Has anyone ever built a 377 Small Block?

[Midnightmoon]

Kind of an intellectual exercise more than anything else at this point. But, has anyone here ever built a 377 CID Small Block, combining a 400 block with a 350 rotating assembly? From what I have read, the combination isn't as popular as it once was, especially with everyone building the classic 383. Other than the obvious main bearing spacers, what else would be needed to make this work assuming that you already had a 400 block and 350 rotating assembly available? I'm assuming it would work out to be a good mid-higher rpm free revving little thing correct?

Thanks as always

Justin

 

[squaredeal91]

id be interested in the pros and cons of this setup. Sounds cool. Probably isn't as popular because the 400 is not as common now.

 

[Bennyt]

Kind of an intellectual exercise more than anything else at this point. But, has anyone here ever built a 377 CID Small Block, combining a 400 block with a 350 rotating assembly? From what I have read, the combination isn't as popular as it once was, especially with everyone building the classic 383. Other than the obvious main bearing spacers, what else would be needed to make this work assuming that you already had a 400 block and 350 rotating assembly available? I'm assuming it would work out to be a good mid-higher rpm free revving little thing correct?

Thanks as always

Justin

Yes, I've been part of a couple builds. Never for a truck as they are/ were best for lightweight cars that spent time in the corners.

You could, or at least you could buy cranks with the larger mains so you didn't have to run the spacers.

I think you could run 6" rods but it's been so long, I don't remember.

 

[Rusty Nail]

Yeah buddy. I betcha 6.125" rods would be possible pretty easy.
Because mother eff 5.7" rods in a 400.
Might have to shop around in STROKER kits to get the ring pack tight enough and the wrist pin high enough to be happy at the end of them long azz Rizzods.

RIZZODZ!

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[Midnightmoon]

Yes, I've been part of a couple builds. Never for a truck as they are/ were best for lightweight cars that spent time in the corners.

You could, or at least you could buy cranks with the larger mains so you didn't have to run the spacers.

I think you could run 6" rods but it's been so long, I don't remember

I'm assuming that the 6" rod would allow the use of a standard height piston correct? Do some people build them with the standard 5.7" rod?

 

[Midnightmoon]

Yeah buddy. I betcha 6.125" rods would be possible pretty easy.
Because mother eff 5.7" rods in a 400.
Might have to shop around in STROKER kits to get the ring pack tight enough and the wrist pin high enough to be happy at the end of them long azz Rizzods.

RIZZODZ!

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We posted at the same time concerning rod length. Wondering if it has ever been done with a standard 5.7" rod and a taller piston. Enjoying this conversation by the way. Hoping that I'm not the only person to walk through the garage, look at a pile of junk and say "wonder what I can do with that"?

 

[TotalyHucked]

I don't know anything at all about how they're built but when I was running HSR/SVRA with my dad and his buddy, there were lots of road race cars from the late 70s-80s that ran 377s and they're nasty, high winding things. Lots of power when done right.

 

[Ricko1966]

The reason to build a 377 is you happen to have a 400 block and a 350 crank laying around,or you have a displacement limit. A lot of stock car racers built them to meet displacement requirements. You'd make more average power with a 406. The reason the 383 is so popular is because 350 blocks are everywhere,if 400 blocks were as common as 350 blocks 406s would be the go to build. A long rod 406 with good heads is a bad Jose.

 

[stroker2]

As stated above just build a 406 , tons more torque for a heavy truck build .

 

[Midnightmoon]

The reason to build a 377 is you happen to have a 400 block and a 350 crank laying around,or you have a displacement limit. A lot of stock car racers built them to meet displacement requirements. You'd make more average power with a 406. The reason the 383 is so popular is because 350 blocks are everywhere,if 400 blocks were as common as 350 blocks 406s would be the go to build. A long rod 406 with good heads is a bad Jose.

That's the exact point of this conversation. Have a complete 350 with good internals and a bad block. Have access to a 400 block so I'm just running the idea through my mind. Negligible difference in prepping that one vs another 350 block.

 

[idahovette]

Yeah Justin @Midnightmoon I can hear the wheels turning from here......lol

 

[Midnightmoon]

As stated above just build a 406 , tons more torque for a heavy truck build .

No interest in a 406 and it wouldn't be specifically for a square. I build lots of stuff so would be just for the fun of building it.

 

[Midnightmoon]

Yeah Justin @Midnightmoon I can hear the wheels turning from here......lol

Like maybe for my Z28 in the future with a set of 4.56's....lol

 

[idahovette]

Better go 4.88s.......it's gonna wind. Had 5.38s in my straight line 56 wagon

 

[fast 99]

The reason to build a 377 is you happen to have a 400 block and a 350 crank laying around,or you have a displacement limit. A lot of stock car racers built them to meet displacement requirements. You'd make more average power with a 406. The reason the 383 is so popular is because 350 blocks are everywhere,if 400 blocks were as common as 350 blocks 406s would be the go to build. A long rod 406 with good heads is a bad Jose.

As I read the OP this is exactly what I was thinking. Back in the late 70's to early 80's 377 builds were more common than 355 in racing, at least here. Required special thicker main bearings. Those were sometimes pinned to halt rotation. Usually RPM's were held in the 7200-7300 range. Low by todays standards. Not to change the subject mushroom lifters were also common.

A 406 was an animal. Even sounded different than a 350. They didn't live more than a few races, expensive. To help the bottom end survive we usually sourced 2 bolt blocks and installed aftermarket splayed main caps.

In business I pulled a lot of 400's out and installed 350's. The 400's were breaking cranks and loosing rings seal.

Was able to locate 2 400 engines years ago in case I ever wanted to build one. With heads available today probably could make a SB perform near BB power.