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454 swap

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Russ, Jun 20, 2000.

  1. Russ

    Russ 1/2 ton status

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    I am looking for any info concerning swapping a late model 454 into my 90 Blazer. I currently have a TBI 350, SM 465 and the 241 transfer case. All of which I am looking at pulling out as I have a lead on a low mileage late model 454. I also have a 465 tranny and the doubler transfer cases in my garage that I just rebuilt. I was thinking of doing the whole swap at once and was curious if anybody knew of any hidden problems with putting the 454 in (other than the computer/harness). I realize that this question has probably came up before, but I could not find much info on it. Thanks for the help,
    Russ
     
  2. BB454

    BB454 1/2 ton status

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    Russ there are no real snags in that swop. I changed my small block to a gen.5 454 and apart from the front springs that compressed a bit too far and the electric fuel pump the 454 needs, it all were done without any problems. I would sugest you upgrade the clutch to something like a Centreforce Duel-friction as I found the standard clutch to be a bit weak to handle the big block. In my case I removed the fuel-injection and run a 750cfm Holley but that is purely because the motor (crate) came without the computer needed to make it work. In your case you should have all that extra little things out of the donor. So have a go - I still think the change to the big block was the best "add-on" I installed in my K5. It sure puts a stop to overworking the gearchange on the SM465 - Once outside city limits, just pop it in 4th and relax. (Hope you have the axles to go with the 454 - hehehehe )

    BB454
    IF IT DOES NOT HAVE 8 PISTONS - IT'S BROKEN !
     
  3. BlazerGuy

    BlazerGuy 3/4 ton status

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    Hey BB454, how do you like the Holley? is it good in the performance area? any perks about it?

    YEEEEE HAWWWWW[​IMG]
     
  4. Russ

    Russ 1/2 ton status

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    BB454,
    Thanks for the info. Should the electric fuel pump that I have already for the TBI be sufficient for the Vortec motor or would it require a higher volume pump? Also I do still have the 10 bolt axles in there, but I figure that if I put the big block and the doubler in , then once I break an axle my wife will be convinced that I need bigger axles. thanks again,
    Russ
     
  5. BB454

    BB454 1/2 ton status

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    The Holly sure has more performance than the stock injection system but even with fine tuning the float levels it sucks offroad when it comes to some angles. The injection would be the best allround setup. The 750 double pumper would also NOT be my choice for fuel economy ... lol

    BB454
    IF IT DOES NOT HAVE 8 PISTONS - IT'S BROKEN !
     
  6. BB454

    BB454 1/2 ton status

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    Russ - The TBI pump should be fine but I am not 100% sure. I normally use the Holley pumps on all of my vehicles. As for those axles - start convincing your wife TODAY. You might have seen the results I had with 10bolts behind my 454. Call me hardheaded - I tried it 4 times before I finally gave up on that one. Might be like some folks say "depends on how you drive it" --- sorry, I have no mercy when it comes to playtime.

    BB454
    IF IT DOES NOT HAVE 8 PISTONS - IT'S BROKEN !
     
  7. bigoletruck

    bigoletruck Newbie

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    Russ,
    The electric pump used with the tbi injection produces about 35-55lbs of un regulated fuel pressure. A standard carb only reqires about 5-7lbs of fuel pressure. As you can see WAY TOO MUCH. You can use the stock pump if the add a pressure regulator WITH a bypass circut to relieve all the excess fuel pressure. The factory tbi has 2 lines in the rear of it. 1 inlet and one return. If you ran the inlet line to the regulator then the "regulated" line to carb you can use the factory return line as the bypass line. Or to make things even simpler, just remove the stock in tank pump and replace with a regular sending unit and use a mechanical(sp?) fuel pump. The in tank pumps are a bitch to shange if when they go bad (and of course very expensive!!)
     
  8. dpearson

    dpearson Registered Member

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    What type of front springs do you have because I dropped a BB into my Jimmy with a 4" Rancho Lift and it is still stiff as Heck!! i am thinking about changing out the lift and would like some input. Thanks
     
  9. Shawn

    Shawn 1/2 ton status Premium Member Author

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    You will need a larger radiator. I used a 3/4 ton truck radiator which is a 4 core and taller. This means you need new upper radiator mounts and shroud. I assume you will use a carb for now. The stock fuel pump WILL NOT work with a carb. I tried to regulate mine and had problems. I finally got a external Carter electric fuel pump (5-7psi) and mounted it on the other side of the filter. This was easy since I could take some rubber lines from the filter to the pump. The return line is blocked until I install FI again. Don't forget a flywheel, water pump, headers, and BB acc. brackets. My front 6" springs were fine.

    If you're planning on keep the Vortec FI on the 454, you will need the computer and every sensor. The stock fuel pump can be replaced with a Walbro high volume in tank pump.

    Shawn
    87 K5 454
     
  10. BlazerGuy

    BlazerGuy 3/4 ton status

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    Will the TH350 hold up with a big block or should I go with a 400?

    YEEEEE HAWWWWW[​IMG]
     
  11. ken

    ken 1/2 ton status

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    I have had a TH350 behind my 454 for 12 years now in my '77 Sub. I am swapping to a TH400 though, as I plan to tow my 8500 lb. boat with it...I don't trust the TH350 to live towing that much!!

    ken
     
  12. Russ

    Russ 1/2 ton status

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    Thanks for all the info. If I go with this motor I am going to leave the FI on it. Mikee (I think I got that name right) told me about a place in TX that does conversion harnesses (Fuel Injection Specialties) so that the motor will wire into the trucks system. The 454 that I am looking at is complete (accessories, brackets, manifolds etc) minus the computer. I would have to locate that. I am going to take a closer look at it tomorrow morning and decide if it is worth picking up. Thanks again for all the input.
    Russ
     

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