I have a 1987 R10 with the factory 305 L03 and TBI. Looking to swap to a 350 L05 or L31. Will my ECU need to be reworked or replaced? Also Holley makes an aftermarket TBI rated at 670 CFM. I’m thinking this would be a good upgrade. I’m planning to acquire a junkyard 350 core, have it machined, and add a cam and heads. Advice appreciated. Thank you.

 

Don't know what a R10 is. Never heard of it.

This forum is for 82-92 Camaro & Firebird exclusively. Is R10 a model of one of those? If not, this isn't the right forum.

However I'll answer that in general, the 305 -> 350 swap is about as much of a non-swap as it can be and still qualify as a swap. Yes you can use your existing ECM. Yes you can use your accessories. Yes it bolts right up to your transmission. For a L31 best thing to do is use a 4-bbl manifold (Performer RPM) and a 4-bbl -> TBI adapter. For either a L05 (largely a waste of time, in 2021) or L31, get the injectors, ESC module, and chip from a L05; and a new 350 knock sensor. You'll want tuning no matter what, even a factory L05 benefits in a MAJOR way from that. "Work" is one thing, "optimize" is a complete OTHER.

Look for a core that doesn't need machining. EFI motors don't trash their bores like motors of old with crappy carbs (*cough*2G*cough*) did. DO NOT touch the short block if you can help it, except for maybe a turned crank a new bearings. Leave the pistons ALONE. Pay acoupla $$ extra if you have to, to get the BEST core the buzzard has in his nest. Doesn't matter if it's $1000 difference; it's still cheeeeeeeeper than dinking with boring, new pistons, rings, and all that.

 

My apologies sofakingdom, I was toggling between forums. I intended to post this question in '73-'87 Square Bodies. Perhaps if I had said C10 you'd recognize the nomenclature. FYI, R10 refers to one year only, the 1987, Chevrolet 1/2 ton Truck. Appreciate your insight. Good Day, Sir.