292 to 427T industrial swap, in C30. Many questions on fitment.

[AyWoSch Motors]

I look extensively threw the treads to find answers. Found a few, but none that applied to my situation and swap exactly. And have a few offball questions too.
Never done a engine swap from 6 to 8, or sb to bb, especially not straight 6 to BBCV8. Only same size to same size.

The truck a 81 C30 Custom Deluxe. Had a 292 in it, still has the th400. I bought an 81 427T industrial, out of a dump truck or a bus or something. I stripped it down, and it runs pretty well.

Now im pretty sure a th400 with a 6 bolt converter will work well behind a big block. I dont think thats an issue, but let me know if you think it is.

First big question is, what engine mount brackets do I/can I use? It obviously has 292 brackets right now, so the one on the passenger side is forward a bit.
I have a set off a 78 C10 that had a "v8". Not sure what type.
1: will C10 parts bolt on a C30?
2: are small block engine mount brackets the same as big block engine mount brackets? 2.5: are they in the same place on the frame?
3: are the cup part of the bracket on the engine side the same from small block to big block?
4: are the mounts, frame side or engine side the same from a 454 to a 366 or 427 tall deck? I assume they are, because the bottom end are roughly the same.

Second big thing. Is there any fitment issues under hood height or width wise?
i know the tall decks are a little taller, and a little wider.
1: Any issues hitting anything left or right?
2: any issues hitting the hood with air cleaner or carburetor?
3: and does it effect exhaust clearance any?

Thats all i can think of right now, but im sure there will be more.

I can take any pics you need on demand.
Truck has clean empty engine bay, truck with engine mounts has clean engine bay, and engine is on a hoist in my shop right now.

I also have a blazer that was a 350 truck that someone put a 454 in so i can use as example or for measurements, but its hard to get to, and i didn't do any of that work.

Thank you for any insight you have.
Hoping to do this swap next weekend, maybe.

The engine, if it helps any....

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[fast 99]

Obviously if any of the brackets use the heads for mounting, they would be different than regular big blocks. None of the small block brackets will fit. Motor mounts and bellhousing bolt pattern are the same.

I have never used a tall truck block for a conversion would assume the exhaust manifolds would be wider and may cause frame interference. Personally, I wouldn't use a tall block unless it is a complete pull out. Parts may be hard to locate. That motor also appears well worn.

If you could provide a picture of the area just above the water pump where the head and block meet can tell you if it is indeed a tall block.

 

[85K304SPD]

Big block trucks use different motor mounts than small block trucks. The bolt pattern on the frame is different. Not sure about 6 cyl, but it seems like the whole front K frame is different. Do you have pictures of the 6 cyl truck K frame? The tall block will "work", but will take some creative adapting. The tall blocks that I have seen in the past will only rev up to about 4000 rpm max.

 

[AyWoSch Motors]

Big block trucks use different motor mounts than small block trucks. The bolt pattern on the frame is different. Not sure about 6 cyl, but it seems like the whole front K frame is different. Do you have pictures of the 6 cyl truck K frame? The tall block will "work", but will take some creative adapting. The tall blocks that I have seen in the past will only rev up to about 4000 rpm max.

Low RPM works for me. Doesnt need to be fast, just powerful.

Ill take some pics...

 

[squaredeal91]

I've swapped big block small block straight 6, v6 and diesel. pretty much all fit that I tried in square body's. All mounts appear to be about the same except the straight 6 was different, im not 100% about all v8 mounts but I always had extras lying around and I never had to buy any special mounts. Difference may be engine fan and shroud, Radiator cooling capability. Otherwise should fit in there well.

 

[DoubleDingo]

The 292 has the offset passenger side frame mount for the engine mount. And of course the accessory brackets are different.

 

[Grit dog]

Tall deck engines are close call with the vac brake booster in my limited experience but fit. Just about anything fits under the hood of a square.
My question is why? Just because you can?
I don’t see that truck ever hitting freeway speeds or pulling large trailers or any trailers on the highway.
427 sure make a nice engine for any of the other plethora of road worthy squares you have IMO.

 

[bucket]

It is true that small block and big block mounts are "different". But, a small block will fit with big block mounts and a big block will mount with small block mounts.

The key is to use the same frame mounts and engine mounts from the same V8 truck. All will be well.

 

[fast 99]

Sorry for the error.
Should have said the 6 cyl mounts need to be removed [frame side] and V8 mounts installed.

I did this conversion but not with a tall deck. It can be done. No frame modifications were needed. Your 427 pan likely won't work. As another said the engine won't like RPM. Truck engines are designed to operate at high load, long pulls.

 

[AyWoSch Motors]

Tall deck engines are close call with the vac brake booster in my limited experience but fit. Just about anything fits under the hood of a square.
My question is why? Just because you can?
I don’t see that truck ever hitting freeway speeds or pulling large trailers or any trailers on the highway.
427 sure make a nice engine for any of the other plethora of road worthy squares you have IMO.

Just because really.

Because i have a truck that needs a running engine, and a i have a running engine that has no specific home. Figured id be a good replacment for that 292. They're both heavy, low RPM, high torque, engines.
And this thing probabaly jas sme srupid rea gear like a 4:56 or somthing. Its never going to be fast, just for putting around the yard.
And id like it to be able to tow heavy trailers around, and mainly be the one for if i have to maneuver in a tight place with.
I would also like it to be able to tow either of my 3 duece and a half, just incase i need to if they die, because nothing else i own will.

I figure that 427 isnt really hood for anything else, because the dont like high rpm. Thought about putting it in my blazer or my impala, because big block fun, but this isnt the right setup. They wont rev high, and they make a lot of power, just torque monsters

 

[AyWoSch Motors]

Obviously if any of the brackets use the heads for mounting, they would be different than regular big blocks. None of the small block brackets will fit. Motor mounts and bellhousing bolt pattern are the same.

I have never used a tall truck block for a conversion would assume the exhaust manifolds would be wider and may cause frame interference. Personally, I wouldn't use a tall block unless it is a complete pull out. Parts may be hard to locate. That motor also appears well worn.

If you could provide a picture of the area just above the water pump where the head and block meet can tell you if it is indeed a tall block.

I ran the numbers, its came back as a 81 427T.

Motor was low mileage. It runs great.

I have all the accessory drive brackety for a big block, and all the old brackets off this 427.

 

[AyWoSch Motors]

I've swapped big block small block straight 6, v6 and diesel. pretty much all fit that I tried in square body's. All mounts appear to be about the same except the straight 6 was different, im not 100% about all v8 mounts but I always had extras lying around and I never had to buy any special mounts. Difference may be engine fan and shroud, Radiator cooling capability. Otherwise should fit in there well.

I have a 4 core RV radiator and BB shroud for it, so no biggy..

 

[AyWoSch Motors]

Tall deck engines are close call with the vac brake booster in my limited experience but fit. Just about anything fits under the hood of a square.
My question is why? Just because you can?
I don’t see that truck ever hitting freeway speeds or pulling large trailers or any trailers on the highway.
427 sure make a nice engine for any of the other plethora of road worthy squares you have IMO.

I have the hydroboost, so no Vac booster.

 

[AyWoSch Motors]

So i had these sitting around. Bolt pattern lines up on the block. These should be good right?

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And this the mount bracket setup it had for 292...

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But i took that passenger side one out, and put in one from my "V8" parts truck C10. Seems to line up right, i think.
Drivers side one seemed the same on both, so i left it in place on both.

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only question i have, is the bolt pattern looks right, but if you put the top 2 bolts in, the bottom 2 disappear, and if you put the bottom 2 in, the top 2 disappear and it seems to sit high. Is this one the wrong one, or is it bent, or do i just bolt the top in, ad redrill the bottoms?

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[AyWoSch Motors]

Another question, there seems to be a dual bolt pattern on the brackets. The "v8" truck had the mount on the top set, and the 292 bracket has it on the bottom set.
Which one fits for BBC?

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