Best Cylinder Heads for a Windsor 347 or 363 Stroker (Buyer's Guide)
TL;DR: A 347 and a 363 are both 302-block Windsors with a 3.400" stroke — the difference is bore, 4.030" vs 4.125" — and that bore difference is what should drive your head choice, not the cubic-inch badge. For a street 347, a 165–185 cc intake runner with a 58–64 cc chamber is the honest answer; for a 363 that will see 6,500 rpm and above, 185–205 cc starts paying. The bigger trap is not runner volume at all: it is valve shrouding, piston-to-valve clearance, and the compression ratio you accidentally build when you bolt a small aluminum chamber onto a flat-top stroker. Pick the chamber first, do the compression math, then argue about CFM.
If you are cross-shopping AFR Renegade against Trick Flow Twisted Wedge against Dart Pro 1 and cannot work out why three heads with the same runner number make very different power on a stroker, this guide sorts the decision into the order it actually has to be made.
Why a stroker changes the head question
A stock 302 and a 347 share a block, a bore spacing, and a head bolt pattern. They do not share an airflow requirement.
More displacement moves the demand curve, not just its height. Airflow demand scales with displacement and rpm together. A 302 turning 6,000 rpm and a 363 turning 6,000 rpm are asking for meaningfully different mass flow through the same port. That is why a head that felt "big" and lazy on a 302 can be exactly right on a 363 — the extra cubes fill the runner and keep port velocity where it needs to be.
But a stroker also caps rpm. The 3.400" stroke in a 347 or 363 lives in a block designed around 3.000". Rod ratio drops, piston speed climbs, and most street strokers are built to live below roughly 6,500 rpm. Head shopping that assumes a 7,200 rpm shift point buys airflow you will never reach and gives away low-lift flow and velocity you use every day. Buy the head for the rpm the rotating assembly will actually survive.
Bore size gates valve size. This is the part most 363 buyers get right and most 347 buyers get wrong. The 347's 4.030" bore is only 0.030" over stock. Put a big-valve head on it and the cylinder wall stands right next to the valve, shrouding it — the head flows on the bench and does not flow in the engine. The 363's 4.125" bore unshrouds the same valve, and that is the real reason larger-runner, larger-valve heads reward a 363 and punish a 347.
Piston-to-valve clearance is not automatic. Aftermarket Windsor heads relocate and re-angle the valves. Combined with a stroker's higher piston position at TDC and any cam with real duration, the valve reliefs in your pistons become a fitment item, not a formality. Clay-check it. Confirm minimum piston-to-valve clearance against your piston and cam manufacturer's spec — the common rule-of-thumb figures are a starting point, not a universal one.
The fitment gates to clear before you shop by CFM
Every head in our small-block Ford Windsor parts hub is filtered against these. Clear them in order.
1. Windsor, not Cleveland. Windsor heads do not fit a Cleveland block and Cleveland heads do not fit a Windsor. The 351C shares almost nothing useful here. If a listing says "351" without a W or a C, stop and confirm the casting family.
2. 302 deck vs 351W deck. A 347 and a 363 are both built from a 302 block, so you want heads listed for the 302 / 5.0 family. 351W-listed heads are cut for the 351W's taller deck and different intake bolt angle. Some castings are sold in both configurations under near-identical names — match the block, not the brand.
3. Intake manifold compatibility. Change the head and you frequently change the manifold. Raised-port and "high port" castings need a matching intake; a stock or Performer-height manifold will not line up. Budget the intake manifold into the head decision rather than discovering it on assembly day.
4. Header and spark-plug clearance. The GT40P iron casting uses a different spark plug angle than every other Windsor head, and it is a genuine long-tube header clearance problem. If you are moving from GT40P heads to aluminum, your existing headers may not be the constraint — but if you are moving to GT40P, they very well may be.
5. Rocker arms, studs and guideplates. Most aftermarket aluminum Windsor heads ship with screw-in studs and are set up for 1.6-ratio roller rockers. Stock-style rail rockers and pedestal mounts do not carry over. Check whether your chosen casting expects guideplates and hardened pushrods.
6. Spring package versus your cam. A head sold "assembled" comes with a specific spring rated to a specific lift and seat pressure. A hydraulic roller grind near 0.600" lift will out-run a mild street spring. Confirm installed height and pressure against your grind before you buy — valve springs are cheap next to a dropped valve.
Runner volume: matching the port to the cubes
Runner volume is a proxy for port cross-section, and cross-section sets the rpm where the port stops being the restriction. The table below is the practical bracket most Windsor stroker builds land in.
| Intake runner | Typical valve size (per spec sheet) | Best on | Usable rpm band | What it does well | Where it hurts |
|---|---|---|---|---|---|
| 160–170 cc | 1.90 / 1.55–1.60" | Stock-stroke 302, mild 331 | 1,500–5,800 | Strong low-lift flow, excellent street velocity and throttle response | Signs off early on a 347; leaves real power on a 363 |
| 175–185 cc | 2.02 / 1.60" | 347 street/strip, mild 363 | 2,000–6,300 | The best all-round answer on a 347 — velocity retained, top end opened up | Slight low-end trade versus a 170 on a stock-stroke 302 |
| 190–205 cc | 2.02–2.08 / 1.60" | 363 with the cam and gear to use it | 2,500–6,800 | Real top-end capability on the larger bore | On a 4.030" bore the bigger valve shrouds; can go soft below 3,000 rpm |
| 215–225 cc | 2.08–2.10 / 1.60" | 408W / 427W on a 351W block | 3,000–7,200 | Race-tier flow | Wrong head for a 302-block stroker in nearly every street case |
Two rules that matter more than the numbers:
- Peak CFM is the least useful number on the box. A head that flows well at 0.200–0.400" lift makes a street stroker feel alive. Peak flow at 0.700" lift is irrelevant if your cam never gets there. Compare the low- and mid-lift columns on the flow sheet, and compare them at the same test depression.
- Exhaust-to-intake flow ratio drives cam choice. A head with a strong exhaust port — many modern Windsor castings are deliberately strong here — tolerates a single-pattern cam. A weak exhaust port wants a split-duration grind with more exhaust duration. Your head choice and your camshaft choice are one decision, made twice.
Chamber volume and the compression you did not mean to build
This is where 347 and 363 builds most often go wrong, because the stroker's flat-top or small-dish piston is already carrying a high static compression ratio before the head shows up.
A 58 cc chamber instead of a 64 cc chamber is roughly half a point of compression on a 347-class engine. That is the difference between a pump-gas street engine and one that needs race fuel or a lot of timing pulled out of it.
| Piston | Chamber (nominal) | Approx. static CR on a 347 | Fuel reality |
|---|---|---|---|
| Flat top, 4 valve reliefs | 58–60 cc | ~10.8–11.2:1 | Aluminum heads and careful tuning; iron heads say no |
| Flat top, 4 valve reliefs | 62–64 cc | ~10.2–10.6:1 | Comfortable 91–93 octane with aluminum heads |
| −5 cc dish | 58–60 cc | ~10.2–10.5:1 | Comfortable pump gas |
| −5 cc dish | 62–64 cc | ~9.7–10.0:1 | Conservative; good headroom for boost or nitrous later |
These are worked estimates using a typical compressed gasket thickness and a near-zero deck. Recompute with your own deck height, gasket bore and thickness, and measured chamber cc before ordering pistons or heads.
Three practical consequences:
- Aluminum buys you roughly a point of effective compression tolerance compared with iron, because it pulls heat out of the chamber faster. That is the real reason an aluminum head lets a stroker run more compression on the same fuel — not a horsepower-per-pound argument.
- Decide the chamber before the pistons ship. Changing chamber cc later means changing pistons or gasket thickness, and gasket thickness is a blunt instrument that also changes your quench.
- Quench still applies. Target a tight, flat quench pad. Getting the piston close to the head on the quench side is worth more detonation margin than any single component choice on this list. Choose the head gasket thickness as part of the compression calculation, not as an afterthought.
Brand by brand — what actually separates them
Our Windsor small-block head catalog currently carries six brands across the 302 and 351W families. Here is how they sort for a 347 or 363.
| Brand / family | Configurations we list | Reads best as | Notes for a stroker |
|---|---|---|---|
| AFR (Renegade / Competition) | 165, 185, 205 for 302; 185 for 351W | The flow-per-runner-cc benchmark | The 185 is the default 347 answer. The 205 belongs on a 363 with the cam and converter to use it. MAP-enforced brand. |
| Trick Flow (Twisted Wedge / High Port) | Twisted Wedge 170, 185, 205 for 302; High Port 192, 225 for 351W | Best clearance engineering | The twisted-valve arrangement unshrouds the valve on small bores — exactly the 4.030" 347 problem. Check header and rocker clearance; the geometry is different by design. |
| Dart (Pro 1) | 170, 195 for 302; 225 for 351W | Heavy-duty castings | Thick decks tolerate high clamp loads and repeated surfacing. The 195 slots neatly between the common 185 and 205 tiers. |
| Edelbrock (Performer RPM / Victor Jr) | Performer RPM #60259 and Victor Jr #77169 for 302; Performer RPM for 351W | Broad street torque | Performer RPM is a proven street pairing with a matching manifold family. Victor Jr is a competition port — wrong end of the range for most street strokers. |
| Ford Performance | Z304 aluminum, GT40 iron, GT40P iron for 302; Z351 and N351 for 351W | OE-engineered fitment | GT40 / GT40P are the budget iron path and carry the plug-angle caveat above. The Z-heads are the aluminum performance castings. |
| ProComp | 185, 205 for 302 | Entry price point | Budget castings vary more unit to unit. Plan on a valve job and a spring check before installation regardless of what the box says. |
Part numbers above are carried in our listings as cross-references — confirm the exact casting and configuration on the product page before ordering.
Browse the full range in cylinder heads, and if you have not committed to a short block yet, the rotating assemblies collection is where the 347-versus-363 decision actually gets made.
Picking, in one paragraph per build
Street 347, hydraulic roller, automatic, 3.55 gear. 185 cc intake runner, 58–64 cc chamber chosen to land near 10.5:1, assembled heads with a spring rated above your cam's lift. This is the combination that makes a 347 feel like the engine people describe.
347 street/strip, manual, 3.73 or steeper. Same 185 cc runner, tighter chamber, and a split-duration grind. Resist the 205 — the 4.030" bore will shroud the bigger valve and you will pay for flow you cannot use.
Street 363. 185 cc as the conservative pick, 195–205 cc as the enthusiast pick. The 4.125" bore is the whole reason the bigger head works here.
363 built for rpm. 205 cc, a stout spring package, head studs rather than bolts, and honest attention to piston-to-valve clearance. At this point the head is no longer the limiting part — the rotating assembly and the valvetrain are.
FAQ
Will 351W heads bolt onto a 347 built from a 302 block? Many will physically bolt on, but the intake side does not line up correctly because the 351W has a taller deck and a different intake bolt angle. Buy heads listed for the 302 / 5.0 family for any 302-block stroker.
Are 347 and 363 heads different? No — the same casting families serve both, because both use a 302 block. What differs is the right choice within those families: the 363's larger 4.125" bore unshrouds larger valves and supports a bigger runner, so it can use heads that would go soft on a 347.
Do I need aluminum heads, or will iron GT40s do? Iron GT40 or GT40P heads are a legitimate budget path and a large improvement over stock E7TE castings. What you give up is weight, chamber efficiency, and the roughly one point of extra compression tolerance aluminum buys you. On a stroker carrying real compression, aluminum is the safer choice.
How much power do heads add on a 347? There is no number that is honest without the rest of the combination. Heads are a system component: with a matched cam, manifold and exhaust they are transformative; bolted alone to an otherwise stock combination they under-deliver. Budget the head, the cam and the intake together.
Do I need new pushrods with aftermarket Windsor heads? Usually yes. Changed deck height, valve angle, rocker geometry, or a milled head all change the required pushrod length. Measure with an adjustable checking pushrod after the heads are torqued down — do not order by catalog length.
Can I reuse my stock rocker arms? Generally no. Most aftermarket aluminum Windsor heads use screw-in studs and expect full roller rockers, typically 1.6 ratio. Stock pedestal or rail rockers are not a carry-over item.
What spring pressure do I need? It is set by your cam, not your head. Match the seat and open pressure and the installed height to the grind's spec card, and confirm the head's spring pocket and retainer package can accommodate it before the heads ship.
Should I run head studs or head bolts? Bolts are adequate for a naturally aspirated pump-gas street stroker with stock-level cylinder pressure. Studs are the right call for high compression, nitrous, boost, or any engine you expect to disassemble again — they clamp more evenly and are re-usable.
Core Powertrain Parts Tech Team. Part numbers, flow figures and compression estimates are per manufacturer data — confirm on the product page before ordering.