Author Topic: Carburated 454 in place of a TBI 305  (Read 1705 times)

Offline BigRock

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Carburated 454 in place of a TBI 305
« on: October 23, 2019, 01:09:22 PM »
Hello,

I have installed a carbureted 454 in my 1987 R10 where the TBI 305 used to be.  I'm needing advice on where to get power from to connect the HEI distributor.

If there is already a thread on this subject please redirect me to it.

Thanks!

Online bd

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Re: Carburated 454 in place of a TBI 305
« Reply #1 on: October 23, 2019, 01:46:16 PM »
Use the same 12-ga pink wire that powered the original distributor.  The pink wire should be paired with a single white wire (used for the tach signal) in a two-wire connector.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline BigRock

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Re: Carburated 454 in place of a TBI 305
« Reply #2 on: October 24, 2019, 06:12:33 AM »
Thanks bd!  I'll try that in a couple of weeks when I get everything together.

Offline BigRock

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Re: Carburated 454 in place of a TBI 305
« Reply #3 on: December 04, 2019, 07:20:46 AM »
bd,

The pink wire you suggested worked perfect!  I fired my 454 last Saturday and she runs great.  Thanks again!

My next question is about the fuel pump.

I have a mechanical fuel pump on the engine and I put new hard lines to the dual tank switch valve.  The truck is a 87 model that came with a 305 and electric pumps in each tank.  I had heard somewhere that the mechanical pump would pull fuel through the electric pumps in the tank but I am not getting that result.

When I fired it up I had to keep priming the carb to get it to run but the inline fuel filter never filled up with fuel so I disconnected it and ran a line to a 5 gallon gas can.  This worked great and I was able to break-in the engine.

So now I need to figure out what to do to get the mechanical pump to pull from the tanks.

Any ideas/advice?

Thanks!

Online bd

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Re: Carburated 454 in place of a TBI 305
« Reply #4 on: December 04, 2019, 11:03:02 AM »
Regarding the inline fuel filter never filling up, there is a widespread misconception that it is significant and representative of some abstract cause.  It isn't.  In fact, as long as fuel is supplied and there are no leaks that allow fuel to escape or air to enter, it is in and of itself irrelevant.  Fuel will wick along and through the filter element with no interruption of supply. 

To the matter of the fuel pump(s), there are several approaches that you can take.  1) Retain the in-tank electric pumps, install a fuel return regulator adjusted to a pressure suitable for the carburetor, rewire the fuel pump relay to energize while cranking, reverting to engine oil pressure control once the engine starts, and eliminate the engine mounted fuel pump.  2) Retain the engine mounted fuel pump and replace the in-tank pickups with pre-1987 senders.  3) Retain all of the fuel pumps, add the fuel pressure regulator, and rewire the fuel pump relay control circuit as described in (1).
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)