block, the crank also gets closer to the cam. So you run into head long into gear tooth interference with the cam and crank gear, depending on how much the align bore moved the crank toward the cam. For a 235 with a fiber cam gear, ignoring that issue is usually catastrophic. The cam gear disintegrates with the gear teeth shoving too deeply into one another. Once that happens, you promptly bend a couple of push rods and intake valves. With the use of an aluminum cam gear, not so much but you still have the gear teeth meshing and stressing and possible breaking, noisy, metal particles, eventually leading to the same result. So the cam gear/crank gears have to be clearanced.

Now you will need to degree in the cam after you have clearanced the gears. With that kind of movement, the cam timing events may end up being off a bit. So to get it right, you have to sort out where each event, exhaust and intake are happening, sort out where they should be happening, and the send the cam out to a cam grinder for correction.

Then you have to deal with the rear main seal. If it’s an early motor, no issue, you just cut the rope seal a little closer, but if a later motor with a neoprene seal, you have to modify the neoprene seal, and hope you got it right, not to much off the ends of the seal, and not too little, otherwise leaks. The other alternative is to use the rope. So, it’s not just the expense of the machine work to take into consideration lots of other stuff. For me and maybe you too, this is too much work, money, aggravation and potential trouble. Believe me, there is nothing worse then having to pull a motor multiple times to fix or trouble shoot a bunch of problems.

Just as an FYI, I have built a lot of these motors over the years, close to 50 (all as a hobby, not professionally). I have never had a 235/261 block that needed a main bore alignment. Frankly, I am pretty sure if and when I ever do, I will take a pass on doing it. It’s just not worth the trouble, expense and effort. You will be Way ahead time and money wise by hanging in there and finding another block. With a block in better condition, you can do a basic rebore, machine the top of the block, new pistons, and you have your self some good bones to work with.

I apologize for not saying a little more on this to help you figure out which direction to take when you first asked your question over at stovebolt but holy cow, could not get a word in edgewise without getting bazooked, lol. Whew.

That being said, if you look at our classified ads, there is a member who is selling a couple of 261s. Maybe he has one for you!