Wiped cam lobe, two different heads..

[rprentiss288]

Just a little bit of backstory,
I picked up a 1978 GMC K15 about a month and a half ago. 350/TH350 Went through the basics, new plugs, wires, oil change, coolant, rebuilt the Edelbrock 1405 and put a new spacer on it. (The spacer that the previous owner had on it didn't clear the secondaries and had been driving it around like that.) Rebuilt drive shafts, rear end, had the Mile marker Part time 4wd kit put in the NP203 transfer case. Drove it for a while and noticed a slight tick, pulled valve covers to find the rocker arms were loose. Cold lashed the valves to tighten the loose rocker. (Find base circle on the cam for each cylinder, tighten to slight resistance when spinning push rod then gave it another 1/2 turn). With valve covers off I could see Cyl 4 Exhaust wasn't moving full travel when engine was warmed,I loosened that rocker a 1/4 turn assuming I just over tightened it and it moved less, let it run for a short period of time to try and refill the lifter to no change. Shut it down, let it cool and it actually backfired through carb when I revved it cold. Let it cool, cold lashed CYL4 exhaust again and it runs without backfiring but sounds like it's missing. Compression test checked out fine.

Now, I'm assuming the cam has worn a lobe. I planned on swapping it myself with the engine still in the truck. Before I called Lunati or Comp tech support to help me pick the right cam I checked the head casting #'s to know what I was working with.. This is where it gets interesting. Driver side cyl head is a 3973487x and Passenger side cyl head is a 333882. Both are 76cc heads, both are 1.94/1.50 valves. I was trying to decide if I should leave most of the motor as is and just swap cam and lifters or if I should just totally rebuild the top-end.

Do I need new heads?
Do I need a total rebuild?
Can I just swap cam and lifters or do I need Pushrods/Rocker Arms/Valve Springs etc?
On a scale of 1-10 how dumb is it that there's two different cyl heads?


Thanks

[Fermentedwaste]

Wouldn't think you'd need new heads if it's the one side that seems to have a issue and compression looks good. Start with the cheapest first. On that lifter take out the pushrod roll it on a table see if it has a bow in it. Inspect for significant Wear on that rocker. Could take out that one suspect lifter n check for bad wear on it without removing the heads. It could just be gunked up n stuck. You can take them apart n clean em up make sure pieces don't fly out when you do.  If you don't see nothing take the head off dunno if you have a valve spring compression tool u could take the springs off and see how well the valves moving In That head. Next you could take out the cam n look at it. You can usually get away with just new cam and lifters as long as everything else looks good and make sure the cam doesn't require different spec springs. I've heard of different number heads used together as long as they're the same specs if ur in a pinch and need to.