The Stovebolt Site Forums The Shop Area Engine Shop installing a 261

Well, I picked up my running 261 from a fellow bolter today (traded my 250 for it), and I have a few questions. First of all, it is out of a '62 suburban and it has the full flow oil filter mounted to the intake and it has the captain's bars and big thermostat housing. I will take some pics tomorrow. It's really a pretty engine.

I am putting it in my '50 pickup and I want to use the original radiator, so I need to shorten the water pump shaft. Is the 235 water pump the same? Where can I get the proper pulley for the short pump? Will the 261 complain if I run a 4 psi cap or does it need more pressure than that to keep from getting steam pockets? Which fan should I use?
Does the flywheel have to come off to remove the bellhousing? I need to swap to my 216 housing so I can use the non-hydraulic clutch and footmash starter.

This is very easy swap, only 3 things normally need attention, water pump,throttle linkage and exhaust. You need to shorten the water pump about 2 inches. Unless you have the right pulley and a press, just buy one ready to bolt on . The 235 pump works just fine on a 261, same impeller, and 4 lbs cap is ok. You may want to bolt the 216 thermostat housing and hose neck on the 261 for an easier upper hose hook up.The engine will bolt right up to the 216 clutch housing, use the original 216 flywheel if you are keeping the 6 volt starter.The stock 216 clutch will be ok if you're not doing burn outs or pulling dead FoMoCo's around. I use a later 164 tooth flywheel and 10.4 inch clutches on both my trucks along with 12 volt starters. 261 original flywheels were the heavy duty 11 inch clutch with 9 bolt pressure plate.The flywheel has to come off to remove the clutch housing.You may have to fiddle around with the accelerator linkage, as the hole for the block mounted bellcrank is in a different place.On our 261 powered 51 truck,the original style full flow filter mounted on the intake is a hassle to change the filter.Same style filter and can as early Chevy V-8's.Gonna change it over to a spin on filter head mounted low on the block like my 37 truck.Of course your exhaust may need some reworking depending on what you have for pipes right now.The 261 is not as smooth of an engine as a good running 216.Its best to change all the motor mounts while the engine is out.Try to buy USA made rear mounts. The imported mounts failed quickly on my 37.Have fun and don't lose the headbolts

Is it possible to swap either the starter nose gears or the ring gears between flywheels? I want to keep the big clutch because I am putting some gofast stuff on the 261 eventually. Doesn't putting the 216 water neck on the 261 ruin the recirculate capability of the 261's thermostat? It has an extra hose between the thermostat housing and the water pump to circulate water all the time even when the stat is closed. Or do I just swap the top part between the top of the housing and the hose?
I have some extra us made motor mounts to put on so that is no problem.

4ontheFloor,

Tony's answer was good and he will most likely respond to your followup. I hope you do not mind my 2-cents worth.

1. Will you be using the starter/generator from the '62. If so, you do not have to swap out the clutch-assembly and flywheel. If you want the foot start and 216 starter, Tony's advice is, of course, good. I do not think there is a "ring gear" on the '62 261's flywheel (there is not one on my '60 261).

2. Are you sure the extra hose fittings on the 261 thermostat housing were for "recirculation"? I thought they were take-offs for a second heater (and are nice for use with a heated intake). The 261 thermostat has a hole in it to allow a little circulation at all times.

This summer I changed my 261's thermostat housing as Tony suggested. Now I can use standard hoses and thermostats. In addition, the 235 housing does not interfere with "dress-up" valve covers (the 261's thermostat housing must be "trimmed" for Wayne-style valve covers). The top/bottom of the 235 and 261 housings are both different.

Well, I got my engine out of an unmolested '62 burb, and the burb had the smaller fittings for the heater from the water pump and the lower part of the thermostat housing, and there was a bypass hose that went from the upper part of the housing (the part that has the bypass holes in the 'stat) back to the water pump. I am probably going to repeat what it had and keep the big neck and 261 'stat. I am going to water heat my Edmunds intake when I install it (with 2 2bbl holleys)

Four on the floor, You just put in a 6 volt alternator?So you want to keep the earlier style flywheel? I tried to swap the parts of a 12 and 6 volt starter one time,but the pieces didn't line up correctly,it might work with a little machine work.You can always use a 12 volt foot starter from a 56-60 truck. I didn't use the bypass hose on the first 261 because it was just a short block,so I used 235 stuff to dress it out.The other engine was complete, but but I switched over the stat housing so I could use regular GM style thermostats.I think the by pass hose is for heavy duty truck use were the driver reams the [censored] out of the engine before its warmed up and the thermostat is opened. Creates localized hot spots and possible engine damage? Most guys with vintage engines drive moderately until the engine is fully warmed up.It certainly wouldn't hurt to use the bypass if you have the parts.

I think what I will do is use the 261 stat housing if I can get it to fit ok and use the 216 flywheel and clutch until I fell like converting to 12 volts. Is it possible to have the 216 flywheel machined to fit an 11" clutch, or is there a high friction clutch available for the 216? I am using an SM420 with the stock gears so it shouldn't be too hard on the clutch I guess.