During my local parts scrounging, I ran across a low mile 88 tbi 454 in a wrecked motor home for cheap. It has a 400 bolted to it but I have a fresh 700r4 in my 88 k5 I'm wondering if I would be a idiot to swap in low mile 454 and pull a high mileage 350? I wonder how much of a performance gain I will see and if it's worth the drop in mpg?
CK5
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454 tbi swap
- Thread starter prolinews
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The Big Block torque is wonderful and you can use the computer and harness from the small block with a few minor mods to keep the lockup function on your 700R4. You will need to modify the throttle bracket on the 454 to accept a TV cable and cut the linkage arm off the 350 throttle body and 454 and swap them (held in place with a small weld). There are a couple of hose differences and you will want a big radiator if you don't already have one. Scrounge as much as you can from the donor truck and it will go pretty easy. I have done this on a couple of square bodies and felt it was worth doing, lost 10-20 percent on the MPG
454Sub
5/8 ton status
Get the IAC wiring off the donor truck, that is the only sensor that doesnt swap between the 454 and 350. Grab the PROM chip from the donor trucks computer, and hook up all the vacuum ports correctly. The 700 will need to be kept cool, and that 454 will eat that 350 up doing anything, and the OD will be helpful. Another trick that seems to work is keep the 700 in 3rd until your steadily cruising above 45 or so.
For 1500. I can have everything from the radiator to the tails haft wiring ecu everything. It has 55k on it. I'm trying to negotiate it down a little since I have to pull it . It has a 400 bolted to it that I really don't want. Seems like it would be a straight forward swap .
You could probably get $300 or more out of a good used 400 to someone in the market. Check to be sure the flexplate has a dual bolt pattern and not a six bolt/same pattern before you get it bolted in.
