engines

could anybody help me on somthing i have a 86 350 4 bolt chevy motor and a 72 400 pontiac and i want to know which one to go with for performance and horsepower :banghead:

Is the 400 a 4-bolt or 2-bolt main?


If the 400 is a 4-bolt main, then go for it. You'll get more overall power from a 400 mill if built right.

If the 400 isn't a 4-bolt. You can still use it, but the rule of thumb for motors around here is if you're producing more than 400hp or turning faster than 6000rpm. It's best to use a 4-bolt block.

But there are exceptions, the DZ302 was a 2-bolt and turned 7500-8000rpm stock. It's all in how well the motor is built.


In short, either motor will produce you great performance if you take the time to build it correctly.

Well first of all what kinda vehicle is this going in? A chevy 350 doesn't bolt up where a pontiac 400 was and vice-versa so whats up?

Anyway, the 400 will cost you $$ to build, but will produce massive torque and good HP figures. You would need to buy the Edelbrock heads($1700) to bump up the compression, or find good older castings with closed chamber heads. In 72 the compression on your engine is probably only like 8.2:1 if that. So you can either pay to have them milled and proted a good bit, or just go edelbrock. The edelbrock heads will come with decent ports, and smaller combustion chambers to up the compression.
The 350 will be dirt cheap to build. You can get 400 HP on a 2500 dollar budget. 300 will be with a 1800 dollar budget, thats including all machine work, so if you can do that yourself than it will be even cheaper. Jegs has plenty of options for heads. And if you got about 3500 to spend you can make a 383 stroker out of it and churn out about 50 more ft/lbs than a 350 ever could. But it all depends on what vehicle this is going in!

I agree. The vehicle it is going in will probably decide the choice. Otherwise, it is just cost vs. power.

well personally i would go for the 400 just to try something new, hehe. the 350 is ALWAYS an all around good engine and ive heard of ppl supercharging one and gettin the tires off the ground runnin under 10 sec. but u have to know what ur doin. now the 400 i havent heard too much about but i do know that the chevy 400, which shouldnt differ from pontiac but u never know, it is all GM, the chevy 400 is a special design that actually has "steam" holes in between the cylinders and u have to get special head for this or else the engine will overheat and this will cost u some extra $$$. but as everyone has been sayin, the 400 will turn better numbers for what u put on it. now for the 350 u can put a very nice set of heads for only 1000 that can up ur compression to 10.5:1 if u get special 10.5:1 pistons that are surprisingly cheap, i thinks its only 250 for 8 forged pistons, dont take my word for it. oh yeah these heads are called Dart Iron Eagles, the company who makes them is Dart. i would seriously look into this. Im not sure, but i think they make the same head for the 400. and yes everyone else is right in saying what car u will put it in will determine it. chevy puts their motor mounts towards the back of the engines and i think pontiac has them up front. good luck with this.


-GearHead

The chevy 400 and pontiac 400 are completely different.

ok thx, i was wondering about that...

-GearHead

The 400 Pontiac will be a better engine for street level performance. They make a LOT more low-end and mid-range power than any SBC. And contrary to what another has said earlier in this thread, they aren't expensive to build. On a dollar-to-horsepower basis, they're actually cheaper to build than the 350 until you get over 550 horse. And a pontiac 400 block does not need 4-bolt mains until it reaches in excess of 600 horse, and even then, it's questionable.
If it's Pontiac body, and you don't want to be "shunned" by the Pontiac family (it isn't just a crowd like the Chevy crowd), put the Pontiac V8 in it.
If you decide to go with the Pontiac, be certain you enlist the help (at least the advice) of a Pontiac builder. If you use the same approach to make power as a small block, it will be a dog AND blow up. Build it right and it will tear the tires off and live a long and happy life.
Those of you that believe building a Pontiac is "something different", well, you're not paying attention. In the last 5 or 10 years, there have been released a multitude of Pontiac performance parts. Unlike the Olds and Buick, Pontiac is not an "also ran" or "point prover". They are a serious performance engine with a long and proud history. The Chevy crowd hates us, and for good reason.
Lastly, Edelbrock heads are nice, but hardly necessary until you get over 600 horses. Compression for a street engine should stay under 9.5:1 to use 93 octane fuel. It's plenty easy to get a combination together with iron heads and flat tappets, to get there.

First of all, I actually like pontiac more than chevy. But if you think building a BB pontiac is cheaper than building a SBC you have marbles in your head!
Second of all, like I said before you either need good old casting heads with the closed chamber design or the edelbrocks to raise compression. 95% of pontiac heads have over 110 CC chambers which is going to yield you at best 8.5:1 compression. And if you can find domed pistons, the $$$ factor will give you a heart attack. Also domed pistons aren't good for a pump gas engine. So, the edelbrocks are the best choice because if you can find an older casting your going to pay $ for them plus the rebuild on the heads would be as expensive as building a whole SBC.
Where can you find pistons for a BB pontiac for $4 a piece? Well, thats how much I paid for the flattops on the SBC I have to get 9.2:1 static compression.
My buddy has a 77' T/A, with a 400 in. Slow as crap, but you have to remember the times. He's got a 71' 455 to drop in it, along with a rebuilt TH400 tranny with a shift kit. The 71' only has 8.2:1 compression, but's thats still better than 72-up 7.6:1 compression (excluding the super duty T/A 455). Even with the 8.2:1 compression, it's gonna make close to 400 HP, and 450 ft/lbs.
However, I have a 73 GMC 1 ton 2WD pickup. Just for fun, built up a 383 stroker with ported vortec heads, 2.02/1.60 valves, 10:1 compression, edelbrock air-gap intake, 750 carb, headers, comp cam, ETC. Even the race weight of 4800 pounds (with driver) didn't keep me from running 12's in the 1/4 mile with street tires. Now, I had my brother do the machine work cuz he works at a machine shop. But the parts only cost me 1500. That includes the whole rotating assembly and balancing too. I'm guessing it would cost around 3K to do all I did to it. Can you get 500 HP out of a pontiac on a 3K budget?

I agree with pwman. Pontiac engines are ancient, heavy designs! Why do you think GM quit making them? Can you make them run? Sure. Some people make old flat head Fords run, too!!

Oh, and Chevy switched to a 4-bolt block on the DZ302 by '69. I wonder why??

Actually, most Pontiac heads made between '71 and '79 have 92 or 98 CC chambers. Only the 455 heads had chambers around 110. One of the more popular tricks is to use the 350 heads (92 CC) on the 455, yielding 9.5:1.
The ONLY year Pontiac used the "closed chamber" with the "large valve" (2.11/1.77) was '67. '68 and newer have a much improved "open" chamber. '68-'70 400 heads are 72 CCs, and too small for "pump gas".
It's a piece of cake to get 400-plus horsepower from a 400 Pontiac. 455s are easier, yet. And yes, it can be done for less than $3K. pwman, you illustrate your lack of Pontiac knowledge when you use the acronym "BB" in the same sentence as "Pontiac". There are no big OR small blocks. There is just the Pontiac. There are, however, large journal (421-up) and small journal (400 and down) block. But in the "Pontiac World", they are not refered to as big or small.
The bare Pontiac 400 block weighs just at 38 lbs. more than the small block (350), and it weighs about 100 lbs. less than a big block. The intake port is the envy of all pushrod engine designs. The production of low-end torque is second to none, and the ports are still efficient enough in stock form to feed a 400 CID engine to 6,000. The exhaust ports leave much to be desired.
GM made the transition to the "corporate mentailty" throgh the mid to late '70s. The Pontiac was considered, but it was decided they were too costly to produce, compared to SBC. Pontiacs have several steps in machine work Chevy simply left out (by the way, we take those steps when we build Chevy race engines). The combustion chamber change in '68 eliminated the need for A.I. R. on any Pontiac until the ugly little 301 (which we, as Pontiac people, don't claim). Even through the early years of catalysts, Pontiacs were the best running cars from GM. In '79, the T/A with the 400 (not the 403 Olds) was the quickest/fastest car GM sold. That was the last year until this year, the fastest/quickest GM car wasn't a Corvette. This year, GM says the GTO is the fast GM car. Of course, it has a modern engine, so it's just for giggles I include it here.
Chevrolet switched to 4-bolt blocks when the large journal small block was intorduced. Due to enlarging the housing bore for the larger main journals, it was thought it would significantly strengthen the block, and it does. No good performance build for a large journal engine shold be without them. the 4-bolt rule for small blocks, though, doesn't apply to the Pontiac. Apples and oranges...

I refer to all pontiac engine's as BB, because the block itself is large. And I've stopped saying it due to the fact of people correcting me, even though I know there is no small block.
But anyway, I hope your 38 pounds is missing the ''1'' in front there. Because a small block chevy bare block weighs about 70 pounds. 38 pounds I can EASILY lift with 1 arm, heck I can lift 38 pounds with 2 fingers. It's a struggle to lift a SBC with one arm, but I can do it. And I am pretty strong, I work construction. I am 6' 1'' and 235 pounds, thats not a weak combination there.
So, why don't you make me up a list with prices on your 400 HP (I said 500 but whatever) engine combo for less than 3K. The machine work alone will be about $1500. And we must not forget, not everybody is capable of putting their own engine together. But just for the sake of argument lets say they can.

Also, a qoute from you-
''The production of low-end torque is second to none''
This I find funny since the Buick GSX stage 1 made the most torque at 510 ft/lbs. It's very apparent you are EXTREMELY biased toward pontiac to make this statement. Mopar was also famous for making extreme torque monsters as well.
So just calm down and stop thinking you are the Pontiac god or something.