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Discussion Starter #1
Hey guys, I’m new here and to forumns in general. I have an 87 f350 with a 460, edelbrock performer intake, and 1411 carb. I rebuilt the carb the other night after a few years since the last good year down. I still had a good hesitation when taking off so I called edelbrock, after getting some basic tuning dialed in and me mentioning the previous owner had installed a 1” and 1/2” carb spacer between the manifold and carb edelbrock said get rid of those immediately. I did, but this manifold had a factory hold on the passenger side next to the carb base for emissions. The spacers I removed had a pipe plug in it to block it off, so I refused the 1/2” spacer and bought an Alan head pipe plug to cap the hole, edelbrock said while you’re at it knock he carbon buildup in that hole down in the intake it’ll just blow out the exhaust.. which if I was using my head I would’ve thought about it having to go through the exhaust valve, etc not just falling out of the header. I got it all together, started it, adjusted idle slightly to 800 rpms, bam. Knocking.. this motors never made a noise before, 35-40 psi warm oil pressure, 50-55 cold, runs great, but knocking sounds like above one of the two back cylinders on the passenger side. I ran some Seafoam through the pcv and carb and oil to see if maybe it was just a little carbon debri needed to break up.. nothing. So before I pull anything back apart I’m hoping someone has some recommendations? I’m assuming that carbon I knocked loose in the manifold emissions hole got down inside of something? Unless my truck just randomly decided after doing a carb rebuild among all the other repairs lately to start having a lifter knock.. any suggestions are appreciated
 

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Yeow.. Depending on how big it was it might have bent a valve or push rod.. Pull a valve cover the check the rockers see if one is extra loose.
good luck
tim
 

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Yeow.. Depending on how big it was it might have bent a valve or push rod.. Pull a valve cover the check the rockers see if one is extra loose. if a valve collapsed on to the chunk it might have stuck to the valve holding it open and gumming it up
good luck
tim
 

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Discussion Starter #4
Hey Tim, I pulled a valve cover (gasket was broken and falling out) but all of the rockers seem right and pushrods seem straight.. assuming stuck exhaust valve? It was real big pieces of carbon buildup. Only a 1/2” hole and I barely touched it with a screwdriver when the carbon fell in the intake through the egr port. One thing I did notice while running it is the plug I put in seemed to be perfectly flat with the top of the spacer but now looking at it with the carb installed it seems like the carb is barely just sitting above it and it did backfire when I revved it earlier while seeing if it ran ok. Do you think a possible vacuum leak could be contributing to any of this? Thanks again
 

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With the valve cover off rotate the motor a little at a time checking movement that the valves and pushrods mocw the same and not exsesively loose when at 0 lash .. When at 0 lash see if you can rotate push rods to see they don't wobble or are bent and to see that the valves are all UP the same height.
Good luck
tim
 
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