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Water Pumps
Pontiac V8 Water Pumps
Bolt Pattern First — Water Pumps for Pontiac V8s
On a Pontiac V8 the water pump does not bolt to the block. It bolts to the timing cover, and it seals against a divider plate and a pair of sleeves behind it. That makes the pump, the cover and the plate one system, and it is why the first question is never brand or finish — it is whether your cover is 8-bolt, 11-bolt or the early 4-bolt pattern.
Butler stocks 11-bolt 1969 1/2-79 4.5" pumps from Butler, Edelbrock Victor Series, Flowkooler, Milodon and PRW, the early-1969 short 4" hub pump with a cast OEM-style impeller, the 1955 to early 1963 4-bolt pump, and Meziere electric pumps.
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1. Which pump your engine takes
Pontiac changed the front of the engine twice, and the pump follows the timing cover, not the displacement. Identify the cover on the engine in front of you before you order anything.
| 4-bolt, 1955 to early 1963 | the earliest pattern. Butler carries a 4-bolt replacement pump with a cast OEM-style impeller for these engines. Gasket is sold separately. |
| 8-bolt, 1964-68 | used on 326, 350, 389, 400, 421 and 428 engines through 1968. Fan hub working height on the 8-bolt pump is shorter than the later pumps, so an 11-bolt pump will not put your pulleys in the right plane even if you force it on. |
| Early 1969 11-bolt, 4" hub | a transitional pump used on early production 1969 engines only. Butler still stocks a new one with the large-vane cast iron impeller like the original. |
| 11-bolt 1969 1/2-79, 4.5" hub | the common one. Fan hub working height 4-1/2", pilot shaft 5/8". This is what most 350, 400, 428 and 455 builds run today. |
Every Pontiac water pump turns clockwise looking at the front of the engine. There was never a counter-clockwise Pontiac pump. Cast and stamped impellers look different because of the blade dynamics, but both push coolant outward.
2. Stock rebuild or high volume
Two different jobs, two different pumps. Do not pay for flow you will not use, and do not put a stock stamped-impeller pump in front of a big-inch stroker.
| Stock replacement | the Dayco-built 11-bolt pump with a stamped impeller is recommended for OEM stock replacement only. It includes gaskets and puts a numbers-correct-looking engine back together without drama. |
| High-volume cast iron | the Flowkooler 11-bolt cast iron pump uses a 16-blade CNC aluminum impeller with an integrated shroud and a very tight impeller-to-backing-plate clearance. That raises system pressure and flow at low rpm, which is where a Pontiac in traffic actually gets hot. |
| High-volume aluminum | Butler's own high flow 11-bolt pump is CNC machined from 6061-T6 billet aluminum with a machined impeller, and works with factory alternator and power steering brackets as well as CVF racing brackets. PRW offers hi-volume aluminum in natural or polished, and Milodon's close-tolerance impeller is rated to increase coolant flow up to 30 percent. |
| Pump and plate together | the Edelbrock Victor Series 11-bolt pump for 389-455 with an 11-bolt front cover ships with the water pump plate and gaskets, measures 4-1/2" from block surface to hub, and uses a 5/8" pilot shaft. |
3. Electric pumps
An electric pump frees up the front of the engine, drops parasitic drag and lets you pull heat out of a hot engine after shutdown. Meziere units bolt directly in place of the stock pump on 1969 and later engines.
| Standard duty | 35 gallons per minute free flow, rated by Meziere for naturally aspirated (N/A) engines up to 650 horsepower. Meziere calls this the right choice for a bracket car. |
| Heavy duty | 42 gallons per minute and a motor rated for 3000-plus hours. Meziere specifies the HD pump for supercharged, turbocharged and high-compression, high-horsepower combinations, and recommends it for a car that sees real street use. |
| Install details | the complete Pontiac unit weighs 5.9 pounds, draws 6-7 amps in normal use, and ships with gaskets and stainless hardware. The standard pump measures 3.78" from the mounting surface to the tip; the heavy duty option adds another half inch. |
4. What has to go on with the pump
A pump is only as good as what it seals against. Butler sells the rest of the front of the engine so you are not chasing one part at a time.
| Divider plate | the plate behind the pump splits flow to both sides of the block. A worn, pitted or wrong-thickness plate kills the tight impeller clearance a high-volume pump depends on. Butler offers 69-79 divider plates in zinc coated and stainless. |
| Sleeves and o-rings | the two sleeves that carry coolant from the timing cover into the pump are a classic seep point. Butler stocks steel and stainless sets with new rubber o-rings, replacing GM 9796347. |
| Alignment help | water pump alignment studs hold the plate and pump in place while you start the bolts, then come back out and get replaced with bolts. |
If your cover is tired, or you are stepping from an 8-bolt front to the later 11-bolt setup, look at the conversion and replacement kits rather than buying a pump on its own. Not sure which cover is on your engine? Count the bolts around the pump and call us before you order.
Not sure what your Pontiac needs?
Call our tech team at 866-762-7527. Tell us your engine, heads, car, and power goal, and we will put the parts together as one combination that works.