Has anyone swapped a big block in place of their 6 cylinder? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

superchevy · 04-14-2005, 09:37 AM

I'm going to be swapping a 454 in place of the 250 six in my '81 C10. I plan on keeping the Turbo 350 that is in the truck now. My question is whether I will have to move the trans back or shorten driveshaft, or is it a bolt-in deal. I have the big block engine towers and mounts.
Thanks,
SC

*gn4u2c* · 04-14-2005, 10:19 AM

Bolt it in and go no problem at all we did this to a 78 6 truck you will need front springs unless you like a little lower ride.

86 GMG · 04-14-2005, 11:14 AM

Sweet Swop Good Luck

hammer · 04-14-2005, 02:14 PM

might want to beef the rear end if its stock. not too pretty when they come out

**Captkaos** · 04-14-2005, 06:48 PM

Done it on more than one occation. Don't expect the TH350 to hold up very long especially if it is stock and you plan to abuse it. The 10bolt will be fine as long as you are putting slicks on it or drag racing it every night. The tranny however will inevitably go bye-bye.

superchevy · 04-14-2005, 07:54 PM

It's got a 12 bolt in it. No prob on the T350, I have a T400 in the shop being built as I write.
Thanks,
SC

cochran63 · 04-14-2005, 09:18 PM

I had to lenghthen my driveshaft, but that was only because I went from a th350 longt tail, to a th400.

04-14-2005, 09:37 AM	#1
superchevy Got big-block? Join Date: Jul 2000 Location: Austin, Texas Posts: 2,453	Has anyone swapped a big block in place of their 6 cylinder? I'm going to be swapping a 454 in place of the 250 six in my '81 C10. I plan on keeping the Turbo 350 that is in the truck now. My question is whether I will have to move the trans back or shorten driveshaft, or is it a bolt-in deal. I have the big block engine towers and mounts. Thanks, SC __________________ '68 CST SWB factory 396/T400 buddy buckets, a/c, ps, pb '72 Corvette convertible 454/4spd/ac, ps, pb '73 GMC Sierra Grande short wide 454/T400 ps, pb, ac '77 K5 Blazer black on red, 350/T350/NP205 ps, pb, ac all original '78 GMC Sierra Classic short wide 454/T400 ps, pb, ac '72 GMC Sprint SP454. 1 of 38 built. '73 GMC Sprint SP454. 1 of 71 built. '75 GMC Sprint SP454. 1 of 25 built. SOLD! '72 GMC K25 4x4 468/4L80e/NP205 build thread http://67-72chevytrucks.com/vboard/s...23#post4324423 SOLD!'55 Chevy gasser 496/4spd build thread http://67-72chevytrucks.com/vboard/s...96#post4324396

04-14-2005, 11:14 AM	#3
86 GMG Registered User Join Date: Apr 2005 Location: Tulsa Oklahoma Posts: 943	Sweet Swop Good Luck __________________ square body trucks an addiction or an investment either way they consume all my extra time and money

04-14-2005, 02:14 PM	#4
hammer Registered User Join Date: Nov 2004 Location: conroe texas Posts: 58	rear axle might want to beef the rear end if its stock. not too pretty when they come out

04-14-2005, 06:48 PM	#5
Captkaos www.73-87chevytrucks.com Join Date: Dec 1999 Location: Birmingham, AL Posts: 6,935	Done it on more than one occation. Don't expect the TH350 to hold up very long especially if it is stock and you plan to abuse it. The 10bolt will be fine as long as you are putting slicks on it or drag racing it every night. The tranny however will inevitably go bye-bye. __________________ Chris Lucas 1973 Chevy C-10 1978 GMC Jimmy (2WD) - SOLD 1987 R10 twin turbo LS 1991 R3500 SRW CrewCab 1985 K5 diesel swapped project 1989 K5 2WD conversion w/ Vette susp Project Captkaos Customs 73-87chevytrucks.com

04-14-2005, 07:54 PM	#6
superchevy Got big-block? Join Date: Jul 2000 Location: Austin, Texas Posts: 2,453	It's got a 12 bolt in it. No prob on the T350, I have a T400 in the shop being built as I write. Thanks, SC __________________ '68 CST SWB factory 396/T400 buddy buckets, a/c, ps, pb '72 Corvette convertible 454/4spd/ac, ps, pb '73 GMC Sierra Grande short wide 454/T400 ps, pb, ac '77 K5 Blazer black on red, 350/T350/NP205 ps, pb, ac all original '78 GMC Sierra Classic short wide 454/T400 ps, pb, ac '72 GMC Sprint SP454. 1 of 38 built. '73 GMC Sprint SP454. 1 of 71 built. '75 GMC Sprint SP454. 1 of 25 built. SOLD! '72 GMC K25 4x4 468/4L80e/NP205 build thread http://67-72chevytrucks.com/vboard/s...23#post4324423 SOLD!'55 Chevy gasser 496/4spd build thread http://67-72chevytrucks.com/vboard/s...96#post4324396

04-14-2005, 10:19 AM	#2
gn4u2c Account Suspended Join Date: Mar 2003 Location: southern pa Posts: 698	Bolt it in and go no problem at all we did this to a 78 6 truck you will need front springs unless you like a little lower ride.

04-14-2005, 09:18 PM	#7
cochran63 Registered User Join Date: Jan 2004 Location: Oklahoma Posts: 1,057	I had to lenghthen my driveshaft, but that was only because I went from a th350 longt tail, to a th400. __________________ Youth soon passes away, but immaturity can last a life time.



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