305 Engine

The good old GM 305 engine, dismissed by most to be an underperforming, lack luster, small block engine not worthy of any kind of recognition.  The 305 Engine had terrible flowing heads from the factory which is what gives them the notoriety of being unable to perform very well.  This motor was a combination of a 265 cubic inch block with a 350 crank that resulted in the not so lovable 305 engine with a bore of 3.75 inches and stroke of 3.48 inches.

This engine is known to mostly reside in 1980’s style Camaro’s and Firebirds.  They are also fairly common in the Monte Carlo SS of the 1980’s.  These cars were choked with unsophisticated Emissions controls and regulations that rendered it under powered.  Introduced in 1976, the 305 engine has gone through 8 different models with varying performance.  These models also overlapped from year to year with updates to some cars and not others and performance variations that put the better performing engines into top model cars.

Starting in 1976, the LG3 305 engine made a whopping 130HP.  The LG4 was the next model and GM made minor improvements to the engine to get it to eventually put out 165HP towards the end of its run.  This was achieved with the addition of a 4-barrel carburetor, improved intake manifold design, and more aggressive ECM programming.  The next model was the LU5 Crossfire 305 engine.  This engine was the same as the LG4 but had the dual throttle body fuel injection setup.  There were no significant performance gains from this setup and due to a lack of knowledge about the systems and some quality control issues on GM’s part, this engine might be better known as the Ceasefire Engine!  The most desired models are the L69 and the LB9 which were found in the High Performance variations of GM F-Body’s.  It was also found in the Monte Carlo SS.  With a Compression Ratio of 9.5:1, achieved with 4-releif flat top pistons, and an aggressive camshaft, this engine put out 190HP.  The LB9 was the Tuned Port Injection 5.0L and started production in 1985.  With the addition of fuel injection, this 305 engine was capable of 230HP!

The above 305 engines were all installed in GM cars, but there were a handful of 305’s that found their way into some trucks.  There was the LE9 which had a compression ratio of 9.5:1, utilized the LM1 camshaft and made 210HP.  There was the LO3 with TBI (Throttle Body Injection) which made 170HP and was the base engine for all C/K 1500 pickups and vans.  Then came the Vortec 5000 305 engine, it made approximately 220HP and achieved this with a 9.1:1 compression ratio, a hydraulic roller camshaft, and (of course) the much improved Vortec heads.

The good old GM 305 engine, dismissed by most to be an underperforming, lack luster, small block engine not worthy of any kind of recognition.  The 305 Engine had terrible flowing heads from the factory which is what gives them the notoriety of being unable to perform very well.  This motor was a combination of a 265 cubic inch block with a 350 crank that resulted in the not so lovable 305 engine with a bore of 3.75 inches and stroke of 3.48 inches.

Now, this is a blog about driving and performance, so the stock 305 engine is not going to cut it for most of us.  I guess if you wanted to keep your car completely stock it would be OK, but this thing needs some help.  There is nothing inherently wrong with the 305 engine, it’s just not a 350!  The heads are terrible on a stock 305 and the camshaft needs to be upgraded if you want to get any kind of respectable power out of it.

If you have to do the upgrades in steps, you would want to change out the camshaft first.  This would give you the best performance “feel” for the upgrade being performed.  You wouldn’t want to upgrade the heads and leave that crappy old camshaft in there.  You may actually hurt the performance.  The only thing that would need to be considered is the valve springs.  Depending on the camshaft that you want to use, you may need to upgrade the valve springs to be able to handle the extra lift.

The next step would be the heads!  This seems to be the weakest link in making power with the 305 engine.  The stock cast iron heads flow terribly and do not bode very well in performance applications.  Replacing the heads with either cast iron later model Vortec heads or custom heads made specifically for the 305 engine will offer large gains in power combined with an upgraded camshaft.

Headers would be a worthwhile upgrade at this point.  A nice set of 1 5/8 inch headers should keep that awesome torque curve of the 305 engine and allow it to breathe properly.

An intake manifold would be next.  This is not a required upgrade but to get the most airflow from the 305 engine (air = power) I would recommend it.  Topping this off with a 600+ CFM carburetor should get this little engine up over the 350HP mark with some minor tuning.  Some people have seen close to 400HP out of this kind of setup.  That kind of power in a street driven 3rd Gen Camaro would be more than fun!

This upgrade path, and the Horsepower numbers that can be achieved, make keeping that little 305 in your car seem a little more feasible.  Getting an awesome, fun to drive, performance car with very little money in upgrades is what I’m all about!  I look forward to giving this a shot.

We can’t really talk about upgrading the 305 engine without mentioning the other option can we?  The other option is to ditch the 305 engine and go with the tried and true 350.  There are a lot of benefits with going this route, larger displacement being the main one, but you will also make more power much easier than with the 305.  Getting around 400HP with the 305 engine is about the max you will get without really dumping some money into it.  On the other hand, the 350 will produce that power relatively easily and with the larger displacement will be able to put out even more.

If your 305 engine is completely shot, by all means I will recommend ditching it and moving up to at least a 350.  I have seen SBC 350 blocks on Craigslist for as little as $150.  With a rebuild kit and a set of heads, you could easily build it up to 400HP for not a lot of money.  I’ve done a quick search on Summit Racing and it appears that a Chevy 350 standard rebuild kit goes for less than $250.  If you just had the block you would also need a Camshaft, that you could probably get for around $250.  Cylinder heads would also be required, they will run you anywhere from $300-$800 each assembled.  This means that the valves, springs, and retainers are already installed and ready to go, you would just need the lifters and pushrods.  If you are very experienced and would like to pick the valves, springs, and retainers yourself you could do this even cheaper.  An intake manifold and carburetor would also be required, you could pick up an intake manifold for less than $200 and a carburetor for anywhere between $250 and $700 depending on what you are looking for.  The Holley carburetors appear to be the most expensive with remanufactured Quadrajet Carbs from Summit looking to be the best deal, 750cfm for around $300.  You would also want to take the block to a machine shop to be cleaned and prepped; this is something that I’ve never done so I’m guessing that it would cost anywhere between $500-$1000.  This site has a list of prices that would most likely be similar at any shop.  Using the largest amount from all of these options, going this route would cost you around $4000!  Wow, I didn’t think it would add up to that much!  Of course that is using the largest amount from all things needed, you could probably cut that in half pretty easily and still have a pretty stout 350.

Now that I’ve seen that large $4000 number, there is another option!  You could go with a 350 Crate Motor!  The cheapest 350 Crate motor that I have seen is the 195HP 350 that is for sale everywhere.  It is a base block and heads and runs a little more than $1500.  You would need an intake manifold and Carburetor still so the cost would end up being closer to $2200.  There are, of course, a ton of other 350 Crate motors that are available.  From mild to wild, they are all covered.  Obviously, the more Horsepower that you want, the more money you will spend.  From the research that I have done, the best 350 Crate Motor is probably the ATK GM Performance 350 that comes with the distributor and intake manifold for around $2800.  What a steal!  Why even bother with rebuilding a derelict?

Now that we uncovered the wonders of the 350 Crate motor, let us not limit ourselves to just one size.  Crate motors come in all sizes and all different combinations of Horsepower and Torque.  The 350 is just the tip of the iceberg!  They definitely make 305 crate motors, but we’re not even remotely interested in that, after all we are trying to upgrade the power in our 305 powered machine not just refresh it!  My criteria for crate motors would be at least 300HP and as drop in ready as possible.  That’s the whole reason for going with a crate motor, it’s easy!

I’m all about bang for the buck and instead of going through all the possible crate motors that you could purchase, I’m going to pick out two that offer the most for the least amount of money.  One small block Chevy and one big block Chevy.

For the SBC crate motor, I would go with the Blueprint GM 383 that produces 405HP and costs around $3300.  That seems like a really good deal, especially considering that if you were building it yourself you would need to take the block to a machine shop, and it would probably cost you more to get the parts yourself.  I know that $3300 is not the final cost in getting the crate motors working properly but for the price, that would be pretty easy.

If you wanted to go big, and drop a big block engine in your car, I would go with……who am I kidding.  There is no way in hell that I would drop five or six thousand dollars on an engine.  I would purchase another car and drop one of the above engines in it and sell it, that’s just what I’d do.  Maybe in the future when I get this thing off the ground and I’m rolling in dough (yeah right) I’ll think about it.  But for now I’m not even going to dream.  This blog is about driving and enjoying cars on a reasonable budget.  I know this stuff is not “cheap” but it doesn’t need to kill us either.

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