What size valves are on a Ford 390 intake?
The stock intake valve size for most Ford 390 FE engines is 2.05 inches in diameter, with exhaust valves typically around 1.65 to 1.72 inches, depending on the cylinder-head casting. Engine configurations and aftermarket heads can alter these numbers.
What follows provides a concise look at the typical factory sizes for the Ford 390’s FE family, explains how to identify the exact sizes on your specific engine, and offers guidance for upgrades or replacements. This information helps enthusiasts restore, tune, or modify FE engines with accuracy.
Stock valve sizes for the Ford 390 FE engine
Before listing the sizes, note that valve dimensions depend on the cylinder-head casting used by Ford during the FE era, and aftermarket heads can differ from stock specifications. The numbers below reflect common factory configurations for the 390, used across various production years and models.
- Intake valve diameter: 2.05 inches (52.1 mm)
- Exhaust valve diameter: typically 1.65 to 1.72 inches (41.9 to 43.7 mm)
These stock sizes represent the baseline for many FE 390s and influence airflow characteristics and combustion chamber design.
Identifying the exact sizes on your engine
To confirm the valve sizes in your specific engine, start with identifying the cylinder-head casting number, which is usually stamped on the head near the rocker-cover rail, or consult the vehicle's build sheet. If you have the heads removed, you can measure the valve head diameter directly with calipers and compare to the head’s service data. For precision, refer to Ford FE service manuals or reputable head-manufacturer catalogs, especially if the engine uses aftermarket or performance heads.
- Head casting identification: locate and read casting numbers (FE head designations) and cross-check with Ford/aftermarket catalogs to confirm valve sizes for that head.
- Direct measurement: remove the valve and measure the valve head diameter with calipers, comparing to the expected 2.05" intake and 1.65–1.72" exhaust sizes.
- Verify all valves: confirm both intake and exhaust valves on all cylinders, as mismatches can occur if different heads or parts were used.
Once verified, you’ll have precise data for maintenance, restoration, or performance upgrades, ensuring compatibility with your chosen valves or heads.
Summary
For most Ford 390 FE engines, expect a stock intake valve of 2.05 inches in diameter and exhaust valves around 1.65 to 1.72 inches, with exact numbers depending on the head casting. When planning upgrades or replacements, identify the head casting, consult service data, and verify sizes before purchasing parts.
