Engine Backfires Through Carb

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mr.demon

mr.demon

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I have a brand new built 340 with maybe 3 hours idle time on it. It started backfiring through the carb yesterday. Today we changed break in oil and filter fired up car still backfiring and dying. Pulled valve cover on driver side along with coil wire. Noticed the valve on #1 cylinder (the one on the left wasn't moving). Called my engine builder pretty pissed. He told me to pull the pushrods and see if one was bent. They don't look bent so i put them back in and i noticed i could push the lifter up and down on the left side and the other on was rock solid. Just to verify is the left side exhaust? And would a collapsed lifter on exhaust side cause all my backfiring? Thanks FABO.
 
Yes, where else is the compressed gas going to escape, to other than through the intake valve. Put a new lifter in and I bet you will be fine.
 
So this isn't gonna cost a bunch of time and money lol? Can I pull the lifter out without pulling the head? Looks like it may come out with the rocker shaft taken off.
 
You may be able to just remove the rocker shaft and use a telescopic magnet to fish it out and re insert a new one. But with the intake off and rocker shaft off will be easy. No need to remove the head. My advice is if you buy a new lifter wipe off packing grease with solvent and pre soak the new lifter in oil for a few hours before installation.
 
Time....yes. But with a fresh build i'd be going back to the builder and let him address the situation.
 
I'd follow Rick's advise on this.
If you mess with it, the builder might void any warantee you might have.
 
You must also break in that new lifter. You can wipe some break in grease on the lifter lobe and cam with a brush on a stick.
 
Yes I'll take the car to him tomorrow. He said he would fix it I was just hoping for an easy fix. I'm ready to drive the car lol.
 
I've been reading about alot of failed hyd lifters lately.....guess quality control ain't what it used to be :icon_smi:. Good luck to you on a simple fix.
 
idleing for 3 hrs is not good for a flat tappet cam, especially at break in. might be a flat lobe. The lifter will tell the tale.
 
It wasn't 3 hours solid its over the couse of a couple months. The cam isn't very big i think a 450 lift. It's a pbm cam i believe the rockers are prw 1.5 rollers. I've not heard of these brands but he say's it should be a good combo for low end torque. He's known for building nasty chevy engines. He admitted that my little 340 was a headache to assemble and machine. He says my motor ate through bits more than chevy blocks. Guess mopars are heavier and better cast than chevys lol.
 
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