Inliners International Forums General Discussion Engines 261 engine - cracked front crank end cap

My engine buddy suggested I take the new bearing cap and the old bearing shell and smear a fingers worth of clean engine oil on the shell and the crank. Then mount the cap and in increments of 10 ft/lbs test how easy the crank turns by hand. I started by torquing the bolts to 30 ft/lbs and the crank turned just as easily as it had without the bearing cap. I continued in increments of 10 ft/lbs up to 90 ft/lbs and the crank was just s easily turned as it was without the bearing cap. I didn't want to press my luck at 100 ft/lbs, but will do that tomorrow. My engine buddy called me the luckiest guy in Dallas. More to come, but in the end the crank will still come out.

That will show that is not too tight but plastigauge will show if it is too loose. While handling the bearing shells have noticed if they have an oversize mark?

So today, I used the green plastigauge to check the newly acquired bearing cap with the original bearing shell and this was the result.





Did I hit the bearing cap lottery?

I would be curious to see how the clearance differs with that of the original cap. Given the clearance the new cap is providing - is there any reason to remove the crank at all?

I did use the green plastigauge on the original bearing cap and shell. While the strip was compressed, it was somewhat less than with the new cap. As it turns out, I forgot to take a photo before I had wiped it off.

As for not removing the crank, while that is possible, my engine builder buddy noted that with the McCulloch supercharger I have for this engine that it would be prudent to have him machine a slot in both the crank and the harmonic balancer for a Woodruff key to help support the torque that the supercharger could put on the crank. He's coming for a visit to inspect the engine on Thursday and I plan on asking him about that further. This truck won't be taking part in any drag racing and maybe I don't need both a belt and suspenders.....

My 80+ year old engine builder buddy showed up today and was impressed with the condition of the block and head. He's going to allow me to work with him on it, learning what I can. He wants to use a dial gauge on the head to ensure that it both straight and flat. He also suggested sonic testing the cylinders given that the cylinders were previously over bored.

Other that we discussed us doing a few others things "while we are at it" such as line boring the block, dipping the block and head, replacing all the freeze plugs, boring a hole in the head that gets tapped, and rattle can painting of the block and head. Seems these engine had a historical problem with over heating due to air in the back of the block/head. By tapping this hole, the engine can be "burped" to get all the air out.

By early next week he's going to give me an estimate of cost and timing, given his other semi-retired projects.....He agreed with me that a small block would be fun and faster to get done (Summit could have one here on Monday), but he also said that my setup with the supercharger and magneto would be too cool to pass up.

His only comment to me was that if the block should fail any of his tests, he'd rather not have me spend a silly amount of money to make it work, when a small block is an option.

There are lots of 270 blocks out there partly because of the expense & difficulty on finding performance pistons.

As you might imagine, I'm getting a little impatient with my "semi-retired" engine builder. He's a great guys with decades of engine building experience for hot rods, race cars, Bonneville competitors, and normal street engines. For a guy that is retired, he seems to have a lot on his plate.

As a result, while I've heard from him that he working on a plan, no real progress on my end has been forthcoming. The engine sits on the same engine stand I bolted it to many weeks ago. My best friend and the guy who sold me the truck has continued his suggestions for either an LS or a small block, which I have resisted for multiple reasons. I recently was told that there are companies that sell re-manufactured straight six engines. If I could get a 261 inline six, I could continue to use my McCulloch supercharger, bell housing and Saginaw four-speed transmission. So far in all my searching I've not found a 261, but I plan on calling a couple of the companies that Ive found with other straight sixes. Anyone aware of companies that I should contact?

Admittedly, this is Plan B as I'd still like to have this engine repaired, but I'm getting impatient........

I retired over 20 years ago and I don't know how I ever found time to work. Maybe it is that retirement doesn't have a schedule and I just think I'm busy.

I doubt if you'll find someone that could build a 261 who has one to rebuild. May be best to take yours to someone else. Texas should still have guys that can do it.

I know it has been a few weeks since I had an update on my engine issue and I thought I give a one now. After waiting weeks to hear from my semi-retired local engine builder for a plan (he was searching for the tools needed to work on my engine). I found a shop in California that not only had the tools necessary but 1) he is convinced that he can either repair my cracked end cap, or 2) make the replacement end cap I had sourced on eBay work, or 3) build me a new engine from one of the several 261 blocks that he acquired.

As a result, I waited another week for my local buddy to get back to me after I sent him a text, then finally I made the decision to load my engine block and associated parts (pistons, lifters, push rods, water pump, intake/carb, magneto, etc onto a pallet and today I shipped the whole kit and caboodle to him.

He expects to start work on it the first week of April and told me to expect four to six weeks for the the whole cleaning, machining, repair, paint, and rebuild. He also will put the engine on a test stand and set the timing, valve clearances, and test the engine for leaks.

It will cost a bit more than I had hoped but from the look at other engine he rebuilt and sent me pictures of, I'm excited to get a rebuilt engine (hopefully my original block) back into the truck finally. More to come as I get updates. Thanks for hanging in there with me.

Thanks for the up date! This will not be the least expensive choice but you'll end up with a tested engine with the class the truck deserves. Nothing cookie cutter here. Thanks for sticking with it and please keep us up to date.

I know I am a little late to the game here but I thought I would mention a few things. Line boring these blocks is not really anything you want to do unless you absolutely have to. Every main is a different size and the machining process changes the orientation of the cam and crank gear, as well as the neoprene rear seal. So if you are going to go this route, you must make it clear that the absolute minimum amount of material possible is to be removed from the caps before the boring, yes boring not line honing.

Me, I would probably weld up/braze the broken lower part and skip the expensive line boring.

The issue of the screws coming in from the pan side to secure the timing cover was a left over from the main shim era. With the big trucks, after a lot of miles, you pulled the truck over the work pit, pulled the pan, removed the two screws from the front main cap, and from there you could remove the bearing cap and adjust the front bearing. Or, you did an in chassis rebuild, including the adjustment of the main bearings. Otherwise, if the screws were threaded to the main cap from the front of the cover, you would have to tear the radiator out, remove the screws from the front, which you may or may not be able to do with the balancer installed, and then pull the front main cap to adjust that particular main bearing.

After 56, the bearings were precision bearings, no shims, and so no adjustments. GM just opted not to redesign the timing cover, plate and front cap.