Engine Blueprint Specifications: 1971 Pontiac 250 HP 350 V8
PONT-71
Issued: 3/10/1971
Last Revised: 1/1/2024
Revisions: 7-25-81, 2-6-08 WR, 1/1/2024
Engine Family: General Motors, Pont V8 Late
Advertised Comp Ratio: 9.65:1
Induction: 1-2 Bbl
Engine Type: V8
Basic Specs: | Bore | Stroke | Main Journal Dia | Rod Journal Dia | Max Bore | Max Stroke | Max Displacement |
| 3.877" | 3.750" | 3.000" | 2.250" | 3.957" | 3.765" | 370.4 ci |
Piston-Rod Specs: | Piston Weight | Comp Height | Pin Weight | Rings | Rings Weight | Rod C/C | Max Rod C/C | Rod Weight | Min Assy Weight |
| 575 g | 1.690" | 90 g | 5/64, 5/64, 3/16 | 50 g | 6.625" | 6.650" | 760 g | 1475 g |
Compression: | Deck Height | Head Gasket | Piston Type | Dome/Dish Vol | Dome/Dish Hgt | Comb Chamber Vol | Max Compression |
| .000" | NA | Flat w/notches | -1.00 cc | 0 | 79.8 cc | 9.74:1 |
Valve Train: | Int Rocker Ratio | Exh Rocker Ratio | Intake Valve | Exhaust Valve | Lifter Type | Spring Type | Lifter Dia. |
| 1.50:1 | 1.50:1 | 1.963" | 1.663" | Hydraulic | Outer & inner | 0.842" |
Camshaft: | Intake Lift | Exhaust Lift | |
| .388" | .424" | |
Cylinder Heads: | Casting No. | | Intake Volume | Exhaust Volume | | |
| 94 | | | | |
Intake Manifolds: | Casting No. | |
| 481732 | Cast Iron |
Carburetors: | Number | Manufacturer | Trans | Type | Primary Throttle | Primary Venturi | |
| 2GC-7041062 | Rochester | Auto | 2-Bbl | .000" | .000" | |
| 2GC-7041171 | Rochester | SM | 2-Bbl | .000" | .000" | |
Power Factors: | Stock Man | | Stock Auto | | S/S Man | | S/S Auto | | GT Man | | GT Auto | | GTFwd Man | | GTFwd Auto | |
Base Factors | 250 | | 250 | | 250 | | 250 | | 250 | | 250 | | 250 | | 250 | |
Accepted Replacement Pistons for Stock Eliminator
Effective 1/9/2023
Specs:
Comp Hgt-1.690"
Pin Dia-0.980"
Rings-5/64, 5/64, 3/16
Distance to Top Ring-0.295"
Piston Min Weight-575g
Accepted Replacement Oil Pans for Stock Eliminator
Engine Group - Pont V8 Late
Effective 5/10/2022
Accepted Replacement Connecting Rods for Stock or S/S
Effective 8/23/2023
Specs:
C/C Length- 6.625"
Min Weight- 760g
Journal Dia- 2.249"
Big End Dia- 2.375"
Pin Dia- 0.980"
Manufacturer |
Part Number |
C/C Length |
Wgt. |
Pin Dia. |
|
|
Carrillo |
C427-76635S |
6.625" |
834g |
0.990" |
Pontiac |
|
Carrillo |
C427-A76635H |
6.625" |
787g |
0.990" |
Pontiac **Discontinued** |
|
Carrillo |
P-455-SS |
6.631" |
760g |
NA |
SUPER STOCK ONLY |
|
Childs & Albert |
389-12 |
6.625" |
NA |
0.947" |
Pontiac |
|
Crower |
F91059 |
6.625" |
NA |
0.981" |
Pontiac |
|
Crower |
ML93015B5 |
6.624" |
773g |
NA |
SUPER STOCK ONLY |
|
Crower |
SP93419 |
6.625" |
830g |
0.947" |
Pontiac |
|
Eagle |
CRS-6625P3D |
6.625" |
760g |
0.947" |
Pontiac |
|
Eagle |
CRS-6635P |
6.635" |
810g |
0.990" |
BB Chev |
|
Manley |
14168 |
6.635" |
830g |
0.990" |
BB Chev |
|
Oliver |
ORPPONT6625 |
6.625" |
NA |
0.981" |
Pontiac |
|
Oliver |
P6225PONT |
6.625" |
790g |
0.980" |
Pontiac |
|
Oliver |
P6625PONTFR8 |
6.625" |
819g |
0.980" |
Pontiac |
|