Ken Lally

Fellas- Only 800 mls or so on my new motor, all of the sudden the thing is clacking and backfiring on the lft side. Any ideas what might be the problem? :confused:

Barry's70LT1

If it is a small block, could be a broken rocker arm or push rod.
Not uncommon if you are using stock rockers.

gdh

can you tell us a little more about the symptons, ie when the "clacking" occurs, backfiring can be cause by a number of things ie. a leak in your exhaust system somewhere maybe at your collectors or headers bolts have loosened up a bit. Just need more info on type of motor, compression, gas you are using, heads, is it valve clatter etc.

red76vette

It sounds like your plug wires could be arcing out on the headers or something else, check for clearances and insulate the wires from the headers as best as you can.

Fevre

Might also had a rocker nut back of, had that happen once and it made a bunch of clacking and ran like dog doo.

IETEK

Im with the rocker arm , that is what it sounds like to me


IETEk :iagree:

Les

We need more info, but based on what you've said I agree w/ the valvetrain diagnosis(assuming it's really clacking & it's from the top of the motor). Pull your left side valve cover off & look for damage or loose rocker arms. Let us know what you find & we can give you more help if you need it. Good luck.

Ken Lally

Thanks all! Will pull the valve cover and start from there-

Ken Lally

gdh

make sure you talk to your engine builder to find out what the valve lash was set at, some recommend set to 0 others + 1/4 turn, whatever you do don't overtighten them.

yellow 72

Don't know all the particulars of your motor but it's not uncommon for higher lift cams and stiffer springs to pull pressed in rocker studs out......

Mike :cheers: