3hirdgenben

Hello, i have a 83 Camaro with the 305, just finished installing a comp k12-212-2 cam with the the return springs, pushrods and lifters all being replaced, after getting the car running it will run/drive but starts misfiring when at temp and backfires out the carb, i’ve relashing rockers, checked plug gaps (although they are not new plugs) and tried all types of advancing and retarding of timing to no avail, any one have any ideas? where should i start

3hirdgenben

i’ve checked my plug wires and they are in the correct order

NoEmissions84TA

iTrader: (1)

ironwill

Did the cam break-in okay? Any noise from the valvetrain now? Valves lashed correctly?

If obvious things such as firing order (double-check plug wires to cylinders #5 & 7; it's easy to get these two crossed) check out okay, the cam timing is suspect. Are you certain you lined up the marks on the cam & crank gears?

redneckjoe

Check the ignition timing carefully.
Unfortunetly theres has been tons of similar reports as yours lately. Seems like the market is flooded with bad lifters right now, and guys wiping cams out left and right.

3hirdgenben

i did have one of my lifters fail after break in but i replaced and set the proper lash, i’ve had zero noise from the value train and i’m really hoping that failure didn’t grind my cam down any.

NoEmissions84TA

iTrader: (1)

After only 20 minutes of break-in time.

Keep a very close eye on your camshaft lobes. As they get machined away, that shrapnel has to go somewhere.
The reality is …… it goes everywhere - cylinder walls imbedding in the piston skirts, all of your bearings, oil pump, and all of the oil passages.
It does NOT just get trapped inside the oil filter.
Hopefully, you will not be rebuilding in short time.

sofakingdom

iTrader: (1)

Back all the exhaust valve rockers off 1 full turn. Crank it up, see if it's better. Ignore any ticking noises for the moment.

Let's hope it's not a destroyed cam lobe. That's just ... disappointing. All too common in 2021.

If the "lifter" "failed", the cam did too. Again, I hope not, buttt.... reality bites. In the butt sometimes.

Might be worth giving us a little history. Has this motor EVER run right? What work just got done on it? Run across anything strange along the way? And so on.

3hirdgenben

relished the rockers and advanced timing to 12 degrees of spark advance and it fixed the problem no backfires no stalling and no funny busnuess!