Just got my rebuilt L48 running. Having issues setting the timing. To get it run right, the timing mark is at about 12 o'clock or about 35-40 * away from where it should be (no vacuum advance hooked up). I set the timing using a vacuum gauge set to highest reading which was only 13-14". No wild cams, just a XE-262. When I connect the vacuum advance to manifold vacuum, the engine dies. The dampener is the same one I took off, and when I assembled the engine, the timing mark lined up with #1 TDC. Seems like I might have a vacuum leak. Disconnected every vacuum line=no change. Sprayed WD-40 around the intake manifold=no change.
I did a compression check before I started it and all cylinders were 160-165 PSI
Where should I look next?

 

walk the sp wires around the clock one position on cap.

 

Pull the left valve cover. Manually rotate the engine until both #1 cylinder valves are closed and the timing mark is at 0 ( Top dead center).

The distributor is now pointing to the #1 spark plug wire. Put the wires on as indicated (proper order) starting with the #1 wire.

If everything else is correct that should solve the issue.

 

Are you 100% sure the timing gears are lined up perfectly and not one tooth off?

 

Your distributor gear could be 180 degrees off .?

 

Did you try rotating distributor and watch the mark move?

 

I think so, but it sure acts like it off.

 

Yes, when I tried to set the timing mark at the proper spot, it won't even run. When I dialed back my timing light to get the mark at TDC, it said 50*.

 

Your distributor is probably off a cog. Not unusual. As stated above, you can find to dead center by pulling the #1 plug, stuff a rag or your thumb against the hole, and have someone turn it over until your thumb blows out the hole. Now pull disti cap and see where the rotor is pointed. Should be approx at #1. If not, move your wires one position.

 

I guess I don't understand how being one tooth off on the dizzy can throw the timing way off. If I rotate the housing so the thing runs, doesn't that do the same thing (just throws the location of the vac advance can off. I just took it for first drive and seems to run well. Lots of power no backfire or popping out the carb. Runs cools at 180* same as thermostat. I am confused

 

Sorry I edited and it didn’t save. As suggested, your wires may be off one position. Double check those - I think No.1 should be at the right edge of the little door on the cap.

 

Sounds as though it runs well enough, but timing marks are off the chart.

WAGs
Regardless of what it seems ... maybe your damper's outer ring has slipped.

Maybe dial-back feature of timing light has failed and is way out of calibration ... won't be the first one to do so. (my WAG top pick for cause)

Maybe timing tab is incorrect or located improperly.

As you assembled motor ... did you verify Piston @ TDC with Damper's Timing Mark @ TDC?

 

motor is blue, a clue it's more likely than not a later HEI piece ... checked OP's profile and seems it's a 79
Points caps have a door/window to adjust gap/dwell ... HEI is not adjustable and no door for use as point-of-reference to locate wires.

 

Hi,
Yes, when I assembled the motor, I verified TDC with the dampener. Right now, it's a little too far advanced since it was slow to crank over cold. I timed it using a vacuum gauge to get highest reading but the most I could get was 13-14" which seems rather low.

 

Correct, HEI dizzy. The #1 wire is where it's suppose to be based on the wire retainer that goes on top the cap. It has the wire numbers molded in.

 

I don't believe the problem lies within the distributor. As the OP says, "to get it to run right", the timing mark is way off. Moving the wires on the cap makes no difference unless the cap cannot rotate anymore due to the vac canister hitting something. So, assuming there is no vacuum leak, either the mark on the balancer has moved or the timing gears are off. Set the #1 piston at TDC by using a dial indicator thru the spark plug hole, or using some sort of piston stop and rotating the engine both ways and marking the balancer where it stops. The middle of these two marks is TDC. This will tell you if the balancer has moved. If not, then I would suspect something is off with the timing gears, BTW, its much easier to rotate the engine with all the plugs out.

 

Are you running solid or hydraulic lifters? Are they adjusted correctly?

 

OK, starting to 2nd guess myself. If I had the dizzy in 180* out would/could the engine even run?

 

Something is definitely wrong and I suspect you may have verified the dampner mark you failed to get it to line up with the timing cover tab when you installed the timing cover. Also did you replace or reinstall the same dampner? Because your timing mark location is now suspect you need to verify #1 @ TDC using a piston stop and that the dampner mark lines up with 0 on the timing tab. Yes it's at least 2 hours work but you can't substitute that verification with internet conversation - you have to get out of your chair and get your hands dirty.

I'm sure you are aware those timing gear marks are for TDC on #6 while for TDC on #1 is with the cam sprocket mark @ 12:00 position.

So let's look at low vacuum. Vacuum is a function of valve overlap while compression pressure is a function of the intake valve closing. Low vacuum could be valves over adjusted that don't fully close. You would see this as a lowered compression pressure from the intake valve closing late as a compression loss and a leak into the intake manifold. If the exhaust valve doesn't seat compression pressure would be lowered as it becomes a leak into the exhaust manifold. You can hear this if you pressurize the cylinder as in a leak down test. You can also tape over your intake entries and use soapy water to observe leaks all the way from a pressurized cylinder.

Last resort you could loosen the intake valve rocker arms and pressurize with a sealed carb (taped) checking for leaks with soapy water. Or you could loosen all the rocker arms and check each cylinder for leaks one at a time. But I would refrain from doing this on a new rebuild motor until fully broken in.

That's enough for now. Good luck and please post your results.

 

I "assume" they are set right. 1/2 turn after zero lash.