BBC 2wd engine mounts

[eric8]

Trying to get a definitive answer on doing a BBC swap on an original small block equipped 77 C10 (2wd). Doing a search on this topic has left me even more confused. Some have installed a big block using all the original small block mount components and say everything fits fine. Others say the engine will not sit properly if you go this route.
So long story short, what items in the following pic are big block specific? I’m trying to get part numbers on exactly what I need to search for to make this swap. It’s my understanding that there are no aftermarket mount solutions to make the big block swap for the 73-87 platform, so junkyard parts are the only option short of fabbing up your own mounts.

[geezer#99]

I swapped a 396 in place of my stock 350 in a 74 sb.
Used the 350 mounts.
Bolted in.

[eric8]

Originally Posted by geezer#99

I swapped a 396 in place of my stock 350 in a 74 sb.
Used the 350 mounts.
Bolted in.

Did you use the mechanical fan and OEM fan shroud? I read that the small block mounts will position the engine lower and cause the fan to hit. The lower mounting position of the engine will also apparently throw off the driveline pinion angles? Some said a mechanical BBC fuel pump will also hit the frame when using SBC mounts.

[geezer#99]

Now you’re stretching my 45 years ago memory! LOL!
Don’t recall any problems.
Bolted right to the stock bellhousing.
New flywheel of course.
Pinion angle not a problem.

Fan and shroud was different though. Original shroud didn’t survive the new flex fan explosion.

[kwmech]

Originally Posted by eric8

Did you use the mechanical fan and OEM fan shroud? I read that the small block mounts will position the engine lower and cause the fan to hit. The lower mounting position of the engine will also apparently throw off the driveline pinion angles? Some said a mechanical BBC fuel pump will also hit the frame when using SBC mounts.

Never had any of those issues. And I've done quite a few conversions over the years. The only thing I've noticed is the fan sits deeper in the shroud. I've had a few customers thank me for doing the conversion. Claimed they were actually getting better gas mileage than the small block. Doing a swap in a 74 K5 right now with a 502 crate and a T400 so there was some frame drilling for the trans x-member. I'll take some pics this week

[Pontiac1976]

I had 2wd Chev a 77 350 TH350 put in 77 454 small block engine mounting hard ware and the 350th on it way out put a trans cooler got 8 yrs trans went lost rear gear and 1 while backing up a hill with trail car on it. This set is ok with stock block shroud 3core rad and clutch & 5 blade fan. The small block 350 can be a real gas killer with a 3.08 gear in rear 235/75/15 tires. The MPH was better down 35-45 at 50MPH the RPM would be some where between 3200-3500 If recall right. Then down size 305 miles for the gas used with the engine mounting that in it.

[Greasey Harley]

I swapped my '73 Jimmy from a sb400, to a bb396, to a tbi350 same motor mounts same radiator and shroud. direct swap every time, no issues.

[blazer2007]

same here

[eric8]

Ok guys after some digging I was able to locate actual part numbers. However, the BBC “clamshell” is of course unavailable anywhere except junkyards. But for the benefit of all, the big block uses a specific engine mounted clamshell (see item #10 below) and its own specific engine mount (item #4). Both SB and BB use the same metal frame cradle (item #1). But as stated by others, you can apparently get by with making the small block stuff work with a big block.

Note:This is from an 85-91 parts breakdown, but I assume that 73-84 would use the same part numbers?

[pound41]

I have a 76 stepside 454 that my Dad left me. I will be where the truck is sometime next week I could snap some pictures if need to see something

[eric8]

Originally Posted by pound41

I have a 76 stepside 454 that my Dad left me. I will be where the truck is sometime next week I could snap some pictures if need to see something

Yes that would be awesome. I’m curious what part number is stamped on the engine mount clamshell (item #10 shown above) on your dad’s truck. You may not be able to see it though if the engine is installed. Should be stamped on the front or rear area of the clamshell like so:

[pound41]

I will look when I go out there
Go to the parts section and scroll down there are BBC Clamshells for sale The guy says in listing BBC same as a 4wd I think

[eric8]

Originally Posted by pound41

I will look when I go out there
Go to the parts section and scroll down there are BBC Clamshells for sale The guy says in listing BBC same as a 4wd I think

Ok thanks. Please keep me posted!