This might be a real newbie Q but I haven't been a Chevy owner for very long so please bear with me. :)

I have a 1990 Chev 1/2T with a 305/TBI and 700R4 in it (~220000 km). I use the truck for hauling my Suzuki junk. The engine seems, well, tired. It is completely stock.

I have a line on a 350 with a RV cam and it is in fairly good condition, recently gone over, new heads, etc., etc. But, it is a carbed engine.

Does it matter? Can I swap in the 355 for a the 305 easily?

Do I need to do anything with fuel enrichment on the EFI to coompensate for the extra displacement or is the GM TBI one size fits all?

Removing the EFI is not an option. I'm in a emmssions test zone.

Thanks!

r@m

Was talking toa friend ojn the phone (mudlite).

He tells me that it should be mostly plug and play except I have to change the injector in the TBI unit and the ECU.

Anyone here done this (just looking for some confirmation).

r@m

You need to be very careful with the cam when it comes to the fuel injection. TBI is REALLY fussy about the cam. If you have too big a cam, it won't idle worth a damn, and overall driveablitly goes to hell. I'm not sure if you can compensate for that with a chip or not. You might also have to hog out the center 2 holes in the intake manifold if the 350 has different style heads. The older ones go in at an angle, where the newer ones go straight up and down. This should only apply if you have centerbolt valve covers and the other one doesn't. It's a do-able project, but will probably involve a lot of work especially if you need to swap the cam. You will also need to swap injectors. IMO opinion, it would be more trouble than it's worth unless you really need the extra power.

You might be better off with a gear ratio change. Also, be carefull towing in OD with the 700r4, they aren't well known for their strenght when towing.

Good Luck. Hope that helped.

Thanks Eric!

I think I'm going to go for it. Worth the effort I think. My engine is tired and sometimes has a tick that is RPM dependent. It comes and goes so it is probably a sticking valve or lifter or something. The engine I will be replacing it with is a bored out 350 with flat top pistons, cam and roller rockers. Should liven things up. Not bad for $300CDN.

Got a quote on a 10 bolt with a LSD and 3.73 gears today as well. $350CDN. Not bad. I know that the 10 bolt is frowned upon around here but I'm sure it will be plenty stout for what I am using the truck for - it is 2wd after all.

r@m

My brother is doing this project. I'm not sure on all the details, but he found an intake manafold that bolts to the 350ci, and accepts the tbi unit. It cost $200.
shaggy

This is all from my own research, nopt from true exp. since I have TPI not TBI, but careful.... Cam, displacement, etc on TBI is thin ice.