Editing Basic modifications for newbies



'''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 understanding concerning these modifications.

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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  nufacturer you have no idea if the TDC notch on the ring matches the timing pointer attached to the block or front cover, even if the outer ring has not slipped at all. There are a multitude of different dampers and three different timing pointer locations on a Chevy. I don't know about other brands. Chevies use 12:00 noon, 2:00 O'Clock and 2:30 O'Clock and if anyone has had the motor apart, you don't know if they used the original damper and timing pointer or other swap meet parts when they went back together with the motor.     

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.

Before starting this operation, measure the outside diameter of the damper and buy a timing tape which matches the diameter of the damper. Also buy a piston stop tool.
http://store.summitracing.com/egnsearch.asp?Ntk=KeywordSearch&DDS=1&searchinresults=false&y=5&N=+115&Ntt=timing+tape&x=22
http://store.summitracing.com/egnsearch.asp?Ntt=piston+stop+tool&x=30&y=5&searchinresults=false&Ntk=KeywordSearch&DDS=1&N=700+115
 
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 which are joined together with an elastomeric material). The ring has a notch cut in it which indicates top dead center when aligned with the pointer on the front cover of the motor. Remove the fan, belts, shroud and water pump pulley. You may have to remove the water pump to gain full access to the ring and do the measuring needed for this operation. This would be a good time to replace it anyway. Pumps and gaskets are not that pricey. Whether or not you replace it, removing it and installing a Flow Kooler impeller plate might be a good move. Summit lists them only for a Mopar, but they wouldn't be that hard to fabricate from sheet metal and install with rivets on a stamped steel impeller. 
http://store.summitracing.com/partdetail.asp?part=BRA%2D4375%2D07&autoview=sku
Space the pump backing plate out with another gasket or two to prevent contact at the rivet heads. 

Anyway, back to the task at hand. First use solvent and then hot soapy water to thoroughly clean the harmonic damper and timing pointer. Remove the valve cover for #1 cylinder and back off the rocker arms for both valves for that cylinder. COUNTING THE NUMBER OF TURNS YOU LOOSEN THE ROCKER NUTS WILL MAKE IT A SNAP TO RE-ESTABLISH THE CORRECT LASH WHEN YOU TIGHTEN THEM BACK AFTER THIS OPERATION. This will circumvent any interference between the timing tool probe and the valves while turning the crank. Turning the motor over by hand will be easier if you remove all the spark plugs. With a socket on the damper retaining bolt and a long socket handle, rotate the crankshaft clockwise until the notch on the damper ring has gone past (to the right of) the timing pointer on the block or front cover by about 1 to 1 1/2 inches. Install the piston stop tool housing into the #1 spark plug hole. Insert the probe of the tool into the housing and screw it in until you feel resistance of the tool probe against the piston crown. 

Affix a 4 to 5 inch length of masking tape to the damper ring with the left end of the masking tape about 1 inch to the left of the timing pointer, positioning the masking tape toward the block-side edge of the damper ring, leaving room at the front edge of the ring to affix your timing tape later. With a ball-point pen, make a thin mark front to rear on the masking tape right at the point of the timing pointer. Rotate the crankshaft clockwise until the piston comes up against the timing tool probe again. Easy does it here, you don't want to bring the piston up against the tool so hard that it will dent the piston crown. Make another mark on the masking tape with your ball-point pen. With your 6 inch caliper, measure the distance between the two marks you made with the pen. Divide this distance in half. Move the jaws of the caliper to show this half distance. With one jaw on one of the marks you made with the pen, the other jaw of the caliper will be at true top dead center. Make another mark on the masking tape at the caliper jaw to show this center position and affix your degree tape onto the ring, aligning TDC on the timing tape with the center mark you made on the masking tape. Remove the piston stop tool housing and probe. Tighten the rocker arms back the same number of turns you used when you loosened them. With your buddy holding his thumb over the #1 spark plug hole, rotate the crankshaft until he feels compression against his thumb. Continue to rotate the crank slowly until the timing pointer aligns with about 10 degrees before top dead center on the timing tape. DO NOT ROTATE THE CRANKSHAFT ANY MORE. LEAVE IT ALONE FOR NOW. Replace spark plugs and wires. Remove the masking tape, reinstall water pump, pulley, fan, shroud and belts. Replace any coolant/water you may have lost in the operation. Remove the cap from the distributor and align the rotor with the cap terminal that coincides with #1 plug by rotating the distributor housing. On a Chevy, clockwise rotation of the housing retards the ignition timing, counter-clockwise advances it.  From #1 plug position on the cap, the wires will be plugged in clockwise around the cap from there and will go in the firing order (Chevy 1,8,4,3,6,5,7,2).
 

Set the valve cover on the head to keep oil from flying everywhere and fire the motor to let it warm up an little. Do final adjustment on the #1 cylinder rockers. (Chevy, back off the rocker 'til it audibly clatters, then tighten it down 3/4 to one full turn). If you want to go ahead and run the valves on the rest of that side of the block, now would be a good time. Replace the valve cover.

Hook up your timing light to #1. Remove the vacuum advance rubber hose from the vacuum canister at the distributor and plug the end of the hose with a golf tee or other suitable plug. Adjust initial timing at the crank to what you want. Some use the factory setting while others prefer to set it a little more advanced for good throttle response. If using a little more initial advance at the crank, make certain you don't have so much mechanical advance in the distributor that you exceed the total timing specified for the motor. Most small block chevies will run best with around 32-34 degrees with fast-burn heads and 35-36 with conventional heads. Ignition curve kits are available to customize the centrifugal advance curve in order to limit it when using more advance at the crank. 

There, you're done. You should feel much better now, knowing that when you time the motor with a light, it's dead nuts on the money.  



         
==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.....