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Best way to find TDC?
I couldn't get my new engine to fire..though it was trying. My builder and I suspect the distributor isn't in quite right. I pulled #1 plug, valve cover and the distributor. Now I just need some guidance in getting #1 piston to TDC. Any suggestions? Thanks.
Dave 310-488-7536 |
Use a remote starter and bump the starter while holding your finger on the spark plug hole of cylinder 1. Once you feel pressure starting to build continue to rotate engine by hand until you have the timing mark on that balancer lined up with the pointer for your initial timing setting. For instance if you want 12 degrees initial timing, line up the 12 degree mark with the pointer. Check to see if the rotor is pointing at the number 1 spark plug wire. If not, get it there. While it is out, pre lube. Double check your plug wire order as well. Once you have the rotor pointing at the number one terminal, attach a vot meter to the positive side of the coil and rotate the distributor body slowly the opposite direction of the direction the rotor turns until the voltage drops. Lock down the distributor double checking that you are still pointing to the number one terminal. Fire it up.
DON'T keep cranking a fresh motor! Rick |
Just how does one "continue to rotate engine by hand"? I couldn't find anything handy that would rotate my rotating assembly.
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Use a socket and short extension on a breakover bar on the front (damper) bolt to turn the crank over. It will turn clockwise looking at the front of the motor. Sometimes you can turn the crank using the alternator bolt, but not likely with a new assy. You could also put it in top gear and roll the car.
Also make sure the firing order on the distributor cap is done in the right direction (same as the distributor rotor turns). |
Am I to assume that the damper bolt has left-hand threads and will not simply loosen when turned counter-clockwise?
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Tommy...er, "oops"! It turns CLOCKWISE when viewed from the front...sorry. That means the damper bolt will not loosen as you turn it. Man, some days it just isn't worth gettin outta bed!
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How perfect do you need it?
If I am just trying to get it in the ball park (a degree or two) then I do the rotate the engine witha finger over the open #1 spark plug hole until I fell air from the compression stroke. Once It is coming up on the compression stroke I take a small screwdriver and put it down the hole (make sure the screw driver handle is bigger than the hole) and watch. Turning the engine slowly (breaker bar, bump start switch, pushing the car in gear, however you want) just watch until the screw driver stops rising and starts falling then fine tune the rotation so the screw driver/piston are at the top of the stroke.
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Tinker51 -
I doubt you can get within a degree or two using the finger over the spark plug hole method. Here's a link to a site describing a more accurate method using a piston stop and degree wheel: http://www.2quicknovas.com/happyTDC.html |
Just printed that page..whoa black background
Tommy
%/ That's a good one thanks. %/ Bernie |
My hot roding experience has only been with FE's. I used to (with a points system) be able to turn the damper to 8°bftdc on compression stroke . Take a grounded spark plug and connect #1 plug wire .With the rotor pointed at the #1 wire position in the cap .I'd slowly turn the distributer untill that plug sparked. It would end being at 4°bftdc. tried that with a Mallory unilite . Man was I off. It ran but not real good .I checked with a light.Turns out it was 12°aftertdc. A FE has 15 teeth on the distributer gear. .One tooth will make a 48° change.When I got the timing set at 12° initial it was roaring had to crank a lot of idle screw out of the carbs to get it back down to the 650 700 rpm range.
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Another idea to be sure your on TDC on the compression stroke is to turn it over with valve cover off and watch the intake valve on #1. Right after the intake closes is should be coming up on TDC. When the timing pointer is at TDC you have it. Adjust to your desired setting and install the distributor and use the volt meter as Rick described. I've seen many a distributor installed 180 off because they didn't verify which stroke it was on.
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Thanks guys! I'll give it a try this weekend once all the other chores are done. One more question:
Does it matter exactly where the distrbutor is positioned when installing it since I'd put the #1 plug wire where the rotor is pointing to? Then I'd attach the other plug wires in firing order around the distributor. Dave |
Theoretically, no. As a matter of practicality though, the vacuum cannister restricts the movement of the distributor to an arc of about 45*.
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Thanks for all your help. I got the car running and off for a cruise on Sunday. I think the distributor position was way off the first time around. This time I pretty much nailed it and it started right up. I have an MSD Pro-Billet with mech. advance so I didn't have to worry about the vacuum pot. Bumping up the cubes from 351 to 427 and adding a roller cam sure makes a big difference!
Dave |
Dave,
We've got to get together soon. If you have the car out give me a call. I've got my motor sitting on the garage floor-should get it in this weekend. Did you get it painted yet? -Bob |
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