454 Vortec Tapping and Knocking

RW22 · February 6, 2019

I have a 1997 k2500 Suburban with the 7.4 vortec. It is a 290,000 mile engine and I was recently doing some work to it. I put new injectors, valve cover and upper intake gaskets, distributor, plugs, wires, and a fuel presssure regulator. This engine was fine before and the only reason I had done this work was because it was cranking for about 5-8 seconds before it would start. When I put everything back together, I got the timing as best as I could (I do not know how to properly time these newer engines) and started it. Immediately, the engine was shuttering and I could hear what sounded like a lifter tap. It was idling very rough and after about 4-5 min a louder knocking sound started up. I immediately cut the engine and checked the oil for metal, and there was none. I am simply baffled at this as I didn’t touch anything when I had the valve covers off. My only two ideas are this. 1) it is not timed right, and I need to figure out how, or 2) the old distributor had some wear on the gear, and possibly the cam has the same wear and isn’t working right with the new distributor. Any help on this would be greatly appreciated. Thanks.

Edited February 6, 2019 by RW22

diyer2 · February 6, 2019

From the info provided and if your mechanical abilities are up to snuf no reason for the knocking.

If it was running right why replace the distributor?

How you expected it to run right without setting the timing correctly after you replaced the distributor is beyond me.

Get the timing set right.

Google it or ask a dealer.

Mikebtte · February 6, 2019

Did you ,ark the distributor and install how it was removed or did you put the engine at TDC and drop the distributor correctly?

You installed new valve cover gaskets. Did you by chance do something that would cause a lifter to tap the valve cover?

SS502 · February 6, 2019

32 minutes ago, diyer2 said:

From the info provided and if your mechanical abilities are up to snuf no reason for the knocking.

If it was running right why replace the distributor?

How you expected it to run right without setting the timing correctly after you replaced the distributor is beyond me.

Get the timing set right.

Google it or ask a dealer.

X2

RW22 · February 6, 2019

50 minutes ago, Mikebtte said:

Did you ,ark the distributor and install how it was removed or did you put the engine at TDC and drop the distributor correctly?

You installed new valve cover gaskets. Did you by chance do something that would cause a lifter to tap the valve cover?

I installed the distributor exactly how I removed it. When it didn’t even start I figured something wasn’t right there. Since I have no scan tool, I pulled the distributor back out and turned it 180 degrees, I made sure the rotor was pointing towards 1 and I also ran a compression test on cylinder 1 to make sure it was firing on 1 and not 6. After that it started up roughly. As for the valve cover, I didn’t touch the rocker arms or anything else in there. All I did was install new gaskets.

Edited February 6, 2019 by RW22

RW22 · February 6, 2019

1 hour ago, diyer2 said:

From the info provided and if your mechanical abilities are up to snuf no reason for the knocking.

If it was running right why replace the distributor?

How you expected it to run right without setting the timing correctly after you replaced the distributor is beyond me.

Get the timing set right.

Google it or ask a dealer.

The reason I replaced the distributor was due to the fact that the gear was badly worn where it meets the cam. I already had the upper intake blown apart and there is no way to do it while the upper intake is on. I’m going to figure out how to properly time it and go from there.