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. Because this is not an authorized NHRA site and verified by NHRA, please double check the official NHRA data before persuing building a race engine using these specs.
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: 1968 Pontiac 340 HP 400 V8 Ram Air II

PONT-68 Issued: 7/1/1968 Last Revised: 1/1/2024 Revisions: 17 April 1995, 11 April 2000, 4/22/13 PC, 2/1/2021, 1/1/2024

Engine Family: General Motors, Pont V8 Late Advertised Comp Ratio: 10.75:1 Induction: 1-4 Bbl Engine Type: V8

Basic Specs:	Bore	Stroke	Main Journal Dia	Rod Journal Dia	Max Bore	Max Stroke	Max Displacement
	4.125"	3.750"	3.000"	2.250"	4.205"	3.765"	418.3 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
	551 g	1.695"	90 g	5/64, 5/64, 3/16	57 g	6.625"	6.650"	760 g	1458 g

Compression:	Deck Height	Head Gasket	Piston Type	Dome/Dish Vol	Dome/Dish Hgt	Comb Chamber Vol	Max Compression
	.000"	.042"	Flat w/notches	0 cc	0	65.0 cc	12.49:1

Valve Train:	Int Rocker Ratio	Exh Rocker Ratio	Intake Valve	Exhaust Valve	Lifter Type	Spring Type	Lifter Dia.
	1.50:1	1.50:1	2.113"	1.773"	Hydraulic	Outer & inner	0.842"

Camshaft:	Intake Lift	Exhaust Lift
	.491"	.486"

Cylinder Heads:	Casting No.		Intake Volume	Exhaust Volume
	96		165.0cc	162.0cc	Round exhaust ports. "R" cast over one end exh port, "A" over the other. "96" over center exhaust

Intake Manifolds:	Casting No.
	9790140	Cast Iron
	9794234	Cast Iron

Number	Manufacturer	Trans	Type	Primary Throttle	Secondary Throttle	Primary Venturi	Secondary Venturi
1901	Edelbrock	ALL	4-Bbl	1.375"	2.250"	1.108"	.000"	AV Secondary. Replacement for GM small venturi Quadrajets. NOTE: Venturi specs include .015" maximum allowable tolerance.
4MV-7028270	Rochester	Auto	4-Bbl	1.375"	2.250"	1.093"	.000"	Air valve secondary
4MV-7028273	Rochester	SM	4-Bbl	1.375"	2.250"	1.093"	.000"	Air valve secondary

Power Factors:	Stock Man		Stock Auto		S/S Man		S/S Auto		GT Man		GT Auto		GTFwd Man		GTFwd Auto
Base Factors	335	1/1/13	340	1/1/13	350	7/31/02	350	7/31/02	340	7/31/02	340	7/31/02	340	7/31/02	340	7/31/02

Accepted Replacement Pistons for Stock Eliminator

   Effective 1/9/2023
Specs:     Comp Hgt-1.695"    Pin Dia-0.980"    Rings-5/64, 5/64, 3/16
Distance to Top Ring-0.320"    Piston Min Weight-551g

Manufacturer	Part Number

Barton

67-79 Pontiac 400

CP Pistons

P1-CP

Diamond

80081

295647

30420

NAPA

1670

Ross

66045

Speed Pro

2227P

TRW

L2262

TRW

L2440

Venolia

400

Accepted Replacement Oil Pans for Stock Eliminator

Engine Group - Pont V8 Late Effective 9/4/2024

Manufacturer	Part Number

Milodon

30770

Moroso

20492

Accepted Replacement Blocks

Manufacturer	Part Number

K&M Performance

MR-1

All Pontiac

APSJB

Accepted Replacement Connecting Rods for Stock or S/S

Effective 12/3/2024
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

SUPER STOCK ONLY

Childs & Albert

389-12

6.625"

0.947"

Pontiac

Crower

F91059

6.625"

0.981"

Pontiac

Crower

ML93015B5

6.624"

773g

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"

0.981"

Pontiac

Oliver

P6225PONT

6.625"

790g

0.980"

Pontiac

Oliver

P6625PONTFR8

6.625"

819g

0.980"

Pontiac

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

Would you like to see a list of all the cars where this engine is used? Click here: