305 to 350 swap

[Hartwell]

What all needs to be changed and what all can be swapped over to the 350? Trying to do this as low buck as possible. I have a 93 Sierra


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[94burbk1500]

I've not seen much on the topic, but the gains from the 305 to 350 aren't significant enough to warrant it, imo. You're talking about an engine swap to gain something like 15 horsepower. Do you just happen to have a spare 350? I think most of the accessories will bolt right on, but I'll let someone with a bit more knowledge of the 305 chime in.

 

[magimerlin]

EVERYTHING, Bolts right up.. it's the same block. They are so close I bet the ecm will not even notice.

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[df2x4]

EVERYTHING, Bolts right up.. it's the same block. They are so close I bet the ecm will not even notice.

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A cousin of mine has an older TBI GMT400 which used to belong to his dad, we call it "Old Blue." It originally came with a 350, but my uncle blew it up somehow a few years back and swapped in a Craigslist 305 (unintentionally, guy sold it to him as a 350 and unfortunately he didn't know any better at the time). It's been running great with no alterations to the factory PCM or anything else for years now. The gas mileage sucks and it runs a little rich, but other than that it's fine.

I'd be cautious doing this the other way around like the OP is describing, though. The 305 PCM and fueling system (same TBI? I honestly don't know...) might cause the 350 to run lean and melt stuff.

 

[98 Nitro]

Just change to a 350 prom and injectors everything else is the same

 

[blacksport]

if you can do it with the budget you have i say go for it.do the prom change or throw a hypertec chip in it https://www.summitracing.com/parts/...BPdeI0EJxw-rZTi2DL8HEfY7efRLVoMQaAmotEALw_wcB
it's not a hp thing it's torque.....the 305 is one of the worst small blocks kinda like a 307 IMO and my truck has a 305. 305's just don't breathe.i have had them in 5 different cars.that being said my truck has 209k on it curps second (corvette servo) and don't leak a drop or burn oil.i want to pull it but i have a hard time pulling a "good motor",when it screws up i'll go 350 or i have a 5.3 siting on my engine stand.
actually you could throw a chip in the 305 and you may be happy.

 

[In the Weeds]

Removed a Very Tried 305, [290,000 miles], about 10 years ago, installed a rebuilt 350, and I've had no problems since...

 

[F Costello]

I did a 5.0 to 5.7 vortec swap with a lt1 cam shorty headers police injectors ,under drive pulleys ,dual E-fans with 98 Tahoe y-pipe and twin cherry bombs on the back .
I haven't touched the prom yet bit ten years has passed and it runs like a champ and not bad on gas .

 

[Eveready]

Mine came with a 305 and got the 350 some time along the way. It runs really well and the truck really likes it.

 

[L31MaxExpress]

if you can do it with the budget you have i say go for it.do the prom change or throw a hypertec chip in it https://www.summitracing.com/parts/...BPdeI0EJxw-rZTi2DL8HEfY7efRLVoMQaAmotEALw_wcB
it's not a hp thing it's torque.....the 305 is one of the worst small blocks kinda like a 307 IMO and my truck has a 305. 305's just don't breathe.i have had them in 5 different cars.that being said my truck has 209k on it curps second (corvette servo) and don't leak a drop or burn oil.i want to pull it but i have a hard time pulling a "good motor",when it screws up i'll go 350 or i have a 5.3 siting on my engine stand.
actually you could throw a chip in the 305 and you may be happy.

305 and 307 for that matter can both be made to run very well. The 305 has almost identical bore to the 265 and the 307 is a 283 bore. My 1999 Tahoe has a L30 305 with a 218/218 @ .050 cam, ported intake base, Volant CAI, long tube headers, 2.25 pipes to 2.5" high flow cats and a dual in/single out magnaflow. It put down 267 rwhp through a 4L60E and 9.5" 14-bolt.

A factory stock Marine 305 Vortec is also a 260 NET HP engine with the tiny 395' Marine cam in it and very restrictive water cooled manifolds.