MassMan
1/2 ton status
Happy turkey day! I've been spending my morning tinkering with the K5 and I'm totally stuck.
The Blazer has started to make a distinct popping sound from its passenger side exhaust. It's a true dual, so It's definitely the pass. side bank on the engine. The popping isn't regular, and it tends to happen every couple seconds, often two or three pops in quick succession before pausing (at 750 idle). The popping increases in frequency as the PRM's increase, but it's never regular. Each pop forces a harge puff of air out of the exhaust (the vapor this morning helped). I can barely hear the popping from the engine bay, though it's very loud from the driver's seat. Every time a pop occurs the engine vacuum drops by maybe 1/2 inch Hg. I've also gotten two backfires through the carb while revving the engine. If it helps, I was able to start the thing up this morning (30 degrees, frosted over) without the help of the choke (mechanical, obviously). It always needs the choke, even on a warm day, when starting cold.
I recently added a belt-driven hydraulic pump for my new plow, a trans cooler, a trans temp gauge, and a new oil pan and pump. I set the timing anew after pulling the dist for the oil pump swap. There wasn't any popping the last time I ran the engine, and there haven't been any changes to the engine or exhaust since then, only the trans cooler stuff.
I've reset the timing to 10 degrees. The vacuum on this engine has always been around 15". The vacuum gauge's needle is set in stone at 15" still, only quivering slightly when a pop occurs. The carb's getting 5.5 to 6.5 psi fuel pressure, and it seems to be relatively in tune. I checked the spark with one of those in-line lights and all the plugs on the pass side are getting a nice regular spark. I do see ether a small exhaust leak or some oil burning off the rearmost runner of the passenger header, but it isn't reacting to the popping, so I doubt it's the issue.
I read on some other forums that this could be caused by moisture in the exhaust, but I doubt it. The popping changes immediately with the RPM. It also seems a bit random for a valve or cam issue, but I've never experienced something like that firsthand, so maybe that's it. Any ideas?
The Blazer has started to make a distinct popping sound from its passenger side exhaust. It's a true dual, so It's definitely the pass. side bank on the engine. The popping isn't regular, and it tends to happen every couple seconds, often two or three pops in quick succession before pausing (at 750 idle). The popping increases in frequency as the PRM's increase, but it's never regular. Each pop forces a harge puff of air out of the exhaust (the vapor this morning helped). I can barely hear the popping from the engine bay, though it's very loud from the driver's seat. Every time a pop occurs the engine vacuum drops by maybe 1/2 inch Hg. I've also gotten two backfires through the carb while revving the engine. If it helps, I was able to start the thing up this morning (30 degrees, frosted over) without the help of the choke (mechanical, obviously). It always needs the choke, even on a warm day, when starting cold.
I recently added a belt-driven hydraulic pump for my new plow, a trans cooler, a trans temp gauge, and a new oil pan and pump. I set the timing anew after pulling the dist for the oil pump swap. There wasn't any popping the last time I ran the engine, and there haven't been any changes to the engine or exhaust since then, only the trans cooler stuff.
I've reset the timing to 10 degrees. The vacuum on this engine has always been around 15". The vacuum gauge's needle is set in stone at 15" still, only quivering slightly when a pop occurs. The carb's getting 5.5 to 6.5 psi fuel pressure, and it seems to be relatively in tune. I checked the spark with one of those in-line lights and all the plugs on the pass side are getting a nice regular spark. I do see ether a small exhaust leak or some oil burning off the rearmost runner of the passenger header, but it isn't reacting to the popping, so I doubt it's the issue.
I read on some other forums that this could be caused by moisture in the exhaust, but I doubt it. The popping changes immediately with the RPM. It also seems a bit random for a valve or cam issue, but I've never experienced something like that firsthand, so maybe that's it. Any ideas?
