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Author Topic: big block to small block and back?  (Read 4743 times)

Offline 425hp87chevy

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big block to small block and back?
« on: June 08, 2010, 09:25:13 pm »
I have a 87 1/2 ton 4x4 350 throttle body with a 4 speed. and a 91 1/2 ton 4x4 454 throttle body 5 speed. I need to switch motors in the trucks (454 in 87 and 350 in the 91) and i want to leave the tranys. Exhaust I'm not worried about. Will the transmissions bolt up? can i switch the bell housing? Will my  wire harnesses work. And what do i have to do with the engine mounts. Any input/advice welcome and any other information needed i can supply. I'm usually good at this stuff but I'm a small SBC guy, big block and throttle bodies are not my thing ???
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Offline Irish_Alley

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Re: big block to small block and back?
« Reply #1 on: June 09, 2010, 01:28:24 am »
the bellhousing to engine are the same the bell housing to transmision i want to say they are all most sure if its a sm465 and nv4500 for 91 im almost sure they are the same. just remembered about the trans how you going to work the transfer cases the 87 is passengers side drop and the 91 is drivers side. need to know what transfer cases and transmisions you have
« Last Edit: June 09, 2010, 02:52:03 am by Irish_Alley »
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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

Offline Blazin

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Re: big block to small block and back?
« Reply #2 on: June 09, 2010, 06:33:23 am »
They will bolt to the bell housing no problem. You said your leaving the trans so the transfer case issue won't be an issue.
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Some people are like Slinkies. Not really good for anything, but they still bring a smile to your face when you push them down a flight of stairs

Offline 425hp87chevy

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Re: big block to small block and back?
« Reply #3 on: June 09, 2010, 10:49:11 am »
i am leaving the tranys, what about motor mounts, what do i have to change
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Offline Irish_Alley

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Re: big block to small block and back?
« Reply #4 on: June 09, 2010, 08:31:43 pm »
Didn't read it right. Thanks blaz
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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

Offline bigblock73

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Re: big block to small block and back?
« Reply #5 on: June 11, 2010, 02:35:58 pm »
Engine mounts are the same as well
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Jeff

'73 swb 2wd

73-87.com

Offline DnStClr

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Re: big block to small block and back?
« Reply #6 on: June 12, 2010, 04:50:08 pm »
For the wiring harness, both trucks use the same ecm, 1227747, so the harnesses should be the same too.
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Don
87 Chevy Silverado
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