Need advice, 71 gto 400

First of all I would like to thank you in advance, Im a bit of a noob.
I have been running a 71 gto 400 in my 69 firebird for a while now and its time for some more power. I have been reading that stroking a 400 with 96 heads is a good combo, but i am more concerned with a good healthy, long lasting motor than going power crazy. My goal is around 400-450 hp, that may be a lot though? Thats why im asking: Do # 96 heads have hardened valve seats? I welcome any advice, thank you again.  

Pontiac didn't use hardened valve seats in 71 .I think it started in 73 or 74 . your 71 400 had 300 hp and 8.2 cr from the factory . The heads are 96 cc heads . Your going to need more compression to get 400 - 450 hp .  

Welcome to the forum thesamuraijoe.
There are different approaches depending on what you are looking to achieve. Are you looking to race at the track or mainly have a strong street car?

You will find that most of the pros on this site lean more toward achieving a maximum amount of torque as opposed to high horsepower figures. The most powerful Pontiacs over the years did not depend on HP over about 375, it was all about getting the maximum amount of go to the rear wheels.

Pontiacs were not designed for really high RPM's, although, with enough cash and precision engineering you can achieve those hp ratings. Let us know what your main purpose is and between the brains here we'll help you out.  

Welcome to the tribe.,. 450 horse is possible and it may help you to read a thread
called, Dawna's 406/433 Build - A Tribute - Heaven Can Wait

Read more: http://forums.highperformancepontiac.com/70/8747136/the-general-discussion/dawnas-406-433-build-a-tribute-heaven-can-wait/index.html#ixzz1lZAhL0g3

 
When The Flag Drops,,,



The Bull Chit Stops,,,


P. Engineer, Engine Builder

My goal is street performance. I would also like to be able to upgrade the heads later on when get the itch and I have enough $ for aluminum.
I don't see myself at the track for at least a few years. I want to maximize the engine that i have and still be able to run pump gas. If I can put a longer stroke cam in the same block, with the same heads that would be great. Is boring over and stroking better? My main concern is stability, i don't want to go over the recommended cr. Would a roller cam be the way to go or could i get away with standard for a while. My budget is around 1500 for right now, but I'm not in a hurry, I would rather be patient and do it right than to screw something up.
I know 400 hp is a lot but just for comparison sake, and correct me if i am wrong but the longer the stroke the more torque. Would 350 hp 400 torque be more realistic?  

Thank you for the welcome words,  and Dawna's tribute was informative and touching.  

Welcome to the forum Joe,
+1 & +2. Your goal is possible but not with the stock configuration. Stroking your motor involves and affects several design characteristics such as cam timing and crank angles. Best advice I can give you is to do exhaustive research on how stroking a motor will affect other items such as cam selection and intake/exhaust selection. If you're going to be making your motor a "bigger" air user then look carefully at your heads intake/exhaust passages and decide for yourself if they would handle the extra demand for air movement. As far as cam selection, IMO 9.5:1 CR is where you can start thinking of more "radical" cams. 9:1 or less, I'd stay with a lower end cam, sometimes referred to as a torquer cam. Even at 8.2:1 CR, that 71 400 would respond well to the correct cam selection.  
Jim,

If all you have is $1,500 to spend on it right now ... seriously you might want to forget about changing crank or heads, and a roller cam won't fit in that budget either. Assuming you are going to "rebuild" the engine, that is. But I wouldn't do those mods to anything that isn't "fresh", its throwing away money. You don't have any wiggle room in your budget, so I suggest contacting your machinist to discuss what is feasible within your means.  

You need more compression maybe dome pistons if you don't want to change to heads .  

We need to know how fresh this engine is.
+1 Id

The 400 will out perform (in most cases) the stroker when using stock iron heads as the more cubes you have the more air flow you will need to feed those cubes and the larger cube engine will run out of air.
I would forget about stroking the 400 they will perform very well with out stroking and even better when there isn't enough air flow to feed the larger cube engine.  
Horsepower sells engines and torque wins races

I am at about $4000 for a mild build including all machine work and engine assembly with non roller cam. Balanced new pistons rods, iron heads, new rockers , pumps , larger pan, and price of the 400 and 13 heads.  There is some one on here selling used edelbrock heads for 1500, good deal, i have 1200 into iron heads!! Dont attempt tp take apart an engine and back together unless its a down and dirty junkyard motor for less than 3500 budget.  Good luck!  
Carlos
70 Lemans(GTO Clone),406,Solid Cam 218 single pattern, 105 LSA
Serious Hobbyist

The history of the engine is a mystery unfortunately. I bought it from a guy who didn't seem to know much about pontiac in general. A friend of his "rebuilt it", and he did not have any record of what had been done. From what he said it had been run 5 to 8 k since the work had been done.
I was under a false conclusion that it was manufactured with hardened seats.
Is there a way to tell if the seats have been replaced?
The only thing i did to it personally was replace the bearings, and it did appear to be a fresh "rebuild". So far you all have been very helpful, I am having a great time throwing questions out there. Would I gain enough compression with domed pistons to make it worth pulling the heads off? Im not looking for a lot, just a little bit. I just have the itch to turn some bolts.
Thank you again  

I would not loose sleep over if heads have hardened seats or not, in the 100 or so sets of heads i have worked on i never seen any effects of not having hardened seats.With low spring pressures on most engines with Hydraulic cams there is no need to worry.