Red99TA

iTrader: (10)

Hey guys,
Looking at buying a cheap '97 ECSB with the 5.0L and then swapping in the L31 shortblock and some vortec heads. Are the intake manifolds and throttle bodies the same? I would also need to get an ECU for an L31 right? I'm thinking everything else can be transferred from the 305 to the 350. So the list of things I need would be:
L31 shortblock
vortec heads...the 305 uses smaller valves and combustion chamber
intake manifold and throttlebody unless it's the same as the 305
bigger (19#) fuel injectors?
stock L31 ECU
Let me know if I missed anything.
TIA!

jakebdb56

iTrader: (24)

I remember lookin around for l31 stuff back when i was doing the efi conversion on the dune buggy. I don't think the manifold/tb is the same, I could be wrong though. I'd just buy an aftermarket intake or maybe could you use an LT1 intake? what're your plans for the motor?

Red99TA

iTrader: (10)

No plans for the motor really. I just want a reliable setup with the power of the 350. I figure I can get the truck cheap and then spend maybe $2K tops on the L31 swap and I'll basically have a new motor. Only mods I would do down the road are maybe CAI and a catback.

adam1803

iTrader: (65)

vortec heads require an intake made specifically for them.

Red99TA

iTrader: (10)

Right but I heard the 305 has vortec heads on the later years...is that right?

02gmc5.3

iTrader: (11)

It does, its a similar head with smaller valves, runners and chambers.

Red99TA

iTrader: (10)

So is the intake manifold the same for both and how about the throttle body?

02gmc5.3

iTrader: (11)

They're the same.

THE-HOE

iTrader: (3)

the 305 and 350 are very simaliar actually. the TB, and intake are the same i believe.

BlackGMC

iTrader: (31)

you could go to autozones website and plug in the year of the vehicle your looking at the look up the part number for the gasket for a 350 and 305 and see if they are the same.