SB to BB Swap questions ? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

teamharvey · 01-18-2005, 08:19 PM

Ok,
In a perfect world I would like to swap the 350 for a big block. I have a 72 4x4 blazer and was wondering what major obstacles I would be looking at as far as mounting ect.

Thanks,
Bret

454_72_4X4 · 01-18-2005, 08:22 PM

auto or stic trans?

Nick's683/4 · 01-18-2005, 09:43 PM

I am in almost done with mine and it hasnt been to bad. The only thing i had to do was to cut the fire wall for my valav covers. Here are some pics. There is some outher suff you need to do just let me know if you want to do this and i will tell you all that i had to do.

**kwmech** · 01-18-2005, 10:31 PM

Years ago when I did my 71, I didn't feel like cutting the firewall or doing a body lift [I hate body lifts] so I moved my x-member forward and redid the drivelines.

teamharvey · 01-18-2005, 10:41 PM

Quote:

Originally Posted by 454_72_4X4

auto or stic trans?

Auto trans.......

Nick's683/4 · 01-18-2005, 11:07 PM

i was going to move the x/member but i didnt have the money for the drive shafts

**kwmech** · 01-19-2005, 12:42 AM

Mine were worn out at the time so it didn't matter much. Nothing like a worn out slip yoke and small dings in the tube with a fresh big block, didn't want any problems when I stomped on it.

**Yukon Jack** · 01-19-2005, 12:13 PM

Here's some info I put together based on my big block swap into my 69 K20.

Big Block into 69 K20

Nothing like a tight fit.

454_72_4X4 · 01-19-2005, 12:58 PM

Here's a couple of pics of my firewall mods;

Right side

Left side;

Clutch linkage;

454_72_4X4 · 01-19-2005, 01:13 PM

Here's a couple of the "54" installed;

I'll be switching to a hydro clutch soon I hope. I'm gonna be putting in a NV4500 5 speed and the only way I can afford to get it in there is to go with a hydro clutch system.

Yukon; What is your clutch master cylinder originally for?
How did you figure where to put it, (so you'd have enough travel and whatnot).
Do you know the bore size of it?

teamharvey · 01-19-2005, 08:42 PM

Great info....thanks guys.

Bret

4x4Poet · 01-20-2005, 03:58 AM

I once read in a now defunct mag (4x4Now?) that one can use a 73-87 engine crossmember to install a BBC into a 67-72 K10/K20. Only need to drill one hole top and bottom each side and the other three holes each side line up with existing holes to guide the drill locations. The 73-87 xmember helps one use clamshell motor mounts and most BBC oil pans. No other mounting mods needed. I haven't seen this done, though. Unverified info.

01-18-2005, 08:19 PM	#1
teamharvey Registered User Join Date: Jul 2004 Location: Turlock, Ca Posts: 578	SB to BB Swap questions ? Ok, In a perfect world I would like to swap the 350 for a big block. I have a 72 4x4 blazer and was wondering what major obstacles I would be looking at as far as mounting ect. Thanks, Bret __________________ 71 Custom 20 Deluxe..soon to be SWB 1/2 ton 1 incredible wife 2 great kids

01-18-2005, 08:22 PM	#2
454_72_4X4 Registered User Join Date: Apr 2004 Location: N.E. MO Posts: 1,749	auto or stic trans? __________________ 72 C20 4X4 454 4 speed 89 Trans Am (was) 305 TPI 700r4 93 C1500 2wd Extended cab 350 700r4 98 Sonoma (TPI outa the Trans Am) 03 Yamaha 660 Raptor 03/04 660 Raptor 07 700 Raptor 85 Honda Odyssey

01-18-2005, 09:43 PM	#3
Nick's683/4 Registered User Join Date: Apr 2004 Location: Oakley CA Posts: 165	I am in almost done with mine and it hasnt been to bad. The only thing i had to do was to cut the fire wall for my valav covers. Here are some pics. There is some outher suff you need to do just let me know if you want to do this and i will tell you all that i had to do. Attached Images __________________ 70 1 ton with a 454 and a 4 speed and a np205

01-18-2005, 11:07 PM	#6
Nick's683/4 Registered User Join Date: Apr 2004 Location: Oakley CA Posts: 165	i was going to move the x/member but i didnt have the money for the drive shafts __________________ 70 1 ton with a 454 and a 4 speed and a np205

01-19-2005, 12:13 PM	#8
Yukon Jack Post Whore Join Date: Feb 2000 Location: Rose Hill, KS, USA Posts: 12,686	Here's some info I put together based on my big block swap into my 69 K20. Big Block into 69 K20 Nothing like a tight fit. __________________ 1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14

01-18-2005, 10:31 PM	#4
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,630	Years ago when I did my 71, I didn't feel like cutting the firewall or doing a body lift [I hate body lifts] so I moved my x-member forward and redid the drivelines.

01-19-2005, 12:42 AM	#7
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,630	Mine were worn out at the time so it didn't matter much. Nothing like a worn out slip yoke and small dings in the tube with a fresh big block, didn't want any problems when I stomped on it.

01-19-2005, 12:58 PM	#9
454_72_4X4 Registered User Join Date: Apr 2004 Location: N.E. MO Posts: 1,749	Here's a couple of pics of my firewall mods; Right side Left side; Clutch linkage; __________________ 72 C20 4X4 454 4 speed 89 Trans Am (was) 305 TPI 700r4 93 C1500 2wd Extended cab 350 700r4 98 Sonoma (TPI outa the Trans Am) 03 Yamaha 660 Raptor 03/04 660 Raptor 07 700 Raptor 85 Honda Odyssey

01-19-2005, 01:13 PM	#10
454_72_4X4 Registered User Join Date: Apr 2004 Location: N.E. MO Posts: 1,749	Here's a couple of the "54" installed; I'll be switching to a hydro clutch soon I hope. I'm gonna be putting in a NV4500 5 speed and the only way I can afford to get it in there is to go with a hydro clutch system. Yukon; What is your clutch master cylinder originally for? How did you figure where to put it, (so you'd have enough travel and whatnot). Do you know the bore size of it? __________________ 72 C20 4X4 454 4 speed 89 Trans Am (was) 305 TPI 700r4 93 C1500 2wd Extended cab 350 700r4 98 Sonoma (TPI outa the Trans Am) 03 Yamaha 660 Raptor 03/04 660 Raptor 07 700 Raptor 85 Honda Odyssey

01-19-2005, 08:42 PM	#11
teamharvey Registered User Join Date: Jul 2004 Location: Turlock, Ca Posts: 578	Great info....thanks guys. Bret __________________ 71 Custom 20 Deluxe..soon to be SWB 1/2 ton 1 incredible wife 2 great kids

01-20-2005, 03:58 AM	#12
4x4Poet Registered User Join Date: Nov 2004 Location: "Under Montana skies." Posts: 1,836	I once read in a now defunct mag (4x4Now?) that one can use a 73-87 engine crossmember to install a BBC into a 67-72 K10/K20. Only need to drill one hole top and bottom each side and the other three holes each side line up with existing holes to guide the drill locations. The 73-87 xmember helps one use clamshell motor mounts and most BBC oil pans. No other mounting mods needed. I haven't seen this done, though. Unverified info. __________________ '71 GMC K20 Suburban, '71 GMC K10 Suburban, '72 Chevy C10 CST Suburban, '72 Chevy K20 clunker pickup.

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