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Old 01-22-2007, 06:21 PM   #1
gangforward
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1990 Suburban 2500 - 350 to 454 Swap?

Just bought a Turbo 400/350FI 1990 Suburban. I've got a 454 out of an 84 one ton - siince the Suburban (2500 3/4 ton) already has a turbo 400 in it, I'm considering swapping it out.

Has anyone else done this? Issues? Mounting location, radiator, springs, other things I need to swap out. I've got questions, just wondering if anyone else has done this.

TIA!
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Old 01-24-2007, 02:13 AM   #2
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Re: 1990 Suburban 2500 - 350 to 454 Swap?

anyone?
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Old 01-27-2007, 10:48 PM   #3
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Re: 1990 Suburban 2500 - 350 to 454 Swap?

wow - it's quiet around here! (67-72) forum rocks btw... ANYONE????
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Old 01-31-2007, 10:42 PM   #4
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Re: 1990 Suburban 2500 - 350 to 454 Swap?

I have a stock 91 burb R2500 that came with the 454.. in most cases you will need to replace or modify the radiator support including the grill and everything else attached to it. As for mounts, it SHOULD mount right up as they used almost the same mounts as I understand but I could be wrong. Also the late 80s to 91 had the computer so it all depends on if you will be using it with the carb or TBI.
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Old 01-31-2007, 11:43 PM   #5
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Re: 1990 Suburban 2500 - 350 to 454 Swap?

The computer used with the 350 is the same for a 454- you will need to swap out the PROM chip for a 454 chip though. All the underhood electrical is basically the same- except the 454 didn't have a knock sensor. Use ALL the senders from the TBI 350. You will need the larger 454 TBI unit with injectors plus the coolant heated adapter plate. You might have to modify the fuel lines to reach. It will bolt right up to your 454 Qjet intake. You will need to weld in an oxygen sensor bung- the old 454 manifold won't have the threaded hole for it. And as screwballl stated, radiator & support are different. Along with the shroud. You can get the parts new reasonably cheap. If you are running the old v-belt stuff, does the a/c compressor sit in roughly the same location so the lines will work?

I'm sure I've missed some details- but I should have hit on most of the major stuff
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Old 02-01-2007, 02:38 PM   #6
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Re: 1990 Suburban 2500 - 350 to 454 Swap?

Jeffs,

Thanks for the information. I have to 454 core, it came out of an 84 dullie, (carbs, eldebrock manifold etc). I'm going to rebuild it first. I have all the brackets, pulley's etc. I plan on electric fans and the bigblock radiator (put them on my 1967 C10 and love them) so I know about the core supports and other issues. Thanks for the update on the computer.

What do you think about the Eldebrock Multiport FI system? I don't know much about it, but was wondering if that may be the best solution for the EFI, and from what I've read it's about an 80 horsepower improvement over the TBI.
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Old 02-01-2007, 10:46 PM   #7
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Re: 1990 Suburban 2500 - 350 to 454 Swap?

Quote:
Originally Posted by gangforward View Post
... I have all the brackets, pulley's etc. I plan on electric fans and the bigblock radiator (put them on my 1967 C10 and love them) so I know about the core supports and other issues.....

Can you tell me about the core supports? My next project is swapping out a 454 with a 350 on my Brother's 84 Suburban and I'm trying to get all the info on doing the swap. I have a pretty good idea of what to do, but haven't heard about the core supports. THanks!!!
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Old 02-02-2007, 02:39 AM   #8
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Re: 1990 Suburban 2500 - 350 to 454 Swap?

The big block radiator is thicker than the small block - you have to remove the core supports and replace them with the big block versions. The tops are easy, they are a simple bolt on (on my truck anyway) - the bottoms were riveted in, you drill out the rivet, and I had to modify the mount a bit, then install the larger bracket. I avoided the fan/fan cowl issues by going to an electric kit with dual fans - and gained power by losing the fan too. I have mine set so it runs till the water is cooled a certain amount even if the truck is off, get lots of looks when I pull into the gas station.

I've even run the truck in a 4th of July parade when the temps were in the high 90's. Temp never went above 190 the whole time.
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67 C10 LWB Fleet, 383, TH400, PS, 4BL-Holley, Headers & 3" Exhaust, 3" drop front, 4" rear springs, ECI shock relocate, Panhard Bar kit, wheels & tires
1995 Z28 Convertible - Borla, K&N, Lingenfelter Motor, C6 Wheels & Tires
1990 2500 4x4 Suburban 3" Catbac System, K&N, 2" Lift, Wheels, Tires

Last edited by gangforward; 02-02-2007 at 02:40 AM.
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Old 02-02-2007, 03:03 AM   #9
rcbildr
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Re: 1990 Suburban 2500 - 350 to 454 Swap?

Thanks! I wasn't planning on swapping out the radiator and I figure the big block radiator should be more than enough for the 350 I'm putting in. Thanks again.
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My Projects:
1960 GMC 1/2ton with 305 V6 (daily driver)
1963 Chevy 1/2ton 2wd...converting to 4x4
1967 Suburban 1/2ton 2wd

My Girlfriends Projects
1985 Chevy Suburban 3/4ton 4x4 with 6.2L diesel, 4" lift, converted to TH-400, Warn Premium manual hubs, & Wildcat 315/75/R16 tires. (daily driver)
1978 Camaro Type LT with a Marine 350 & vortec heads, Rochester Carb, & roller cam
1978 Camaro Z28
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Old 01-01-2013, 06:38 PM   #10
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Re: 1990 Suburban 2500 - 350 to 454 Swap?

Quote:
Originally Posted by gangforward View Post
wow - it's quiet around here! (67-72) forum rocks btw... ANYONE????
well I just put 454 into my 1995 gmc 1500 2wd long box and it droped right into place all that was need was biger rad and some small exhaust mods other than that was very easy ill never look back to the old 350 that was in there way more balls GM should of put the 454 in the 1500s not just the ss
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