My 261 build and discussion thread!

[wolffcub]

Found a 56 261 early summer. Got it home and found out under all the crud it had a cracked water jacket from front to rear. Found another fresh 261 block that was on its original bore and already fully cleaned up in the hopes that its all good and has no cracks.

Already took the 848 head off the first 261 and had a shop clean it and check for cracks. Found out today all is good and its ready for machine work.

Any thoughts what i can do other than my list below or anything better i can do to it. Want it to be for a street build.

Here is my current wish list.

Head work:
- Mill face true
- larger intake valves (possibly from Tom L)
- New valve springs (already have new on hand)
- New exhaust valves
- Have brass valve guides installed
- Have the new style of valve stem seals installed
- Hardened valve seat installed
- Check and possibly port match the headers to the head exhaust openings if required.
- New rockers (Im actually missing 6 so I want a full new set)
- New rocker shafts (Im actually missing them also but have the perches)

Block work
- Bore block to .060
- Deck block as much as possible
- New pistons (not sure what to do)
- New rings (not sure what to do)
- Reuse connecting rods / pins
- Machine Crank
- Balance Crank
- Check and possibly replace oil Pump
- New Cam from Delta Camshaft (Same as what im using in my 235)
- New solid lifters
- New Pushrods
- New crank gear and aluminum timing gear
- Leave oil system stock as a bypass system and not go full flow.
- Stick with rope crank seals
- Timing cover bolt modification
- New water pump (old one is damaged)
- need new oil pan (old one has holes)
- Drill the crank for the pulley bolt

External Stuff
-Swap over as many parts form my 235 when its time to change over. Hei, dual intake, headers, pulleys, fuel pump, remote oil filter, and other stuff.

[59chev]

261's are a neat engine, externally they look the same as a 235, except for the "Captains Bars" cast on the side of the block near the starter. My 59's original 235 had a cracked block from one end to the other the first time I rebuilt my truck, so I swapped in a running 261. Drove it for a few years with that engine with stock suspension and drivetrain. The engine ran great but the stock tranny and rear end meant I couldn't do much more than 50 mph. I was thinking about just keeping the 261 for a while and putting an overdrive behind it, but finally decided to switch to a 327 and 700r4 when I did the camaro clip.

[curmudgeon]

I have a '62 261 in my '54 truck, you will enjoy the increased low end torque compared to the 235. I remember your earlier thread about your trans/rear end gearing charts, I was able to gear my rear higher (3.08) so I could keep up with Northern Cal freeway traffic. You have a good plan for rebuilding, more than I did, however you've probably found out how expensive it is to rebuild the old sixes. Even with less machine work than yours, compared to a sbc, I've spent twice as much for half the HP.

Keep in mind the '56 block is for the TF engine bay, when you replace the H20 pump you need the Jim Carter pump/pulley higher relocation kit to run the stock fan, otherwise if you use the '56 pump, the pulley is larger and lower. (I use an electric fan)

[wolffcub]

The 55 i have now has the lower fan issue already but i have yet to have cooling issues in any way. Only time my gauge starts to go up was in traffic on a hot summer day. never had a overheat issue but still installed a secondary electric fan in front of the rad that is on a manual switch.

What tire size are you using? what trans ratios?

[wolffcub]

Cost is not an issue. Just want it done right. Im not a fan of the cookie cutter v8 swaps.

[wolffcub]

This is the first block I started with. Turned out to have a crack from back to front.



Took it apart and removed the internals. The plan is to reuse the crank and con rods from this block.



This is the 848 head from the damaged block prior to cleaning. Got word back it all perfect and ready to be rebuilt.



This is the other good block i got that I am planning to use if it checks out. #7012. Still measures to be on its original bore.



Strange thing is this block has no provision to select full flow or bypass for the oil. Im just not used to seeing this style of block. I also wish it had the 3 hole mount so i could have used it for a remote filter mount but i will make due.

[curmudgeon]

I also read with interest your Langdon carb install, however I was lucky and my dual Carter/Webers run great out of the box. The straight six with dual carbs and Wayne covers does attract lots of interest and compliments at car shows though. I like the idea of using the stock fan with the electric back/up, I have to see if my stock fan will clear the radiator.

I have a 3.08 Camaro rear with a 2-groove Saginaw (3.11 - 1.00) with 215/75 - 15 front, and 235/70 - 15 rear. I have to slightly slip the clutch on a hill, but good spacing up to freeway speeds once I get going. I do have an old S-10 T-5 (4.03 - 0.76) but that means new driveshaft and rear gears.

[wolffcub]

Got word today the second block i had is good to go. It still on its original bore and has 6 thou of wear. It was all cleaned and read for me to take back home. I want to clean up a few things on the block prior to having the machine work completed. The lower side of the block at the oil pan lip is very sharp and i want that beveled and cleaned up. Also want to take the extra time and just ensure all the passages are thoroughly cleaned using a rifle brush and such.

[wolffcub]

So on the weekend i ran into a random guy and we started talking about inlines. He mentioned to me doing a 261 was a waste of time. Granted it just one guys opinion but he said if my 235 was running correctly going to a 261 is pointless. The gains are so minimal and not work the effort and money he said. He had one in a old car he had a long time ago.

This swap over from my 235 to the 261 really worth my time and money? I have never had the chance to feel what a 261 go like so im going into this build blind.

[curmudgeon]

The hp gains going from a 235 to 261 are minimal, however the noticeable improvement is in torque, especially at lower rpms which will enhance day to day driveability. As stated above, I was able to gear the trans/rear significantly higher than stock to run freeways speeds. Our trucks weight-wise benefit from the increased torque of a 261 (compared to a car), after all they were originally in big trucks and school buses. Plus, with the extra enhancements you are planning (0.60 bore, head work), you'll end up with more hp/torque than the stock rebuild I did. Is it worth the money? Absolutely not! I have more $$$ in a stock 261 rebuild than the cost of a GM crate 350. However, nowadays, having a modified 235 is rare, having a modified 261 with dual carbs/split exhaust and T-5 is rarer. The cost/time question is subjective, my wife thinks my whole truck is a waste of time and money.

[Coach529]

Inlines are very cool......but the $$$ scared me away. I picked up a 261 and a 235 with a 848 head, dual intake and tube headers for about $400.00.

After crunching the numbers on the rebuild and associated parts I got cold feet and went with a SBC.

[wolffcub]

In terms of being worth the money i mean to build a 261 vs keep using my 235 with only 5000 miles on it. I know its cheaper to get a v8 but i have no interest in going that way. But when im done someone might buy my 235 so i might make some money back.

[Coach529]

With that few of miles on the 235 I would be tempted to leave it in there.

[curmudgeon]

From a strict cost/benefit analysis: 5K mile 235 vs rebuilt 261, the answer is probably no. There is not much of a market for used 235's except for period stock rebuilds, but the shipping from your location would be expensive unless you find a local buyer. However, you already expended the time/cost in acquiring not 1 but 2 261 blocks plus you stated in post #5 you're not doing this with cost in mind. I am happy with my 261, you are minimizing your expense by bringing the engine in for professional machine work but you are doing all the install and dialing in yourself. Hope to see you continue with the rebuild and to enjoy the increased torque.

[wolffcub]

Im all over the torque aspect. After i spent last and this summer playing with carb settings, timing and changing the cam im very happy with the way the 235 behaves now, but being your typical guy I want more torque. Im 90% city driving and love to have the get up and go when just cruising in the city. when putting around in second, third, fourth and then punching it i just want it to get up and go faster.