[MandevilleBird]

In what ways? As Poncho guys, we all seem to insist that you can't use a chevy attitude when building a pontiac engine. I don't have knowledge or experiance to know why.

Whats the deal?

[b-man]

No sealer on Pontiac head bolts, just oil because they enter a 'blind hole' (not drilled through). On a Chevy they need sealer because they don't enter a blind hole, they are drilled all the way through to the coolant passages and will contact water.

The Pontiac cam has a thrust plate that limits travel fore and aft, a Chevy has no such thing from the factory. Chevy builders and Pontiac novices often mess up installing the fuel pump eccentric that holds the cam gear on.

Pontiacs have a non-adjustable valvetrain on 99.999% of them where you just torque the rocker nuts to 20# (the rare RAIV engines had an adjustable valvetrain for example), on a Chevy you have a self-locking nut and must you adjust the valves.

When putting a high-performance cam in a Pontiac it is almost mandatory to convert it to an adjustable valvetrain, something a Chevy builder might not be aware of. Lots of Pontiac cam and lifter sets have been ruined by the unaware.

The slight imbalance built into every Pontiac flywheel, and neutral-balanced harmonic balancers. Chevy flywheels are built neutral-balanced, and some balancers are neutral-balanced and others are built with an imbalance (400 SBC and 454 BBC).

Lots of other little things that others here will surely add.

You just have to be familiar with Pontiacs, as you would have to be with any other engine type that has its own little differences and quirks that will require the proper knowlege to deal with correctly.

[llwta76]

You guys correct me if I'm wrong but simply put Pontiacs are torque engines. That's longer stroke and smaller bore then the other guys' engines of comparable cubes. They do their best work under 6000. The best street engine ever! Yeh! Awesome power @ street rpm.

[72blackbird]

Another thing Chevy guys typically mess up when trying to build a Pontiac is the timing cover assembly- they loose/leave out the alignment dowels, water pump divider plate, water pump O-rings and sleeves, and not clearance the divider plate to the w/p impeller.

I admit the Chevy setup is much simpler, but if you're going to build any engine you have to know the specific details required to do it correctly.

Geno

[Steve C.]

".... insist that you can't use a chevy attitude when building a pontiac engine."

Ok, some good assembly differances were listed. But did you mean 'attitude" as for example 'we' should rely on building lower rpm truck motors and don't think about operating at a higher rpm on the street ? Or the fallacy that if you use Edelbrock heads on a street engine instead of iron d-port heads the low rpm torque will suck really bad because of the larger runner volume ?

[b-man]

Originally Posted by Steve C.

".... insist that you can't use a chevy attitude when building a pontiac engine."

Ok, some good assembly differances were listed. But did you mean 'attitude" as for example 'we' should rely on building lower rpm truck motors and don't think about operating at a higher rpm on the street ? Or the fallacy that if you use Edelbrock heads on a street engine the low rpm torque will suck really bad because of the larger runner volume ?

I'll agree with you here Steve, not every Pontiac street engine needs to be built using a mostly stock recipe to shifted near 5000 RPM.

However most of the Pontiac street engines out there really won't need to be shifted much past the 5500 to 6000 RPM range, even with higher-flowing aftermarket heads and more aggressive cams.

In the case of the engines you like to build Steve, they are more race-oriented than most of the street Pontiac engines you see.

A lot of the SBC builders have been running their race-oriented engines in the 8 to 10K rev range for close to 50 years now, the early SBCs all had forged rods and cranks and a 3" stroke that made high revs easier for the bottom end to live with. Plus the SBC was always the small-cube underdog back in the day, and a small-cube package needed to rev to keep up with the big boys.

Not every Pontiac street engine need be built like a truck engine, but they run pretty well on the street when you take advantage of the low to mid-range grunt they already have built into them. Even with higher flowing heads and more aggressive cams.

There's quite a few low-11 second full-bodied Pontiac street cars out there shifting at or before 5500 RPM.

[Steve C.]

b-man I agree.

That said, I do feel we are seeing some positive changes in our hobby as many are reaching for higher horsepower goals. Like 600 plus horsepower on the street is not that uncommon. Yes I know Pontiac people 'must' talk torque and not mention the evil hp word And higher rpm operation is becoming less of a stigma today with the avialability of better suited parts.

Here is a quote by Mr P-body that helps with my point......

"Why NOT rev the Pontiac? It can be nearly impossible to "tune" the low-end torque out of a big-cubed Poncho. But with good heads, solid lifters and good rod/piston combinations, they can rev 6,500 and still make enough low-end to drive it like a "normal" car. Our self-imposed rev limits are due to parts and paradigms. Now that the "parts" problem has been solved (good rods, cranks, pistons, heads, blocks, etc.), break the paradigm!!!"

[mikeb]

Lets see, the valvetrain has been covered, as has the blind head bolts and the crankshaft balance deal.

Pontiacs use a seperate "pushod cover" to separate the area below the intake from hot oil. Now you see "air gap" manifolds that have the same idea for chevies and fords. Pontiacs use fully machined combustion chambers. The stock cast iron intake is actually quite good, and for most street apps can be retained.

As far as tuning goes, pontiac heads have an advantageous valve angle and smaller, higher velocity ports. This is where the torque comes from. Because of that you can run taller rear gears than chevies. 4.11s are generally a mistake on a pontiac, 3.55s or 3.33s are generally a better match to the pontiac torque curve. Pontiac ran flat top pistons on most of their engines, and varied combustion chamber volume as needed to vary cr. The cylinder head is called a "d port" based on the shape of the exhaust ports, although you'll hear of "round ports" as well. Round ports were reserved for high performance heads, and can be tough to find and expensive to buy. All d ports basically have similar flow values.

Parts are generally interchangeable across the line except for the bastard 301. 400 and smaller engines have 3 inch mains, larger than 400 has 3.25 mains. Of course, pistons are application specific, but rods will freely interchange. Also, there was a design change I believe somewhere around 1967 with the exhaust crossover passages. The hole size changed, so if you mismatch the intake and heads you have an exhaust leak.

Also, engines can be freely swapped. There are two bolt patterns available, the pre 70 2 bolts and 70 and later 3 bolt. Blocks produced between 1970 and 1976 have both patterns. Also, some later 400 blocks (mid 75 and later with exceptions) are thin wall and should be avoided (casting 500557).

I'd suggest you get a copy of jim hand's book and read thru it. It has a lot of good tips for getting the most out of a street pontiac.

None of what I said applies when you get into a full race pontiac setup. It all changes LOL...

[GT182]

Here's another thing that puts a Pontiac engine way above a Chevy. It's tough as all h3ll.. When Donny took my 389 apart, he put all the pistons and rods in a box still all assembled. He said pick em out and take a look at them. So I picked one up and it looks ok. Same for 3 more. For the next 4, I picked them up and the rings just fell off them to the floor. That's the way they came out of the block, with broken rings. Believe it or not I drove that car from July of 2006, when I bought it, to Cruise Nights and some shows up until I put it away after the Dover Monster Mile show in October of 2007. It smoked and threw oil like crazy but it ran strong. If I was back up north I coulda killed a zillion mosquitos. Tell me a Chevy engine would do that. I think not, it would have been just a piece of scrap metal.

[mikeb]

Originally Posted by GT182

Here's another thing that puts a Pontiac engine way above a Chevy. It's tough as all h3ll.. When Donny took my 389 apart, he put all the pistons and rods in a box still all assembled. He said pick em out and take a look at them. So I picked one up and it looks ok. Same for 3 more. For the next 4, I picked them up and the rings just fell off them to the floor. That's the way they came out of the block, with broken rings. Believe it or not I drove that car from July of 2006, when I bought it, to Cruise Nights and some shows up until I put it away after the Dover Monster Mile show in October of 2007. It smoked and threw oil like crazy but it ran strong. If I was back up north I coulda killed a zillion mosquitos. Tell me a Chevy engine would do that. I think not, it would have been just a piece of scrap metal.

Yeah, the 400 I just pulled down had been knocking to the point of wearing a discernable .050 "ledge" of metal between the rods on the journal between #1 and #2. But apparently it was still running LOL.... (the crank was toast).

[GT182]

Yeah I hear ya Mike. I don't think a Ford engine is as tough as a Pontiac either..... but don't tell the Ford guys. They might want to switch and put Pontiac engines in their Fords.

[mikeb]

Originally Posted by GT182

Yeah I hear ya Mike. I don't think a Ford engine is as tough as a Pontiac either..... but don't tell the Ford guys. They might want to switch and put Pontiac engines in their Fords.

Well, the one pontiac powered fairmont that i'm aware of is kicking ass in texas true 10.5 competition LOL.....

[GT182]

Originally Posted by mikeb

Well, the one pontiac powered fairmont that i'm aware of is kicking ass in texas true 10.5 competition LOL.....

That's great. If it's yours, I'd like to shake your hand.

[mikeb]

Originally Posted by GT182

That's great. If it's yours, I'd like to shake your hand.

Nope, I believe it belongs to steve coombs and john dinkel.

http://forums.maxperformanceinc.com/...irmont+pontiac

[Thumpin455_GTO]

A good way to confuse a Chevy type machinist. Tell him your 455 build will use reconditioned stock 350 rods and either 400 or 428 heads with 2.11" intake valves. Then if you mention flat top pistons with any head, it will suddenly become a 10:1 engine. Have been going through this with a new guy doing a simple valve job for me.

Really, finding a shop that is well versed with both Mopar and FE Ford engines will make building a Pontiac less of an educational experience for them.

[Steve C.]

"Nope, I believe it belongs to steve coombs and john dinkel."

The Fairmont belongs to John. And really today I can't take much credit since the current engine combination has been changed a bunch since we put my old 700 hp motor from my Trans Am into his car. A few years ago after the first season of racing we felt it was pushing things a bit with the factory block used in conjunction with a 300 or so hp nitrous tune up so I bought the IAII block and a few parts toward the current upgrade.

The car rocks..... 5.18 at 136+ mph in the 1/8 mile.

[MotorHead_811]

Or have someone that builds chevy motors tell you that 455's blow to easy like he told me lol

[71firebird400]

Originally Posted by Thumpin455_GTO

Really, finding a shop that is well versed with both Mopar and FE Ford engines will make building a Pontiac less of an educational experience for them.

Haha, I agree- if someone can figure out the rear main seal in an FE, then they can probably build a Pontiac!

[71 Ventura II]

Originally Posted by b-man

The Pontiac cam has a thrust plate that limits travel fore and aft, a Chevy has no such thing from the factory. Chevy builders and Pontiac novices often mess up installing the fuel pump eccentric that holds the cam gear on.

Hey b-man just wanted to add to the cam thrust plate. The camshaft "Thrust plate" controls only the forward "walk/movement" of the cam. The rearward camshaft movement is controlled by a combination of the "cam gear" and the amount of engagement by the "fuel pump eccentric" over the nose of the camshaft. The camshaft should see a variance or runout between .004-.008 fore and aft movement. FWIW

I had always just bolted my eccentric on with good success until last Summer when I found something was wrong after installing my gear drive. Once the cam bolt was torqued to spec the cam was bound up unable to rotate! I mic'd every detail eventually finding the "snout" on the cam gear was very slightly longer than required. I had the option to have the cam gear machined, machine the engagement ring on the eccentric, or eliminate the eccentric with carefully selected hardened machine washers to get the clearance I needed. It ended up having .008 runout which still "feels" pretty tight. Just helping out. Oh, and yes I'd say a very high percentage of "Chevy" builders will not have this knowledge. JD

[65gto69]

How about engine rotation.

Pontiac rotates opposite of a chevy, so when putting those spark plug wires on make sure you go counter-clockwise around the distributor or you will have real headaches like Barry White had on his TV show "Wrecks To Riches". Quite an embarrassing moment for him in front of plenty of Pontiac viewers when he was building that GTO/Lemans.

Mark