3 speed behind a 292

[Furno68C20]

Is a 292 too much for the 3OTT?

The 292 was usually with a sm420 or sm465 right?

I have a 1/2 ton with a bad 250. I can either put in a 307 or a 292.

Any suggestions? The 6 swap would be much easier.
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[Accelo]

No the 3-speed was available with the larger motors including the 350ci.
Listed as HD, maybe others will know how to ID the non-heave duty 3-speeds?
It appears the HD 3-speed was even an option behind the 400 V8.
List below is from 1971 C10;

[67 twins]

I might be a little biased, but I say go with a 292. Love mine that I swapped from a 250.
Just be aware the 292 takes a different passenger side motor stand that can be hard to find sometimes.

[special-K]

I've had two big block trucks with 3spd transmission. The 3spd was standard transmission in the 4wds, even K/20s.

[old51sedan]

Originally Posted by Furno68C20

Is a 292 too much for the 3OTT?

The 292 was usually with a sm420 or sm465 right?

I have a 1/2 ton with a bad 250. I can either put in a 307 or a 292.

Any suggestions? The 6 swap would be much easier.
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My truck came with a 250 and an automatic. I switched to the 292, you will need a different frame mount on the right side only. The theromstat housing is a little different than the 250 too. Also if you have PS on the 250, it will not fit the 292, other than that your good to go. Picture shows difference in housing.

[Furno68C20]

I’ve got the passenger side mount. Everything else should line up where the 250 sat.

One other question, can I use the 250 radiator for the 292?
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[old51sedan]

Originally Posted by Furno68C20

I’ve got the passenger side mount. Everything else should line up where the 250 sat.

One other question, can I use the 250 radiator for the 292?
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I did with mine.

[Steeveedee]

Originally Posted by old51sedan

I did with mine.

And you put AC in it, right? Did you install a fan shroud? I don't recall all the details. Just that I really like that truck!

[54blackhornet]

Years ago I was given a 68 GMC 1500 with a blown 250. I located a 292 just because I figured why put a 250 back in when the 292 would fit ? I never could keep the crappy Chinese rubber engine mounts from ripping out. The three on the tree and stock 250 rear end imo did not play well together.

[old51sedan]

Originally Posted by Steeveedee

And you put AC in it, right? Did you install a fan shroud? I don't recall all the details. Just that I really like that truck!

As you can see it has a full fan shroud, I bought this truck out of southern CA about 6 years ago and it came with a 3 core radiator and the shroud. Yes I added the vintage air, a 200-4R and the PS.

[Keith Seymore]

Originally Posted by Furno68C20

Is a 292 too much for the 3OTT?

The 292 was usually with a sm420 or sm465 right?

I have a 1/2 ton with a bad 250. I can either put in a 307 or a 292.

Any suggestions? The 6 swap would be much easier.
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You should be ok.

We had a 292 bored to 305 cu in, with three Rochester 2bbls (and Pontiac tripower progressive linkage) with a Saginaw four speed behind it, and it was fine.

K

[RichardJ]

Originally Posted by Furno68C20

Is a 292 too much for the 3OTT?

The 292 was usually with a sm420 or sm465 right?


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I am thinking it might have made a difference if it was a C10 or a C20. My 2500 GMC that i have had since '85, has the 292 that originally had the 3spd. the truck has a steel bed, leaf springs and a Dana 60 with 4.56 gears. The rear half of the 2-piece drive shaft is beefy and looks at home with the DANA. The front half of the drive shaft was smaller, anemic looking and seemed to belong with the small non-syncro 3spd. It looked like the truck was built to be a heavy duty 3/4 ton and I don't think GM wanted a 3spd in there, but they went with what some people ordered.

I replaced the 3spd with a SM465 and put 3.54 gears in the DANA. The new, longer front half of the drive shaft is more appropriately sized.

The truck is much happier with the truck 4spd.

[RichardJ]

A 292 bored .060 is 301 cubes, which is what I have. You have to go .090" to get 305.23 cubes. I've seen one that was .080" over that ran for years, but eventually it cracked a cylinder bore.

[Furno68C20]

Good info here. The 292 I have was out of a grain truck. 28k miles on the truck Score! Are the rubber mounts different on the grain than the c10/20/30?

I’d prefer to use the OEM mounts instead of new.
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[LockDoc]

Originally Posted by Furno68C20

Good info here. The 292 I have was out of a grain truck. 28k miles on the truck Score! Are the rubber mounts different on the grain than the c10/20/30?

I’d prefer to use the OEM mounts instead of new.
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I have two complete 292ci engines out of the larger grain trucks but I have never looked at the mounts that close. I know one of them has power steering on it. I will have to check them out. I think the block pads would be the same but the frame brackets may be different than the 292ci pickups.

I will try to remember to check them out.

LockDoc
.

[Furno68C20]

Originally Posted by LockDoc

I have two complete 292ci engines out of the larger grain trucks but I have never looked at the mounts that close. I know one of them has power steering on it. I will have to check them out. I think the block pads would be the same but the frame brackets may be different than the 292ci pickups.

I will try to remember to check them out.

The OEM c50 and up rubber engine mounts will fit a c10/20/30 frame.

LockDoc
.

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[LockDoc]

Originally Posted by Furno68C20

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I wrote myself a note to do this tomorrow. Thanks....

LockDoc

[LockDoc]

-
The rubber pad mounts are different for the C40, 50, 60 292 but the block brackets are the same, so the C10, 20, & 30 rubber pad mounts will work with the C40, 50, & 60 block brackets.

The big truck rubber pad mounts are about 3 x 5 inches and mount horizontally. 3 Bolt holes on the top side and 1 center bolt on the bottom. I will remove one of them and update this with a picture when I come back in later....

EDIT: Here are the pictures.

1st picture is front of big truck rubber mount. Second is the back. Third shows how holes line up with a C10, 20, 30 rubber mount, and 4th is the block bracket. The bottom hole in the block bracket has a weld nut in it.

LockDoc
.

[LockDoc]

-
Bump to top.... Edited my last post and added pictures.

LockDoc

[Furno68C20]

Nicely documented Dr.
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[LockDoc]

Originally Posted by Furno68C20

Nicely documented Dr.
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Thanks.

LockDoc