GMC 305 V-6 to sbc swap...question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**grumpy** · 10-21-2007, 07:41 PM

I have a 63 GMC burb with a 305 V6 and a 3spd.

A local guy said I can direct swap a sbc into the big6 spot, and hook up the the 3spd.

Is this so??

I was going 350/350 or 700r4, but if it's a direct swap, maybe leave the 3spd for now....

anyone with knowledge of this swap?

Thanks

68GMCCustom · 10-22-2007, 01:17 AM

I'm doing the same thing and without more info its hard to say. Most likely the carb linkage is different. Alternator is probably internal reg and your '63 is external unless you changed it. If the V8 has HEI you'll need to make some wiring changes. And of course there's the exhaust. As far as the mounts...I got lucky and didn't have to deal with that part so I can't say.

shouldn't be anything hard though.

60-66 Nut · 10-22-2007, 11:07 AM

Your 3 speed is about the only thing that will fit a small block V8. Everything else is different, bell housing, flywheel, engine brackets, clutch linkage, and probably a few more things I'm forgetting.

60-66 Nut

**grumpy** · 10-22-2007, 04:33 PM

Cool. Then out comes the big6 and 3spd then. I'll just go 350/350 or 700r4, and be done with it.

Appreciate it

68GMCCustom · 10-22-2007, 08:55 PM

Thats what I did, basically. I swapped the pedals and column from the '72 C10 along with the complete chassis, which has a late 80's 305 with a 4V and a t350.
When the body gets joined back with its chassis it will have a clutch again, with a built LSX (carb'd w/MSD setup) and either a TKO-600 or a built up T-56.

10-21-2007, 07:41 PM	#1
grumpy Registered User Join Date: Feb 2007 Location: NE Ohio Posts: 737	GMC 305 V-6 to sbc swap...question I have a 63 GMC burb with a 305 V6 and a 3spd. A local guy said I can direct swap a sbc into the big6 spot, and hook up the the 3spd. Is this so?? I was going 350/350 or 700r4, but if it's a direct swap, maybe leave the 3spd for now.... anyone with knowledge of this swap? Thanks

10-22-2007, 01:17 AM	#2
68GMCCustom Truck and auto performance nut Join Date: Feb 2007 Location: McKinney,Texas Posts: 3,848	Re: GMC 305 V-6 to sbc swap...question I'm doing the same thing and without more info its hard to say. Most likely the carb linkage is different. Alternator is probably internal reg and your '63 is external unless you changed it. If the V8 has HEI you'll need to make some wiring changes. And of course there's the exhaust. As far as the mounts...I got lucky and didn't have to deal with that part so I can't say. shouldn't be anything hard though. __________________ Kurt - '68 GMC short step - NIB '09 LY6 6.0L crate motor w/mods, NIB '12 crate 4L85e w/billet 3k stall Circle D, 3.73 posi 12 bolt, DynaTech f-swap headers, 3/4 drop, handling mods, etc. - my toy '72 Chevy LWB C-10 Highlander - 350/350 ps/pb/tilt/ac - not original but close '06 Chevy TrailBlazerSS - LS2/4L70e - little black hot rod SUV - my DD '18 Kia Sorento - wife's econo-driver '95 Chevy S10 - reg cab shortbed, LS, 4.3, auto... my '68's powertrain and chassis build -links broken A surprise phase - carb to efi -links broken

10-22-2007, 11:07 AM	#3
60-66 Nut Professional Beer Tester Join Date: Aug 2004 Location: Louisiana Posts: 453	Re: GMC 305 V-6 to sbc swap...question Your 3 speed is about the only thing that will fit a small block V8. Everything else is different, bell housing, flywheel, engine brackets, clutch linkage, and probably a few more things I'm forgetting. 60-66 Nut __________________ 60 Ford F100 Custom Cab 61 Apache Short Fleetside 64 C10 Short Stepside 65 C80 409 V8 5spd(X-Firetruck) 83 GMC 350 Olds Diesel 85 GMC Short Bed 86 GMC Short Bed 90 GMC R3500 Crew Cab 92 GMC 1500

10-22-2007, 04:33 PM	#4
grumpy Registered User Join Date: Feb 2007 Location: NE Ohio Posts: 737	Re: GMC 305 V-6 to sbc swap...question Cool. Then out comes the big6 and 3spd then. I'll just go 350/350 or 700r4, and be done with it. Appreciate it

10-22-2007, 08:55 PM	#5
68GMCCustom Truck and auto performance nut Join Date: Feb 2007 Location: McKinney,Texas Posts: 3,848	Re: GMC 305 V-6 to sbc swap...question Thats what I did, basically. I swapped the pedals and column from the '72 C10 along with the complete chassis, which has a late 80's 305 with a 4V and a t350. When the body gets joined back with its chassis it will have a clutch again, with a built LSX (carb'd w/MSD setup) and either a TKO-600 or a built up T-56. __________________ Kurt - '68 GMC short step - NIB '09 LY6 6.0L crate motor w/mods, NIB '12 crate 4L85e w/billet 3k stall Circle D, 3.73 posi 12 bolt, DynaTech f-swap headers, 3/4 drop, handling mods, etc. - my toy '72 Chevy LWB C-10 Highlander - 350/350 ps/pb/tilt/ac - not original but close '06 Chevy TrailBlazerSS - LS2/4L70e - little black hot rod SUV - my DD '18 Kia Sorento - wife's econo-driver '95 Chevy S10 - reg cab shortbed, LS, 4.3, auto... my '68's powertrain and chassis build -links broken A surprise phase - carb to efi -links broken

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