knuckless

ok either im a complete moron, or im just misunderstanding what i thought i knew.

i put a new cam and timing chain in my 289 and ive been trying to get it to fire for the past few days. i rotated the crank to the timing mark i made with the old cam and chain at 14* TDC and then aligned the rotor to point to the number 1 spark wire. but the car wouldnt start, i pulled the spark plug and check that the piston was all the way to the top and it was. i rotated the crank 1 full rotation back to the timing mark and the distributor rotated only a half rotation pointing the direct opposite way.

so how do i figure out where TDC is if the distributor is pointing two different ways at the same point on the crank. all im getting is a bunch of fuel shooting out the carb

CyprusMustang

easy, take out spark number one, turn it over very slow (not to start engine) and stop, stick in a pencil or screwdriver and feel if the piston is there. if not, keep doing it until you feel it there. then you may have to turn the crank by wratchet until you feel it at its highest point. then pull off the distr cap and make sure its at one. when your at one, that is top dead center.from there you get a timing light make a few marks and your on your way...

knuckless

i did that, and it was at the mark that i had made before with the old chain and cam. but how do i know that this is on tdc compression stroke and not tdc exhaust? especially if the distributor rotor points two different ways at the same crank mark

CyprusMustang

you answered your own question, take off the valve cover and look when it comes to v8, there is no easy way out

KMatch

Pull the number one plug, put your finger over the spark plug hole as best as possible, and bump the starter while avoiding plug wires. Once you feel compression, you're on your way to finding TDC for number one on the compression stroke. Roll it the rest of the way by hand to TDC and you've found it.

With the half turn of the distributor, this is how things work. Number one has 2 TDC positions just as all the cylinders do. When timed properly, the dist will point to #1 when #1 is on TDC compression stroke. When the dist is pointed away, that will be #1 on TDC of the exhaust stroke. The dist (and cam) only makes one revolution for every 2 turns of the crank. All 8 cylinders will see one compression AND one exhaust stroke for every one turn of the distributor.

67t5ponycoupe

That applies to all 4 stroke engines not just V8's

kalli

either put a finger on the hole while someone turns engine by hand, you will feel the compression, or
take an old rag and shove it into the hole. But don't shove into cylinder, just so that the rag blocks the hole, then crank the engine, but make sure the coil is dosconnected so it won't fire.
as soon as the rag pops out stop you are very close to TDC on compression

You can do as Cyprus says with taking the valvecover off. Both valves should be closed when you have the correct TDC (where it should fire). both valves closed the pushrods relaxed, the rockers not lifted on pushrod side.
The other TDC will be just before intake stroke, means the intake valve will be open), but I'm just too lazy for this and therefor use the rag
just don't shove it into the cylinder, just block the hole

Randys66gt

In other words, the compression, you will feel the air being pushed out against your finger rather than sucking it in. Hope this helped to make sense.

knuckless

well ive been busy with work and havent been able to work on the car to much lately but i did try to get it going yesterday but again it still wont fire. i tried it at both TDC to see which one would fire but its still not firing. everytime i press the throttle to give it some gas when cranking the fuel shoots out the top of the carb?

im going to check all the gaps on my spark plug and see if maybe they are gummed up too. other then that i know im getting fuel so i cant figure out why it wont fire

gjz30075

Hope this doesn't mean you set the cam to 14* also?? Please tell us you set the new cam in with its mark pointing to the same mark on the crank gear. If so, then find TDC by any of the various methods previously mentioned. THEN, set the distributor rotor to #1 plug wire.

If gas is shooting out of the carb, your cam could be way out of whack. Did you buy a cam for the correct firing order for you motor?