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quick info needed: 350 to 454 swap

T

tacoma

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tooele UT
I may have to start on this TOMORROW, so any help is MUCH appreciated:

1. When swapping a 454 in place of a 350, am I going to be lucky enough to be able to use the 350 exhaust? I am thinking NO, but maybe.

2. Are the fuel lines the same for the two engines? I have a TBI 454 in the work truck I could pirate parts from if necessary, but I'd rather know RIGHT NOW LOL

3. Any issues using the 350's 700r4? I have the 454 flywheel.

4. Any wiring issues? I have a spare 454 harness I could use if required.

Basically, my 350 has lost a LOT of "power" over the last week... and it's puking oil out of everywhere. 250k on the clock. :(
 
Question one: Don't know, but doubt it.

Question two: Can't answer because I don't know what your putting it in.

Question three: The bolt pattern on a 700R4 torque converter is different (smaller diameter) than on a Turbo 400. If your 454 flywheel is drilled for both bolt patterns, you're in luck, if not, you'll need a new flywheel (you can't use the one on the 350).
Question four: See answer to question two.
 
sorry, it's going into a Blazer LOL

#@$(&@#!!!!! forgot about the flexplate issue. :mad:
 
tacoma said:
I may have to start on this TOMORROW, so any help is MUCH appreciated:

1. When swapping a 454 in place of a 350, am I going to be lucky enough to be able to use the 350 exhaust? I am thinking NO, but maybe.

2. Are the fuel lines the same for the two engines? I have a TBI 454 in the work truck I could pirate parts from if necessary, but I'd rather know RIGHT NOW LOL

3. Any issues using the 350's 700r4? I have the 454 flywheel.

4. Any wiring issues? I have a spare 454 harness I could use if required.

If the 350 is TBI you're also going to need the chip from the 454 truck.

Basically, my 350 has lost a LOT of "power" over the last week... and it's puking oil out of everywhere. 250k on the clock. :(
Click to expand...

(1) Exhaust manifolds are different and the 454 s going to use a larger pipe than a 350

(2) Need to know if both engines are TBI, if so then fuel lines are the same.

(3) Automatic transmissions use a flexplate not a flywheel, 454's are external balanced so you must have a 454 flexplate with the correct bolt pattern for the convertor.

(4) If both engines are TBI you will need an adapter harness for the IAC and maybe one for the TPS depending on what year 454. This is the IAC harness you'll need.
http://www.turbocity.com/product_info.php?cPath=16_23&products_id=44 Here is the TPS harness you might need. http://www.turbocity.com/product_info.php?cPath=16_23&products_id=50

If the 350 is TBI you're going to need the chip from the 454 truck.
 
You still haven't said what year the Blazer is and whether it is carbureted or fuel injected. Fuel injected vehicles use an electric in-tank fuel pump. Carbureted ones use a mechanical engine mounted pump.

GM never put the 700R4 behind a 454. They used the Turbo 400 and then the 4L80.

The 700R4 uses a lock-up torque converter, the turbo 400 doesn't. You will need a method of getting the 700R4 to lock-up. There are several ways. I suggest you go to Bowtie Overdrives and look at what they offer.

Over the years GM made a number of changes to the 700R4 (which became the 4L60). There is a 4 pin plug on the left side of the 700R4. In different years there are different numbers of wires that are used. IIRC in 1986 only one or two were used. In 1989 three wires were used.
 
1989 Blazer, TBI 350.

I know they never used a 700r4 from the factory. I've got a Summit dual pattern flexplate planned for order later today, after I verify that it's the RIGHT dual pattern LOL

I have the harness and computer for the 454.


So it looks like I need to steal the TV cable bracket from teh 350's TB, get the right flexplate, and a new y-pipe. Ok.
 
You will need to fab a way for the TV cable to attach to the 454 TBI, i took the side plate off of a 350 TBI throttle shaft and welded it to the 454 TBI throttle shaft.
 
In addition to the above considerations, 454's use a much thicker radiator than a 350. They also use a different radiator shroud, different fan and different fan clutch. (My '88 "donor" Suburban also had an auxiliary electric fan, which came from the factory) Of course, radiator hoses are different as well.

As I said in an earlier post, you need to figure a way to lock-up the torque converter. If you don't, you'll generate a lot more heat and heat isn't a good thing for automatic transmissions.

This is the way the factory torque converter lock-up wiring is done (but you have other options):
Your 1989 transmission plug should have three wires:
Pin A is a purple wire that goes to the brake stop lamp switch.
Pin B is a light blue wire that goes to the ecm. (It tells the ecm the transmission is in fourth gear)
Pin C is not used
Pin D is a tan wire with black tracer that goes to the ecm. (This is the wire that the ecm uses to tell the torque converter to lock-up.)

Your 454 harness will not have these wires. Also your 454 ecm is not programmed for torque converter lock-up, so you'll need a custom chip as well.

In terms of the TV cable hookup, I did the same thing as 4x4HIGH on the TBI unit.
You will also need a bracket to hold the TV cable. If your 454 has cruise control, the bracket that holds the cruise control servo bolts to the throttle cable bracket. I cut off that portion of the cruise control bracket and welded it to the throttle cable bracket. Then I cut and shaped a square hole in the new bracket. I don't recall where I found it but I found a drawing of what that cut out should be on the internet.

I'm not a "full member" so I can't (and wouldn't know how anyway) post pictures. If you PM me, I'll send you a photo of the TBI and the TV cable bracket modified.
 
His rig that's getting the donor 454 already has a 700R4 and he doesn't need to change the ECM or any wiring other than add the adapter harness(s) that i linked him to.
 
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