need help with cam and torque converter

[Julian1999]

Hey everyone! I own a 1970 skylark two door witch a Small Block Chevy 350 and a TH350 Transmission. I am about to make the jump for a positraction and 4.11 gearing and was wondering what would be a good cam and converter for my engine and transmission to make a lot of torque?

The car is street/strip, but its mostly a weekend car, so I'm okay with mods that will really change the way it drives

Though a really lumpy cam is preferred, I am putting performance first and want what will get the best bang for my buck

 

[HotZ28]

First of all, you will have to describe the year of the transplant & code of engine?? There were many, high/low compression 350-cui engines built back in the days. Is it fuel injection, or carburetor?

 

[Julian1999]

First of all, you will have to describe the year of the transplant & code of engine?? There were many, high/low compression 350-cui engines built back in the days. Is it fuel injection, or carburetor?

Its carbureted with an edelbrock 1403. id give as many specifications as I could, but the serial number was ground off so I can't tell a lot about it. It was originally a guys just basic driving car. nothing special, nothing fancy. Havent dino'd it, but probably makes around 250-280 horsepower.

 

[Julian1999]

Its carbureted with an edelbrock 1403. id give as many specifications as I could, but the serial number was ground off so I can't tell a lot about it. It was originally a guys just basic driving car. nothing special, nothing fancy. Havent dino'd it, but probably makes around 250-280 horsepower.

and even more, I looked through the papers of the car, and theres nothing about a transplant. The only reason I know is because it is 100% a chevy 350 and not a buick 350

______________________________

 

[LARRY70GS]

A 1970 Buick Skylark only came with a 250 CID straight 6 cylinder engine and a Buick 350. There is NO doubt that a previous owner put the Chevy 350 in there. People do that because it is way cheaper. That's a shame because the Buick engine is what makes it a Buick. The Buick engine is lighter and makes more torque. By far the biggest mistake that people new to the hobby make is to over cam an engine. They end up with an engine that idles rough, has low vacuum, and it gets beat on the street by a Toyota Corrolla.

An engine will make more HP the higher you can spin it PROVIDING it can breathe at that higher RPM. The higher the RPM, the less time available for air to enter and exit the cylinder. A cam holds the valves open longer so the engine can breathe at higher RPM where it can make more HP. The longer you hold the valves open, the more overlap you have. Overlap is when both valves are open at the same time. Overlap reduces engine vacuum but increases engine breathing at high RPM. While a cammed engine can make more HP at higher RPM, it also loses some low end because overlap bleeds away some cylinder pressure at lower RPM. For every 10* increase in intake valve duration, the effective power range of the engine moves up 500 RPM. A stock engine power range is roughly 800-4500 RPM. A high performance cam with 230* or more of intake duration can have a power range of 2000-6000 RPM. The bigger cams require steeper rear end gears and higher stall converters to get the engine in it's power range quicker from a stop or low speed, like in typical street driving. All of that reduces street ability and gas mileage. An over cammed car with mis matched components will be slow on the street, and get old really fast and not be fun to drive.

Picking a cam requires some thinking about exactly what you want out of the car, and how it will be used. You also need to know the compression ratio. This is because the intake valve closes as the piston is on it's way up the cylinder on the compression stroke. Different cams close the intake valve relatively earlier or later. That is why if you look at a camshaft description in a catalog, you'll see a compression ratio minimum. Figuring the compression AFTER the intake valve closes gives you DYNAMIC Compression Ratio (DCR) DCR an be 7.5- 8.4:1 and still run on pump gas. Any higher than 8.4 will require Race Gas. More info on DCR,

Dynamic CR

A little more complicated than you thought, right?


My advice to you is to ditch the Chevy 350 and find a 430 or 455 out of an Electra. Put that engine in, change the rear gear to something like 3.42 or so, and the car will put a smile on your face from ear to ear.

Have a look at the videos in my signature. The car runs mid 11's and is very streetable. Traction is my main problem. The engine made 602 HP and 589 Ft Lbs. TQ. It's far from stock of course, and it costs lots of money. A stock Buick Big Block will give you a great starting point, and more importantly, it will be a Buick again.

 

[LARRY70GS]

If you do decide to put a Buick engine in it, head over to www.v8buick.com You'll get lots of support there.