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  #16 (permalink)  
Old 12-22-2006, 08:59 PM
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Quote:
Originally Posted by runn141
chevrolet has always been close to my heart same as the s10s, alot of people tell me im stupid about that, but i say fu<k em!
no one on this website though has said that
I think I already told you this but a guy in our club just got done with a 454 s/10 this summer. It was awesome when he opened the hood, got many questions and it sounded the look and backed up the sound with acceleration. Nutn wrong w/ the s/10. I have a Dakota w/318 5 speed and 3.90 gears on a short bed 2 wheel drive regular cab. I would like to blast the frame and get the truck and frame repainted. I am considering a 360 for it though. I am pretty open minded but get bored real quick.

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  #17 (permalink)  
Old 12-22-2006, 11:07 PM
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Quote:
Originally Posted by QuenchPiston
I think I already told you this but a guy in our club just got done with a 454 s/10 this summer. It was awesome when he opened the hood, got many questions and it sounded the look and backed up the sound with acceleration. Nutn wrong w/ the s/10. I have a Dakota w/318 5 speed and 3.90 gears on a short bed 2 wheel drive regular cab. I would like to blast the frame and get the truck and frame repainted. I am considering a 360 for it though. I am pretty open minded but get bored real quick.
they dont know what think when they get outrun by pickup truck
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  #18 (permalink)  
Old 12-22-2006, 11:10 PM
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Quote:
Originally Posted by Artemis Entreri
suggested I just use a pontiac 400. I figured cubes are cubes, pontiac 400s seem alot easier to come by, why dont more people do it?

So my question is a few fold, are there major differences between pontiac and chevy 400s, or engines in general?
How do pontiac engines compare to chevy engines? (Or is it a taste thing?)
And I assume they are, but are the mounting brackets very different in a pontiac and chevy motor?
Oh, and does anyone know off hand the bore/stroke of a pontiac 400?

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Bore and stroke on the Chevy 4.125" x 3.75" = 400.9
Bore and stroke on the Pontiace 4.121 x 3.75" = 400.1

Pontiacs are a bit heavier and bulkier than Chevys. Stock deck height on the SBC is 9.025" and the Pontiac is 10.24". Compare that with a BBC's height of 9.8" and you can see that its a big engine, more like the BBC tall truck block. The heads are a bit bigger as well meaning that its just physically a larger engine. Weights of a typical SBC compared to a Pontiac (both with aluminum intakes and iron exhaust) you can expect about 550 and 650 lbs, respectively.

The Pontiac block uses the same bellhousing pattern as Buick, Olds, and Cadillac. The Chevy pattern is Chevy-only, so just get a corresponding tranny to match up.

The Pontiac does use different engine mounts, but depending on the car and year, chances are its set up for either engine.

Basically consider everything different. Its possible that the starter, fuel pump, and other accessories are on different sides of the motor and will require modification of fuel lines, wiring harnesses, etc.

Its also often much more expensive to modify a Pontiac. You also don't have the wide selection of stock performance heads like you do with chevy, nor do you have the insane aftermarket selection. So, when you say cubes are cubes, that's true. Efficiently getting air in and out of those cubes might be harder and much more expensive in the Pontiac.

That answers why not many do it... The only real question is, if you're willing to pony up a bit more cash for the build and swap, is there any reason NOT to do it?
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  #19 (permalink)  
Old 12-23-2006, 12:39 AM
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you gotta pay attentioon to the finer details

one thing about pontiacs is that everythings interchangable.
326 heads will fit on a 455, so theres a large range we can go with..
another thing is that every cast iron head made by PMD had a machined combustion chamber. for uniform combustion.
sure pontiacs have been known to have weak rods.... thats where the wallet comes into play!
pontiacs are more expensive to build.. and the people that want it cheap ( most hotrodders) go chevy...
any performance part you want for a chevy, you can get for a pontiac, just be ready to shell out a few more clams and look around.

as far as a 350 mopping up a 400... mabe if the 350 was 060 over and @ 10:1 vs a stock bore 400 thats 7.6:1..
400's are great blocks and have potential of being extreme monsters, IF YOU DO YOUR HOMEWORK.

myself, i prefer the 389's
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Old 12-23-2006, 10:23 AM
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If your going to have any kind or unbiased and logical discussion of comparing a Pontiac 400 and a chevy 400 why don't we break them down to their basics. For arguments sake they have the same bore and stroke. Both use a ball stud rocker set up, both used pressed and threaded studs. Starter, oil filter and fuel pump are located on opposite sides between both engines however, electric fuel pumps eliminate one of the three differences. So far we have the same engine since you need a oil filter mount and starter mount regardless of which engine you chose. Wire will fix the starter differences and your lazy arm will cure the oil filter position, big deal.

They both use the same valve layout but as you know a sbchevy has the valves at a rumored undesirable 23 degrees, otherwise why do they have all sorts of heads for competition with valve angles near 15 degrees plus or minus about 3 degrees. A Edel. Performer RPM head bare costs $410 each bare from summit. To try to match the 14 degree valve angle of the stock Pontiac head you would purchase the Edel Chapman Victor 15 degree head at an additional $860 each bare. I wont even get into the additional costs of the valve train and intake and headers and pistons to match those heads but lets just say so far you are $1720, or a total cost of $2540 for bare heads, in the hole just to match the factory heads of the Pontiac. Bahhhhhhh but you say you have to do all kinds of port work to match those Chapman heads. Ok we will buy the Edel Performer RPM Pontiac heads assembled for $1740 ASSEMBLED/PAIR. Thats still an $800 difference in cost but you have no internals with the Chapman heads yet.

For $570 I can purchase a complete rebuild kit for the Pontiac 400 which leaves me with $230 left for a budget port job to the heads or I can buy a Performer, RPM or a Torker intake.

So far I have the Pontiac nearly done and just to keep things on a level playing ground the chevy 400 is still at the bare cylinder heads.

Oh yea, I forgot to mention. To make things equal we are going to purchase longer rods for the Chevy since the Pontiac has 6.625 inch long rods, (new ones cost $660 if you are really scared to run the stock ones which will do fine since you don't have to scream Pontiac engines) lets see the chevy rods will be, the longest ones available from Summit are the 6.25 inch long rods at a cool $600. Oh shucks, you have to buy custom pistons for the chevy which will cost you some more boocoo dollars. The Pontiac, well the replacement pistons from the rebuild kit will fit just fine.

Chances are the Guy with the Pontiac build will have his on the street and running and winning many races since the 15 degree headed 400 chevy probably will never see the street due to budget shortfalls.

Well so much for the chevy being a cheaper engine to build apples to apples.

As far as engine weights go, wow, a whopping 75lb difference between the two. Boy thats a lot of weight difference there. Ok so your really picky on engine weight, well you could just switch to an Oldsmobile 403 which is even closer to the same weight as a sbchevy. Oh did I mention that the Olds has a valve angle of 6 degrees? You cant even find a head for a gen 1 sbchevy at that valve angle unless you come close with the Dart Buick head for the sbchevy at 10 degrees and I see them used at around $3000.

But all this does not matter because the sbchevy is...........just better? I am still trying to decipher that for myself.
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  #21 (permalink)  
Old 12-23-2006, 11:13 AM
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Your argument is very in-depth, but several things don't really make much difference on the dyno. If you really want to compare apples to apples...

1) the longer rods (although helpful with side loads) have been shown to offer no power
2) regardless of the valve angle, the net flow past the valve into the cylinder is the key. Stock pontiac heads don't do that very well, and aftermarket pontiac heads do that about as well as chevy aftermarket heads. You don't have to compare angles, its all about how much air and fuel make it into the cylinder, and you can accomplish that without the expensive chevy 15 degree heads.
3) There is also a point at which too little valve angle is no good. In the case of the Olds (which have notoriously poorly-flowing heads) its too much of a sharp turn. Its not just about angles, its about how the ports are shaped. If the Olds head were big enough, you could smooth out the transition, but there is so much more than just valve angle involved.
4) And when its all said and done, the pontiac is still a much heavier rotating assembly with heavier pistons, rods, and crank, plus more journal diameter. Getting the same level of power will require more BTUs in the Poncho than the chevy, and the heavier rotator arguably will reduce acceleration.

While I agree with the things you mention, look at the bigger picture. A 400hp/400 pontiac will cost more on the average than a 400hp/400 chevy, and the extra weight (even though it is only about 100 lbs) can be a big difference concerning handling, acceleration, and braking.

And, please don't think I'm a chevy lover. I would much rather spend an extra $1000 on a build if it was anything BUT a chevy, but just comparing numbers to numbers, there is a reason why A) the aftermarket doesn't spend as much R&D on pontiacs B) people don't build as many pontiacs, C) parts cost more for pontiacs.... Its all a very mild difference, but just because pontiac heads have a valve angle that is considered "performance" on a chevy, doesn't mean that the pontiac heads are better. Apples to apples.

Last edited by curtis73; 12-23-2006 at 11:19 AM.
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  #22 (permalink)  
Old 12-23-2006, 11:49 AM
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We have built Pontiacs, Fords, Chevies, Olds, Buicks, Hondas, Mopars and others over the years. Most all have been on the dyno and the heads always on the flow bench. 14 degree valve angles have no bearing in this conversation and are meaningless. In fact, stock 14 degree Pontiac big block heads are TERRIBLE flowing heads and to claim that's something special makes their actual flow even more laughable. Even Stock Edelbrock heads are NOTHING to right home about. Almost any decent aftermarket 23 degree Chevy head is either going to equal a stock Pontiac head with the better CNC variations blowing away even the Edelbrock head, all 14 degrees of them. NOW, step up to a RR 23 or 21 degree or 13-18 degree Chevy small block head and your in a different ballpark compared to the typical Pontiac aftermarket head. Only the very best Pontiac big block aftermarket heads are going to be in the same range as what these upper level types of heads offer. I won't even get into what GM Performance is releasing now for the LS motors that makes every other cylinder head selling in the $1000 to $1200 range look like it belongs in the junk cabinet.

Rod ratios, not a concern. If a Chevy small block came stock with a 9.5 deck height then you'd need a longer rod. The rod connects the piston to the crank, that's all it does.
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Old 12-23-2006, 01:13 PM
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Yea your right about the dynos and flow benches and the other guy says its laughable when a Pontiac head is on the flow bench yada yada yada but the last I checked we don't race dynos and flow benches, at least I wasn't driving a flow bench when I beat a camaro in my Dakota. Ehhhhhh, scratching head.

But we race on the drag strip for instance and when you set records you can argue all you want but the record still stands.

SS/MA 10.89 121.42 10/08/06 Carroll Warling - Arvada, CO
'74 Pontiac Kearney, NE

D/SA 10.40 125.39 03/30/06 Scott Burton - Golden, CO
'71 Pont Firebird Tucson, AZ

H/SA 11.11 10/14/06 Tony Goodman - Zeeland, MI
'77 Firebird Indianapolis, IN

F/S 10.97 04/16/05 Adam Strang - Jericho, VT
'68 Pont GTO Mohnton, PA

J/SA 11.25 115.85 11/07/04 Bob Mulry - Gilroy, CA
'74 Pontiac Las Vegas, NV

SS/MA 121.74 04/02/05 Carroll Warling - Arvada, CO
'74 Pont Grand AM Tucson, AZ

I know its hard to accept but the sbchevy is no longer cream of the crop and it never has been. Fact is there is always going to be someone faster and they are in some cases do it with parts that are laughable. Yea a rod does not make more power etc but why do so many sbchevy fanatics in here ask for longer rods, why do they sell them. Must be some kind of sbchevy logic that I do not understand. Maybe they don't like their skirts collapsing, thrust faces wearing, pistons separating, I don't know. Like I said, must be some sbchevy logic and sbchevy money floating around here that I just don't understand or make.

Here is a quote of sbchevy logic here:
"?Really, the mainstay engine in circle track racing today is still the 18-degree small-block, which is a subtle variation of the original 23-degree engine,? Sperry explains. ?It?s a roll of the casting to stand the valves up and get the ports up in the air a little higher. The SB2 is a bigger departure from that, it does have some compound valve angles in it on the intake side and it does have a little more reach as far as rocker-arm geometry, but it is still fundamentally a small-block Chevy. Maybe you?re taking some of the big-block thinking and marrying it into the small-block design, but it?s still the same engine.?" (Ron Lemasters, Jr., The History of... The Little Engine That Could The Chevrolet Small-Block Is Still The Engine Of Choice In American Circle-Track Motorsports, http://64.233.161.104/search?q=cache...s&ct=clnk&cd=7, retrieved Dec, 2006)

I think I will squeeze a nut over that!

Pontiacs are inferior to the sbchevy, especially that 3 inch main that slows them way down. Must be that .350 diameter difference that sets these engines apart. Valve angles don't matter and only hinder performance when they are brought closer and closer to vertical on other engines besides the sbchevy, thats why the sb2.2 head has them so close to vertical, a head that resembles no sbc ever used in a gen 1 engine but had to have it to remain competitive. Hmmmmm must be more of that sbchevy logic. Funny how the 23 degree heads for NASCAR racing has Pontiac cast on them, must be more of that sbchevy logic.
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Old 12-23-2006, 01:26 PM
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Quench, you argue to argue.
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Old 12-23-2006, 01:27 PM
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Again, you can't compare a 23 degree chevy head to a pontiac 16 degree heads. You can't compare a 4-cylinder head to any other head.

Sometime take a cross-section of all these heads you're discussing. Take a look at how VASTLY different they are and you'll reallize how one valve angle that works on one head won't work on another. What is most important in valve angle is not its relation to the stroke, its the relation to the PORT. That is one reason why raised runners make power, and the low ports on an Olds make terrible flow with that 6* angle.
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Old 12-23-2006, 01:35 PM
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Quote:
Originally Posted by QuenchPiston
Pontiacs are inferior to the sbchevy, especially that 3 inch main that slows them way down. Must be that .350 diameter difference that sets these engines apart. .
Actually, it does make a big difference. That .350" diameter translates to over 1" of circumference gain, which increases the bearing speed by 13.22%. Since friction is muliplied by the square of speed, it can mean roughly 75% more friction sucked up by the bearings compared to the chevy
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  #27 (permalink)  
Old 12-23-2006, 04:36 PM
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the sbc has been on the market alot longer than a pontiac engine for some reason. when was the last pontiac engine made ? 1981.
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Old 12-23-2006, 05:03 PM
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Originally Posted by curtis73
Actually, it does make a big difference. That .350" diameter translates to over 1" of circumference gain, which increases the bearing speed by 13.22%. Since friction is muliplied by the square of speed, it can mean roughly 75% more friction sucked up by the bearings compared to the chevy
Curtis, would you agree that roughly 70 to 73 percent of friction in an engine is caused by ring drag? If you do, that would leave us with 27 to 30 drag within the rest of the engine lying elsewhere in other parts which includes the camshaft/valve-train and related crankshaft bearings, 8 rods and 5 mains. Take the cam shaft and extend it out of the block through additional material like the cranks shaft snout so that you now have two snouts sticking out of the block, no timing chain/gear attached. Take the rings off the pistons and put the pistons rods and crank back in the engine. Now you have the whole engine together minus piston rings and timing chain and gears. Tell us which shaft you can turn over with one hand, the camshaft or the crankshaft with rods and pistons attached? Since I have to cover all bases in here, which one is more difficult to turn over for you burly guys?

Now with just the crankshaft and nothing else on it except main caps and bearings, what would 75% be of in your example? The rotating resistance of a crankshaft can be measured in inch/ounces. Are you talking about a 75% increase over the 400 chevy inch/ounce crankshaft resistance which would be?

I believe the main bearing friction of the Pontiac main can be canceled out by the piston skirt friction of the shorter rod chevy thus we are back to equal bottom end friction loss wise.

Last edited by QuenchPiston; 12-23-2006 at 07:24 PM.
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Old 12-23-2006, 05:05 PM
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Originally Posted by Rick WI
Quench, you argue to argue.
Huhhhhhhhhh? I believe its called debating.
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  #30 (permalink)  
Old 12-23-2006, 05:20 PM
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As an old dirt track racer my experience is with 400 chevys. Unless I was wanting to stay with a pontiac motor for purity reasons I would build the 400 chevy with a stroker (4.00) crank. And for a few dollars more you could buy Little M block and have something that lasts. I have to remind myself that on the street stroke and torque are King over horsepower numbers. You don't need to turn huge RPM's but that torque is what moves a heavy object. Now the 400 pontiac is good if you got one already but the aftermarket has soooooooo........ much more chevy 400 parts. Just my 2 cents worth. Good luck dude on whatever you build and let us know how it turned out.
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