ok so i have an 87 trans am and it has the 305 in it. Im looking for something i can drive on the street but take to the strip on friday nights. would taking a 350 and boring over to a 383 be a good coversion? thanks

 

Welcome aboard thirdgen.org.

What you said wouldn't be a good idea, because it isn't possible. But, a 383 is a pretty good combination.

A 383 is made from a 350 block by boring the cylinders to 4.030" and putting in a crankshaft with a 3.75" stroke - the stock 350 (and 305, for that matter) crank stroke is 3.48". The 3.75" stroke was originally used by the factory in 400 cubic inch engines, which also had a 4.125" bore (which was a different casting than 350 blocks). The 400's had larger main bearings than 350's as well, but used shorter rods to keep the piston wrist pin in the same place relative to the piston crown as the 350's. The factory added weights to the harmonic damper and flywheel/flexplate to achieve balance with this longer stroke. Sometime in the 70's somebody figured out that 400 cranks that had the main bearing journals wiped out could be turned down to the 350 main bearing size, and put into a 350 block that needed to be bored .030" over. The block oil pan rails had to be ground back a little to clear the wider swing of the rods on the crank, and you had to use the weighted damper and flywheel of a 400, but that's how the world's first 383 was born.

Nowdays 383 "kits" are very common. You can get a brand new crank with pistons made to properly handle the normal 350 rod length of 5.7", and with a .030" over-bored 350 block and some grinding of the oil pan rails, you too can have a 383. You can even get the crank "internally" balanced so you don't have to use the weighted 400 damper & flexplate.

Having said all that, do you need a 383 to accomplish your stated objectives? No, in fact you don't even need a 350. You didn't say what induction system your '87 has, but if it's the carb'd version, that's good news because you can easily achieve good performance from it, and it will easily support a 350 or even a 383. If you have TPI, then life is going to get pretty expensive in order to get the same level of performance out of the 305, or a 350 or 383.

 

well a 383 is a streetable moter but i wouldnt say it would be an economical daily driver.Plus you'll have to buy the crank kit to make it a 383 and probably a whole bunch of other stuff.You cant just bore it to a 383,it takes a longer crank to change the stroke.It all depends on how much money you want to spend.You can get plenty of power out of a 350 just depends on what you want.Are you keeping it TPI,carp,mini ram,HSR OR WHAT
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hE BEAT ME TO IT

 

If you fill the water jackets slap full with hard blok You might be able to do it then I would put it in a ford so it would break down in a couple miles :P

 

well its a good thing i have the carb. but anyways my plan was to take the 350 and bore it and put one of those 383 kits in it. it doesnt have to be an economical driver just a weekend cruiser and one that i can take to the dragstrip. thanks

 

well then i say go for it with the 383.I prefer fuel injection even though it is more expensive to make power,but if i had the stuff for a carbed 383,thats what id go with.It should make a great strip/street car as long as your combo is set up right,so do a lot of research and double checking cause i made a couple mistakes in picking parts that im stuck with for now.Good luck,have fun,spend a bunch of money.