Topic: Which would be the best engine?

[jphillips3333]

400 - I'd read an article on a Pontiac site that went through some of the recent detroit iron blocks.  The Pontiac 400 was listed as best choice as I recall - I wouldn't change it.

[4SPEED]

stay true to you trans am. rebuild it

[kjkjkcjkcj]

How much power do yuo get out of your 455. what did you do to it.

[Mr. P-Body]

   Anything a 455 can do, a 400 can do "better".  Cubic inches are power, that's for sure. We've found the best combination of factory parts and a little "aftermarket" thrown in, would be the 461 "stroker", based on a 400 block. Eagel and others offer a complete "kit" to make the 400 a 461. These are tougher than 455s. They also mimic 455 for power production and efficiency.

   Consider that the "hole" (main tunnel) down the middle of the block is 1/4" smaller in diameter with 400. Also consider that the centerlines for the cam and crank, and deck height are all the same, 287 through 455.  Logic indicates, the smaller the hole, the thicker the bulkhead. There's an additional 1/8" of "meat" in the bock and another 18" in the caps.

FWIW

Jim

[BusDriver]

Get the 400 checked out by a Pontiac-familiar builder before you panic. Even a rod knock or some such doesn't mean the block isn't rebuildable.

461" stroker FTW.

[famguy]

Just curious, does it matter what year Pontiac 400 you have. I have a 400 in my Trans Am but it's not numbers matching, my motor was from a 76 A or B body. Also, what heads would you use with the stroker kit? How much?

[Mr. P-Body]

famguy,

   It is generally accepted, the 400 blocks from '70-mid'75 are the better ones. Last three digits of the casting are 998. The "557" is the weaker one of all. Unfortunately, if yours is from a '76 "big car", chances are it's the 557. Did it have a "whole" harmonic balancer on it, or just the center "hub"?

   The Eagle kit is, IMO, the best out there. It has been flogged and sorted, sorted and flogged. They live AND make power.  A couple of the Pontiac vendoprts have pieced together their own kits, and are usually pretty good.  As long as they use a 6.8" rod w/BBC rod journal and light-weight forgings for pistons, they'll do just fine. Using the standard dimension Pontiac rod is okay but not "optimum". Between the rod bearing and the rod/stroke ratio, the BBC 6.8 rod is the "hot lick".

   The 6X or 5C heads are just fine for the stroker. Installing the 1.77 exhaust valve and doing some judicious port work REALLY pays off.  An open plenum intake works best with these, too. For the T/A, we like Edelbrock Torker (1) or Holley Street Dominator, as either will fit under the shaker without modification.

Jim

[famguy]

Unfortunately it is a "557 = weaker" engine. What makes it weaker? It has 6X-8 heads. No harmonic balancer. I really like the idea of stroking the motor if its worth it rather than spending the big bucks on a Butler Performance engine but I really want it to be bullet proof. Suggestions? (Sorry if I'm hijacking the thread)

[Joker (§ir£Ğragon)]

Generally later model blocks were cast with less nickel content and had metal removed from areas that were deemed "less critical" making them weaker than the earlier blocks. This is true of engines by most manufacturers.

[Mr. P-Body]

famguy,

   The main bearing bulkheads are the area of concern. I've heard before, the alloy issue of less nickel as sirdragon says, but have no real evidence of that. We hear that about certain 350 Chevy blocks, too, and that has turned out to be an "urban myth".  This is not to dispute what he said, just to clarify. If anyone knows of a real "study" where the alloys were analyzed, I would be most interested in reading it.

   6X-8s are an excellent place to start for a 461 or 467 "stroker". If you keep power levels under 550 HP or so, your block shoould be fine.

   We like the Eagle kit the best.  Others will tell otherwise. Ask "Why?" Get clear and concise answers. If they say the Eagle isn't "good", run away!!!  If they say they market their own "kit", ask about the specific compononents. At least one Pontiac vendor out there will tell you his stuff is better because his pistons don't require a support rail for the oil ring. Ask why that's better, or more importantly, ask why a support rail is "bad". We've been using them in small block race engines for over 30 years, before "stroker" Pontiacs became popular. Never saw one "fail".

   In any case, if the vendor is at all vague or offering evasive answers, go elsewhere.  If the word "perfect" is used to describe certain parts, go elsewhere (nothing man-made is perfcect).
 
   There many good Pontiac shops out there, of which Butler Performance is one.

FWIW

Jim

[kjkjkcjkcj]

Hmmm interesting would you suggest if i went with a 461 stroker which is something i really wanna do should i go back to my 6x-8 heads. i have a set of those and a set of #62s. i would have thought the 62's with a dished piston would be the best setup. what do you guys think

[Mr. P-Body]

   Six of one, 1/2 dozen of the other.  That assumes you have the heads "done" by a competent Pontiac shop (or other competent shop that does actual research). 6X is a very good head, once it gets the large exhaust valve and some judicious porting. The 62 is, as well, but may need "hard" exhaust seats (not a "given"). The little bit longer "short turn" is the only REAL advantage, and that's minimal.

   The 6X-8 is ideal because it needs no "adjustments" to the chamber volume to make a good 9.2:1 on a 461 CID engine. The 6X-4 may need some chamber enlargement. They MUST be measured to be sure, no matter WHAT head you choose.

Jim

[kjkjkcjkcj]

Yeah what kind of power would i be talkin with the 6x-8 heads i have more compression right now without the stroker kit

[famguy]

Excellent information! Thanks Mr. P-Body. Question, what dangers are there with having the compression generated with the stroker kit and 6X-4 heads? I'm not complaining that I have the 6X-8 heads, I am just trying to get a better understanding on the dangers and how it all works. Thanks.

[dabatman99]

So was the idea that Pontiac built engines that were a compromise of both practicality and also performance potential?  They were building these engines at a period where emission controls forced manufacturers to derate their engines just to pass emissions.  So for a few bucks I can squeeze out alot of ponies without radical upgrades?  If this is so, that is great!  I'll be staying with Pontiac, because of the idea and ingenuity of engineers who were able to forsee what these engines could become.  Why don't we still engineer this way today?  Seems that the status quo is just good enough for manufacturers today.  Maybe that forsight of years past might be what GM and Chrysler needs today.