389 Block

Pontiac V8 389 Block

Between The Sizes — 389 Block for Pontiac V8s

389 Block rings sit between the 350 and the 400 in bore size, which is exactly why they get ordered wrong. A 389 lands in the 4.090" to 4.123" range once it is honed, so a 400 ring set will be too big and a 350 set far too small.

Butler stocks Sealed Power moly-faced replacement sets at .030" and .060" over for a stock 389 rebuild, plus Total Seal Classic Race file fit sets covering 4.090" through 4.123" bores for performance and stroker builds.

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Sealed Power - Sealed Power Ring Set, Pontiac 389, .030" Over (4.093") SPR-E253K-030
Rings - 389 Block - Sealed Power - Sealed Power Ring Set, Pontiac 389, .030" Over (4.093") SPR-E253K-030
Sealed Power Ring Set, Pontiac 389, .030" Over (4.093") SPR-E253K-030
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Description: Sealed Power (Speed-Pro) engine ring set for Pontiac 389 — .030" Over (4.093" bore). Cast moly-faced ring pack: 5/64" top, 5/64" second, 3/16" oil. Complete set for one V8.
Item #: SPR-E253K-030
Condition: New
Price: $167.98

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Sealed Power - Sealed Power Ring Set, Pontiac 389, .060" Over (4.123") SPR-E253K-060
Rings - 389 Block - Sealed Power - Sealed Power Ring Set, Pontiac 389, .060" Over (4.123") SPR-E253K-060
Sealed Power Ring Set, Pontiac 389, .060" Over (4.123") SPR-E253K-060
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Description: Sealed Power (Speed-Pro) engine ring set for Pontiac 389 — .060" Over (4.123" bore). Cast moly-faced ring pack: 5/64" top, 5/64" second, 3/16" oil. Complete set for one V8.
Item #: SPR-E253K-060
Condition: New
Price: $139.95

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Total Seal - Total Seal Ring Set, Classic Race, 4.090-4093" Bore, (4.095" Ring) File Fit TSR-CR3690-95
Rings - 389 Block - Total Seal - Total Seal Ring Set, Classic Race, 4.090-4093" Bore, (4.095" Ring) File Fit TSR-CR3690-95
Total Seal Ring Set, Classic Race, 4.090-4093" Bore, (4.095" Ring) File Fit TSR-CR3690-95
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Description: 4.095 1/16 1/16 3/16 TS Classic Race Rings- File Fit (Set)
Item #: TSR-CR3690-95
Condition: New
Price: $164.63

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Total Seal - Total Seal Ring Set, Classic Race, 4.100" Bore, (4.105" Ring) File Fit TSR-CR3690-105
Rings - 389 Block - Total Seal - Total Seal Ring Set, Classic Race, 4.100" Bore, (4.105" Ring) File Fit TSR-CR3690-105
Total Seal Ring Set, Classic Race, 4.100" Bore, (4.105" Ring) File Fit TSR-CR3690-105
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Description: 4.105 1/16 1/16 3/16 TS Classic Race Rings- File Fit (Set) Commonly used in 4.100" bore. Must file to fit
Item #: TSR-CR3690-105
Condition: New
Price: $164.53

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Total Seal - Total Seal Ring Set, Classic Race, 4.120-4.123" Bore, (4.125" Ring Size), (4.120" Oil Ring) TSR-CR-1008-5
Rings - 389 Block - Total Seal - Total Seal Ring Set, Classic Race, 4.120-4.123" Bore, (4.125" Ring Size), (4.120" Oil Ring) TSR-CR-1008-5
Total Seal Ring Set, Classic Race, 4.120-4.123" Bore, (4.125" Ring Size), (4.120" Oil Ring) TSR-CR-1008-5
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Description: 4.120 +5 1/16 1/16 3/16 TS Classic Race Rings- File Fit (Set)
Item #: TSR-CR1008-5
Condition: New
Price: $179.96

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Items 1-5 of 5

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More About 389 Block

1. Know the finished bore before you order

The 389 is the one Pontiac bore where guessing costs you a set of rings. Measure, then order.

.030" over, 4.093"Sealed Power Speed-Pro replacement set, 5/64" top, 5/64" second, 3/16" oil, moly-faced top ring.
.060" over, 4.123"The same Sealed Power pack at the larger overbore.
4.090" to 4.093"Total Seal Classic Race file fit supplied as a 4.095" ring, 1/16, 1/16, 3/16.
4.100"Total Seal Classic Race file fit supplied as a 4.105" ring. Butler notes this one is commonly used in a 4.100" bore and must be filed to fit.
4.120" to 4.123"Total Seal Classic Race supplied as a 4.125" ring with a 4.120" oil ring.

2. Stock rebuild pack or race pack

5/64, 5/64, 3/16The Sealed Power replacement thickness. This is the pack a stock or cast replacement 389 piston is grooved for.
1/16, 1/16, 3/16The Total Seal Classic Race thickness, which is what a modern forged Pontiac piston is usually cut for. Thinner rings seal better and cost less drag.
Check the piston firstThe groove in the piston decides this, not the block. Have the piston part number in hand when you order rings.

3. File fit on a 389

Most of the 389 sets Butler stocks are file fit, meaning the ring arrives a few thousandths oversize and gets filed to the end gap the engine needs. That takes a ring filer, a feeler gauge and the patience to fit each ring to its own cylinder, but it is the only way to set the gap for a specific combination. A mild driver wants a tighter gap than a nitrous engine, and a file fit set lets you choose. If your bore or ring thickness is not shown, Butler will either have it in stock or can get it.

Not sure what your Pontiac needs?

Email our tech team at tech@butlerperformance.com. Tell us your engine, heads, car, and power goal, and we will put the parts together as one combination that works.