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#1 |
Registered User
![]() Join Date: Sep 2003
Location: Wichita, KS
Posts: 3,728
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Big Block and 4x4 Question
I have a 402 big block I would like to put in my '72 K20. There recently were a couple of threads talking about this, but I couldn't find them. If I remember right there was someone who had to cut out some of the firewall of their cab in order for the bb to fit. What is it about a 4x4 that creates a problem with a big block, and what modifications will need to be done in order for everything to fit?
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#2 |
Post Whore
![]() Join Date: Feb 2000
Location: Rose Hill, KS, USA
Posts: 12,684
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I had to modify my firewall but some people have to do nothing, not sure why. You can see some pages on my website in my signature where I detail putting the bb in my 69 K20. Big blocks are taller and wider than small blocks.
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1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14 |
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#3 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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A body lift will help quite a bit too.
not only does the size of the engine make it a PITA, but the 4X4 trucks have the engine sitting back further than a 2 wheel drive does...that's why you can get them in 2 wheelers, but was never an option in 4X4 trucks. |
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#4 |
Registered User
![]() Join Date: Sep 2003
Location: Wichita, KS
Posts: 3,728
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thanks guys, that was exactly the info I was looking for. Why then do the engines sit farther back on the 4x4s....is it for clearance issues somewhere? Forgive me if this is an obvious answer, but I am a learning 18 year old...thanks...John
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#5 |
Senior Member
![]() Join Date: Mar 2003
Location: Colfax-California
Posts: 8,550
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Body lift to clear the rear of the cylinder heads, or you can move the x-member forward and redo the drivelines like I did. The only other modification would be the x-member itself for possible clearance of the oil pan--depending on the pan.
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#6 |
Registered User
Join Date: Nov 2004
Location: "Under Montana skies."
Posts: 1,836
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Doesn't moving the engine xmember foward also move the oil pan's rear sump within shot of the axle and/or diff pumpkin cycling up?
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'71 GMC K20 Suburban, '71 GMC K10 Suburban, '72 Chevy C10 CST Suburban, '72 Chevy K20 clunker pickup. |
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#7 |
" SHOW ME"
Join Date: Jan 2003
Location: shelbyville illinois
Posts: 2,624
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when i set the bb in my blazer i hardly had to do anything , the only firew wall mods i ddi was 2 eggsized dents i put into the firewall for valve cover clearance , it does have a 3 inch body lift which i dont like but it made it easier ,, you cant even see the dents when the motors in , they are very small
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#8 |
Special Order
![]() ![]() Join Date: Nov 2004
Location: Mt Airy, MD
Posts: 85,859
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Personally,I keep the big blocks for street(2wd)trucks.You can get how ever much power you want from a small block for 4-wheelin`and they are lighter.I think the idea sounds cool,great braggin`rights,but I`ve never done it,never needed to.
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"BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~ |
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#9 | |
" SHOW ME"
Join Date: Jan 2003
Location: shelbyville illinois
Posts: 2,624
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Quote:
![]() ![]() ![]() ![]() never gonna pull the same torque out of a small block that you will a big block , sure they are a little more expensive , the weight difference isnt enough to make to squirts , you really ooughta try it sometime , |
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#10 | |
Senior Member
![]() Join Date: Mar 2003
Location: Colfax-California
Posts: 8,550
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Quote:
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#11 |
I need another Barley Pop
Join Date: Feb 2001
Location: Grants Pass, OR
Posts: 1,629
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I'm also running a BB in my 4x4. Fit's tight, no firewall mods, no body lift and not enough room for an HEI so I opted to go with a Mallory Unilite dizzy. The stock exhaust manifold would not clear the passenger upper frame rail and it had to be notched (or ground) to clear. Same issue with the headers I now run. Hope this helps...
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67 Short Fleet 4x4 04 Honda CRF450R 89 Toyota 4-Runner 34 Ford 2 door sedan - Long term project ---------------------------------------------- There is a very fine line between "hobby" and "mental illness" ![]() |
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#12 |
Special Order
![]() ![]() Join Date: Nov 2004
Location: Mt Airy, MD
Posts: 85,859
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I knew I`d get a reaction from you,Mac67.Not trying to raise hairs.I just never bothered with it.I wanted badly to buy Bad4x4`s 454-powered K/20,too far.With 4wds I look for torque from gearing;axles&T-case gears.Ever wheel a doubler equipped rig?If I was to swap from a small block out for more torque,I`d run a diesel.Worth the added weight in torque(like a big block,just more).And,you get fuel injection,another off-road plus.I plan on this one day.Meanwhile,I`m content with the power from the 400,383,and even the 350 powered trucks I have.
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"BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~ |
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#13 |
Roadtrip!
![]() Join Date: Feb 2003
Location: Grand Rapids MN
Posts: 13,736
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Couple things i found out are: Corvette valve covers are notched in the back on one cover, this worked good on drivers side.
Exhaust manifolds are off a 77 454 pickup. Just had to grind a "nub" off the manifold to fit. Stock hei fit to the firewall with a little caressing of the firewall. Hope this helps. Mine is a 1/2 ton with no body lift.
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67 gmc custom lwb dakota truck. Sold...And bought back 69 swb 4x4 project (in progress) 70 c-10 lwb texas truck 70 4x4/BB/bkts/posi/tach(retired) 70 swb (wifes) 70 jimmy camper 71 K-5 factory 2wd 71 cheyenne 4x4/tach/posi/ plow rig 71 Cheyenne20 BB, buckets, tach, tilt, 4 speed 72 jimmy CST wyoming rig 72 jimmy Colorado rig 72 lifted texas 4x4 3/4 ton burb 65 fury conv. 383/auto 65 chrysler 300 "L" 413 auto |
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#14 |
Special Order
![]() ![]() Join Date: Nov 2004
Location: Mt Airy, MD
Posts: 85,859
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That ain`t bad.At first it was sounding like alot of trouble:moving cross-members,oil pan clearance,body-lift(yuk!).You have to dent the firewall for HEI on a small block,too.
__________________
"BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~ |
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#15 | |
Registered User
Join Date: Feb 2000
Location: Center City, MN, USA
Posts: 3,254
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Quote:
You do have to remove the cap first. And it is a tight squeeze. But it makes it.
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'70 cab, '71 chassis, 383, TH350, NP205. '71 Malibu convertible '72 Malibu hard top Center City, MN |
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