The Stovebolt Site Forums The Shop Area Engine Shop 327 VS 305

I haven't been able to figure out why the exhaust smells so bad on my 327. I bought it years ago from someone who swapped it out for a BBC but he didn't have any issues with it. Not sure how long it sat before I bought it, but I didn't install it for a couple of years later (bought the motor before I found the truck). I stored it covered outside but did notice some water in the oil during the install. I changed it but have noticed a little smoke & a pungent odor. I came across someone who rebuilds early Camaros. He has a 305 out of a 93 Z28 with 40K miles that he wants to trade. I know I can have mine rebuilt, but this is free. Yes, not as much power as the 327 but I'm not planning on racing anyone. What do you think?

Put some miles on it first, just needs to be "run in" again,
Scott

I wouldn't give up on the 327 just yet. Check out the fuel system and run it some more and see how it does. The odor could be coolant so possibly head gaskets are in order.
The 305 has a roller cam and can be a decent runner. However, some of the components are different. The flywheel or flex plate from your early engine will not fit. Also the Camaro was fuel injected, and early intake manifolds will not fit. There may be some issue with the fuel pump as well.
Fred

The 305 has a 1/4" longer stroke than the 327, so it just might have more low-end torque. The street-stock 327's I worked on back in the 1960's and 70's were notorious gas-guzzlers, although they made very good dirt track race engines after some pretty radical modifications. A low-mileage 305 will probably make a better street engine for you.
Jerry

The 327 was one of the best (versatile and reliable) engines General motors ever produced . I would never change one out for a 305 (grandmas 78 Impala) engine

I would have to agree with red1946. I think the 327 is one of GM's best engines, and would not trade it for a for a 305.
Just my thoughts for what it is worth.
Jim

And my thoughts for consideration.
I grew up with the 327--saw them replace the 283 and saw them replaced by the 350.
I've bored them, owned them,tuned them, raced them,broke them and cussed them--all in all great engine.
The early ones differed from the later improved ones.
Before 1967 we hardly found a factory Chevy V8 that wouldn't use a quart of oil in 1500 mi.The factory didn't install positive valve guide seals and rod/cylinder oiling system over lubed the cylinders.
The early V8's seemed to have poorer quality of metal in the block as indicated by the high instance of wear on the cylinders.I know my hone and boring bar says the later blocks are harder and this includes the 350 and 305 engines.
When they changed to the larger bearing crank this all seemed to take a change for the better.
As Hot Rod says the long stroke 305 will be better for street use where the 327 has some advantages when you want to make power above about 5000 RPM.That ain't my working range right now.
The 305 described sounds like the high HP factory version and should deliver well up higher but even the truck type with quadrajet responds well to a proper cam.And the improved low end torque of the long stroke allows higher gears for fuel economy and towing.
The 305 would be my choice unless I wanted to build a high RPM engine.

Good point about the later castings. I was amazed to find virtually no cylinder wall wear on a hard-worked small block 400 with 75,000 miles on it from a dually pickup that spent its time towing a gooseneck cattle trailer. We changed a set of cracked cylinder heads after an overheating episode, honed the cylinders, did a re-ring and standard diameter bearing job, and the guy put another 50,000 hard miles on it before he sold the truck. The thinwall casting blocks and heads must have better alloys!
Jerry

2 years ago a pair of heads was brought to me from a 1992 305 in a country pickup which was smoking on startup and idle but little oil consumption.
The truck had over 200,000 on the clock--engine was fairly clean inside except for hard carbon as in baked, built up 1/4" thick in the drain back area between the two center cylinders.This prevented proper drainage and flooded some of the guides when high flow was present.
The valves were great, the guides were relatively tight and the cylinders had factory crosshatch visable within 1/2" of the top.
I reamed for OS stems, new seals, and a proper valve job and the customer was reportedly happy.
The late small blocks will run 300,000+ with reasonable care.

The Chevy 305 is a fantastic engine. I have a 1986 Bayliner with a 305 in it and it has never had the intake off. Starts first bump every year and with a Unilite Dist it produces killer power and has for the 20yr I have owned it (am the second owner). Has a 4bbl Rochester on it and stock manifiold and I run
it with straight 30W oil due to most hours at a steady 3600RPM.
Can't say enough good about the 305cid. **have not owned a 327cid**

TC

I think a lot of the long wearing traits of the later motors is from the f.i. systems keeping excessive gasoline off of the cylinder walls not so much as a diff in iron alloys- also the new ring designs have less tension on the walls too. Them f.i.s and computers are wondermus on performance and fuel milage.