EngineSpecs

Expanded Blueprint Specs:

The first thing you will notice is a whole lot more data than you get from the NHRA Tech Bulletins pages. That is why individual engines are shown rather than every available engine for the year-make.
The additional data that is not included on the NHRA Tech Bulletins pages is not authorized or approved by NHRA so do not assume that this has the same authority in those areas as the information on the official NHRA Technical Bulletins. The data from the NHRA web Technical Bulletins is included here and every effort is made to ensure that this data is the most up to date information published by NHRA.
An interesting tool is the link on the right side of the page to show all the cars that use the engine you have selected. You will find that information valuable in considering options for class placement for this engine.
You will find all the relavent information from NHRA for accepted replacement parts - pistons, rods, oil pans, etc. - is all located in this one page. You do not have to look anywhere else to find that information.

Engine Blueprint Specifications: 1971 Chrysler 425 HP 426 V8

CHRY-71 Issued: 3/10/1971 Last Revised: 8/6/2019 Revisions: 6-29-72, 4-2-76, 5-13-85, 1-9-93, 5-24-94, 3-16-95, 2-16-96, 7-1-96, 2-16-98, 5-13-03, 10-25-06 JS, 10-13-08 WR, 4/21/10 PC, 6/7/11 PC, 9/20/11 PC, 4/3/12 PC, 1/8/13 PC, 7/19/16 PC, 10/21/16 PC, 1/1/17 PC, 2/17/17 PC, 8/6/19 WR

Engine Family: Chrysler Corporation, Chry Hemi V-8 Late Advertised Comp Ratio: 11.10:1 Induction: 2-4 Bbl Engine Type: V8

Basic Specs:	Bore	Stroke	Main Journal Dia	Rod Journal Dia	Max Bore	Max Stroke	Max Displacement
	4.250"	3.750"	2.750"	2.375"	4.330"	3.765"	443.5 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
	805 g	1.965"	95 g	5/64, 5/64, 3/16	61 g	6.861"	6.886"	842 g	1803 g

Compression:	Deck Height	Head Gasket	Piston Type	Dome/Dish Vol	Dome/Dish Hgt	Comb Chamber Vol	Max Compression
	.536" AB	.018"	Dome	88.30 cc	0	167.7 cc	11.49:1

Valve Train:	Int Rocker Ratio	Exh Rocker Ratio	Intake Valve	Exhaust Valve	Lifter Type	Spring Type	Lifter Dia.
	1.57:1	1.52:1	2.250"	1.940"	Hyd	Outer w/damper	0.903"

Camshaft:	Intake Lift	Exhaust Lift
	.490"	.480"

Casting No.	Intake Volume	Exhaust Volume
2531110-M2	198.0cc	101.0cc	Aluminum replacement
2780559	189.0cc	107.0cc
2780559-M	189.0cc	107.0cc
2780559-M1	189.0cc	107.0cc
2780559-M2	189.0cc	107.0cc

Intake Manifolds:	Casting No.
	2780543	Aluminum Manifold has both 2780543 and 2780544 numbers.

Number	Manufacturer	Trans	Type	Primary Throttle	Secondary Throttle	Primary Venturi	Secondary Venturi
1404	Edelbrock	ALL	4-Bbl	1.437"	1.686"	1.201"	1.578"	Replacement for OEM Carter AFB 1962-68. NOTE: Venturi specs include .005" maximum allowable tolerance.
1405	Edelbrock	ALL	4-Bbl	1.437"	1.686"	1.201"	1.578"	Replacement for OEM Carter AFB 1962-68. NOTE: Venturi specs include .005" maximum allowable tolerance.
AFB-4969S	Carter	SM	4-Bbl	1.437"	1.686"	1.186"	1.563"	Rear
AFB-4970S	Carter	Auto	4-Bbl	1.437"	1.686"	1.186"	1.563"	Front
AFB-4971S	Carter	ALL	4-Bbl	1.437"	1.686"	1.186"	1.563"	Front

Power Factors:	Stock Man		Stock Auto		S/S Man		S/S Auto		GT Man		GT Auto		GTFwd Man		GTFwd Auto
Base Factors	430	7/10/07	430		455		455		450		450		450		450
w/Rep Heads: MoPar 2531110-M2	435	1/1/13	435	1/1/13	465	1/1/13	465	1/1/13	460	1/1/13	449	1/21/20	460	1/1/13	460	1/1/13
Exception: Challenger	430	7/10/07	449	3/20/18	455		455
w/Rep Heads:	435	1/1/13	424	1/1/20	459	1/1/19	453	1/1/20
Exception: Dodge					455		455
w/Rep Heads:					459	1/1/19	459	1/1/19
Exception: Valiant	430	7/10/07	449	3/20/18	455		455
w/Rep Heads:	435	1/1/13	424	1/1/20	459	1/1/19	453	1/1/20

Accepted Replacement Pistons for Stock Eliminator

   Effective 3/28/2023
Specs:     Comp Hgt-1.965"    Pin Dia-1.031"    Rings-5/64, 5/64, 3/16
Distance to Top Ring-0.355"    Piston Min Weight-805g

Manufacturer	Part Number

Arias

M661

CP Pistons

M9-CP

Diamond

ST HEMI 66-71

1599

Ross

68472

Accepted Replacement Connecting Rods for Stock or S/S

Effective 8/23/2023
Specs: C/C Length- 6.860" Min Weight- 842g Journal Dia- 2.375" Big End Dia- 2.500" Pin Dia- 1.032"

Manufacturer	Part Number	C/C Length	Wgt.	Pin Dia.

Carrillo

CR-426SS

6.879"

833g

0.991"

SUPER STOCK ONLY

Carrillo

CR-JCESS

6.880"

842g

SUPER STOCK ONLY

Carrillo

Hemi 426

6.858"

843g

1.030"

426 Hemi

Carrillo

HEMI-SS

6.859"

842g

0.927"

SUPER STOCK ONLY

Carrillo

MP-HEMI-SS

6.861"

842g

SUPER STOCK ONLY

Childs & Albert

300-426-07S

6.860"

905g

1.032"

426 Hemi

Crower

B93934

6.860"

880g

426 Hemi

Eagle

6860C

6.860"

890g

1.032"

426 Hemi

Manley

14077

6.865"

882g

1.032"

426 Hemi

Manley

14080

6.865"

891g

0.991"

426 Hemi

Manley

14177

6.865"

905g

1.032"

426 Hemi

Manley

14277

6.865"

842g

1.032"

426 Hemi

Manley

14280

6.860"

Molnar Technologies

DH6860YVB8-A

6.867"

863g

1.029"

MoPar Hemi

Oliver

M6860BB8

6.860"

Note the calculations for actual displacement the maximum actual compression ratio.

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