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JT88K5

JT88K5

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I have a friend who recently purchased an 86 k30, primarily for the 1 ton axles. The donor truck ran fine, and only had 56k original miles on it, legit based on title history. Just had a lot of rust. Drivetrain is 454/TH400/205.

My 87k5 is 350/700r4/241c with SYE and 1 tons. MY 350 has 156k on the original motor, needs valve seals but otherwise runs good. I have been thinking about a re-power for a while. The 700r4 was rebuilt with the good parts so I’m not really worried about toasting it.

I don’t want to run a carb. Fuel injection is a must. I’m looking to swap in the 454, I don’t mind spending the money for an aftermarket fis. I like easy, don’t necessarily want to learn to be a tuner. How would you proceed? Is my stock TBI compatible with the 454, chip and bigger fuel injectors required. Better to go with something like sniper 2? What else needs addressed?
 
tbi will require chip for any cam other than stock .

th400 / 205 over the 700r4/241 = BARF on gear ratios in the swap . . . th400 will be a dog .

true tbi is a 454 unit over sbc unit .

aftermarket i would stay away from sniper crap . .

i have a line on a almost new fitech port efi unit for a bbc engine if you want something and your not far from me also .
 
End game is 454/700r4/241. I wasn’t clear on that.

With the stock cam, is there hp gained by going with the fitech vs stock Tbi setup? I am guessing most folks on here would upgrade the cam and go with EFI. I am inclined to do that.

Any guesses on Torque/HP that one could expect from a mild cam and stock heads from an 86 454.

@sweetk30 I would be interested in the fitech.
 
The 700r4 may not last long behind a 454. I wanted to do the same for my blazer but the more I read about it, the more i'm convinced that the right thing to do while building the 454 is start saving money for a 4l80e swap.
 
Polymath said:
The 700r4 may not last long behind a 454. I wanted to do the same for my blazer but the more I read about it, the more i'm convinced that the right thing to do while building the 454 is start saving money for a 4l80e swap.
Click to expand...
4L80 same crap gear ratio as th400 just overdrive and lockup .
 
The 86 454 has retarded cam timing. If you changed the timing gears to a straight up set the engine will wake up.
Not saying drag racer, but better than before.
I did this to 1989 efi Ford 460, in our coach. Much more pleasant to drive, hills are a bit easier climb.
 
I’m always in for big block fun. Though that generation is in need of some help like others have indicated. On a mild 454 you could fortify a 700r4 to survive if you wanted the better first gear and OD it would have over a 400. A 4L80 would be better strength wise but certainly lacking in the first gear ratio. Plus the added cost to obtain and stand alone computer to run it.

I’d run some math over with the axle ratio, tire size and OD or no OD and see what your cruise rpm at highway speeds might be. Put into context also how often it might see highway duty. You might not have to shoot for an OD trans if your highway time is low and or your cruise rpm isn’t too high with the tires and axle ratio you want to run.
 
Aside from being underpowered, I like the 700r4, ratio wise, it was rebuilt and beefed up Somewhere I have the parts list, corvette servo etc, this was done just before I purchased it back in 2016. cooler installed. I don’t tend to beat my stuff, don’t intend to drag race. Normal trip is to drive 50 miles up hill on I 80 at 75mph, couple miles of dirt roads, do some wheeling, stay at camp, then go home. It’s on 35’s with 1 tons and 4.56 gears. No idea what RPM I’m running at 70 now but I would guess it’s not much over 2k on ~level ground.

The engine is free, thought with only 50k miles on it that it might be worth sticking in to get what I’m missing and avoid replacing the entire drive train. Requiring, gauges etc.
By the remarks, doesn’t seem like this engine is worth the time. I appreciate the input.

Let’s say I just want to replace the original motor, keeping the existing trans etc. Somewhere between 300 and 400hp. Budget would be $5Kish.
???

I need this to be easy, not necessarily cheap.
 
I'd do it in a minute. If you get engine and don't do it, i am already scheming how to get to az lol
 
Don’t fret over the difference in low gear ratios between a 700R4 and a TH400 with a big block - the reason the 700’s were designed with that low of a first gear was because of the swing towards very low numeric axle ratios being the norm with very anemic small block engines. Tho point is that the extra help in the gear department was needed with under powered set ups but that just ain’t the case with a 454 - even a lame choked up smog version.

A 700 behind a 454 will feel great but keep in mind that the basic upgrades that most builders do to a 700, such as the Vette servo etc, were needed in general just to help make them live behind regular small blocks - think about it as parts that they should have come with instead of extra upgrade type of mods.

By all means put a mild cam ( not a hassle) and injection on that 454 and you will never long for a small block again.
In lame smog version stock smog form they were 230 HP and around 400 FT LBS of torque way down low in the RPM range. Wake it up with a little more cam combined with the velocity of those peanut port heads and you’ll never be in lack of a power band - the torque alone will make it feel incredible!

Don’t miss out on an opportunity to go with big block power in a 4WD - even a bone stock smog version feels good in any gear combo and will feel tremendous with a 700R4 and 4.56’s w/ 35” tall tires.
As for that trans living a long life behind a true torque maker that all depends on your driving habits - use that skinny pedal to the far right accordingly.
 
This is a simple and cheap swap. You can run the 454 TBI with the harness that is already there. Find a '87-'90 454 TBI parts truck. It will have the throttle body, and the GM adapter to run it on a four barrel intake.

Keep the TH700R4/NP241. That 454 will not be too much for a TH700R4, and it will have better low end torque than the current small block. It will be an upgrade across the board.

Martin
 
Thanks for the comments, those were more in line with what I was hoping for. I totally understand the doing it right once perspective with the best speed options. Maybe if I drove an LS swapped blazer with 450 HP/4L80 twin stick transfer case etc, I would change my mind. OK, I would definitely change my mind. But then I would want 4 links, coil overs and the list goes on.

Keeping it cheap and easy is always good in my book.

Assuming I do what Martin suggested and KISS. Do I need the ecm from the donor too?

Am I going to run into any fitment / clearance issues? I have crossover steering set up, sticks in my mind that I might need a new front cross member? Anything else I need to consider?

I installed ORD springs ~2 years ago. They are on my call list, I know Im gonna have to do something there with the added weight.
 
As anemic as the later 454 is, it can be woke up. the 454 TBI is larger than the 350 TBI. you can use the 454 TBI. the wiring is almost the same. but you will need the 454 computer. I definitely suggest a prom. the TBI 454 in my Dually actually pulled very well.
As far as the 700R4 goes, against popular belief, i am a fan! with the right person building them, and the right parts used, i have used them in some pretty high powered street cars.
 
I will also say that I would run the 700R4. I have 50K on mine behind a big block in my '70 K10.
Sounds like you have a good plan going. If you decide to install a slightly better cam, then I would look to Howell EFI if going TBI.
I have only tried Edelbrock PF4 as far as aftermarket injection. It's been good for me.
 
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