305 to 350 l98 swap

[McSweeney]

Hey so my truck has the vortec 305 with cpfi. I just bought a L98 4 bolt main 350 from an 86 c20. So my idea is to throw out almost everything exept the block obv and covert it to a vortec with mpfi. So i know that the late 90s 350 vortec heads will bolt right up to the block and then i need to get a new intake and injectors and all that stuff. Most of it should be straight forward, but theres a few sensors im worried about for the new ecm. So i didnt look when i looked at the block, but i don’t believe it has a crank sensor port. Will this be a problem? And will there be any other problems with this swap? Thanks

 

[Erik the Awful]

Here's a writeup I did on the differences between Vortecs and TBI motors, much of which will apply to what you're doing.
https://www.gmt400.com/threads/how-to-put-a-vortec-motor-in-a-tbi-truck.49463/

The crank sensor goes into the timing cover. You'll need the Vortec timing cover anyways to fit around the reluctor wheel. Then you'll also need a Vortec balancer because it's shorter to fit the reluctor wheel.

Also note that your '86 has a two-piece rear main seal and no provisions for a roller cam. The later motors have one-piece rear main seals, and your current 305 has the provisions for a roller cam. Without the bolt holes for the roller cam spider and dogbones, you'll either need to drill and tap holes to mount the spider (not the same as the intake spider), or you'll need roller cam retrofit lifters. Alternatively, you can put a hydraulic flat-tappet cam in your Vortec instead of the stock roller cam.

 

[McSweeney]

Awesome thank you!


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