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Old 12-04-2008, 04:15 PM
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305 to 350 SBC build questions

I have a 97 GMC c1500 with a 305 and a rod knock. I am going to overhaul it eventually and want to turn it into a 350. Can someone explain what is involved in the conversion? IS the diff only in the bore or stroke and bore?
Here are some things I have heard so far that need to be changed:
Knock sensors
ESC Module (is this just the cpu?)
350 Chip (where would this go?)

Any help or references would be awesome. Thanks, Brian
PS: If Im going to 350, how much harder would it be to go 383?

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Old 12-04-2008, 04:24 PM
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305 to 350 requires a 350 block and crank. The bore and stroke of a 305 is 3.736" X 3.48". The bore and stroke of a 350 is 4.000" X 3.48". The block is different and the crank is different, even though they both share the same basic length of stroke.

If you're going to start with a 350 block, you may as well use a 3.750" crank in it to make a 383.

As far as the electronics questions, I don't have a clue.
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Old 12-04-2008, 05:38 PM
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Short answer is that you cannot "turn" a 305 into a 350 The biggest displacement from a 305 is 334. And you will spend so much money that you could have had a 383 or a nice 406 for the same price.

Scrap the 305. Get a nice rebuilt 350 shortblock for a few hundred bucks I think Competition products sells them for like 750 bucks. Everything from your 305 will bolt on and if you use the same heads and everything then you don't have to make any EFI changes
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Old 12-04-2008, 05:48 PM
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305 to 350 SBC build questions

find you a van , unmolested 350's in them are 4 bolt main
or hit the craigs list in your area , around here the blocks needing rebuild go for as little as $100
find you a set of 993 heads or 882's , but beware of cracks in them 882's.
if you go with your 305 heads , run a dish piston for sure .
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