The Stovebolt Site Forums The Shop Area Engine Shop 216 for 261

Hi all,
I'm looking to upgrade from a 216 to a 261 in my CMP. Has anyone on here already done this?
Looking for any info...
I've read the 216 and 261 use the same engine mounts, is this correct?
Are the distributors in the same place?
What are the differences externally between the two engines apart from Carter/Rochester carb?
Could a Carter carb be re-jetted to suit the 261?

Any info greatly appreciated,

Dave

What's a CMP?

Depending on the year of manufacture of the 261, the water pump will probably be mounted several inches lower on the front of the engine block, which creates problems with the position of the fan in most applications. There is a conversion plate available from one of the members here that allows the 216 style water pump to be fitted to the late model 235 and 261 blocks. The original equipment carb for the 261 was a Rochester with a larger venturi than the 216 or the 235. They are relatively scarce. The small bore 216 carb would starve the engine for air, not fuel, and run very rich. It would rob a lot of high-RPM power.

The distributor position is the same- - - -it might be necessary to swap the front timing cover plate from the 216 to the 261, or re-drill the later plate to accept the front motor mounts. Your 216 bell housing, starter, flywheel, and clutch should be a direct bolt-on swap.

Good luck!
Jerry

Maybe this would give you some needed information. The 235 and the 261 are very similar. Tech Tip 216 to 235 Swap

Thank you for the prompt reply's some great info there.

Jerry - As in link above from Pre '68 Dave, Canadian Military Pattern.
I have ac30cwt of the first variant called an 11 cab.
I'll get some photos loaded later.

Many thanks,

Dave

I don't know about military trucks. Though if your
truck has the same fitment issues as the regular
Chevy trucks then what you want is a 1954 or earlier
truck you want a 1954 261. If your army truck is a
1955 or later then you want a 1955 or later 261
this way you avoid water pump and fan issues.
Jeffrey

I'm sure you've got this link already, but just in case you don't:

Canadian CMP 235 & 261 conversion

Many thanks for the reply's, a lot of great information. I guess the hunt is on for the correct 261...

You have company on Stovebolt with CMP ownership. RAC1812 owns a cab 11 C15A with a 261 transplant (USA large truck style) and I have a cab13 C15A with a 261 (Canadian Pontiac style). If you aren't already aware of it, there is a wealth of CMP information available at http://www.mapleleafup.net/forums/

Hi Grant, great to know there are a few of us on here.
I have an 11cab C30 which I'm hoping to put the 261 in. I would be very greatfull of any info you have on installing this engine in the C15A as its the same cab style.
What are the differences between the Pontiac and USA large truck engines?
How do they perform on the road?
I can get my C30 wound up to 40mph on the flat which I'm happy with but any sniff of an incline and I'm down through the box, most hills round my way leave me in 2nd at about 5mph.
My dad used to have a C15A 12cab, he's on Maple Leaf Up - thanks for the link, I'll have a good nosey through.

The major difference between the Canadian Pontiac 261 and the truck 261 (Canadian & USA) is the truck 261 has mechanical/solid lifters and the Pontiac 261 has hydraulic lifters.

The Pontiac 261 might have a different air cleaner than used on a truck.

Someone might know if the 58 and later Canadian Pontiac/truck 261s had the set-up to allow full-flow oil filtration (as available in 58-63 USA 261s).

Someone might know if the Canadian Pontiac 261 had the same front motor mount(s) as used in your truck (what year is your truck)?

Tim, it's 1940.

Is either one more readily available?
Is either one better for replacement parts?

Has anyone dealt with remanufactured.com? See link below...

http://remanufactured.com/Chevrolet_6_Cylinder_Engines.htm

Thanks,
Dave

Dave, I've never dealt with those guys, but I noticed that they also offer a 261 as well- if you're going to use them you might want to go that route...?

Good evening "Dasher"

Yes later 261 engines will bolt right in a cab 11.

It is a tight fit..... a very tight fit.

You will need to use an adapter plate to relocate your water pump to fit length wise and also to center it better in the mid of the radiator. Plan on using your 216 distributor which is shorter and uses a shorter dizzy cap. Strongly recommend using the Pertronix system which will eliminate the points and condenser and eliminate the need to remove the cab to adjust the points. Most truck 261 engines will have the front plate engine mounts and fits perfectly.

I am using a carter YF carburetor as recommended by Carb King. I used a professionally rebuilt Rochester 261 carb but found it was leaking badly when negotiating very steep gulleys while testing the rolling chassis.
It seems that the Rochester is vented somewhere on the top section and does not like being pitched too seriously. Knowing how tight and how hot the engine compartment can get I did not think that hoozing gasoline on a hot engine would be safe. The Carter YF is a bolt on, very responsive and a dream to install.

Since you seem familiar with the MLU forum look us up on the Hammond Barn in the restoration section. There are quite a few of us using the 261 for added "Humph".

Engine wise the 235 and 261 have a lot of similarity and even if harder to find the 261 is worth the effort. Parts are still reasonably available. There are quite a few members in the UK and the Continent that would be more than willing to share their experience and possibly trade parts. Finding an engine rebuilder in the UK maybe a little more difficult but it has been done before.

Any body else who wishes to see what a "Monkey face" Blitz CMP truck looks like, is invited to look up the Maple Leaf Up forum which has members around the world.

The early CMP like yours were based on British specifications....very tight driving compartment meant for a late teenager of 5'6" and 140 pounds, right hand drive, more of a tractor than a truck, geared very low, with a top speed of about 44 mph flat out.

CMPs where a joint effort between Ford and GM..... most body parts were interchangeable except for the engine/tranny....GM used a 216 L6 and Ford used their V8. Fords had the typical split axles and GM the banjo type of axles. You will noticed that your Chev has Ford brakes, Ford door handles and may have a Ford grill. Some Ford CMP were built with banjo GM front and rear axles when parts shortages would otherwise have stopped production.

Since CMP Canadian Oshawa made trucks were shipped to the UK, Europe, Russia, Australia, Brasil and Argentina NOS parts in the original cosmoline wrappers are still being unearthed by collectors. Big dealer in Holland and a UK chap has recently been transporting sea cans full of original parts from South America for resale to truck nuts like us.

Hoping to see you on MLU.

Bob Carriere

Dave - I am going to go the for a 261 if I can find one, they seem to be fairly elusive though!

Bob - many thanks, I have had a mooch about on MLU, it's a great site.

Dave