The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1973 - 1987 Chevrolet & GMC Squarebody Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 10-24-2021, 09:40 AM   #1
eric8
Registered User
 
Join Date: May 2013
Location: Utopia
Posts: 215
BBC 2wd engine mounts

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.
Attached Images
 
eric8 is offline   Reply With Quote
Old 10-24-2021, 10:22 AM   #2
geezer#99
Registered User
 
geezer#99's Avatar
 
Join Date: Aug 2009
Location: Bowser
Posts: 13,495
Re: BBC 2wd engine mounts

I swapped a 396 in place of my stock 350 in a 74 sb.
Used the 350 mounts.
Bolted in.
geezer#99 is offline   Reply With Quote
Old 10-24-2021, 11:51 AM   #3
eric8
Registered User
 
Join Date: May 2013
Location: Utopia
Posts: 215
Re: BBC 2wd engine mounts

Quote:
Originally Posted by geezer#99 View Post
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.
eric8 is offline   Reply With Quote
Old 10-24-2021, 12:58 PM   #4
geezer#99
Registered User
 
geezer#99's Avatar
 
Join Date: Aug 2009
Location: Bowser
Posts: 13,495
Re: BBC 2wd engine mounts

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.
geezer#99 is offline   Reply With Quote
Old 10-24-2021, 01:31 PM   #5
kwmech
Senior Member
 
Join Date: Mar 2003
Location: Colfax-California
Posts: 8,356
Re: BBC 2wd engine mounts

Quote:
Originally Posted by eric8 View Post
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
kwmech is offline   Reply With Quote
Old 10-24-2021, 03:39 PM   #6
Pontiac1976
Registered User
 
Pontiac1976's Avatar
 
Join Date: Oct 2015
Location: Ottawa, Ontario, Canada
Posts: 750
Re: BBC 2wd engine mounts

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.
__________________
1977 REG cab Long Bed with a 1984 Front Clip, 82 305 .60 over 9.0.1 flat top pistons, 4bbl, TH350, w/84 SS-intake & cam , w/ 1977 big block rad, 1975 gear box, 1984 master w/ metric fittings top & SAE fitting @ portion block, 1975 3.42 gear open diff. Duel 77-87 Factory air cleaner, duel inlet from rad support . Down sized 9' to new 8' Steel flat bed
Was a 77 454 w/308 gear. Taken out 550 lbs. up front with motor clip change.
Pontiac1976 is offline   Reply With Quote
Old 10-24-2021, 03:46 PM   #7
Greasey Harley
Registered User
 
Greasey Harley's Avatar
 
Join Date: May 2013
Location: Post Falls, ID
Posts: 884
Re: BBC 2wd engine mounts

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.
__________________
Insert clever text here:
Greasey Harley is offline   Reply With Quote
Old 10-25-2021, 10:15 AM   #8
blazer2007
Registered User
 
Join Date: Jan 2007
Location: vernon b.c.
Posts: 3,019
Re: BBC 2wd engine mounts

same here
blazer2007 is offline   Reply With Quote
Old 10-25-2021, 04:09 PM   #9
eric8
Registered User
 
Join Date: May 2013
Location: Utopia
Posts: 215
Re: BBC 2wd engine mounts

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?
Attached Images
  

Last edited by eric8; 10-25-2021 at 04:14 PM.
eric8 is offline   Reply With Quote
Old 10-25-2021, 06:36 PM   #10
pound41
Registered User
 
Join Date: Dec 2002
Location: Northern Virginia
Posts: 1,266
Re: BBC 2wd engine mounts

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
pound41 is offline   Reply With Quote
Old 10-25-2021, 09:15 PM   #11
eric8
Registered User
 
Join Date: May 2013
Location: Utopia
Posts: 215
Re: BBC 2wd engine mounts

Quote:
Originally Posted by pound41 View Post
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:
Attached Images
 
eric8 is offline   Reply With Quote
Old 10-25-2021, 10:21 PM   #12
pound41
Registered User
 
Join Date: Dec 2002
Location: Northern Virginia
Posts: 1,266
Re: BBC 2wd engine mounts

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
pound41 is offline   Reply With Quote
Old 10-26-2021, 11:56 AM   #13
eric8
Registered User
 
Join Date: May 2013
Location: Utopia
Posts: 215
Re: BBC 2wd engine mounts

Quote:
Originally Posted by pound41 View Post
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!
eric8 is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 05:26 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com