The Stovebolt Site Forums The Shop Area Engine Shop Finally, after all this time

Yes, fellow stovebolters, this is the momemt you have all been waiting for with baited breath......

After several false starts and cash deficient attempts, I have begun assembling my 261. A heated shop sure is nice, even though I am renting it from my mother-in-law whom I seem to get along with a lot better now (scary, ain't it). I had the block bored .030 and the piston fit is perfect. The standard crank miked very good, so standard bearings are going in (.0015-.002 rods and mains clearance).

One thing that still puzzles me a little. As I was tightening down the rear main bolts to 110 ft lbs with my 6 month old Snap On torque wrench, 3 of the 4 bolts began to stretch. The threads were perfect on the bolts and the block, and I ran a tap and die on both to make sure. Luckily I had an old junk 235 laying around with good rear main bolts, so I cleaned them up and use them in the 261. I have never had main bolts stretch before. The bolt holes did not have any liquid in them. Anyone run into this before?

All I have to do is put in the pistons in #1 and #6 holes, slap on the 848 head I redid last winter, install my split manifolds and prepare to drop the engine in my '42 1.5 ton. It seems like every week I get another 2 cylinder John Deere tractor to work on so the truck had better be ready to do some hauling/towing.

Also, how tight is the pinch bolt supposed to be for the wrist pin clamp on the rod. I tightened them to 35 ft.lbs. since it was a fine thread 3/8 bolt, but it sure didn't say the exact torque in the 1958 Chevy shop manual I was using.

Racecarl,
I don,t know about a 261, but I just looked it up in my ole Motors manual for a 235, and it was 35 to 45. Hope this helps you out. BTW when I was a kid we always used 235 specs for 261's.
Dennis

Racecarl, two things about stretchy head bolts. Some head bolts are intended to be stretched as this guarantees that the bolts all hold with the same force. I have not seen this type of bolt used on anything older than about 1980. Second, if you have an old set of bolts that stretch while being tightened, this is indicative of major overheating of the bolts at some time and annealling/softening of the steel. Throw them in the junk bucket to be used as pins or something later in life. Glad to hear you are making progress, can't have Tony enjoying all the fun rebuilding motors!

Ken, I got another Chevy 6 on the way here.A friend is a outboard boat motor collector.He came across a free? Chevy 6 cylinder boat engine. He says its the newer style. Hope its a 292.Probably is reverse rotation. Come on Racecarl ,get that engine together.At one time I searched all over for a set of NOS 235/261 head bolts.Never found any.Finally got some off a junk engine.Mushy head bolts are unpleasant.

Yes, I had the same thing happen to me when I assembled my 261. The rear main would only hold about 85 ft/lbs. Picked up some ARP studs and was able to get the full torque.

One more thing to add to what Ken said. Severe overtorquing could also be the reason for overstretching of the bolts. Remember that when you are torquing a bolt to specs, the design is to stretch the bolts slightly.

What are you using for lube on the bolts. Torque values are based on using engine oil. If using anti-seize or moly compound deduct 10% from your value. Do not try torquing a dry bolt. ARP has a good article on their website about the mechanics of torquing bolts, even shows how to measure your torque by measuring bolt stretch, which is far more accurate.

Thought about you Saturday, was at an antique tractor pull. Gonna get one of those ol johnny poppers going to do some pulling?

Well, I don't feel so bad about these rear main bolts, since it happened to someone else. Tonight I took my 6 year old son along with me to the shop and he 'helped' me install the #1 and #6 pistons. We then installed the cylinder head and torqued it down. The head bolts all were fine. On all the bolts I use a light coating of 30 weight oil.

On John Deere engines, the head bolts are 9/16" and are tightened to 90 ft lbs and then turned another 90 degrees. The head bolts marked SPECIAL are used in high output engines and are turned 130 degrees after torquing. The rod bolts are torqued to 60 ft lbs and are turned an additional 90 degrees.

On the rod nuts on the 261, I lost some of the little stamped steel 'pal' nuts. I have some fine thread jam nuts at work that would fit all right, what would be the harm in installing the jam nuts with locktight? I would use the jam nuts on all the rod bolts, just to keep thing even.

CC to Fred--I have my first customer's tractor in the shop now about half torn down waiting on him to tell me how much he wants to fix. I have 5 more to fix up, including 2 complete overhauls, so I better quit messing around with this truck motor and get back to the two lungers. At least I will be better able to use the truck after the 261 is installed. After I get this bunch of tractors done, I should have enough money to really be able to go through my 51. Maybe I can get it fixed up like Steve's someday.

As far as pulling, if they weigh the tractors and you are rated on what percentage of the tractor's weight you are able to pull, nothing beats a John Deere B, 50, 520, 530. These are not big tractors but they really pull hard. A good running stock B will usually pull 110% of its weight every time.

I hate those pal nuts. With the thin jam nuts you don't have to use loctite, but it certainly wont hurt. At some time in the 50's Chevy quit using the pal nuts, didn't use anything but the regular nuts.

I don't know just what they were using for classifications. In the class II, the Allis-Chalmers WC's were outpulling the J.D. A's. Most of the B's were in class III. I wasn't able to stay long enough to see the whole show. Was told a 68 binder took the top prize overall, but the guy who told me didn't know what class he was in.