366 engine in a squarebody worker?

[zieg85]

While combing through my local scrap yard I stumbled across a 366 that looks to be freshly rebuilt in a C60.  Everything I've purchased thus far has been dirt cheap but obviously would have to get a price and then go through the work of getting it running before taking it out of the truck.  Would those engines be any good for low rpm torque in a towing application in a 1 ton?

[1967KaiserM715]

We have a 366 in our C60, 4 spd with split rear. It could move some serious loads, it's not a real high revving motor, but it is certainly a nice low rpm torque engine; I think it would work great.

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[zieg85]

We have a 366 in our C60, 4 spd with split rear. It could move some serious loads, it's not a real high revving motor, but it is certainly a nice low rpm torque engine; I think it would work great.

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Thanks for the input.  I am going to try and find the engine specs on these.  I know my 454 does well with a 4 speed and a 3.21 rear end.  Hoping that a 366 would do better, more economically with the next build I am trying to plan out.

[bd]

The 366 was the long-standing standard workhorse of the C5500 - C7500 GMCs.  It is a reliable, torquey engine with a strong bottom end - runs happiest below ~4,200 RPM.  It is by no means economical; in fact, somewhat fuel thirsty.  Works well coupled through an Allison automatic or 6-speed manual with button clutch, but generally prefers a two-speed axle behind a 4-speed or 5-speed.

For fun:  Eaton transmissions   

[Stewart G Griffin]

i feel, generally, the key is, in cases like this is, do you like the engine?

For example, i really dig the gmc v-6's, but unless you're treating this like a hobby and actually have the time to pursue it with conviction then i feel the fastest, easiest, cheapest most efficient way to get a truck running is small block chevy, big block chevy and to a lesser extent the 4.3 and inline 6's.

Now i realize the 366 IS a big block externally ( i think?)  but there are still differences between it and the much more common 454/427/396 etc. and therefore i consider the 366 to be a more "exotic" shall we say  ( i don't want to say "oddball") engine.

i also have a hunch that the 454 would be more flexible all-around vs. the 366.  The 454 might offer better mpg (despite being 90 cubes larger) and might offer just as good if not better low end torque.

The only experience i have with a 366 is also the only experience i've had with a big block-----in a 6500 u-haul truck.  It wasn't bad.

But the bottom line is do YOU like the engine?

[zieg85]

i feel, generally, the key is, in cases like this is, do you like the engine?

For example, i really dig the gmc v-6's, but unless you're treating this like a hobby and actually have the time to pursue it with conviction then i feel the fastest, easiest, cheapest most efficient way to get a truck running is small block chevy, big block chevy and to a lesser extent the 4.3 and inline 6's.

Now i realize the 366 IS a big block externally ( i think?)  but there are still differences between it and the much more common 454/427/396 etc. and therefore i consider the 366 to be a more "exotic" shall we say  ( i don't want to say "oddball") engine.

i also have a hunch that the 454 would be more flexible all-around vs. the 366.  The 454 might offer better mpg (despite being 90 cubes larger) and might offer just as good if not better low end torque.

The only experience i have with a 366 is also the only experience i've had with a big block-----in a 6500 u-haul truck.  It wasn't bad.

But the bottom line is do YOU like the engine?

Just getting an opinion, have no experience with a 366 at all.  When you stumble upon one that can potentially be very cheap to buy is why I asked the question.  I figured if it moved a 2-3 ton truck it should move a 1 ton well with very little effort.  454's don't do bad if you keep the rpm's down thinking 90 CU less may do better. 

[Stewart G Griffin]

i guess what i am trying to say is that i have a hunch that a 454 can give you everything a 366 can give you---AND MORE.

But if you have that burning curiosity about a certain engine AND you can get it cheap, then that is a good enough reason to pursue it   (Assuming you have a back up truck)

i mean with me, i love the 90 v-6 engine and i pursued it.  Of course in retrospect it was probably a mistake to have the truck tied up for all those months, but now that it's running everything is cool.

Will discuss more.  i'm getting sleepy and i think you are looking at it in more practical terms vs. hobby terms?

[zieg85]

i guess what i am trying to say is that i have a hunch that a 454 can give you everything a 366 can give you---AND MORE.

But if you have that burning curiosity about a certain engine AND you can get it cheap, then that is a good enough reason to pursue it   (Assuming you have a back up truck)

i mean with me, i love the 90 v-6 engine and i pursued it.  Of course in retrospect it was probably a mistake to have the truck tied up for all those months, but now that it's running everything is cool.

Will discuss more.  i'm getting sleepy and i think you are looking at it in more practical terms vs. hobby terms?

This is a build so anything is possible.  I don't even have the truck yet, just ideas.  I am all about making something out of next to nothing.  If this engine is going to be hard on gas I am not going to pursue it.

[big_al273]

The biggest differences between the 366/427 medium duty "Truck" engines and the 454 from our trucks is an increased deck height and taller pistons with 4 rings instead of three, there are more differences such as the cam height, timing cover, water pump location ect but ALL 366/427 "truck" motors come with Forged cranks and Bore X stroke ratio that is very well suited for high torque low rpm setups, Aftermarket support used to be lacking for these engines but from what i understand this has been changing and MANY "Car" big block parts are compatible

[Stewart G Griffin]

i mean if you can get it cheap i'm sure it would do great as a tower.   And gas is cheap and probably going to stay that way for a while.   How much driving are you planning on doing?


i think the 366 suffers from the same "problems" as the GMC v-6---very heavy crank, pistons, rods.  Really overbuilt, which is great for durability, not so great for mpg.

[Captain Swampy]

I had a 305 V6, it was a torque monster. Other than I was young and wanted the V8 sound it was a great engine. I think your 366 will be a good project. The V6 snapped the spider gear pin into 3 pieces. In your application it should even get decent MPG.

[Stewart G Griffin]

i guess the bottom line of what i'm trying to say is that the 366 is a decent engine, but it's sort of like getting a 305 for free or cheap;  There may be even better or more flexible choices, not that either of those two engines are bad.

For example IF i were going to put a big block in a crew cab (which i wouldn't, but if i did) then i would want a "regular" 454 because i think it will have more rpm range, more top end which is important for highway towing in order to keep up with traffic....... and possibly even more bottom end and possibly as good or better mpg than the 366 depending of how it's built.

UNLESS the 366 was real cheap and it could be verified that the 366 was recently and properly manufactured.   Because i can certainly understand putting something together for next to nothing although i'm not operating in that phase anymore.

[Engineer]

The biggest differences between the 366/427 medium duty "Truck" engines and the 454 from our trucks is an increased deck height and taller pistons with 4 rings instead of three, there are more differences such as the cam height, timing cover, water pump location ect but ALL 366/427 "truck" motors come with Forged cranks and Bore X stroke ratio that is very well suited for high torque low rpm setups, Aftermarket support used to be lacking for these engines but from what i understand this has been changing and MANY "Car" big block parts are compatible

Only partially correct.

The 366 is a tall deck, 10.2", engine. The difference is the block deck height only. Only difference with commonality of parts is the block, pistons, push rods, distributor, and intake manifold. All other specs are the same as the passenger 9.8" deck height blocks. Cam location, water pump location, etc. are the same.

All 366s, and truck 427s were 4-bolt main and used the same steel crankshaft forging as the L88 Corvette 427 until the switch to one piece rear main.

And a little side note: The ZL1, L88, and LS6 engines used 7/16" bolted connecting rods. ALL OTHER big block Chevy engines used the exact same 3/8" bolt connecting rod from 1965 until the 496/8.1L engine replaced it in 2001.

The 366, and 427 truck/tall deck with its much heavier piston should never be revved beyond 5,000RPMs.