Crow Cams Pushrod Lengths on the L67: Which Size Is Intake and Which Is Exhaust?
Two lengths, two sides — here’s how to sort it
When a Crow Cams Stage 3 kit ships with two different pushrod lengths — commonly 7.050″ and 7.100″ — one is spec’d for the intake side and the other for the exhaust side. That 50-thou difference isn’t a mistake or a spare. It reflects the different geometry between where the intake rockers sit and where the exhaust rockers sit relative to the camshaft centreline. Get them crossed and you’ll be running off-geometry valvetrain on both sides, which bleeds power and wears parts faster than it should.
Check the kit documentation first
Shortest path to the answer: the spec sheet in the box. Crow Cams kits come with an instruction card or booklet that explicitly lists which length belongs on the intake and which on the exhaust. Check the packaging inserts, any folded paper in the cam bag, and the pushrod bags themselves — sometimes the side assignment is printed right on the label.
No paperwork? Ring Crow Cams directly. They have technical staff who field this question regularly and can confirm the assignment for your exact kit number in about two minutes.
Why the L67 needs two different lengths
The L67 supercharged 3800 Series II is a pushrod V6. The intake and exhaust rocker arms on any pushrod engine don’t sit at identical heights relative to the cam — the ports come off the head at different angles and depths, so the geometry on each side is slightly different. A performance cam like a Stage 3 profile can have a different base circle diameter compared to stock, which shifts those geometry requirements further away from OEM.
The pushrod length controls where in the rocker’s sweep arc the contact sits when the valve is on the seat. Correct length means the rocker tip tracks across the centre of the valve stem tip through its full travel. Wrong length means it walks off to one edge under lift — and that’s where wear and lost motion begin.
Crow Cams calculates both lengths to suit their specific cam profile against the stock L67 head geometry. The numbers aren’t interchangeable.
How to verify placement before final assembly
If the documentation is missing and you want to confirm rather than guess, use a pushrod length checking tool. This is an adjustable dummy pushrod — set it to approximate length, drop it in with the cam, lifter, and rocker assembled, torque the rocker to spec, then mark the valve stem tip with a felt-tip pen and hand-rotate the engine through one full cam cycle.
- A centred wear track on the tip: the length is right
- A track that drifts toward the edge: the pushrod is too long or too short for that position
Check one intake position and one exhaust position. The pattern will show immediately whether the assignment is correct. This takes maybe 20 minutes per side and saves hours of teardown later.
What running swapped pushrods actually does
At idle and low rpm the effect is subtle. At the higher lift of a Stage 3 cam it becomes real. The rocker tip begins dragging across the edge of the valve stem rather than rolling through the centre. Short-term: you lose some of the cam’s intended lift and duration at the valve. Longer term: accelerated wear on the rocker tip and valve stem end, and in a worst case the rocker starts riding off the tip entirely under peak lift.
It won’t grenade the engine on startup. But it will quietly cost you the performance you installed the cam to gain, and you’ll be pulling it apart sooner than you planned.
A quick mock-up check anyone can do
Before final assembly, set the engine to base circle on one intake lobe. Drop in the pushrod candidate for that side, torque the rocker, and confirm correct lash (or zero lash on a hydraulic setup). Rotate through the full lift event and watch the rocker sweep. It should travel cleanly across the stem tip without riding off either edge. Repeat on one exhaust lobe with the other pushrod length. Two minutes per check, and you’ll know before anything is buttoned up.