I stated to put the L31 crank reluctor on the TBI engine?Don't forget the disc behind the balancer. You will need that as well. The L31 balancer has a shorter snout than the TBI, and you won't be able to use the TBI balancer if you use the Vortec injection.
I knew zero about this before I did my Vortec/TBI engine build. There is a learning curve, and if you come from a non-GM background you need it dumbed down. Here's a thread on what I learned:
"Can I swap a Vortec motor in place of my TBI motor and does it just bolt in place?" Yes, you can swap a Vortec motor in place of a TBI motor, but no, it doesn't bolt in place. So, what does it take? Head and Intake Differences: The Vortec manifold has eight bolts, two on each corner, drilled...www.gmt400.com
Also keep in mind that the cam on a Vortec has a smaller bolt circle than a TBI cam, and uses a different timing set.
I would keep the TBI bottom end and swap the Vortec heads and intake onto it. Plug the water pump bypass hole on the block and run the Vortec water pump.
The water pump bypass hole does not need to be plugged using stock Vortec heads. The matching hole in the deck surface of the head is cast closed. Nearly every L31 block I have had came with that port in place, standing wide open. The only time I have had to plug it is using aftermarket heads, then it is a simple operation to tap the hole with an 1/8NPT tap and put an 1/8" NPT pipe plug in.
The budget 880 block L31 I built earlier this year. Bypass port is blocked by the aftermarket Vortec head casting. I can say the Assault castings also used by AFR for their Enforcer line do not plug this off. It has been so many years since I ran them, but I want to say the Etec170s did not either.
I only mention not having to plug the bypass because it is wasted time, effort and expense if running stock Vortecs. He would be tracking down the 1/8" NPT tap and matching plug for literally no reason at all.
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