Hitman's Pontiac Trans Am Forum
Trans Am Information => Trans Am Tech => DriveTrain => Topic started by: dabatman99 on March 30, 2009, 12:24:53 PM
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If you had a Pontiac 400 in your Trans am, what would be the next easiest engine to install? Olds 403? Chevy? Buick? I was told that as far as performance and cost, chevy would be the best choice. But then comes the questions about the shaker hood, exhaust manifold, motor mounts...etc... Just would like to hear some people's opinions and why!
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Well i guess my question is why would you want to put a different motor in it. the 403 will require new motor mounts as for the chevy prob some custom work, why would't you consider another 400 block or possibly a pontiac 455. less hassel. and keeps it original.
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Well finding good pontiacs are quite rare around here. Years ago, alot of these vehicles went to the scrapyards or got crushed. I was just curious what would be the next best replacement engine to get and why someone would choose it. Thanks for your help!
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Where is "rare around here?"
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Yeah check the parts for sale area. someone will have a good 400 block that way you can keep her original. ;) Or perhaps a 455. mmmmmmmmmmm delicious 455 ahhhhhhhhh
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"If you had a 400 Pontiac in your Trans AM..." why would you consider ANYTHING else? Hard to argue with a 400 Pontiac. GTO did NOT earn a reputation for losing, and the VAST majority had 400 in them. Not much difference between the GTO engine and yours. Nothing that can't be changed with a few nuts and bolts...
Who ever told you it's much cheaper to build a Chevy hasn't done it for a while, or their sights are set a bit low as far as power is concerned.
You already have the better engine. Build IT! And if you need more cubes to keep up (on the bench) with your Chevy buddies, stroke it to 461. Add Edelbrock heads and a Comp roller, and go out and run low 11s on them (93 octane, to boot!)! Can't make a 4,000 lb. Camaro do that without power adders or a 502-plus engine...
IMO
Jim
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THREE CHEERS FOR THE 400. HIP HIP HORRAY
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Where is "rare around here?"
Maine/New Brunswick border... I just gotta look in people's back yard and see what they got!
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Where is "rare around here?"
Maine/New Brunswick border... I just gotta look in people's back yard and see what they got!
LoL I hear that. Do you ever get down to the Mass. area? Lots of them down that way.
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I know a guy who has a 400 block in NH if you would like i can call him and see what he wants for it i think i remmeber him saying like 300. but if you want more info on it i can give him a call. what is wrong with your motor if you dont mind me asking.
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Motor has a knock in what seems the lower end. I have to take it out of the car to check the crank and rod bearings. Someone told me it might be a valve sticking and hitting the piston. I'm just preparing myself for the worse and trying to come up with a backup plan.
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Where is "rare around here?"
Maine/New Brunswick border... I just gotta look in people's back yard and see what they got!
LoL I hear that. Do you ever get down to the Mass. area? Lots of them down that way.
I wonder if they have a free advertiser or something online besides craig's list. In maine alot of people use Unclehenrys to find all kinds of stuff.
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well pm me if you need a 400 block because i can get you one. i wanna say its a mid 70s when i asked him. but im sure he still has it. he wasn't in desprate need of selling it.
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Motor has a knock in what seems the lower end. I have to take it out of the car to check the crank and rod bearings. Someone told me it might be a valve sticking and hitting the piston. I'm just preparing myself for the worse and trying to come up with a backup plan.
As Mr. Pbody says, if your going to pull that motor have THAT motor rebuilt. It fits perfectly in the car and it can run with the big boys.
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Another vote for sticking with the 400. Worst case, the easiest swap would be a Pontiac 455. You can use all your accessory brackets, accessories, motor mounts, and tranny (beef it up though if you're putting serious power to it). Not to mention your air cleaner and shaker can be reused as long as you stick with the factory intake or use an Edelbrock Performer (NOT the RPM) intake.
What I did was pull my numbers matching block, put it in the basement for safe keeping, and dropped a Pontiac 455 bored 60 over in between the fenders. I can flog the 455 if I want and should it break, I can still put the original numbers matching engine back in. It's only numbers matching once in its life.
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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.
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stay true to you trans am. rebuild it
(http://www.78ta.com/gallery2/main.php/d/14780-2/block+2.JPG) (http://www.78ta.com/gallery2/main.php/v/4speed/block+2.JPG.html)
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How much power do yuo get out of your 455. what did you do to it.
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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
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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.
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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?
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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
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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)
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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.
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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
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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
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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
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Yeah what kind of power would i be talkin with the 6x-8 heads i have more compression right now without the stroker kit
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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.
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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.
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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.
What happened is that Pontiac engines of this vintage were originally designed for much higher horsepower without consideration of emissions and (to a certain degree) fuel economy. The original Pontiac V8 design was done in 1954 (for the 55 model year), when gasoline was $0.19/gallon. Nobody had heard of "smog" (I'm not sure the word had been invented) and the idea that the government could tell you how you could tune your car was something that sounded like it came out of the Kremlin instead of Washington. As emissions controls came about, Pontiac responded by "detuning" their existing designs and thus retained as much power as they could. Finally the EPA ratcheted down the emissions requirements to the point that further detuning wasn't possible, so it was "ADIOS" to the Pontiac V8. They tried again with the 301 engine but never had the chance to develop it before the beancounters at GM decided to use a "corporate" V8 fleet-wide.
Today, it's a different world. Emissions requirements change at the whim of the EPA. The wizards in Washington decide how many MPGs cars will get (and now they're firing the CEOs of the car companies). Designers have no forward vision because you can't outguess insanity.
"And in the real world, they're shuttin' Detroit down..." - Big John Rich
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What Rick says about the Pontiac engines' demise is a sad, but true story. Pontiac probably stayed with the block because it saved money vs designing something new. They had to keep decreasing compression to meet emission standards ... until they were running 7.6 to 1 and had 180 HP motors in the late 70s. The block and head design was essentially the same from years back. 1978 was the last year of the 400 blocks. The 455 was finished in '76 ... and the 301 came out in '80/'81 but it never really got off the ground. Pontiac engineers didn't want to go this road ... this was the dreaded CAFE standards that spelled the end of the muscle car era. I'm sure there are some people to string up, I mean, thank for that effort.
You mention why don't we engineer with that way today? We engineer engines far better today than in the 60s/70s/80s - computer design, CFD, materials science, fuel injection and tooling have all gotten engines & technologies to be far more advanced. You can squeeze 100HP or more out of Corvette motor pretty easily ... and at 505HP out of the gate, they're not exactly slacker engines. The ZR1 is a 640 HP supercharged 6.2 liter engine ...top speed of 205 MPH.
That's a production car that could probably run the 24 hours of Daytona and actually hang with most cars with a tire swap.
I hope GM gets their crap together ... I really don't want to buy a Japanese import or a, gasp, Ford, down the road.