SFI Flexplates by Engine & Bolt Pattern

A flexplate is the automatic-transmission counterpart of a flywheel: the starter ring gear and the torque converter both bolt to it, and on an externally balanced engine it also carries part of the engine’s balance weight. Every plate on this page states SFI Spec 29.1 in its own listing - the rating sanctioning bodies ask for on a race flexplate. This page pulls together 24 in-stock SFI 29.1 flexplates from PRW, Allstar Performance, TCI Automotive, ATI Performance and Pioneer, from $55.49 to $375.95, sorted by engine family the way the choice is actually made: Chevy and GM (10 plates), Ford (7), Mopar (5), and Oldsmobile and Pontiac (2). Every tooth count, balance, seal and material figure below comes from that plate’s own listing. Every order over $200 ships free.

OUR SFI FLEXPLATE PICKS

Product	Spec (from the product listing)	Price	Why it is here
Flexplate CM Steel SFI Mopar SB/BB 6-Bolt	SFI 29.1, chromoly, internal balance, 6-bolt crank, Mopar small/big block (per listing); tooth count not stated	$55.49	The floor of this page and its only chromoly plate under $84: a 6-bolt Mopar plate whose listing names the crank pattern and the balance but never a tooth count - the first honest gap on this page, printed rather than filled in.
Flexplate 153T SFI Internal Balance	153 tooth, SFI 29.1, steel, internal balance, 2-piece seal, Small Block Chevy (per listing)	$65.99	The cheapest Chevy plate here: 153 teeth for the smaller-diameter starter position, steel, and the 2-piece rear main seal fitment the listing states. If your small-block is internally balanced and pre-1986 style, this is the pattern to match.
Chromoly Flexplate - SFI BBC 168T - Ext. Balance	168 tooth, SFI 29.1, chromoly, external balance, 2-piece seal, Big Block Chevy (per listing)	$95.14	The big-block hero: an externally balanced 168-tooth chromoly plate for a 454-style combination, where the balance weight is part of the plate and fitting an internal-balance plate instead would shake the engine. Balance is the spec that cannot be guessed.
LSA LSX Flexplate SFI 29.1 8 Bolt Crank	168 tooth, SFI 29.1, steel, internal balance, 1-piece seal, 8-bolt crank (per listing)	$120.17	The only plate here whose title names its crank bolt count: 8 bolts for the supercharged/LSX-style crank. Note the flag in the guide below - its own fitment line reads GM GenV LT-Series, so confirm the application against the maker’s guide before ordering.
SFI Flexplate GM LS1	168 tooth, SFI 29.1, steel, internal balance, GM LS-Series (per listing)	$375.95	The ceiling of the page: TCI’s LS1 plate at three times the PRW LS plate’s price, with the same headline specs stated in its listing - same tooth count, same rating, same balance. The page prints both and lets the maker’s name and your tech inspector make the call.

STEP ONE: THE CHEVY SHELF - 153 OR 168 TEETH, AND WHICH SEAL

Chevy plates split first by ring-gear teeth, because the tooth count sets the starter position: 153-tooth plates are the smaller diameter, 168-tooth the larger. At 153 teeth this page carries Allstar’s steel internal-balance plate for a 2-piece rear main seal ($65.99) and Pioneer’s steel internal-balance plate for a 1-piece seal ($76.99) - same teeth, same balance, different seal era, which is exactly why the seal line is printed on every row of this page. The external-balance Chevy plate here is Allstar’s 168-tooth plate listed for 1986-up with a 1-piece seal ($69.99) - the one-piece-seal small-blocks are externally balanced at the flexplate end, and this listing’s year note is the tell. At 168 teeth the internal-balance shelf runs PRW chromoly ($90.77), TCI steel ($137.95) and ATI steel ($253.02), all three stated 2-piece seal, and the big-block shelf is PRW’s chromoly external-balance plate ($95.14). Questions before you order? Call 213-549-4279 (Mon-Fri, 9am-5pm PT) and we will read the listing with you.

STEP TWO: LS AND LATE GM

Three LS plates, three price points, near-identical headline specs: PRW’s chromoly 168-tooth internal-balance plate for 1997-up LS, 1-piece seal ($103.18), PRW’s Pro Series 8-bolt-crank plate ($120.17) and TCI’s LS1 plate ($375.95), whose listing states no seal type. Two honest flags. First, the 8-bolt plate is titled LSA/LSX but its own fitment line reads GM GenV LT-Series - both are printed here because both are in its listing; match the part number (2036470, per the listing) against the maker’s application guide for your crank before ordering. Second, no LS listing on this page states a converter bolt pattern or a crank-to-converter spacing, and LS swaps into older transmissions are exactly where spacing bites - that dimension has to come from the maker’s guide for the specific plate, not from this page.

STEP THREE: FORD - 157 OR 164 TEETH, 28 OZ, 50 OZ, OR INTERNAL

Small-block Ford splits by teeth and by the external balance weight, and the weight changed with the model years: the 28 oz shelf is PRW’s chromoly 164-tooth plate ($91.70); the 50 oz shelf is PRW’s Sportsman plate titled for the 1982-95 302, also 164 teeth ($96.70); Allstar’s 164-tooth plate for the 289-351W states external balance but no ounce figure in its listing ($94.99), so none is claimed for it here - on a Windsor the ounce figure is not a detail, it is the balance. Internal-balance small-block Fords are covered by Allstar’s 157-tooth plate ($94.99) and PRW’s Pro Series 164-tooth plate ($128.69). The big Ford plate is the outlier on teeth: PRW’s 184-tooth FE plate, internal balance, 6-bolt per its listing ($106.16). The modern Ford entry is PRW’s Coyote plate for the 2011-17 5.0, 164 teeth, internal balance ($152.31) - its 2018-up sibling sits in the parent collection below, not on this page.

STEP FOUR: MOPAR, OLDS AND PONTIAC

Mopar opens the page on price: PRW’s chromoly internal-balance plate titled 6-bolt for small and big block ($55.49) and Allstar’s external-balance plate for the 383/400/440 ($57.99), with Allstar’s internal-balance SB/BB plate above them ($109.99). Read the honest note below before choosing among them: none of the three states a tooth count in its listing. The Gen III Hemi shelf does state one - PRW’s Pro Series plate is 131 tooth, internal balance, 1-piece seal ($147.89) - while ATI’s Hemi plate for the 5.7/6.1 states its balance and rating but no tooth count ($160.99). Oldsmobile and Pontiac close the page at 166 teeth each, both PRW chromoly with a cadmium finish per their listings: the Olds plate externally balanced ($105.33), the Pontiac 326-455 plate internally balanced ($105.63) - same teeth, opposite balance, one more reason the balance line is never skipped.

AN HONEST NOTE ON BOLT PATTERN

This page’s name promises sorting by engine and bolt pattern, so here is exactly what the listings support. Crank bolt count is stated for only three plates: the Mopar 6-bolt, the FE 6-bolt, and the LSA/LSX 8-bolt. Torque converter bolt pattern is stated in none of the 24 listings - not the bolt circle, not the converter bolt count - so this page prints none, for any plate. If your converter is a non-stock bolt pattern, get the pattern from the plate maker’s spec sheet for the exact part number before ordering; a flexplate that bolts to the crank and not to your converter is a return, not a build. Also deliberately not here: the wider range’s non-SFI plates, its flexplate bolt kits, dust covers and shields, starter/flexplate combo kits, and the Cummins and Ford diesel plates - they live in the parent collection below; this page is SFI 29.1 passenger-car and performance V8 plates only. And no listing here prints an SFI certification date or recertification interval, so none is claimed for any specific plate - read the SFI tag on the plate you receive for its date. For reference, SFI 29.1 certification runs three years from the date on that tag (per JEGS’ published SFI guide); whether a given plate can be recertified afterwards is its maker’s call, and no listing here states one way or the other.

QUESTIONS BUYERS ASK US

Flexplate or flywheel - which do I need? A flexplate is for an automatic: it is a thin steel plate carrying the starter ring gear, and the torque converter bolts to it. A flywheel is for a manual transmission and carries the clutch. They are not interchangeable, and every plate on this page is for an automatic.

Internal or external balance - how do I know which my engine is? It is a property of the engine’s rotating assembly, not a preference: some engines are balanced entirely inside the crankshaft (internal, neutral), others carry part of the balance weight on the flexplate (external - a Chevy 400 or 454, a 50 oz small-block Ford). Fitting the wrong type puts a vibration into the engine that no tuning removes. Every plate here is labelled with the balance its own listing states; if you do not know your engine’s type, find out from the engine builder or the crank maker before choosing.

153 or 168 teeth on a Chevy - does it matter? Yes: the tooth count is the ring gear’s diameter, and the starter mounts to match it. Count the teeth on the plate you are replacing, or match the starter you run - a 153-tooth starter position does not reach a 168-tooth ring gear. Both counts are on this page for the small-block, each labelled with its seal type.

What does SFI 29.1 actually certify? Spec 29.1 is SFI’s standard for flexplates - the plate’s construction and material are certified to it, and it is the spec drag racing tech inspection looks for; whether your class requires it, and at what ET, is in your sanctioning body’s rulebook - check that rather than taking this page’s word. Every plate on this page states SFI 29.1 in its own listing. The certification runs three years from the date on the SFI tag on the plate itself (per JEGS’ published SFI guide), and no listing here prints a date.

Can I reuse my old flexplate bolts? That is a fastener question this page does not answer from these listings - none of them covers bolt reuse or torque. Flexplate bolt kits for most of these engines are in the parent collection below; follow the engine or plate maker’s torque and reuse guidance for the bolts you run.

Shopping the wider range? Browse the full Flexplates and Components collection, read our guides on the News & Builds blog, or see the page that came before this one: Performance Carburetors by CFM.

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