Engine Components- Internal
Pontiac V8 Engine Components- Internal
The Stack That Decides Everything — Engine Components- Internal for Pontiac V8s
Internal engine components are where a Pontiac build is decided. Crank stroke, rod length and piston compression height have to add up to the deck, the rod journal has to match the rods, and bearing clearance has to suit the RPM. Get the stack wrong and no amount of top end makes up for it.
Butler stocks cast, forged and billet crankshafts in 3.00" and 3.25" mains, I-beam and H-beam rods from 6.625" to 7.100", forged pistons from Ross, DSS, Icon and Keith Black, Total Seal rings, Clevite, King and Federal Mogul bearings, billet main caps, oil pumps and complete rebuilder kits by block.
Select a Sub-Category
Popular Brands:
-
ARP
-
Bryant Racing
-
Butler Performance
-
Callies Performance
-
Clevite Bearings
-
Crower
-
DSS Racing
-
Dura-Bond
-
Eagle Specialty
-
Federal Mogul
-
GRP
-
Icon
-
Keith Black
-
King Racing Bearings
-
Manley
-
Melling
-
Milodon
-
Molnar
-
Ohio Crankshafts
-
Oliver Racing
-
Pioneer Automotive
-
Pro-Gram Engineering Pontiac Parts
-
Ross Racing Pistons
-
Scat Crankshafts
-
Sealed Power
-
Silv-O-Lite
-
Titan Speed
-
Total Seal
More About Engine Components- Internal
1. Crankshafts: Main Size First, Then Stroke
A Pontiac crank has to match the block's main journal size before anything else matters. The 326, 350, 389 and 400 use 3.00" mains; the 421, 428 and 455 use 3.25".
| Rod journal | Factory Pontiac rod journals are 2.250". Most stroker cranks move to a 2.200" big block Chevy rod journal, which opens up rod and bearing selection but means your stock rods will not bolt on. Butler stocks both. |
| Cast | New cast steel cranks from Eagle and RPM in 3.750", 4.000", 4.210" and 4.250" strokes. Butler's position is that a new cast crank is an excellent, affordable upgrade over a thirty-plus-year-old factory crank for a street engine without a power adder. |
| Forged 4340 | Eagle, Scat, Molnar, Ohio and RPM in strokes from 3.750" up through 4.000", 4.210", 4.250", 4.350", 4.500" and 4.650". Butler calls it cheap insurance that leaves the door open to add power later. |
| Billet | Bryant, Crower, Moldex and Scat custom billet cranks where you specify stroke, mains and rod journals. |
| Reconditioned factory | Butler also offers turned and blueprinted factory cranks, 3.750" for the 326-400 and 4.000" for the 421-455, plus crank balancing service. |
2. Rods: Length Comes From the Stroke
Butler organizes rods by length because that is the number that has to work with the stroke and the piston compression height.
| 6.625" stock length | Pontiac 2.250" rod journal, for stock stroke rebuilds and mild strokers. |
| 6.700" | The common pairing for a 4.000" stroke. |
| 6.800" and 7.100" | Stroker lengths on the 2.200" big block Chevy rod journal, where the long rod assemblies live. |
| I-beam or H-beam | Eagle FSI I-beams are for pump gas street engines with no power adder. H-beams from Eagle, Scat, Callies Compstar and Crower are the choice for boost, nitrous and high RPM. |
| Bolts matter more than the beam | ARP 8740 is rated at 190,000 psi and ARP2000 at 220,000 psi, with L19 above that. Eagle rates its 4340 H-beams for competition use up to 1500 hp with L19 bolts. |
| Billet aluminum | Available for the race side of the catalog. |
3. Pistons and Rings
Pistons are where compression ratio actually gets set, and where lead time bites people.
| Forged | Butler's exclusive true-Pontiac strut-style Ross forging is the house piston, described as some of the lightest and strongest available and nitrous safe. DSS 2618 alloy FX series, Icon and Keith Black round out the shelf, by block from 326 through 455 and aftermarket. |
| Flat top or dish | Tell Butler the chamber volume and the compression ratio you want and their techs work with Ross to design the dish to hit it. Custom dish pistons run a 10 to 12 week lead time, so order early. |
| Bore | Butler starts bore options at .030" over so the block cleans up and the rings seat within spec. Have the pistons in hand when the cylinders are honed so piston-to-wall clearance is set off the actual parts. |
| Rings | Total Seal is standard on Butler assemblies. Classic Race plasma-moly is the baseline, AP Advanced Stainless gives longer life and tighter tolerance, and Gapless Top seals cylinder pressure between the top and second rings. Ring sets are offered drop-in and file fit by bore. |
| Clearance warning | On several stroker piston combinations, stock cast rods may need to be narrowed and the balance pad removed to clear the inside of the pistons. |
4. Bearings: Series and Clearance
Bearings are not a commodity on a performance build. The series and the clearance are the spec.
| Clevite series | H series is the place to start when unsure, with medium eccentricity, high crush, enlarged chamfers for crank fillet clearance and no flash plating, aimed at mid to high RPM. P series is fully grooved with the greatest eccentricity for very high RPM where rod bore close-in is severe. V series carries over the former Vandervell parts at low to medium eccentricity. |
| King | The HP series was developed for drag race use with a structure harder than a Babbitt overlay, and also suits street and strip engines on nodular cast iron cranks. The AM series holds tolerance to plus or minus .0001. |
| Federal Mogul | Tri-metal half-groove mains and the Competition Series Super Duty alloy H-14 three-quarter groove sets for the 350, 389 and 400. |
| Extra clearance | Several sets are offered in .001" extra or .001" less clearance, plus the usual .010" through .040" undersizes for a turned crank. |
| Cam bearings | Standard and coated Pontiac sets from DuraBond, Clevite and Federal Mogul, a +.010" oversize OD set for blocks machined to accept it, and 50mm and 55mm roller cam bearings for aftermarket blocks. |
5. Rebuilder Kits and Rotating Assemblies
Butler groups its kits by block, 326 through 455, so the parts arrive already matched to each other.
| Balanced assemblies | Crank, forged pistons, rods, Total Seal rings, Federal Mogul or Clevite bearings, pin fitted and internally balanced in Butler's shop. You choose bore, compression ratio, ring type and rod style. |
| Build your own | The same matched parts supplied unbalanced for you or your machinist to assemble, with balancing available separately. |
| Read the block note | Butler does not recommend its longer stroke assemblies for blocks with casting numbers ending in 557. Those should be limited to a 4.000" stroke and under 500 hp because of thinner main webbing. That single line has saved a lot of blocks. |
6. Main Caps and What They Cost You in Machine Work
Billet and ductile iron caps eliminate main cap walk and reduce main bearing bore distortion, but they are never a bolt-in.
| Line boring is mandatory | All aftermarket billet main caps require line boring, and the thrust surface has to be machined to match your particular block. Plan the machine work into the budget before you buy caps. |
| Butler billet | Front and center steel caps machined in Butler's own CNC shop for both the 350-389-400 and the 421-428-455, with dowel pins and notches on each end for removal. |
| Splayed outer bolts | Milodon ductile iron and Pro-Gram billet caps with splayed outer bolts add strength, and several of those may require an oil pan that accepts an external dipstick because the stock tube needs extensive modification. |
| Studs | ARP main studs are the recommended fastener, with a splayed outer stud kit available separately. |
7. Oil Pumps, Driveshafts and Windage
The last thing assembled and the first thing that kills an engine.
| Butler Pro pumps | Offered in 60-70 psi and 80 psi versions, both remachined and blueprinted with anti-gall dimples in both gears, a diamond lapped .250" plate, micro polished shaft, honed idler gear, blueprinted bypass ball and spring, a copper gasket and a flow chart. Because the Pro plate is thicker, a pickup with a mounting tab may need the tab bent up and the hole elongated. |
| Pickup clearance | Butler recommends 1/8" to 1/4" between the oil pan and the pickup, and says to check it with every pump and pickup regardless of pan. |
| Prep before install | Open, clean and inspect a new pump, then prime it with assembly lube or clean oil. Do not pack it with heavy chassis grease, which can clog passages. |
| Driveshafts | Hardened shafts in standard length for factory blocks and a 1/8" longer shaft for IAII aftermarket blocks. Shafts without retaining tangs install through the distributor hole. |
| Windage | Windage trays and crank scrapers to keep oil off the rotating assembly. |
If you are piecing a bottom end together, call with the block casting, the bore you expect after cleanup, the stroke you want and the chamber volume of your heads. Butler will work the stack from the deck down so the crank, rods, pistons and gasket all land on the same compression ratio.
Oil Pumps & Accessories Bearings Rods Pins Pistons Main Caps Rings Crankshafts
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.