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Tractor Talk Discussion Forum

2000 GMC 350 conversion to 454 C/K 2500

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jmducks

01-01-2008 16:02:38




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I have a 2000 GMC C/K2500 crew cab with a 350 with auto and 3:73 gears 115K on it and it has no power. It has a hard time pulling 5000lbs. What can i do for more power? Does a 454 fit in there with no trouble. I would think trans is same i am wondering about computer stuff? any info would be nice!




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Mike M

01-02-2008 11:16:32




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 Re: 2000 GMC 350 conversion to 454 C/K 2500 in reply to jmducks, 01-01-2008 16:02:38  
Go have your converters checked for being plugged up !!!!! !!!!! !!! Easy to do there is a little tool you screw into the o2 senser ports and check pressure. Alot of the muffler shops have these.



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jmducks

01-02-2008 15:46:01




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 Re: 2000 GMC 350 conversion to 454 C/K 2500 in reply to Mike M, 01-02-2008 11:16:32  
The cats were rattling inside so I knocked all the stuff out then put them back on. I thought it helped alittle. The best mpg was 14 average 12



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buickanddeere

01-03-2008 18:25:39




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 Re: 2000 GMC 350 conversion to 454 C/K 2500 in reply to jmducks, 01-02-2008 15:46:01  
What did you do with the O2 sensor(s) after the converter(s)? They will now be throwing a trouble code via the VCM.



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buickanddeere

01-01-2008 22:08:57




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 Re: 2000 GMC 350 conversion to 454 C/K 2500 in reply to jmducks, 01-01-2008 16:02:38  
Lowest cost upgrade would be to trade it for a later GMC 2500 with the 6.0L for 300HP. If you change the pipe between the filter and the throttle body for an AirRaid unit. Bypass the hotwater hose around the throttle body's heater so the intake air is cooler. And re-program with the Diablo kit. There is an honest 325-335HP.



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Roy in georgia

01-01-2008 20:50:10




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 Re: 2000 GMC 350 conversion to 454 C/K 2500 in reply to jmducks, 01-01-2008 16:02:38  
you know now that others said it I agree that 350 should do the job fine I didn't pay enough attention earlier on why you wanted the 454 but I love those small blocks that was my nick-name where I used to work because I worked on the 350s and built some while I was there



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MarkB_MI

01-01-2008 18:35:04




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 Re: 2000 GMC 350 conversion to 454 C/K 2500 in reply to jmducks, 01-01-2008 16:02:38  
As others said, it sounds like your 350 isn't putting out what it should. But assuming you're getting full power out of the engine, the easiest way to get more pulling power is to swap the 3.73 ring and pinion for a 4.11 set.



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Jon Hagen

01-01-2008 19:02:46




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 Re: 2000 GMC 350 conversion to 454 C/K 2500 in reply to MarkB_MI, 01-01-2008 18:35:04  
A couple of thoughts, might need a good tune up,ignition, fuel filter,air filter,clogged cat converter at 115 K ??

Another thing is that a 2000 model is going to have an overdrive trans,are you towing in OD ? Either automatic or manual in overdrive will give you less than 3/1 final drive ratio,far too high for towing anything with a small V8. Tow only below overdrive gear. How large are the tires ? Huge mudder tires reduce towing power.

My older K3500 with a small engine and no overdrive would be worthless for towing if it did not have 4.10 gears, so maybe 3.73 is a bit tall. Even my 92 K3500 with 454 and 4.10 gears is not happy towing a heavy trailer in OD, it overheats the OD auto trans and lugs/overheats the engine.
Anything larger than a small snomobile trailer gets towed with OD locked out.

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jmducks

01-02-2008 15:50:02




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 Re: 2000 GMC 350 conversion to 454 C/K 2500 in reply to Jon Hagen, 01-01-2008 19:02:46  
it has 265 16" tires and do not pull in od.



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dlplost

01-01-2008 18:26:06




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 Re: 2000 GMC 350 conversion to 454 C/K 2500 in reply to jmducks, 01-01-2008 16:02:38  
third party image

Heres My 1997 vortec 350 auto C2500 with a JD 2010 on the trailer, 65 mph no sweat. Checked the weight at the local gravel pit scales, just under 11,000 for dozer and trailer combined.
Why not fix what you got?? If it wont pull 5,000# theres something wrong..

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Lee in Iowa

01-01-2008 18:11:18




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 Re: 2000 GMC 350 conversion to 454 C/K 2500 in reply to jmducks, 01-01-2008 16:02:38  
I know lots of people myself included that pull 4500 lb 7x20 stock trailers filled with 12000 lbs of cows on a regular basis with GM 350's. One friend put almost 200k miles on his dually before he had any serious problems. Get the motor checked out maybe switch to 4.10 gears. Lee



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buickanddeere

01-01-2008 18:00:29




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 Re: 2000 GMC 350 conversion to 454 C/K 2500 in reply to jmducks, 01-01-2008 16:02:38  
Put it on a chassis dyno and she if she's making factory rated. GM has factory crate small block snoretech engines with 300+HP. Far better choice than a rat block. Or get the Whipple Blower kit with the screw compressor system. Very efficient.



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Roy in georgia

01-01-2008 17:20:11




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 Re: 2000 GMC 350 conversion to 454 C/K 2500 in reply to jmducks, 01-01-2008 16:02:38  
some have said the trans would need to be changed but in the 2500 series the trans is the 4L80 so it is the best one available from the factory.If you can go to auction and pick up one wrecked with a 454 and do a complete swap of the engine and all the computer and wires it's not that tuff if you have time and some imagination it will work.Those trucks are all Vortec and they are particular about the computer. I changed one that was a 4.3 with the w engine code put a z code engine in and it would not run changed the injector and it ran perfect.

good luck,Roy

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gene walkowicz

01-01-2008 17:19:22




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 Re: 2000 GMC 350 conversion to 454 C/K 2500 in reply to jmducks, 01-01-2008 16:02:38  
Get rid of the truck and get a disel cost more but it will last a lot longer and hall more #



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ErnieDD

01-01-2008 17:12:18




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 Re: 2000 GMC 350 conversion to 454 C/K 2500 in reply to jmducks, 01-01-2008 16:02:38  
I have a '98 1/2T ext cab(350), pulled 4000# on a tandem axle trailer, had another 500# of tools and what not in the box. Went down the road real nice, lotsa power, kept up with the flow as much as I wanted to.

When was the last time the fuel filter was changed? The fuel management system will cut back on the power to the point the transmission won't shift into high if horses aren't fed. Won't miss or skip either, ask me how I know.

I would make sure all the horses were awake and well fed, if two wheel drive, put shorter gears, but really it should latch on and pull 5K like no tomorrow.

Do you have a transmission cooler? Not supposed to tow >3k without a cooler. I converted to synthetic to help on the temperature.

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Allan In NE

01-01-2008 16:19:52




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 Re: 2000 GMC 350 conversion to 454 C/K 2500 in reply to jmducks, 01-01-2008 16:02:38  
What Jon said.

Looks easy at first glance, but will take ya til spring to do it.

Believe me, easiest way is to fix the 350 or trade 'er off. Those rat motors never did impress me much.

They suck fuel like there's no tomorrow and not really that much improvement in power.

Allan



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steve from mo - dangit!

01-01-2008 16:17:08




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 Re: 2000 GMC 350 conversion to 454 C/K 2500 in reply to jmducks, 01-01-2008 16:02:38  
The 454 uses the same body and frame, but you"d want everything else bigger. Radiator, transmission, etc. Don"t know about computer. A friend of mine did that exact swap between a 1978 and a 1979 but they would have had much simpler electronics. If you had a donor truck with the 454 you could easily make the swap. Piece by piece would be tough.



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Allan In NE

01-01-2008 16:23:07




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 Re: 2000 GMC 350 conversion to 454 C/K 2500 in reply to steve from mo - dangit!, 01-01-2008 16:17:08  
For sure,

Just about every blessed thing has to be changed from one to the other.

Computer/fuel system will adjust to the demand. About the only thing ya don't have to swap out.

Allan



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RobMD

01-01-2008 16:16:34




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 Re: 2000 GMC 350 conversion to 454 C/K 2500 in reply to jmducks, 01-01-2008 16:02:38  
save yourself the time and avoid a pain in the arse by getting rid of your truck and buying something with a stick in it.



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Jon Hagen

01-01-2008 16:13:17




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 Re: 2000 GMC 350 conversion to 454 C/K 2500 in reply to jmducks, 01-01-2008 16:02:38  
454 can be fitted, but not without pain. All acessory brackets,hoses,belts linkages,radiator, flywheel, exhaust system,starter Plus ECM/PCM is different.

Your pickup is either a C (2WD) or K (4WD). many parts books that list a part as fitting a C/K 2500 means it is the same part for both 2 and 4 wd.



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