347 Windsor Stroker Cost — Rotating Assembly, Heads and Cam

TL;DR: Most 347 budgets get written as three separate numbers — rotating assembly, cylinder heads, camshaft — and that is exactly why they come up short. On a Windsor those three are not independent purchases: the piston decides which heads clear without flycutting, the block year decides whether a roller cam is one purchase or two, and the balance weight decides whether the damper and flexplate on the engine are usable or scrap. Buy them in the wrong order and you pay for at least one twice.

Why this page has no dollar figures

Crank, piston and cylinder head pricing moves with forging capacity, alloy cost and each manufacturer's MAP policy, so any dollar figure printed in a blog post is wrong within a quarter. Live pricing sits on the product pages. What does not move is the structure of the cost — which line items exist, which are optional, which hide inside the phrase "machine work," and which only appear after you have spent money elsewhere. Take this page to a shop as a checklist, not a quote.

What people mean by "347 kit" — three different things

The phrase covers three products nowhere near each other in price. Read the contents list before comparing any two.

A crankshaft only. A 3.400" stroke cast or forged crank on 302 journals. Least useful alone, because the longer stroke forces a matched piston compression height and usually a specific rod length.

A rotating assembly. Crank, rods, pistons, rings and bearings as a matched set, usually balanced as shipped. What most people mean, and what most of this guide addresses.

A short block. That assembly already installed in a bored, honed and decked block — the assembly plus the entire machine-work line, and the honest comparison point if you do not own a block yet.

Put rebuild kits and crankshafts side by side and the spread stops looking mysterious.

The displacement math, and the assumption inside it

A 347 is a 302 block with a 3.400" stroke crank and a 4.030" bore — that is, .030" over stock.

Displacement = 0.7854 × bore² × stroke × 8

The practical consequence: "347" already assumes your block cleans up at .030" over. A high-mile 5.0 with a ridge, a scored cylinder or prior machining may not, and a factory 302 has thin enough walls that .060" is the ceiling rather than a casual next step. Sonic-check before buying the crank, not after. If it will not clean up, the answer is a different core — 363 is no escape hatch, because 4.125" requires a thick-wall aftermarket block and a different budget entirely.

Kit manufacturers publish their own recommended bore for a given advertised displacement; confirm against the kit's spec sheet before ordering pistons.

The four decisions that set the total — in order

Work them in this sequence.

1. Which 302 block do you have?

The block year decides the camshaft type, and the camshaft type is a much larger line than most people expect.

• 1985 and later 5.0 HO blocks are factory hydraulic roller — lifter bosses machined for link-bar lifters, with the spider and dogbone provisions. A roller cam here is just a camshaft.
• Pre-1985 302 blocks are flat-tappet. A hydraulic roller camshaft means a retrofit kit — link-bar lifters, a retainer arrangement, dogbones, usually a matched timing set. That line appears nowhere in a rotating assembly quote, and it is the most common omission in a first 347 budget.

On a pre-1985 block with a tight budget, a good hydraulic flat-tappet grind is a legitimate answer rather than a compromise — if you accept the break-in discipline and run oil with adequate ZDDP.

2. What is the balance weight?

The 302 is externally balanced, and Ford used two weights: 28 oz-in through 1981, 50 oz-in from 1982. The counterweight lives in the harmonic damper and in the flexplate or flywheel, not in the crankshaft — and 347 assemblies are supplied all three ways, including internally balanced (neutral).

That matters in dollars because a neutral assembly makes the damper and flexplate on your engine unusable; both must be replaced. A 50 oz-in kit into a 5.0 that already has 50 oz-in parts costs nothing extra. Getting it wrong is not a performance compromise, it is a vibration that destroys the thrust bearing. Confirm the scheme before ordering a harmonic damper, and settle the flexplate or flywheel at the same time.

3. What are the piston's valve reliefs?

A 347 uses a short-compression-height piston, and the valve-relief depth machined into it decides your head options. Trick Flow's Twisted Wedge castings use a revised valve angle specifically to clear stock 5.0 pistons; AFR, Edelbrock Performer RPM and Dart Pro 1 heads generally assume the piston has adequate reliefs for their valve locations.

Order the heads first and you can end up paying a shop to flycut a new set of forged pistons, or reselling heads. Buy pistons first, get the valve-relief and clearance data, and choose the cylinder heads against it.

4. Flat tappet or roller — and therefore which distributor gear?

Cheap to get right, expensive to get wrong. A steel roller core takes a steel or specifically approved gear; a cast flat-tappet core takes iron or bronze. The wrong pairing destroys the gear within a few hundred miles and sends the debris through the oiling system on its way out. Buy the matching gear with the cam, not as an afterthought from the ignition components shelf six months later.

The line items, laid out

Lines 7, 8, 10, 12, 18 and 20 turn a "finished" budget into an unfinished engine. None is exotic, and all are decided by choices made in the first three.

Rotating assembly tiers, as a buy decision

Three tiers exist, and the honest way to choose is by rpm ceiling and power adder, not by aspiration.

Cast crank, hypereutectic or entry forged piston, I-beam rod. Correct for a naturally aspirated pump-gas street 347 under roughly 6,000 rpm — a large majority of 347s actually built.

Forged 4340 crank, H-beam rod, forged piston. Where the build belongs the moment nitrous, boost, a converter that lets it rev, or track use enters the picture.

Premium forged (non-twist forging, profiled counterweights). Buys dimensional consistency and abuse tolerance, not power. Choose it for a build revved past what the mid tier is rated for, or one you do not intend to open again.

One platform-specific caution: the factory 5.0 HO cast piston has a narrow top ring land known to crack above roughly 400 flywheel horsepower. A plan that runs boost on the stock short block "for now" has a piston line item in it whether you budgeted one or not. Choose pistons and rods against the real rpm and power target.

Heads: where the money actually buys power

On a 347 the displacement is already there. Airflow is the constraint, and heads are the largest single lever on the curve — larger than the camshaft, considerably larger than the intake. Two forks decide the line:

Bare or assembled. Assembled heads arrive with valves, springs, retainers and seals installed to a stated rate. Bare heads are cheaper and then need a valve job, the parts and the labor — which frequently lands within sight of the assembled price. Assembled is usually correct unless the spring package has to be cam-specific anyway.

Runner volume. A 165–185 cc intake runner suits a street 347 and keeps port velocity up. A 205 cc runner makes more peak power and less of everything below it. Displacement alone does not justify the bigger port.

Two Windsor traps, both of which cost money after the fact:

• Windsor heads do not fit a Cleveland block, and vice versa. Confirm on the fitment lookup before ordering.
• GT40P castings (the budget favorite off 1997–2001 Explorers) use a different spark plug angle and foul most long-tube headers — a header purchase hiding inside a cheap head purchase.

The camshaft, and the parts attached to it

A camshaft is never a single line. Selecting one commits you to at least three more:

• Valve springs rated for the cam's lift, with adequate installed height. Assembled heads supplied with a milder spring package turn that package into a replacement item — check the rate.
• Pushrod length, measured after the block is decked and the heads milled rather than carried over. A checking tool and one set of pushrods stand between correct rocker geometry and accelerated guide wear.
• A timing set. Replace the nylon-tooth cam gear on any Windsor you have apart past a hundred thousand miles — when those teeth shed they go into the pan and then the oil pickup. A true-roller timing set is cheap insurance and mandatory on a roller retrofit.

Match the camshaft to the head flow you actually bought and the converter and gear the car actually has. A grind sized for heads you are "going to get later" makes a car unpleasant now and no faster later.

Machine work, and the contingency line

Machine work covers bore and hone to 4.030" (ideally with a torque plate), deck, align hone, cam bearings, cleaning, and final balance. Ask which of those the quote includes — "machine work" as a single line is where budgets go to die. Two additions are specific to this build:

• Block clearancing. The 3.400" stroke can bring rod bolts close to the cam and pan rails. Ask whether it is quoted or billed on discovery.
• Balance validity. A kit is balanced as supplied. Substitute pistons, rings, rods or even rod bolts and the balance is void — the real cost of "upgrading one part" of a matched kit.

Budget roughly fifteen percent contingency against what the shop finds once the block is stripped. On a forty-year-old core that is arithmetic, not pessimism.

What to do next

1. Sonic-check the block before buying anything.
2. Establish the block year — it decides the cam type and the retrofit line.
3. Establish the balance weight, and price the damper and flexplate against it.
4. Buy pistons, then choose heads against the piston's valve reliefs.
5. Buy the cam, its springs, its distributor gear and a true-roller timing set together.
6. Get machine work quoted item by item.

Start from the Ford Windsor collection and work the list in that order.

Frequently asked questions

How much more does a 347 cost than a stock 302 rebuild? A rebuild reuses the factory crank and its existing balance; a stroker adds a balance job and often clearancing. The larger gap is that a 347 is almost never built with stock heads and a stock cam, so the real comparison is a rebuild versus a build.

Is 331 cheaper than 347? Marginally, and not by enough to decide on. The two cranks are close in price, the machine work is identical, and the same heads and cam suit both. Choose 331 for its rod-to-stroke ratio and longer piston skirt, not to save money.

Do I need a new harmonic balancer and flexplate for a 347? Only if the kit's balance scheme differs from what the engine has. A 50 oz-in kit into a 1982-or-later 5.0 with 50 oz-in parts needs neither. An internally balanced kit needs both, in neutral.

Can I use a hydraulic roller camshaft in a pre-1985 302? Yes, with a retrofit package — link-bar lifters, a retainer arrangement and a compatible timing set. It is a genuine line item rather than a bolt-in, and belongs in the budget from the start.

Will Twisted Wedge heads fit 347 pistons? The Twisted Wedge valve angle exists to clear pistons other heads will not, which is why it is a common 347 pairing. Clearance must still be measured at mock-up, because the piston, cam and head determine it together.

Does a 347 need forged pistons? Not universally. A naturally aspirated pump-gas 347 under roughly 6,000 rpm is served well by a quality hypereutectic piston. Boost, nitrous or a high shift point moves the requirement to forged.

Which distributor gear does a 347 need? The one the cam manufacturer specifies for that core material — iron or bronze for a cast flat-tappet core, steel or an approved equivalent for a steel roller core. A mismatch destroys the gear in a few hundred miles.

Figures here are general to the Ford Windsor small block. Confirm balance scheme, journal sizes, recommended overbore, valve-relief depth and distributor gear material against your kit's documentation before ordering, and verify fitment on the fitment lookup.

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    {"@type": "Question", "name": "Do I need a new harmonic balancer and flexplate for a 347 stroker?", "acceptedAnswer": {"@type": "Answer", "text": "Only if the kit's balance scheme differs from what the engine currently has. The Ford 302 is externally balanced at 28 oz-in through 1981 and 50 oz-in from 1982, and stroker kits are also supplied internally balanced. A neutral balance assembly requires both a neutral damper and a neutral flexplate or flywheel."}},
    {"@type": "Question", "name": "Can I use a hydraulic roller camshaft in a pre-1985 Ford 302?", "acceptedAnswer": {"@type": "Answer", "text": "Yes, with a retrofit package consisting of link-bar roller lifters, a retainer arrangement and a compatible timing set. Pre-1985 302 blocks are flat-tappet blocks, so this is an additional line item rather than a bolt-in change, and it should be in the budget from the start."}},
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    {"@type": "Question", "name": "Which distributor gear does a 347 Windsor need?", "acceptedAnswer": {"@type": "Answer", "text": "The gear specified by the camshaft manufacturer for that camshaft's core material: iron or bronze for a cast flat-tappet core, and steel or an approved equivalent for a steel roller core. A mismatched gear is destroyed within a few hundred miles and sends debris through the oiling system."}}
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    {"@type": "HowToStep", "position": 1, "name": "Sonic-check the 302 block", "text": "A 347 assumes a 4.030 inch bore, or .030 inch over. Measure cylinder wall thickness before buying a crankshaft, because a block that will not clean up at that overbore is not a 347 core."},
    {"@type": "HowToStep", "position": 2, "name": "Identify the block year", "text": "1985 and later 5.0 HO blocks are factory hydraulic roller. Pre-1985 302 blocks are flat-tappet and require a roller retrofit package to run a hydraulic roller camshaft. This decision sets a large and frequently omitted line item."},
    {"@type": "HowToStep", "position": 3, "name": "Establish the balance scheme", "text": "Determine whether the rotating assembly is supplied at 28 oz-in, 50 oz-in, or internally balanced, then price the harmonic damper and the flexplate or flywheel against it. A neutral balance assembly requires both parts in neutral balance."},
    {"@type": "HowToStep", "position": 4, "name": "Choose the pistons first", "text": "Select the piston tier by rpm ceiling and power adder, then obtain the manufacturer's valve-relief and valve-to-piston clearance data. The piston determines which cylinder heads will clear without flycutting."},
    {"@type": "HowToStep", "position": 5, "name": "Choose cylinder heads against the piston", "text": "Match runner volume to the intended rpm range rather than to displacement, and decide bare versus assembled by whether the spring package must be specific to your camshaft. Verify the heads are Windsor and not Cleveland."},
    {"@type": "HowToStep", "position": 6, "name": "Buy the camshaft with its attached parts", "text": "Order the camshaft together with valve springs rated for its lift, the correct distributor gear material for its core, and a true-roller timing set. Measure pushrod length after decking rather than carrying the old length over."},
    {"@type": "HowToStep", "position": 7, "name": "Get machine work quoted item by item", "text": "Ask which of bore and hone, deck, align hone, cam bearings, cleaning, block clearancing for the 3.400 inch stroke, and final balancing are included, and which are billed on discovery."},
    {"@type": "HowToStep", "position": 8, "name": "Add oiling, consumables and contingency", "text": "Oil pump, hardened oil pump driveshaft, pickup clearance check, gasket set sized for a 4.030 inch bore, head fasteners, assembly lube, break-in oil with adequate ZDDP for a flat-tappet camshaft, and roughly 15 percent contingency for machine shop findings."}
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