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.
