Hi guys, I was helping a friend with a top end swap today and when we went to find TDC on the engine, when the harmonic was at 0, the air was long gone from the compression stroke and the distributor was not lined up with cyl 1 when seated properly. I am positive that it was the compression stroke and all that. Now, my question comes because when we found TDC without using the harmonic marks, the distributor sat even farther away from cyl 1 position. Anyone have any ideas? It was a stock 305, Edelbrock intake, 1406 carb and stock distributor.

Thanks, Chris

 

Is this a stock balancer with a stock timing comb on a stock timing cover?

 

The 305 is an AC Delco remanufactured factory engine so everything is factory except for the top end work

 

Ignore the timing mark. Put the engine at #1 firing and assemble it. If you really care about the mark, then once you find TDC, put a new mark on the damper that lines up with the tab and move on.

 

That's what I tried to do, ignoring the timing mark, but after finding TDC, the distrib was not even close to the 6:00 position where it should have been.

 

Then take it out and put it back in at the right spot.

#1 should be just to the driver's side of straight ahead.

 

The distributor only seats itself all the way at two positions, both being way off from cyl 1.

 

It doesn't matter where the rotor points - you can restab the distributor and have the rotor point anywhere you like - bottom line is, when the motor is at TDC compression stroke, no matter where the rotor points, THAT has to be #1 plug wire.

Everyone wants to think some magic occurs at TDC and the rotor points to #1 plug. There is no magic at all, the rotor points where it points - no matter where that is, it has to be the #1 plug wire. If you want it to point somewhere different, then YOU have to restab the distributor until it points there. The distributor will restabd wherever you want it - just a matter of getting the dist gear to mesh.

 

THen turn the oil pump so that the dist seats at the right place.

It is true that the engine will run exactly the same no matter where the dist is. However, "retentive" people like me, like their motor to be assembled correctly; and, the plug wires make the least of a bird's nest when the dist is right.

You can get the OP rod to cooperate by dropping in the dist so that the rotor points where you want, and turning the engine with the starter while gently helping the dist to go in the rest of the way. THe dist will spin with the engine and at some point engage the OP rod and drop n the rest of the way.

Or, you can pretend you know what you're doing, and assemble it right...

Rotate the engine in the direction it runs until you reach the point where you want it to fire; a good starting point is about 15° before the instance of #1 TDC where it fires. (don't forget, #1 is at TDC TWICE during one engine cycle, but only ONE of those is firing) Turn the OP drive rod with a large screwdriver or the like until it is about 30° away from straight front to rear, going from front driver's side to rear pass side; hold the dist above the hole with the body in th eright spot (vac adv can about 45° to the front of straight to the pass side) and the shaft turned where the rotor points about 15 - 20° to the front of straight to the driver's side; and drop it in. As the gear teeth engage the rotor will turn. It will engage the OP drive rod and drop the rest of the way in. The rotor should be pointing a little to the driver's side of straight to the front. Then, turn the dist body clockwise until the vac can hits the valve cover; pull up on the dist shaft, and rotate it CCW against the teeth as hard as you can to take up the play there; rotate the body CCW until the star wheel teeth just almost line up; and tighten the bolt untill the dist is firmly held in place but you can still turn it. Put the rotor, cap, & wires on; wires will be in the order 18436572 clockwise starting at the terminal just to the driver's side of straight ahead. Note that 6 of the 8 wires will already be on the side they belong on, minimizing the steel wool effect on their routing. Wire 2 should cross from left to right in front of the dist, and wire 3 should cross the other way behind it. It should start up and run perfect and the timing will be within a few degrees of where you had the crank set.