305 and 350's

[celeryman22]

Guys, can you let me know what the difference is between a gm 305 and gm 350? Is it only the displacement of the cylinders? Do 350 parts fit on a 305? Ie. intakes and exhaust manifolds...


Thanks
Mike

 

[tscott9330]

all the external parts will, i.e. cylinder heads intakes etc.. the main differnces in most chevy v8 small blocks berfore 1987 is the bore and stroke of the engine. so some internal parts are interchangable and some are not. if you dont mind, may I ask what you intend to swap?

Tom

 

[celeryman22]

The motor in the corvette from what I can tell is a 305 not original, not a California model. I was thinking of putting in a new 350, but because money doesn't grow on trees, I am thinking I will clean up this engine, put a new intake, exhaust, etc. and tweek this motor until I can afford a new 350. But I didn't want to get new headers, intakes, etc. if they won't fit on a 350, maybe they wont but we will see.

Thats what I was thinking.

Mike

all the external parts will, i.e. cylinder heads intakes etc.. the main differnces in most chevy v8 small blocks berfore 1987 is the bore and stroke of the engine. so some internal parts are interchangable and some are not. if you dont mind, may I ask what you intend to swap?

Tom

 

[pgtr]

If I recall correctly the 305 (not to be confused with a 302 or 307) is the same stroke as a 350 but w/ a smaller bore. If so it should be a good motor to build for torque. I think it also was known for good gas mileage in it's day.

 

[yellow77]

Only word of warning is dont put big valve 350 heads on a 305, the valves will hit the edges of the bores.

 

[MMM]

350's and 305's have the same stroke, 3.48". The difference is the bore, 350 is 4.001" and 305 is 3.736" (the first version of the SBC was the 265, a 3.75" bore). While the 305 was manufactured in a High Output version for Camaros and rear drive Monte Carlos (SS), it was only manufactured as a 2 bolt main block and small valve heads. A 350 is a drop-in replacement for a 305 and it costs about the same to rebuild either engine. And the choice of aftermarket or high performance parts is much greater with the 350. So unless you have a California 305 'Vette that you want to keep numbers matching, I'd dump the 305.
Mike

 

[Stingray6974]

Another minor but important difference. In 1980 the oil dipstick and tube was changed from the driver side to the passenger side of the engine.

Mike

 

[craig32]

small block parts

Yes, they are generally the same. The 305 was a later engine, built with the same components. But remember - if you have a two barrel engine and you put a four barrel intake and carb on it, you'll want to change the heads as well. Basically, the heads all bolt the same to the block, and the intakes all bolt the same to the heads, as do exhaust manifolds/headers. All the gingerbread (water pump, distributor, etc.) should mount the same too. Small block connecting rods (original) are all the same, the difference in stroke being on the throw of the crank. The only difference to note: If you are building an older engine, in '68 or '69, the crank journals got bigger. I never owned one, but I've heard the cams are weak in them.

Craig

 

[BLACKDOG]

celeryman22 - I have had my 1980 California Vette with the 305 LG4 since July 1998. Even though it was a low HP motor (rated @ 180), it was a nice cruiser with a bit of low end pull. I would get around 18-22 mpg. Earlier this year I started talking with numerous small block gurus around the country trying to get opinions on building the 305 or going with a 350 crate motor. The overwhelming consensus was to dump the 305 if HP was the main factor. I ended up going with a new crate motor rated at 290 HP for about $1500. Everything on the 305 (intake, distributor ... etc) was a bolt-on to the 350. A rebuild of the 305 was going to cost just about the same, even a bit more, depending on where I wanted to take it to. Since you don't have the original 305 in there anyway, I'd save the $$$ towards a new crate motor, and not put it into a non-original 305. If you want to keep the 305 in there for some reason, Edelbrock has a kit for the 305 (intake, heads, & cam) to kick it up a bit, but I never checked into it anymore than that. Good luck and enjoy the ride !!