Author Topic: SBC to BBC swap?  (Read 3728 times)

Offline gtfireftr

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SBC to BBC swap?
« on: May 23, 2018, 04:53:06 PM »
I am a minute from purchasing a 1986 swb with a 305.... I will probable leave the engine until the winter, but then I am considering a BBC swap.... My question is will the BB just sit in the mounts of the SB??
TIA

Offline Irish_Alley

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Re: SBC to BBC swap?
« Reply #1 on: May 23, 2018, 08:52:07 PM »
just curious but why a BB? not saying dont but it will be cheaper and easier to mod the sbc. you could buy a 350 now and build it up (cam and heads) and have a decent power making engine for under 2k and you will be pushing 400 hp/tq.
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Offline VileZambonie

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Re: SBC to BBC swap?
« Reply #2 on: May 24, 2018, 07:57:52 AM »
Ever owned a BBC? No comparison, it's the girth  8)

V8 mounting location is the same.
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Offline Rattler12

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Re: SBC to BBC swap?
« Reply #3 on: May 24, 2018, 08:03:35 AM »
There ain't no substitute for cubic inches ……..:)  Besides a 305 doesn't lend itself to getting the most bang for the buck with mods.  And there's not much difference in 10 mpg and 12 mpg. Beside a BB just looks awesome in a square body. To answer the OP's question the BB will bolt right in but needs its own mounts to the block
83 C-10 shorty 454, 5spd, 3:73 posi

Offline Stewart G Griffin

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Re: SBC to BBC swap?
« Reply #4 on: May 24, 2018, 11:19:16 AM »
There ain't no substitute for cubic inches ……..:)  Besides a 305 doesn't lend itself to getting the most bang for the buck with mods.  And there's not much difference in 10 mpg and 12 mpg. Beside a BB just looks awesome in a square body. To answer the OP's question the BB will bolt right in but needs its own mounts to the block

DO You mean the clamshell mounts in the second picture?

i'm asking because i'm looking for a 3/4 suburban/crewcab or van...........and you know which direction i'm going engine-wise IF it comes with a BB..........

Offline Rattler12

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Re: SBC to BBC swap?
« Reply #5 on: May 24, 2018, 01:10:48 PM »
There ain't no substitute for cubic inches ……..:)  Besides a 305 doesn't lend itself to getting the most bang for the buck with mods.  And there's not much difference in 10 mpg and 12 mpg. Beside a BB just looks awesome in a square body. To answer the OP's question the BB will bolt right in but needs its own mounts to the block

DO You mean the clamshell mounts in the second picture?

i'm asking because i'm looking for a 3/4 suburban/crewcab or van...........and you know which direction i'm going engine-wise IF it comes with a BB..........




Those are the same...….. the "rubber"mounts that bolt to cross member are different but not by much. The hole in the BB rubber mount is a bit higher than the SB mount if memory serves
83 C-10 shorty 454, 5spd, 3:73 posi

Offline ehjorten

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Re: SBC to BBC swap?
« Reply #6 on: May 24, 2018, 01:59:39 PM »
The Truck Motor Mounts that bolt to the crossmember are different from SBC to BBC.

The SBC Truck mounts have this mounting pattern, but only use 3 holes:


The BBC Truck mounts have this mounting pattern:


The pieces that the motor mounts bolt to are swap-able, as they simply bolt in!

The difference in the pattern looks like this:
-Erik-
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1968 Chevrolet Step-side Pickup - 300HP L6

Offline Irish_Alley

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Re: SBC to BBC swap?
« Reply #7 on: May 24, 2018, 03:47:47 PM »
There ain't no substitute for cubic inches ……..:)
the more CI you push the more gas you need to feed. this is why the ecoboost is a decent motor in my mind. fuel saver when its not in use and the power when you need it. besides that stock vs stock yes the bb would be a better choice if you plan on towing all the time if you want an all around truck and care about MPGs sb or diesel imo. dont get me wrong a BB can outperform diesels and SBs but each one has its drawbacks

Besides a 305 doesn't lend itself to getting the most bang for the buck with mods.
cant really argue that but like i said for around 2k (cam+ crate motor) you can have a 400 hp/tq motor and that will out perform most BB
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes