The Stovebolt Site Forums The Shop Area Engine Shop New to me 261

I suppose this is more of a project journal than anything but I'm sure I'll have questions com up along the way so I'm posting it to The Engine Shop.

Here's on question: So far as any of you parts experts know, did Chevrolet supply 848 heads with valve rotators on 261 truck engines. This appears to be a crate motor installed at a later date. Do all rear motor mounts fit all years of 235 powered trucks? Will a six bolt clutch fit inside the old 9-bolt clutch bell housing, if I find a Six-bolt flywheel? Are twelve-volt starters available outright or only exchange?

A 261 I bought sight unseen from an auto wrecker showed up on the freight truck yesterday. The block casting I'm told matches the Wrecker's description as a 62 - 261. It has an 848 head with exhaust valve rotaters, a PCV system, big vacuum connection for vacuum brakes and no air cleaner. Too bad, that. It also has no oil filter and does not appear to have ever had one.

I pulled the valve cover and things look reasonably clean inside but when I pulled the plugs, which were all only hand tight, they were quite black. There is no serial number stamped by the distributor and the sheet metal is painted yellow while the castings are bright orange. A tag wired on says among other things "Note 140PSI."

I conclude from all these clues that this was probably a crate, long-block sold sometime after 1962. I might have gotten lucky and not have to overhaul it before I use it but it has no flywheel and no bell housing so I can't run a compression test until I get them from some other motor. Besides, good compression doesn't necessarily mean it isn't using oil. I use the pickup that it's going in daily so I don't want that apart for weeks on end while I wait for parts or machine work.

As you probably know, a bellhousing, flywheel and clutch from a 235 will bolt on and work OK- - - -the only real difference in the 235 and the 261 is the bore size- - - -even the crankshaft is identical to a 235. The setup you describe sounds like the engine spent its time in a big rig- - -particularly with the big vacuum connection. The 848 head and valve rotators sound like it's been built up and upgraded a little. 235/261 exhaust valves are identical in head diameter, stem diameter, and length to a small block V8. When rotators were used on the SBC, the exhaust valve springs were about 1/8" shorter in overall length than the intakes to compensate for the thickness of the rotators. Good luck!
Jerry

Rotators:
https://www.stovebolt.com/ubbthread...valve-rotators-need-advise-see-pics.html

Rear mounts:
The mounts go between the bell housing and frame crossmember. The design of the crossmember changed in 1954. For example, to put a 1954 235 engine in 1949 frame, use the 1949 bell housing and 1949 mounts.

Clutch questions (did you look here?):
https://www.stovebolt.com/ubbthreads/ubbthreads.php/topics/1278237/all/clutch-info-needed.html

Starters:
Both. Used outright. Rebuilt (rebuilding service), you pay core price and get get deposit back when old one sent in. Most rebuilt sales will specify core charge if one is required.

Oil filter:
Hard to believe but an oil filter was optional.

Tag with 140 PSI:
Maybe a cylinder compression test was performed. Results were 140 PSI or higher on all cylinders.

In the order of importance, what I follow to identify a 261 engine.

Captain's bars
Block casting number
Block date code
Block serial number (near distributor)
Head casting number
Head casting date
Engine color
(record results, pencil in your owners/shop manual)

With debate on engine colors:
1954 green
1955 green some may be yellow (mine was green)
1956 yellow
1957 yellow
1958 to 1963 green

Orange is the V8 color but is also the most common spray paint used by Chevrolet engine rebuilders. Looks better than rust.
When it came to 261 engines used in working or commercial big trucks, parts are parts as long as they are interchangeable.
Appearance is less important. Whatever it takes to get the big truck back in service.

Bouymaker: Thanks for the info. I'll use the pre-54 bell housing. I can now see why the sheet metal is yellow. Unit was probably a crate motor swapped into a '56 or '57 truck. So far I have seen no rebuilder's tag but I'll keep looking. I wonder if Chevrolet just painted everything orange in the replacement engine department. Both the head and block are orange, everything else is yellow. For some reason I dislike orange. Maybe it dates back to some ill-fated hot rod of my youth.

Paint: Dear me. What color. Loadmaster Grey to match the 51 Truck? Not much else is factory '51 so it probably doesn't mater, at least to me but I'll be dead before it sees another engine change (I hope) but the next caretaker might care. I've been trying to wear it out for a long, long time but haven't succeeded yet. So far I haven't done anything that can't be returned to factory easily. Just fill some bolt holes and repaint it with the original wheels.

I've been running a six-volt starter on twelve volts for about 20 years and it starts fine. I once asked the motor/generator rebuild shop if they could convert it over to twelve volts and the guy said "Why?" That said, the reason for my present starter question is that I want to get away from the 9-bolt clutch and they were only on six-volt flywheels. Those clutches are expensive and a couple weeks away unless I want to drive 500 miles to Vancouver/Portland. So a 12-volt starter and flywheel solves several problems. I followed up on the thread about clutches and I'm satisfied that the six-bolt clutch will fit inside the old bell housing. I wondered because last time I changed the nine-bolt clutch it was really a tight fit, holding the clutch assembly with one hand while threading a bolt in with the other.

FWIW some years before the last clutch change I used an 11-inch V8 clutch disc as I couldn't get the 10-3/4" inch locally. It worked but the clutch always juddered on take up. I think that was because the V8 disc had a different number of torsion springs. I don't remember if it was more or less springs but the six-cylinder clutch has always been very smooth.

HRL: Thanks for the heads up on the valve springs. I'll use the valve rotators. Wish I'd had some last time the head was rebuilt. The shop put in stainless valves and seats but recommended against stellite seats. I did get bronze guides, though. That head has been in service about 40,000 miles and cured the constant valve adjustment problem I'd had before. So I'm tempted to use it with the addition of the valve rotators and springs.

Exhaust valves on heavy-duty gasoline truck engines have always been an issue. Years ago I did a valve job on a 322 Lincoln out of an F8 Ford. It required several new sodium-filled exhaust valves. The shop foreman cautioned me to never try to make a center punch out of a sodium-filled valve as it would explode when I cut the head off with a torch. I encountered those valves on 392 Internationals and 534 Fords. Mercedes/Thermo King diesels had them, Mercedes cars too. I don't recall them on GM engines, though. Probably overkill for a 261 Chev even if they were available.

So, today I'll pull the head and see what's under it and maybe a valve or two if I can find my valve spring compressor. I'll keep you posted on what I find that's interesting.

Pulled the 261 head today. I may have got lucky. Sight unseen from a wrecking yard and here's what I found:

Hadn't been steam cleaned and wasn't apparently leaking oil. Warped intake manifold. Standard bores, 0.003 taper, no scratches, no apparent ridge. Head and block have "steam holes" but the gasket does not. It hangs over the edge of the bores a little. Head has had 2 exhaust valves replaced or those are the one that weren't replaced. I pulled 2 exhausts and one intake so far; the stems on the odd valve is worn 0.005 and has stellite tip while the one that's like the other 4 is not worn and has no tip, intake is fine. I may have to replace at least one guide. Don't know yet. Looking at Rock Auto, they list what look like guide inserts (0.030 or 0.060 wall) but they don't have any in stock. I'd rather replace the whole guide. Were these heads integral guides? Other 50s era Chev sixes I've encountered had replaceable guides My other 848 head now has bronze guides. I apparently can get stellite valves for $7 ea. But the machine shop I used on my other head opted for stainless didn't recommend stellite. Any opinions about that? Any opinions on umbrella valve-stem seals vs the factory quad rings? I've never had a problem with the factory setup but always ready for an upgrade.

At this point, I'm thinking I may replace whatever guides and valves it needs, clean it up, swap the accessories from the engine now in service and put it in. Well, maybe a new oil pump; ya for sure a new oil pump. It's only a hundred bucks. But here's the rub, the head that's in service has no-lead seat/valve combo and I don't know what this 261 head has in that regard. The head that's in service is a 235 head and I'd have to drill six cooling holes. That's not the end of the world but I'd rather not do it if I don't have to.

Might look into the oil filter issue more. Seems to me by 1962 the 261 was a full flow oil filtration set up. But I could be all wet.

Roy Rodgers: That has been my understanding also. My 261 has the plug, that obstructs the oil gallery to force oil through the filter, flush with the surface of the boss. I believe that is the no-filter position. The bosses that would hold the pipe fittings for the filter are plugged. I suppose I could move the plug to the external-filter position and find a suitable external filter. I also might let sleeping dogs lie. I'll look at the bearings in a few days. That might give me a further opinion on filters.

With the block plug in the "out" position, it's still possible to run the same type of bypass fiter that the 216's and 235's ran for decades. The small diameter ports are sti there. If you choose to push the pug in, you MUST run large diameter lines and a full flow filter or the engine will get no oil at all from the pump.
Jerry

Jerry,
That external full-flow filter option seems like a disaster waiting to happen. I have had several external oil lines rupture over the past 50 years and at the very least if makes an awful mess. With a full flow filter I fear I wouldn't get it shut down in time. I'd run a switch to the ignition and a buzzer; maybe I could adapt one of those wig-wags for low air-pressure that hangs down from above the windshield. Maybe I could leave it as is.

If I ever decide to build a full flow 261, I'm going to plumb the filter with hard copper lines and silver soldered fittings, like a HVAC system uses. Like you, I don't trust flex lines, except maybe the single braid high pressure style used on 3K PSI hydraulic systems. Even then, I would use 6" long pipe nipples screwed into the block to get past the exhaust pipe before connecting the flex lines. Forget the warning buzzer- - - -wire a "normally closed" pressure switch to the oil gallery that kills the ignition if oil pressure is lost. Lots of the big rig Diesel engines I worked with for years had a similar system so low oil pressure or high coolant temp would kill the engine.
Jerry

For the sake of others who might do a 261 rebuild, would you please take pictures of the head gasket, block and head.

You may have a Victor Reinz FS3210 FS7782B head gasket. Since the head has drilled steam holes, just curious, are they angled?
https://www.stovebolt.com/ubbthread...ead/Board/1/main/185946/type/thread.html

Wish I could help with info on the decision for the type valves, seats, guides etc. but I'm always interested in learning.
The worst situation I can think of is hauling logs up Pike's Peak, running E10 on a 110 degree day.

Jerry,

Seemed like everything had a buzzer, low air, low oil, high temp, seat belt, on and on. And they all start up as soon as you turn the key. Used to drive me nuts. I didn't need that at 4 in the AM.

Buoymaker:

I haven't go things cleaned up yet but I did stick a drill in the holes in the head and they appear not to be angled. I hope they line up with the holes in the new 261 gasket that's still in the package. I will take some photos when I get it presentable. Probably be a week or so. At this time I'm thinking I may re-ring it since it's out of the frame and I'm going to pull the pan anyway. It has a PCV system and the intake ports and plugs are oily and the oil had to come from somewhere. Maybe it's blowing oil into the PCV, in which case I'd bet on at least stuck rings. Easy to do now, hard to do later. So far, I haven't found std. rings for a 261, or a 235 for that matter but I haven't checked for a few days. Maybe they're back in stock.

Just checked gaskets: The new head set is a Fel Pro7782B. The HG has steam holes and they line up with the head. The early valve cover gasket I got from Jim Carter's is a Best Gasket. I could not get overhaul sets for either a 235 or 261 and rear main seals come in those sets. I had to order piecemeal from Carter's and Rock Auto. I want a Best Gasket rubber rear main seal, 2 ea. They don't sell direct.

As long as the drilled hole is in the water jacket.

My 261 has the original PCV valve that screws into the draft tube. The draft tube has a oil mist collector inside.
The other end of the PCV valve has a metal pipe (~5/8") going to a hex brass fitting on the intake manifold.
Air cleaner to valve cover has 5/8" rubber hose. The diameter of the hose and pipe is important to get the proper flow through the PCV valve.
The valve operation can be checked. It can also be disassembled (unscrewed) for cleaning.
The engine picture is my original 261 with the intake removed to fix damper valve.

Just curious. Are you running the original 261 Rochester B? Mine (7015013) ran rich.

As far as I can tell, the steam holes someone drilled in the 235 head go into a water jacket. They're not blind holes. The block lacks some large water holes between cylinder 1&2 and 4&5 on the push-rod side that the 235 gasket makes provision for. As HRL has said, that may force water through the "steam holes". The gasket not having steam holes doesn't seem good to me in light of the lack of the big holes in the 261 block. So all in all, I would say that it's necessary to drill the 235 head when used on a 261 block. And also NOT to use a 235 head gasket on a 261, even though it'll fit.

My 261 did come with a Rochester B on it but no tag number or other ID. I'll probably use the dual Zenith 228 setup off the other engine. They have adjustable main jets. But I wonder if I can safely drill out the vacuum port in the Offy manifold to take a 3/4 pipe fitting. It presently is drilled for 1/4 pipe. I need the big fitting to take the PCV and brake vacuum connections.

I took the PCV Valve off yesterday and checked that the gizmo inside is free to move. On another 235 with a road-draft tube, when it began throwing oil out of the tube I popped the top off the mist condenser and found the oil return holes were completely plugged. I took a torch and burned out the residue, which cleared out the little holes, popped the top back on with some RTV and that fixed the problem. Perhaps that's what's wrong with this one. I'll look.

See picture. Red arrows. No holes in this block either or I am missing something? A properly drilled head should work.

With the 261 Rochester B you basically have to check all the parts to make sure they are correct. The collage is of things to look at to ID what you have. My B rebuild was cold natured. Ran okay warmed up. I swapped out for a Carter YF 2100s. Excellent carb but you can tell that a least little bit is missing on the top end hence the need for a carb with a littler more flow.

I wouldn't take the big fitting out of the old intake for fear of cracking the old brittle cast iron. If it where a must, I would heat the manifold a lot to expand then fingers crossed it works okay. You can also find equivalent plumbing for the Offy. If you plan to do engine work that requires break-in, I would have a known good carburetor setup to use. Too many unknowns can happen at the same time.

I had a draft tube from a 1957 235 that sludged badly. Didn't have a PVC system. I ran solvent through it but still sludged. A torch to get it going. Placed in a metal drum. It burned itself out after about an hour. Clean as a whistle. Engine ran a little better. Less oil leaks afterwards.

If you mark the head gasket for the locations of the steam holes and then drill straight down, only one of the two pairs of holes will be in the water jacket. The need to be drilled at 12 degrees.

Took my "848" 235 head to my local machine shop and had them drill the coolant holes. Don't remember him even charging me for it.

If I remember correctly the angle is important because the holes will somewhat miss the coolant channel in the head....or at least two of them. After mine were drilled I could shine a light in there and see the he hit the water channels dead center.

You can see the two screwdrivers I stuck in them to show their angled.

Thanks for the drilling and carburetor tips, guys. Follow the inliners link and look at the cut-away photo. As they say, "A picture is worth a thousand words."

I checked the head on the bench and it is drilled at 12 deg. It also has casting numbers like this:

Between #2 and #3 spark plug - on the flat above
B 61 848
850
The head on the in-service 235 has the same external casting numbers.

Under the valve cover on the head on the bench is:
Between cyls 2 and 3 CON 12
Between cyls 4 and 5 H20 2
Neither has a long casting number ending in 848.

On-the-bench head has valve rotators on 6 exhaust valves and hard tips on the two with worn stems.

The Rochester B carb has 5140 stamped on the mounting flange and the bore is 1-3/4 not 1-7/8 on Bouymakers photo. I takes a clamp-type air cleaner. I suspect this is a 235 rebuild carb. It might fall a little short on the top end. I have no experience with Rochester Bs.

I have planned to use the Offy/Zenith setup off the in-service 235. The 235 runs very well (except for the oil consumption) and holds ~ 1- 2in. HG @ WOT at 3,000RPM. That should feed a 261 OK, I think. Odd thing I had pointed out to me a couple of months ago about my Zenith 228s: one of them has "Bendix" cast on the side where the other has "Zenith." I have used identical kits in them and they have the same jets as I recall. Tag numbers are different. They are #3 mounting flanges. As you probably know, GMC used 228s for about 30 years on the inline 6 engines. I took them in part trade for a load of cordwood about 50 years ago.They replaced a Carter YF when I got the Offy manifold.

Bores:
1-1/2" = 235
1-11/16" = 261
1-3/4" = 292

5140 on the flange would be the throttle body for tag number 7005140 for 261 engine.
Heads-up on rebuilding. There is a ton of info on this website for rehabilitating the B.
What to do for warping. The weak link can be the power piston and wear. Float needs to be set lower than spec.
Fingers crossed, the result MAY give you a driver quality carburetor.
Ebay fetches top dollar on a 261 carburetor for a restoration truck.

Buoymaker: Thanks for the size update on the Rochester B. So these use a vacuum piston rather than metering rods? That's how the Zeniths work. I think I prefer the Carter metering rod system. I've worked on many of those, eg. YF and AFB. I used to have a little box full of AFB metering rods. Don't know what happened to them; probably in he same place as the Delco distributor advance weights and springs.

If I overhauled the B, do you think I could I sell is as a "rebuilt" carb on E-Bay for enough to make it worth the trouble to overhaul it, provided it doesn't need throttle-shaft bushings? I suppose I could use it myself but the manifold appears to be warped; I have another good one off a 235 truck. Is the bore in the manifold the same? However if I did that I'd have to revamp the dual exhaust system.

Don't get tied up on the B. It's one of those things that require time to research, rebuild correctly only to have it fall on it's face. But one can be made to work. I would hang on to the carburetor in case you want to go a different direction in the future are if you need it for the other (or another) 261. You can also give it to me..big grin. The 235 and 261 manifold can interchange.

If not severely warped, it is common for manifolds to be machined flat again. The head on the I6 is not a 12 port. To squeeze out a little more horsepower/torque involves physics "scavenging and pumping effects" with design of manifold size and shape. But, in the end, the result is a small improvement in typical highway driving. Most of us just want the old truck to startup well and run good. A decent MPG is always appreciated. The biggest bang-for-the-buck is to increase cubic inches. In my opinion the best bolt-on option for the 235 engine is a 261.

I've gotten the 261 torn down to the bare block. On the way I've discovered 1 burnt piston, milk-can style lifters worn concave, 10-1/2" pushrods, a cam no longer usable (with "GM" aluminum gear attached), crank ground -0.010 (rods and mains), neoprene rear main seal (didn't appear to be leaking).

Five pistons have "854" cast by the pin boss and one piston has CSxx something I don't remember. I weighed the burnt piston with rings and pin at 835 grams, so I'm guessing 854 is the nominal weight. The rest of the pistons don't appear to be scuffed but do show minor wear.

Questions:
1) Did GM identify their pistons with "GM" or some other mark?
After breaking the glaze with a 200 hone, the pistons have a couple pound drag on a 0.004 feeler. That's more than I would like for quietness and oil control and way over factory spec for original pistons. Could these not be factory pistons and require greater clearance? The bores are 3.752 now I honed them. Had I measured the clearance first I'd have stopped honing sooner but now the bores are straight anyway. Near as I can tell, the pistons are 3.748 and cam ground so they measure way less over by the pin boss. Maybe I can get them knurled.

2) Did GM go back to the milk-can style lifters on the late production? After '60? This is theoretically a '62 engine and the '60 manual specifically shows the short style lifter and shows the milk-can with an X through it and the short one as being OK. I'm guessing that someone replaced the lifters with what they had around at some point. They have 1 groove around the upper third that I presume is an ID mark.

3) There is a special hollow head bolt for rocker oil; and the '60 cut-away drawing shows this being fed from the cam bearing. My engine however, has the old-style tube running from the rear cam bearing to the center head bolt boss. Is this a belt-and-suspenders deal? I ran a piece of welding rod down the bolt hole and it goes to the cam bearing shell. It seems that it should go all the way to the bottom of the cam bore. Maybe somebody put the wrong bearing in that position and one with an additional hole should be there.

I found 2 ea. std. "Sealed Power" pistons, new, for sale cheap and bought them both so I'll have a spare. I hope the weights are reasonably close or a little heavy, in which case I can grind the pins shorter to make the weight proper. The alternative is a $300 set of pistons of unknown brand and a bore job. What do shops charge per hole for running a boring bar?
261 pistons and rings are rare in my usual supplier catalogues. Lots of 235 stuff.

New cast-iron ring gaps are about 0.026" mid way down the bores. That seems like a lot. My rule of thumb has been 0.0035 per inch of bore, which would give ~0.014" gap; and the manual says lots less. Ring-land side-gap seems OK at 0.002." The old rings are out to about 0.050." It wasn't my intention to do a complete rebuild but more of a thorough overhaul since it doesn't seem to need any machine work, so far.

This may be more than some of you want to know but maybe it can serve as a bit of a guide to someone else doing similar work. I keep reminding myself, "It's expensive but it's even more expensive if you don't do it right the first time."

No, milk can lifters were not brought back into service. They were also generally made of chilled iron which is not compatible with the later cast cams. Sealed power purportedly changed the material maybe in the 90s to be comparable with both steel and cast cams. But don’t mess with this kind of mixing and matching. If the block is later then 56, use the 56-62 261 solid lifters, not the milk cans. Use the longer push rods. Fresh cam, or fresh regrind, and new gears.

The drilled bolt, that was used in conjunction with a plug for the deck of the block, when you were using a fitted replacement block 59 and up, on a 55-58 vehicle, and reusing the early 55-58 head and rockers. If you are not doing that, you don’t need the drilled bolt and plug.

I am wondering if what you have is a later replacement fitted block, and all the stuff from a 54 motor swapped in?

Tommy -- It's interesting what you found when you tore the engine down. Prove's Jerry's advice about always treating an unknown engine as a "Rebuildable core."

I have gotten the block cleaned up and honed and now I look at the full flow filter plug. It is presently in the out position. It had a nice center punch mark that I could use to drill and tap a blind hole so if I ever wanted to I could pull it back out per Hot Rod Lincoln's idea.

1) How deep can I drill?
2) How hard do I need to tap it to get it to move? I have seen warnings not to do this lest I crack the block.

I like the idea of a full-flow filter in conjunction with a Franz filter, if those are still available. There were several on a fleet buses I took care of years back and they did keep the oil clean, as did the Luberfiner 750 on a Mack Thermodyne diesel that served the same purpose. It had a cloth sock over the filter element as I recall.

Another advantage of the full-flow filter is that I could plumb in an oil cooler in series but I would want a thermostat too.

3) What might be the downsides of such an arrangement aside from springing an oil leak?

I have decided to use one of the serviceable cams I have, either Howards or Crower, with either the lifters that came off the Crower cam (numbered) or refaced lifters on the Howard's; and use the long tubular pushrods I already have. That solves the cam and lifter problem. I can't find a cam I like on-line.

There's an old trick that still works well on pistons with a little bit of extra skirt clearance- - - -knurl the skirts to tighten things up a little. I've added as much as .004"-.005" to skirt diameter at times. .002"-.003" is easy. We had to do that on a couple of the pistons in John's 261 when I helped do the buildup on it. Any machinist worthy of the name can do that operation with a lathe, or box 'em up and send them to me and I'll be glad to do it. If you include the connecting rods, I can also recondition the big ends so the rod bearings will fit correctly and have the proper "crush" when they're torqued into the rods.

Rather than hammering on the "full flow" oil gallery plug, you can probably use a big C clamp or a ball joint press to push the plug in, as long as the oil pan is removed. Drilling and tapping the plug about 3/8" to 1/2" deep with a 5/16" fine thread ought to give you plenty of bite to pull the plug back out if you ever decicde to go back to bypass filtering and eliminate the full flow filter. I've got a couple of 261's with the full flow capable in/out plug. I'm considering pulling that plug all the way out, threading the hole, and using a screw-in blockoff plug instead of the one that's hammered in and out for the full flow/bypass choice. An Allen set screw with some of the threads machined down smooth would work well, since all it has to do is block off a passage between the oil pump and the main oil gallery that runs from front to rear down the driver's side of the block.
Jerry

I don't know what a over bore cost would be. But my 261 had a bad sleeve, it was $150 to replace it. $150 x 6 would be $900 dollars.
I'm not sure if that's a logical way to estimate what it may cost to over bore all 6 cylinders.

Roadworthy: I once put dry sleeves in a 40's era I-H tractor. They were lots less expensive than new 4-ring pistons as I recall. My labor time was almost free in those days as it again is. I Welded a bead up the sleeve to shrink them and drifted them out. I used dry ice to install them. R&R was an all-day job for 4 cylinders. Wet sleeves on Cummins is much easier.

So my pistons are sent off to the machine shop for knurling and the crankshaft is installed in the block. I shimmed the main bearings to get 0.0015 on the rear main and 0.002 on the others. I have a set of new rod bearings but I'm short on tapered shim stock so I'm hoping I don't have to shim them to get 0.002 clearance. The crank is round but is worn 0.001 or so.
I could probably shim a couple of them but that's all. My local parts man said he doesn't deal with his engine guy anymore over some long ago argument so he can't get tapered shim stock. More news when I get my pistons back and UPS brings me more parts.

Tommy, if you still have everything apart ... I *highly* recommend you send your rods to Jerry for reconditioning. Its easy to check to see how far out of round they may be and I can personally vouch for Jerry's expertise at this. You ought to take him up on his offer!

By the way, I watched him knurl my piston skirts -- it was pretty neat ... In a Mennonite machine shop, by a window (for light) on an ancient lathe powered by belts from a 6-71 Detroit. Talk about "Old School"

So John, is that Jerry's usual shop? I'd had thought being that close to Nashville and all those guitar amplifiers some of that electricity would filter out to the countryside. I mean we even have electricity here and it's an hour's drive to the nearest BPA dam. Granted it took a shooting war to get BPA power up the valley.

Along about 1968, I got a part for my 66 Pontiac machined by an old fellow in Leominster, MA. He was 90 then and told me his father had built the machine shop, starting by hand-building a lathe for which he had the headstock cast in Boston and hand built the rest. From that he used the lathe to make the rest of the tools, all driven from above by flat leather belts running on pulleys of various sizes. It had been powered by wood-fired steam and eventually coal and after WWI they converted to oil. When I saw it the power was from a huge electric motor that you could see into and watch the brushes arcing. It was like the history of the American industrial revolution in one shop.

Today, a lifetime later, I came in for lunch and it's too hot to go back to work so I'll write up the latest on my 261 overhaul. It got to a hundred yesterday and today is supposed to be 106. My machinist is only working till 3PM these days because he's got no air conditioning. Neither do I. So yesterday morning I drove to the neighboring town to collect my knurled pistons and my rods. My pistons now have a nice Perfect Circle logo knurled into the skirts.

I had checked the con-rod bores and could tell they were round to 0.0005 but with the heat I couldn't tell how big they were. My Jo-block is as hot as everything else -- hardly room temperature. Anyhow the machinist keeps his jo-blocks in the fridge and knows what the mic should say on a refrigerated Jo-block. A Jo-block is a piece of metal of known size used to calibrate micrometers and such. Anyhow, he had checked the rods and said they were right on and still straight and he didn't charge me for that. The piston knurling was $10 each and I though that was reasonable.

He was of the opinion that knurled pistons should be fitted tighter than I ever have, basically filed down so you can just get them in the bore and they'll seat themselves. That scares me. These are solid skirt pistons destined for heavy-duty truck work and I've replaced a few Cummins sleeves and pistons when the drivers weren't watching the pyrometer and stuck them. Those are the same guys that pop head bolts. Sometimes you can head that problem off because you can see antifreeze stains on the block from the heads bouncing up and down. Write a little note and put it in their box with their dispatch so they know you're watching. But I digress...

I compromised and set the pistons to a stiff pull on a 0.002 feeler. Hopefully they won't slap and they won't stick. Oil catches in the knurl so oil control is better and you can fit them tighter. He did a good job. I told him what bore sizes I had and numbered the pistons. In the end it only took a couple whacks with a file to set the clearance. That was yesterday.

A month has gone by since I last posted. The 261 is alive and well and powering my 3800. I will have to change my signature to match. When I last posted I had fitted the pistons. Most of the reassembly went without incident. However it had to wait for me to pull the 235 out of the pickup to get some needed parts. I took the head I'd had gone through about 40,000 miles ago and the Crower cam, lifters pushrods and rockers and the dual-carb intake and Fenton exhaust manifolds . I pulled a few exhaust valves and checked the seats and stems. All was good. No stem wear or guide wear with bronze guides and PC umbrella style seals.

I drilled the 235's 848 head for the 261 block with a 3/8 hand-drill motor, duplicating the 12 deg. angle. One thing I noticed was that the combustion chamber volume was noticeably smaller on the 235 head than the 848 head that came off the 261. When I had the 235 head done I was concerned with valve/piston interferance and cautioned the machinist about milling the head. He said he only took a skim cut to make sure it was flat. I wonder if the late 235 heads were factory milled to get 8.25:1 compression. So now I calculate that I have 9.2:1 compression and so far no pinging on 87oct. gas in hot weather. I used the 235 distributor whose gear matched the cam and set the timing to 5 deg advance. When installing the cam with a new gear set I came up with 0 backlash, which bothered me but it wasn't negative and I didn't know what to do about it anyway. Both are Melling gears for that application.

While on the subject of the head, the head gasket that came with the Felpro kit is composite. I'm used to installing copper-sandwich gasket with spray-on Copper Coat cement or aluminum spray paint. I've never had a head-gasket failure and hope I never do. I've always gone a few hundred miles before re-torquing the head. Any opinions on this with a composite gasket? Sooner perhaps?

I found a Franz oil filter on E-bay and put that on in parallel with an external, spin-on kit from Deve. For anyone following in my footsteps, this combination of external full-flow filter and Fenton dual exhaust creates a plumber's nightmare. There are many pipe connections and I felt they must be done after the engine is in the frame lest I risk breaking some pipe fitting or block casting when swinging the motor. It is now in but I had to chase a leak that required some disassembly after the fact. If doing this, use pipe dope AND tape. I used yellow gas tape on the repair. there are some 90 deg. joints where you have to decide whether to risk splitting a fitting if you take a whole additional turn or leaving it a little too loose. I ended up routing the pressure line behind the front exhaust pipe rather than outboard because to go outboard of the exhaust pipe puts the oil pipe too close to the hot exhaust pipe while still clearing the steering box. I wonder if the frame rails on a 1-ton are narrower at the front. I believe Deve mocked up his kit on a 1/2-ton chassis. BTW it's a nice kit using stainless pipe and fittings and AN swivel fittings for the braided-stainless hoses. I only had to add additional tee for the Franz filter.

I also installed a coolant filter bracket I scrounged from an old Cummins marine diesel. I used the side motor-mount bosses on the block. One reason I did this was because both engines had so much sediment in the back left corner that the block-drain was plugged despite being flushed every couple of years. And it was a bit of the chore to mechanically remove the sediment with a pressure hose and a screwdriver through the various holes in the block. Hopefully, that won't happen again with a new Wix filter element for an up-to 4 gallon system.

So now a long job is done, road-tested and all that's left is to wash the truck of many greasy hand prints.

Thanks for the heads up.
However, w/r/t "Crower... rockers":
No 235 rockers have been made in the last 50 years, and not by Crower.
The rockers listed by cam companies are Gen-3 stud-mounted and completely different than what is needed.
Picture or listing of what you used?

Panic:
Re rockers: The rockers are the factory ones associated with the head that came off the 235. Perhaps I missed a comma in that sentence of my report. They were in better condition than the 261's rockers. The pushrods are tubular ones from Crower. I was disappointed not to use the valve rotators off the 261 but they were in poor condition and perhaps not needed anyway. The lifters came from Crower at the time I bought the cam and were properly radiused to match the cam profile per Crower's instructions. FWIW the cam and lifters showed no wear in 80,000+ miles.

I used the composite gasket last year on my 261 after using copper gaskets for 45 years. I had the same concerns as you. In the end, perfect. I have not even bothered to retorque the head. And my motor uses high compression forged pop up pistons. Still no issue and the motor has at least 40 runs down the drag strip over the last two years.

Oopps, my bad, jumping to conclusions.
Of course, I should have suspected as much.