Editing Basic modifications for newbies

I HAVE MISTAKENLY DELETED MOST OF THIS FIRST SERIES ON FINDING TDC....GRRRRR.....and will replace it when I find time.....GRRRRRR.....



'''There are numerous sources of information to assist the untrained individual in the rebuilding or repairing of specific components of a vehicle, but there needs to be a place where he/she can learn what to do and what not to do in the modification of their vehicle(s). This article will attempt to fill in the blank spaces in their education concerning these modifications.'''
VERIFYING TOP DEAD CENTER AT THE DAMPER/POINTER WITH THE MOTOR ASSEMBLED.

First off, the large round hub on the front of the crankshaft is called a harmonic damper by some and a harmonic balancer by others. If it is bolted to the crank of a 350 Chevy that is internally balanced, then it serves only the function of being a harmonic damper, dampening vibrations (harmonics) that are created in the crankshaft. If it is bolted to the crank of a 400 Chevy, then it is both a balancer and a damper because the 400 is externally balanced by using eccentric weights on the balancer/damper and also on the flexplate.  

In this exercise, I am suggesting that you install the piston stop tool with the Factory TDC notch on the damper ring to the right of, or past the timing pointer so that you can turn the crank clockwise through the whole operation. If you install the stop before you are to TDC and then turn the crank backwards until the piston comes up against the stop again (counterclockwise), you may  loosen the bolt in the crank that retains the harmonic damper. Then you have to get your buddy to crawl under and hold a large flat-blade screwdriver into the ring gear teeth to keep the motor from turning while you tighten the bolt back. Far better to just turn the crank clockwise only (keeping the bolt tight) and sidestep a problem before it occurs. Been there, done that.

You'll need to get everything out of the way so you can work on the damper ring (the damper is made up of two metal parts that are joined together with an elastomeric material) is the outside ring which has a notch indicating top dead center when aligned with the pointer on the front cover of the motor. TO BE CONTINUED......   




==The first modifications to be made to your vehicle==
It is usually cheaper and easier to begin making mods to the motor and that's where most everybody starts in their quest to make the vehicle faster/quicker. 

The problem with this approach is that you're starting at the wrong end of the vehicle. Unless you're starting with a scratch build, you're probably modifying an OEM vehicle which was engineered at the factory to provide good gas mileage (numerically low ring and pinion, (probably something in the 2.70 to 3.00 range) and a tight torque converter (maybe somewhere around 1,200-1,400 rpm stall).
This vehicle was designed for all sorts of people, the vast majority of whom expect good fuel mileage and quiet operation. The cam, intake manifold and other parts that came stock in the vehicle were matched to the ring/pinion and the torque converter to accomplish this goal. When you begin changing parts on/in the motor, you are upsetting this balance of parts that were built into the vehicle at the factory.

The first things that a newbie usually changes are the cam, intake manifold and carburetor (if working on a pre-efi motor) in an effort to make the ol' hoss a world beater.

First things first. The cam must be matched to the static compression ratio of the motor. The OEM's have super computers that tell them exactly the timing points to be ground into the cam to match the c.r. and make power at the rpm's the public expects. This is usually idle to around 4,000 rpm's or a little higher. Any cam that you bolt into the motor will have an operating range of roughly 3,500 rpm's. In other words, it will be efficient from idle to 4,000 or 1,000 to 4,500 or 2,000 to 5,500 or 3,500 to 7,000 or whatever, depending on the valve opening and closing points ground into the cam when it is manufactured. It will also have a wide Lobe Separation Angle (max lift intake point after top dead center added to max lift exhaust point before top dead center and divided by 2) for good manifold vacuum to properly operate power brakes and other vacuum operated accessories and contribute to a smooth idle (Grandma doesn't want the motor going RUMPETY-RUMP when she's on the way to bingo). An OEM cam might be measured at 114 to 118 degrees LSA for instance.

Now, the newbie comes along and decides that the motor needs more cam. In most cases, he has no idea what the static compression ratio of the motor is or the piston deck height or the squish clearance or anything else about the interior of the motor. All he knows is that he wants the RUMPETY-RUMP that he heard coming from the Super Comp motor he heard at the drag strip. What he may not know is that the motor in that car has upwards of fifteen to twenty thousand dollars invested in it and is maximized for racing. It idles like that because the cam has to be very agressive to work with the 14.0:1 to 16.0:1 static compression ratio that is built into the motor. It may have been designed to make power from 4,500 to 8,000 rpm's for instance and will be coupled to a very loose torque converter that stalls at around 5,000 rpm's for instance. 

I'm just throwing these numbers around to show you that the cam in the Super Comp motor will not work in your street-driven 350 Chevy. 

I've gotten a little off track with my explanation. We need to go back to what a newbie should do  to his vehicle FIRST. 

Number one is a new rear gear. A good compromise between mileage and acceleration in a street car is somewhere around 3.70:1 ratio.   

To be continued.....