Q&A

Mailbag: How to Get 400+HP from a Pontiac 400 Engine

pontiac 400 with edelbrock performer package

(Image/Street Tech Magazine)

You’ve got questions, we’ve got answers. We work with the Summit Racing tech department to help you tackle your auto-related conundrums. In this week’s Mailbag, we’re recommending a parts combo to get 400+ horsepower from a Pontiac 400 engine in a 1968 Firebird.

Q: I want to build a Pontiac 400 engine for my 1968 Firebird. What parts would I need to build a sweet-running engine that makes around 400 horsepower? (Money is no issue!)

A: We think the Edelbrock Performer RPM package would be ideal for you. Here are the parts you’ll need:

The Edelbrock cylinder heads have Ram Air exhaust IV ports—so you should use this set of Hedman headers. Keep your compression ratio at about 9.5:1.

According to Edelbrock, this combo will yield 422 horsepower and 441 foot-pounds of torque on pump gas.

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12 Comments

  1. You mid-read the catalog!!! There’s no way the Performer cam will get anywhere near 400 hp. Barely mid 300’s is more likely.
    The Performer intake must be run with a 1” spacer to out perform a pre 1972 factory iron intake! The Performer RPM would be the recommendation.
    I realize the tech guys try to sell certain products but outside the heads and intake Edelbrock leaves a lot on the table with their generic cams and carburetors.

    Dyno proven 405-419 hp @5400 rpm 470 TQ @4100 rpm.
    400 9.50-9.70-1 Compression (Iron D-port heads)
    Crower #60916 Cam w/1.65 rockers
    Edelbrock RPM intake
    Holley 750 carb jetted 74/84
    This combo idles strong at 900 rpm and pulls 15# of vacuum. Shifts around 5500-5700
    Add in a set of Edelbrock heads your well over 405-419 hp and can pull 6000 rpm.

  2. Do you work for C & C?

  3. Here is what we did with a ’69 GTO 400 that was an original W/T package (350 hp, manual transmission)..thoughts??

    Original 400 block, +.030 bore
    Performer RPM intake
    Holley HP 750 cfm carb
    Lunati 10510704 cam shaft
    Lunati springs, locks retainers
    Comp Cams roller tip 1.52 rocker arms
    Original 48 heads reconditioned, milled .010, with Manley SS valves
    Speed Pro L2262F-30 pistons

  4. Also allow the height of the performer rpm vs the performer manifold. The original performer is at OEM height of 6″ and the performer rpm is 7.4″ tall

  5. U can get a great set up from Butler performance dyno proven just saying lol upgrade rods and bolts 6500rpm 455 SD red line 7000

  6. Murray MacDonald says:

    Hi Murray is my name im in Australia just finishing up a 400 .4.185 bore 4.210 stroke OHIO FORGED CRANK. SRP FORGED FLAT TOPS (5CC VALVE RELIEFS)SCAT H BEAM FORGED RODS ARP2000 BOLTS JEFF KAUFFMAN BALANCED AND SUPPLIED ROTATING ASSEMBLY EDLBROCK RPM PERFORMER HEADS AND INTAKE PORT MATCHED AND 310CFM RUNNERS HOWARD HYDRAULIC ROLLER CAM 550/575 LIFT 110 LSA JOHNSON HYDRAULIC ROLLER LIFTERS
    SCORPION ENDURANCE SERIES ROLLER ROCKERS BEST OF EVERYTHING MSD PRO BILLET. 6AL DIGITAL .BLASTER COIL 9MM LEADS .1000HP ADJUSTABLE MECH FUEL PUMP 5/8FUEL LINE 850 HOLLEY DP HP ULTRA HP575/650TORQUE IN 69 FIREBIRD CONVERTIBLE

    • David Speechley says:

      Hi Murray may i ask who did your machining/engine build ? Hard to find a decent pontiac guy in Sydney Thx Dave

  7. i have a 68 firebird 400, 5spd Doug Nash transmission. Engine needs a refresh. I need advice on building a stout 400+ hp engine & looking to get great torque numbers. What parts combo would you recommend.

  8. Wayne trump says:

    Put an edelbrock carb on that build maybe 250 hp. Put u an 850 #4781 850 prob 435 hp.but those edelbrock carbs do make GREAT door stops

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