Author Topic: 1973 Pontiac 400 Question  (Read 223 times)

0 Members and 2 Guests are viewing this topic.

Offline dany_boy_1972

  • Jr. Member
  • *
  • Posts: 8
  • Referrals: 0
1973 Pontiac 400 Question
« on: October 18, 2019, 08:02:26 AM »
Hello everyone , i have a 1980 Trans Am with the original 301.  The 301 still works and runs like a charm but i am wanting a bit more HP.  Having 2 kids :)  I don't have tones of money to throw into this motor so I purchased a 400 at a good price.  The motor came out of a 1973 Grand Prix and it's  the 230 HP motor, X5 block with the 4X heads.  The motor is being rebuilt as we speak.  It will stay motley stock minus an upgraded cam but i was wondering about the heads.  Should i keep an eye open for a set of Pontiac 6X heads?  If so what year should i be looking for? 

Thanks



Offline Aus78Formula

  • Adv. Member
  • ****
  • Posts: 2274
  • Referrals: 0
Re: 1973 Pontiac 400 Question
« Reply #1 on: October 18, 2019, 04:49:25 PM »
Why even mention the kids? No one has extra money, but some expect a sticker.

Offline b_hill_86

  • Sr. Member
  • ***
  • Posts: 671
  • Sterling to Starlight
  • Referrals: 0
Re: 1973 Pontiac 400 Question
« Reply #2 on: October 19, 2019, 09:09:45 AM »
6x4 heads from 75 thru 79 (came on Pontiac 350s and the W72 400s depending on the year) would have a slightly smaller combustion chamber thus slightly increasing your static compression ratio but your only talking like a 5cc difference. Honestly if that motor is already 230 horsepower stock your already 10 hp over a stock W72 400 and maybe ahead of the game.

I guess a lot depends on what you want out of it. I put a set of 6x4 heads on my 400 with an aftermarket cam. I had the heads milled to increase compression ratio along with port matching the intake runners. Between that, dipping, checking for cracks, and all the other labor I could’ve had some nice aluminum heads for a few hundred more.
-Brian-

1977 Trans Am 400 4 speed hardtop

Offline dany_boy_1972

  • Jr. Member
  • *
  • Posts: 8
  • Referrals: 0
Re: 1973 Pontiac 400 Question
« Reply #3 on: October 21, 2019, 09:15:12 AM »
Thanks for the info, appreciated