Common Problems with Chevy 305

Common Problems with Chevy 305 & How to Fix Them (Guide)

General Motors’ 305 Chevy engine has been one of the most popular engines produced by the company. This engine is compact in dimension, durable, and rugged.

Because it is an old engine, it has common problems that you and other users may encounter due to design and performance limitations.

This article discusses the top 10 common problems with the Chevy 305 engine and how to fix them.

Top 10 Common Problems with Chevy 305

Below is a list of some common problems with Chevy 305 and their fixes:

Fix common Problems with the Chevy 305 engine

1. Small Bore Size Problem

The 305 engine was introduced to meet the federal emission standards and improve General Motors vehicle’s mileage average. So, they introduced a small 3.736 bore that reduces the air-fuel mixture’s space. This resulted in the engine having less power and performance ratings.

How to fix it: Upgrades to the engine can help to improve the horsepower and performance of the engine. Changes to the camshaft can improve the intake and exhaust and by doing so improve the engine’s performance.

2. Design of The Stock Headers

The design of stock headers also contributes to lowering the air intake due to emission restrictions. With a little upgrade, the air intake can be improved and the emission restrictions will still be met.

How to fix it: This problem can be solved by upgrading the air filter assembly with a modern unit to help the engine get more air on the intake.

Check out this 350 Chevy Engine Diagram to know more about the design of this engine.

3. The 305 Chevy Engine Uses a Flat-Tappet

Before the use of hydraulic roller cams, the flat tappets in use were more mechanical and therefore, had more friction between the moving parts. This in general, reduced engine performance over long usage.

How to fix it: This problem can be solved with the installation of the hydraulic roller cams for older versions. Upgrading the camshaft can also help reduce the friction of the engine.

4. The 305 Chevy Engine Has Large Valve Heads

The 305 engine by Chevrolet has a large valve head that can lead to valve shrouding, which reduces the airflow. And, less air means lesser power.

How to fix it: The solution to these types of Common Problems with Chevy 305 is having a larger exhaust valve installed so that the shrouding will be eliminated.

5. Peripheral System Failure

As with most vehicles made in the 80s and before, peripheral systems can wear out before the engine.

How to fix it: The only remedy to this chevy 305 problem is to change those parts before it breaks down. No one would love to be stranded in the middle of nowhere because the nylon-toothed cam gear used to reduce noise failed. This gear is fragile and breaks down easily so should be replaced with a solid steel gear.

6. Engine-Powered Water Pump

The water pump that is powered by the engine increases the workload on the engine. This leads to a reduction in overall power and torque output.

How to fix it: The solution is to change it to an electric version which will help reduce the workload on the engine.

7. Stock Radiators Easily Break Down

The stock radiator is prone to breaking down and always needs replacement. This made the 305 economically disadvantageous.

How to fix it: It is advised to opt for the lightweight three-row aluminum model that reduces weight.

8. Design Limitations

The 305 design was targeted at moderate power while maintaining relative efficiency. Drivers looking for great mileage and sufficient horsepower were left disappointed.

How to fix it: The solution to this 305 Chevy engine problem is upgrading and modifying the engine to deliver 350hp. You can also correct the initial engineering problems with newer versions of the components that allow the engine to work more efficiently while boosting both power and mileage.

9. The 305 Engine Has a Low-End Torque

The stock camshaft of the 305 is small and this results in very low-end torque. Having a small camshaft will increase the average mileage but that affects the overall horsepower output.

How to fix: Upgrade the stock cam to the 350 cam. The stock 350 cam is the best for mild street racing. This is because it behaves like a bigger cam in a smaller displacement. Check out this article on the Best Street Cam for Small Block Chevy.

10. Hard Cold Starting Problems

Cold starting is tough on 305’s. On a cold day or after staying inactive for a while, the 305 always had a hard time starting.

How to fix it: The solution is an overhaul of the carburetor. With all the linkage adjusted correctly and float set at the proper level, starting will be a lot easier.

How To Avoid Common Problems with Chevy 305

Check and maintain these things to Avoid Common Problems with Chevy 305:

  1. Engine oil.
  2. Coolant.
  3. Grease fittings.
  4. Differential fluid.
  5. Change oil and filter every 5000-10000 miles.
  6. The spark plugs, caps and rotors, batteries, and fuel filters.

Is the Chevy 305 a Reliable Engine?

Chevy 305 is a reliable engine because it has one of the best mileage for engines of its era. The efficient fuel economy hampered the power output but this could improve with some aftermarket modifications if the owner wanted more power.

How Long Does a 305 Engine Last?

Just like with any other great engine ever made, the chevy 305 will last depending on how you use it and maintain it. On average, the engine can go 130,000 miles before it needs a rebuild.

Is Chevy 305 Good or Bad?

Depending on what you want from the engine, the Chevy 305 has a very good fuel economy but the power output is not great. You can easily modify the engine to increase performance but the same cost of modification on the 350 engine can give you more speed and power.


The 305 Chevy is a reliable and strong engine for the streets, however, it has some flaws as stated in this article. These design and performance flaws can easily and affordably be corrected. Upgrading some of the parts is one of the best solutions to making the engine a versatile option for many users. To get the best out of it. Do the advised parts upgrade stated in this article on Top 10 common problems with Chevy 305 and how to fix them.

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