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#1 |
Registered User
Join Date: Aug 2006
Location: Powell, Wy
Posts: 135
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Big block into 71? Crossmember built
Going to put the 454/ TH400/ Doubler into the 71. It is currently in an 83 frame. What do I need to know about motor mounts? Will the ones from the 83 fit? Crossmember clearance? It has HEI and tall valve cover to cleare roller rockers. I am putting a 1" body lift on the rig. Will I need to do some creative BFH mods to firewall to fit it? It also has hedman headers, will they fit? Looking in a jegs mag it looks like the application could be the same. Any other tips regarding the swap?Thanks
Last edited by MNorby; 10-09-2006 at 07:45 PM. |
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#2 |
Account Suspended
Join Date: Aug 2006
Location: vacaville ca, because it as far from indy as i can be
Posts: 777
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Re: Big block into 71?
as long as the 83 frame has v8 mounts you are all good to go. bbc is a direct swap in the 73+.
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#3 |
Senior Member
Join Date: Dec 2004
Location: Southern Pines NC
Posts: 3,853
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Re: Big block into 71?
Talk to a couple of guys on the 4x4 forum. I have heard many different ways depending.......
A good start would be to use al the brackets, crossmembers etc off the 83, install the lift and get out the measuring tape. I am in the process of putting a 83 6.2 diesel in a 68 burb frame with a 72 body, it started out being a BB swap. the BB and the diesel use the same mounts. I had it mocked up using the 83 stuff, crossmember etc and measured it, it was close but looked like it would work. |
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#4 |
I'm a poor spectator
Join Date: Aug 2006
Location: San Antonio, Tx
Posts: 2,287
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Re: Big block into 71?
I put a 369 in my 71 after the sbc with south. I took it out after realizing that it would require me to either move it forward or put a body lift. From my experience I would say that at least a 2 inch body lift would be necessary. I don't think 1 inch would be adequate. Mine had the MSD pro billet distributor and stock valve covers ( I originally had tall aluminum ones but sent them back as they wouldn't clear ). Also I noticed your putting an automatic in it instead of the 4 speed, that's good because the clutch linkage posed another problem for me with headers and clearance in general.
__________________
2006 Jeep Unlimited IMPACT ORANGE 1993 Chevy 2500 4x4 ExCab LWB 454/NV4500 Tow rig ![]() 1977 Ford F100 2x4 LWB 1st truck I owned, still have it!!! ![]() 1979 Ford F150 4x4 SWB Built Ford Tough!!! ![]() 1971 Chevy Blazer 350 / SM465 / NP205 UNDER CONSTRUCTION Soon to have a LQ4 6.0!!! |
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#5 |
Registered User
Join Date: Oct 2003
Location: Central Vermont
Posts: 8,538
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Re: Big block into 71?
Have you tried the search function?
![]() There's been several (lots) of big block threads over the last year or so, I'm sure there's great post's with tons of info that have been all but forgotten about. I can think of three right off... *Yukon Jack *Burt4x4 *Orangeuoval All these had threads going not to long ago about their installs. Last edited by vtblazer; 10-04-2006 at 06:41 AM. |
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#6 |
Registered User
Join Date: Aug 2006
Location: Powell, Wy
Posts: 135
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Re: Big block into 71?
i read through alot of old posts but haven't really figured out what way to go it really the "best". I think I am going to go with the 83 crossmember so hopefully my headers fit. I think that is my biggest thing is header fitment and how far forward to move crossmember. Maybe I should drill it for 1" more forward and another set for 2" forward then if 1" isn't enough I can just slide it ahead
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#7 |
Registered User
Join Date: Aug 2004
Location: Denver, CO
Posts: 28
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Re: Big block into 71?
I have a 72 blazer with a 454 HEI, th400, np205, 6" spring lift, 44/14ff. The PO pounded the heck out of the fire wall to fit the distributor. Since I got it, the engine has been moved forwad 2".
Without moving the engine, the top frame rail needed to be trimed 1/4"x2" to fit the headers, and the old headers were dented by the frame. With the engine moved, they fit well (trimming still there) I did not have tall valve covers when I removed the motor, but have bought them to put on my rebuilt 496 when I get it back next week. ![]() The body lift will not be necessary if you move the motor forward. Last edited by ugly; 10-05-2006 at 08:15 AM. |
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#8 |
Registered User
Join Date: Aug 2006
Location: Winfield, Ks
Posts: 13
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Re: Big block into 71?
I did the 454 swap into my '72 3/4ton 4x4. I did a 3" body lift and had no clearance issues. Itwas a 4-speed and my only issue was the headers. I went through 3 sets all of which had problems with clutch pivot, Finally bought a set of Hookers-problem solved, they fit great.
Shane |
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#9 |
Registered User
Join Date: Aug 2004
Location: Denver, CO
Posts: 28
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Re: Big block into 71?
I bought headman elite, but they are not on the truck now. Still waiting for the 454, .20 over 450 HP, 550 torque
![]() Sould be soon. The motor mounts needed to be changed when I bought it, and the cross member is custom. Alot of good stuff was done to the truck before I bought it, but the #1 upgrade I did was the rear disc brakes. Now it stops on a dime, with no skidding. |
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#10 |
Registered User
Join Date: Aug 2006
Location: Powell, Wy
Posts: 135
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Re: Big block into 71?
rear disks rock. The 14FF i am putting in rear has disks, 4.56 gears, detroit locker, and a diff cover I built out of 3/8" plate, and tringulated shocks.
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#11 |
Registered User
Join Date: Aug 2006
Location: Powell, Wy
Posts: 135
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Re: Big block into 71?
well got then 350/465/205 out this weekend and got my 454/th400 out of the other rig and ready to strat the swap. I want to move the engine forward an inch or so forward for firewall clearance and driveline lengths. Here are the 80s style engine mount towers bolted in the frame with the center of mounts roughly 1 inch forward. I messed around with the 80s style crossmember but it looks like a hack job to use it so gonna build something like this out of 1.5x3/16" sq tube. Opinions?
I already have the scale blueprints drawn out. Should have 1" clearance from oil pan. This drawing was just for visiual aid. Last edited by MNorby; 10-08-2006 at 09:42 PM. |
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#12 |
Registered User
Join Date: Aug 2006
Location: Powell, Wy
Posts: 135
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Re: Big block into 71?
went ahead and built a crossmember out of1.5" 3/16 sq tube. Just need to make mounting holes and tabs.
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#13 |
Post Whore
![]() Join Date: Feb 2000
Location: Rose Hill, KS, USA
Posts: 12,684
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Re: Big block into 71?
How soon do you think it will be before you get to take it for a test drive?
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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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#14 |
Registered User
Join Date: Aug 2006
Location: Powell, Wy
Posts: 135
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Re: Big block into 71?
i'll get the tranny in tomarrow. Procrastinating today... then see how well the doubler fits in the floorboard and go from there. Gott put the 60 in the front and the power steering/crossover box in too.. then shafts....
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#15 |
Registered User
Join Date: Feb 2000
Location: Modesto, CA
Posts: 1,842
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Re: Big block into 71?
Cool! Big Blocks are fun
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__________________
1972 K5 MPFI454/Sm465/Np205/D60/14FFd/Re-Centerd H1s w/Swamper Iroks ![]() |
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#16 |
Registered User
Join Date: Jun 2006
Location: washington
Posts: 133
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Re: Big block into 71?
sick
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#17 |
Registered User
Join Date: Aug 2006
Location: Powell, Wy
Posts: 135
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Re: Big block into 71?
got the th400 bolted up and the headers and such installed. Got the external regulator removed and re-wired for internal reg alt. Still gotta rewire for HEI and find a place to mount my fuel pump. Still waiting on getting body mounts to put doubler in and finish it up.
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