Tony P. wrote this in 2002... With the exception of the pistons, every part is interchangable. Like the posts above state, they may require modification.Besides the steam holes on a 261 head(#850) the 261 head supposedly has larger combustion chambers.My observation is ,GM lowered the compression by lowering the piston height at TDC.Perhaps someone has actually CC'd the combustion chambers?The #848 head is the only 235 replacment offered by GM in later years, but I have seen a few other casting numbers on 55-56 engines. 261 rods fit properly on a 235 crank, but the wrist pin holes are larger ,so custom pistons are required.The crank shafts have the same part number as do the valve springs, but 261's use rotaters on the exhaust valves.The water pump impellers and bolt pattern are identical but the castings have different fittings and so on. The intake on engines with governors is a lower profile .My old GM parts books list the same part numbers for most every thing except the differences mentioned. Original manafacturer replacement parts are often standarized more than the original stuff to lower dealer inventory costs.
Thank you! It's been a labor of love for too many years... The first rig with my name on the title. Dad surprised me with it as a thank you for working one summer in his muffler and brake shop when I was in high school. That was 1994, so pre internet. It was in a news stand "Penny Saver" classified ad with no picture. He asked if I wanted to go look at it... so I thought we were just going to look at it since I was fascinated with NAPCO trucks even back then, and had never seen one in person. After I crawled underneath it and told my dad it was the real deal, he pulled out cash and paid the man. There were three other guys there crawling over it so he knew it was a "shit or get off the pot" moment. Totally shocked me! We bought it from the son of the original owner. We were able to drive it home after getting the full story on the truck, which he knew because he was with his dad when he bought the truck new and also when he had it converted to 4x4, which was on either day one or two of owning it. Anyway, I'm just happy that even though it's not a show stopper hundred point restoration that I can drive it and share it with my boys now. People do seem to get a kick out of it!
261 set-up progress Fuel line to opposite side Fuel line bracket created from 1” copper pipe, flattened, drilled, formed Bracket approximately midway from pump to carburetor, supporting weight of fuel filter and less than rigid copper/nickel fuel line PCV, vacuum, and fuel lines, STILCO oil filter
Has anyone installed Williams headers? I had an original pair of Fentons I was going to install but one of them is warped too far out of flat to mill. I really don't want to use the foreign knockoff Fentons if I can avoid it. The Williams headers are made in Iowa. I've heard that they are very nice parts from a guy that saw them in person at a swap meet where they were being sold, but not from anyone that has run them. Current pricing on them is $295 a it says they are no longer drilled and tapped for the heat plate kit... So that'd be an extra cost. I feel like it'd be worth it though to buy domestic. Thoughts?
Came out really, really well. 3x primer, light coats, 3x color light coats. Baked in the outdoor grill, 30 min 250, 30 cool down 30 min 400, 30 cool 30 min 550, (grill was making noises so I didn’t go higher) cool to handle It’s ON THERE!!!
I never knew they existed until I saw Roadrunner had used them on his 261. I found a set years ago in Canada. I knew shipping, and possibly damage were two drawbacks. I asked one of my Canadian acquaintances if he knew of anyone in a town of the headers owner. He said, "As a matter of fact I do, my son's girlfriend lives there and he's going to see her next week!" Son nabs the headers, my friend brings them to Virginia for one of our old truck get-togethers! I'm a lucky man for several reasons.
Fenton shows this style in the 1959 catalog. I lucked out, buying the rear header at one swap meet and then finding the front header at another.
Love your hardline plumbing Cosmo, mine still is a mess, but I'm working on it - still have to figure some things out.
I am looking for some information on this one. Does anyone know a what has to run modern roller rockers (I was told these are Big Block Chevy) on a BlueFlame? Does it have anything to do with the side cover on the left side?
Robert, I don't understand your questions. I do have a friend that I believe is doing roller rockers on his 261. I will ask him what challenges he has encountered as far as fitment/interference. I do believe it has been done before. What are the advantages?
That's certainly not a 261 Chevy head with those roller rockers. The exhaust valves are not angled inward, as Chevy head would be. With straight valves and the head bolt arrangement, it looks like a GMC to me.
Definitely a GMC. I’ve never seen individual rockers but there is a 1/2” plate on the other side of the springs for the screw in studs for them. There also would need to be guide holes in it the push rods. The 7 head studs on that side hold the plate valve gear. The cam drives the fuel pump and a belt drives the dry sump pump. Appears to be a Wayne cover with the name removed. I’ll bet he had time to measure rockers to fine ones close in length. Very nice machine work.
I believe that is Bob Corbett's (out of Colorado) GMC in his dragster. He did make an adapter and a lot of work to use individual V8 Chevy rocker arms. He did do nice work and had that GMC on nitro running in the 8's at Bandimere Dragstrip. His billet headed GMC ran in the 7's.
A-ha I was very confused what was going on and how the valves weren't canted, I have never gotten involved with the G.M.C. I knew about the difference in valve arrangement between Chevy and the G.M.C the number of freeze number of freeze plugs. Stronger, less friction freeing up a little power and being an aftermarket hi-performance, the ratio is going to be right on the money
Reduces side loading on the valves, so you don't wear out your valve guides prematurely. Chevy and GMC rocker geometry is not good for high lift cams. At the least, rocker stands need to be machined to correct the geometry.
Since we've started talking about roller rocker arms for the 261 (and its brethren) you should be aware that there are 4 different rockers required for the engine. Because of the angle of the valves and the pushrod locations there are two different rockers required for the intake and two for the exhaust. Long ago, I started a project to build a set, but never finished. The stock rockers have always performed OK in my 261 race engines. If anyone wants to build a set for themselves, this is the design I came up with. You may want to tweak things a little, but the geometry is correct for the stock 1.5:1 rocker ratio.
Dang Walt, what a weird coincidence...or is it? Several years ago when I built the blown 261 in my avatar, I also drew up a set of alum roller rockers very similar to yours, with just a little different oiling arrangement. And, like you I didn't complete them either, only got as far as cutting blocks of material. I also ended up using (refaced) stock arms which seemed to work very well. I believe they're still ticking, somewhere in Idaho now.
Gloss Rustoleum Grey. A little touch up and then the peripherals. Brush painted in a 50* garage, beautiful (for me) self leveling paint very forgiving.
Hahahahaha, yes, kind of where I'm going. I originally used what I thought was a yellow that was a documented color of the late 50's but I thought it would make my red truck look too 'McDonald's-ish', you know, red and yellow, so I went with this grey.
Hey Cosmo,I built the last 261 about 11 years ..bad bores so had to go.080".. Ross forged zero decked pistons,head milled about .040 with .040 headgasket for tight squish...Good valve job but no typical porting.Mild Oregon Cams regrind,fabricated shorttube header single exhaust.I reworked a stock intake to fit a largebase Rochester 2bbl.....actual static compresion was 9.1 ,ok on regular gas. It ran very well but I drifted back into bikes......Sold the truck...
Posted by Guadalupe Manuel Torres on Facbook 848 head for use on a 261. What is the speed secret on milling intake/exhaust mount?
I’m doing a few hours every day. I’ll do some touch up of chipped paint at the end, chasing ghosts while trying to make progress isn’t fun. I will be needing an XL horse shoe as a support on the carburetor side fender rod. The rod interferes with the carburetor, so the horseshoe will curve around it. My friend, ‘Pastor Grigg’ married Ms Clifford to Mr Fenton. Clearance to the width of this gasket which resides between the mated pair. Straight edge shows true alignment. I mated the intake to the right header with integral heat plenum.
LOL -yeah my 261 is also grey. It was called "Battleship Grey" back in 41 - had a nice ring to it There is one thing I always see, when it comes to painting engines, and it seems to be an American thing. The engine gets assembled and than painted all over it. From a German point of view that's seems a bit strange. I paint all my stuff first, and than put it together. I mean it's just a personal preference, but for my motor Feng Shui, I don't like my gaskets, nuts and bolts sprayed over. I always wondered if this is a cultural thing. Frank
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