Small Block Pontiac 307

[WetWillie]

I was going to offer my two cents but you seem to have the right guy on the job

I was going to suggest a Xtreme Energy Cam from Comp Cams... RPM range 1300 - 5600. And as for a tranny I was going to recomend a Street Figher TH350 Chev Tranny, the downside to this is that is will hurt the wallet greatly, Kevlar and heat treateted... You just know is gonna be a pretty penny... But the way to go about that is exactly what was recommened by Dan. You have time to look for the tranny thus you never know you might find a great deal a bit later on, Or you might have the money then.

Willie
Good Luck

[Dan_in_WA]

Yeah, a lopey cam would be one with LOTS of duration and overlap - intended for higher RPM use. Not what one really wants on the street, because of the way it kills the torque curve in the lower RPM ranges.

A cam that will really get you off the line will also have a smooth, or at least good, idle quality.

Between idle and 5000 RPM or so, I'd think about .350" to .400" should be plenty of cam lobe lift. Maybe even less, with the bigger intake valve. The cylinder just doesn't need to have the valve shoved way down out of the way, at the air flows you'll see at street RPM. And the extra movement of the valve costs power!

The valve duration (degrees of cam rotation that the valve is open) is primarily what causes the 'lopey idle' associated with too much cam.

The whole reason for lots of lift and duration is that at higher RPM, the TIME available for filling the cylinder with fuel/air is reduced. This is how the engineers compensate for less time to fill the cylinder.

Overcamming an engine is one of the most common mistakes made, and it's almost always in the quest for that big peak HP number. But what most guys forget is that to get that big number, they sacrifice power below about 3000 RPM. In street race terms, this means that the guy in the Honda next to you at the stoplight may be making 250-300 HP, but the torque curve doesn't even start climbing until 3500 RPM. So unless he's got 5.37 to 1 gears in his transaxle, you'll come off the line first, and be eating his lunch by the next stoplight! All he can do about it is "The Ricer Flyby".

$537 is a good number, especially for your first efforts! And you're on the right track. Here's a little, true story:

My friend Kevin has a '68 Fastback Mustang. 302 4V (5.0L four-barrel Holley carb) engine with a stock rebuild and a set of headers, done by his dad in the garage. Back in high school, this was by far the fastest car in the parking lot. There were a couple other cars, that had a whole lot of money dumped into the engine bay that were hard-pressed just to keep up with that thing. One guy had a '63 or so Chevy II with a built, and I mean BUILT, 327. Built to the tune of $3500 in engine work alone! Align-bored main bearing saddles, gear drive, big Crane (or was it Isky? No matter.) camshaft, high-rise single-plane intake manifold, ported heads, headers, oh bleep, you name it.

Kevin's car would waste it off the line, every time. The guy had to play catch-up, and never got ahead unless they were doing a rolling start out on the highway.

So why was this? Back to Math Class: You know how to take an average of several numbers, right? Add up all the numbers, then divide the sum by the number of samples. OK, let's discuss that. (I'm pulling the HP numbers out of thin air, to explain the overall concept.)

Starting at 1500, measure the HP of both engines at every 50 RPM increment, up to 4500 RPM. i.e.; 302 makes 75 HP @ 1500, 82 HP @1550, 88 HP @1600, 93 HP @1650, and so forth. All the way up to 4500 RPM.

Now, let's look at that built 327. At 1500 RPM with the big cam and intake, OH BLEEP! We're only making 49 HP at 1500 RPM!! 1550 is a little better, we see 56 HP. 1600 gets us to 61 HP. Why? Because that 327 was set up to run between 3500 and 6500 PRM power band! We don't see much of that RPM range in town - only once we get out to the highway, and the engine gets revved up. But with those 3.30 to 1 rear end gears, the engine only runs about 2900 RPMs when cruising down the highway in 4th gear, at the speed limit.

Taking the average HP number of both engines for the stated RPM range, which one would come out higher? The 302. The 327 has a bigger PEAK, but that's just one single reading on the chart. The 302 comes out with a higher AVERAGE, below 4500 RPM. Right where it's needed most.

See how important it is to match the engine, trans and gear ratios to the intended use? And what can happen when the engine power band is too high to be of any practical use on the street?

I know in my old Isky catalog, before they'd recommend a cam, they had to know the drive ratio in the rear end. If you have a certain 350 camshaft in mind, find out what the gear ratio usually was in the car equipped with that engine.

You're well on your way to learning a whole lot. And what fun it is! BTW, when I was your age, I was so badly addicted to cars I didn't have time for drugs or getting in trouble. Might let that idea slip out to your parents....

Whew! Will write more later.

Dan

[Dan_in_WA]

Originally Posted by WetWillie

I was going to suggest a Xtreme Energy Cam from Comp Cams... RPM range 1300 - 5600.
Willie
Good Luck

That is EXACTLY the right kind of cam for a street engine!

WW, have you seen any articles or comparison tests between that cam and others like it?

I don't believe Consumer Reports has ever done THAT one.... Too Bad, too.

[68 Stang]

Whoa! Lots of information, but I think I followed it. So don't go with a 350 cam? Look for a good low RPM xtreme energy cam? How much will this run me? I hope not too much, but if it is a little bit of money, I will start saving. If I do have a fairly strong, high torgue cam, are there any other components that would need to be upgraded to handle the power? What about oil pumps, I already plan on a new water pump, but what about the oil pump? Long shaft, short shaft. Aluminum, or iron? So many questions! Great help with this engine so far though, really thanks a lot. I was thinking 3:42 gears, so what cam would go good with that?

Grant

[WetWillie]

Originally Posted by Dan_in_WA

That is EXACTLY the right kind of cam for a street engine!

WW, have you seen any articles or comparison tests between that cam and others like it?

I don't believe Consumer Reports has ever done THAT one.... Too Bad, too.

No I dont belive I have... I would be interested in seeing them though.
Im only working on a 3.1L V6 right now, stock enigine for my 91 sunbird. But I have been looking at other things. 3.1 just doesnt have what I want

[Dan_in_WA]

I can't say whether or not to go with the 350 cam yet; I'm saying "Keep Your Options Open". A good cam and lifters will cost about $300 or so, stock items are a little less expensive, but not much.

Personally, I wouldn't choose the cam for the engine until I knew what the rest of the car was going to be like: aka auto or manual trans, final drive gear ratio, about how much the whole thing weighs, etc.

If you already have a cam handy that fits your needs, go ahead and use it. But if you're going to plunk down ca$h for new stuff - you want to be pretty sure you choose the best cam for your chassis/engine combination.

If worst comes to worst, the cam isn't THAT hard to change in a small-block Chevy, with the engine still in the car. You have to pull out the radiator, but I've done it. Just try to avoid the situation of "Gee, I wonder if I would have been better off with Brand X cam instead of Brand Y" after you've got your money spent and the thing is installed in the car.

And when installing a new or used cam, I always install new lifters. NEVER install used lifters, unless the used lifters still have their 'crown' on the bottom, AND the cam lobe still has it's 'crown', AND the original lifter is installed on the same lobe that it came off of! Mis-matched used parts will quickly self-destruct, due to the enormous forces applied between the cam and lifter faces.

That's all for now,
Dan

[Dan_in_WA]

Originally Posted by WetWillie

Im only working on a 3.1L V6 right now, stock enigine for my 91 sunbird. But I have been looking at other things. 3.1 just doesnt have what I want

I have the same engine (3.4L though) in my wife's Montana.

Have you been to http://moates.net site yet? Great stuff for GM fuel injection! Not expensive, either!

[68 Stang]

I apologize for the late post, I have been on vacation to a little Inn in Indiana. WHOOOO!! On the way their, there were so many old Ford trucks with what appeared to just be surface rust on they way there! Almost made me cry! Oh well, now I know where to go when I have money, and my dad allows me to get a car. I was thinking, how cool would it be to go old school with the looks of the engine, and smooth the block? I think it would be sweet, I am thinking about going for it. But I have to get the block boiled first before I do anything. Thanks again for the help!

Grant

[WetWillie]

anytime.... Sorry I couldnt be anymore help

Good Luck

[Dan_in_WA]

I think we've covered the topic of the engine pretty well. Another subject I'd like to bring up is suspension, and choosing wheels and tires in particular. Brakes will also be mentioned.

Most guys will go out and buy/install the biggest wheels and tires they can fit into the fenderwells. Then they'll set about 45 degrees of negative camber on the front wheels; and heat or cut the springs to slam the car on the ground.

They may be stylin', but this is h3ll on performance! A wheel/tire combination is just like a gyroscope. Same goes for the rotating mass of the brake - the disc or the drum. Weight of the combination is just as important as the width of the tire tread - and most guys completely overlook this point!

More later, time to go to work!
Dan

[68 Stang]

I would like to go with about 17" wheels, and a mustang II front suspension. I don't know what to do with the rear!? I would also like the truck to be as low as possible without losing ride quality. So not to the ground, but a 2" drop probably. Thanks for the post.

Grant

[Dan_in_WA]

Here's a little something to try: Call the local tire store and ask the guy behind the counter if he knows what the rims WEIGH.......

Grab a bathroom scale, if you will, and set some stock-type tires and stock rims on it. Do a few sets. This will give you a baseline of what a factory steel wheel weighs, and what a generic 70 series tire will weigh. These are just two factors you're trying to beat, when choosing a "High Performance" tire. Lighter is Better! As I mentioned before, you're driving down the road with what is practically four gyroscopes on each corner of the car. And the heavier they are, the more they'll resist a change in direction (or velocity) of motion.

Let's take an example of the BF Goodrich Radial T/A. If you look in their catalog, you'll see MANY sizes of this tire. What works on one car may not work on another!

I'll write more soon. My computer is showing signs of cutting my internet connection.

Dan

[68 Stang]

I am starting to get psyched up about the engine, got some X-mas money today from my aunt + uncle. This will give me enough to boil the engine, I think. I hope to get a job doing some body work on a '60s Ford Bronco, which will bring some good money in if I get the job. At least I will have my engine boiled soon though! After that, the engine will be at my house, and waiting for a HP makeover! I will look into that low-rpm cam, but I don't want to lose gas mileage on the highway because of this. Can you confirm if I would or not? Glad to be back in business with the engine. Still looking for a good four barrel carb, and if not I'll stick with the 2. Thanks for the help so far, and I hope to get started up on it again!

Grant

[Dan_in_WA]

A good RV cam won't cost you any gas mileage, as it will be pretty close to the stock cam specs. It may vary 1 or 2 mpg, either way.

Actually, I'm running a stock cam out of a 2-barrel 327 in the 307 in my Camaro. I was a little short on cash at the time, and this cam passed the "razor blade" test - which means all the lobes still had their crown -
so I put a new set of lifters on top of this cam. It sounds great; in fact most people refuse to believe I've got "just a stock" cam in there!

The stock profile is meant to provide a somewhat lazy'er (sp?) valve action, due to warranty and reliability issues. Without choking off the engine entirely.

An aftermarket RV cam grinder is less concerned about factory warranties and more concerned about producing a cam lobe profile that will help the engine breathe it's best, for a given RPM range.

Hard to believe it's been just over a month since I wrote to this thread - hope you're still watching for it!

Will write more, soon.

[307Malibu]

Good to hear that there is someone out there who is seriously thinking about building a 307. I have a '71 Malibu with 35k original on it and I didn't want to swap to a 350 because of the low original miles and excellent overall mechanical shape. Everyone told me to go w/ a 350 though. In my opinion the 307 is a great compromise motor. Everyone bashes it, but no one bashes the 283. The 307 is a stroked 283!!! Also, with gas creeping above $2/gallon, 20+ mpg makes a lot of sense on a daily driver.

My cam advice is this: Don't go too hot. I, on the advice of a buddy of my dad's that used to hot rod old chevys in the early '60s, put in a 327/350 hp cam from Crane. It's a 222/222 with .447 lift. My Chevelle now has no power at all until about 3000-3500 rpms. This could be because I have not swapped to headers yet, or it could be because of the tall (2.73) gears and stock converter, but overall it had more overall go before. I'm thinking of taking it out for a later 350 swap into a '47 Ford, and for now I'm going to try something like a 210/210 cam and see how that goes. I'm not sure if it's worth putting headers on first and trying those or just getting rid of that cam for now. I'm also thinking about springing and pocket porting the heads, but with the 165cc Dart heads or the Pro Topline Torker heads going for 550/pair complete, I might opt for that instead. Speaking of, if anyone has experience (+/-) with these heads, let me know.

Good luck, and long live the 307!