Strange SBC Issues - Misfire, Knocking, & Timing Too Advanced

[@shootermcgavin2819]

Your rough running problem by the way you described it sounded like you had a hot ember in cylinder 7. A hot ember can be casting flash or debris. Just make sure the piston face is polished and the combustion chamber smoothed as well. Lap those valves in. make sure all gaskets are sealing, could be an air leak. Oh and your bearings are toast. Polish your journals and put new bearings in. Make sure your crankshaft damper is not spun.

[@CarGuyV8]

Thank you for your input.

[@charliejones7574]

Remember to chase out your oil circuits

[@CarGuyV8]

Good advice. I already did that prior to putting the rotating assembly back together. The passages were suprisingly very clean.

[@williamdishon4440]

That stuff in the valley looks liike gaget tack...

[@CarGuyV8]

What is that stuff?

[@charliejones7574]

Check your cam....someone may have put an "out of specs" cam in it

[@CarGuyV8]

Quite possible. I ran the numbers on it but I couldn’t find anything concrete. Looked like some kind of stockish camshaft that wasn’t made by GM just based on the numbers.

[@CarGuyV8]

CWC 8838 were the numbers on it.

[@charliejones7574]

@@CarGuyV8 my Son is having similar problems with a "racing" 350 ..sbc. i'm trying to talk him into swapping that cam out for a std "RV cam", but he only hears what he wants to hear. His timing was running around 30° !! ...while wondering "why his truck was running so poorly"

[@CarGuyV8]

@@charliejones7574 big cams are fun to play around with adequate heads, but with mild or stock heads he’ll be worlds ahead with a good torquey rv style camshaft.

[@jimmccauley9099]

Did you resize the big end of the rod while it was down?

[@CarGuyV8]

No. They were already .030 undersized just like the crankshaft.

[@jimmccauley9099]

Resizing the rod returns the big end to factory spec. Ask your machinist. Good luck.

[@CarGuyV8]

@@jimmccauley9099 Will do. Thanks

[@camd266]

How did the cam timing look?

[@CarGuyV8]

Stockish cam that was dot to dot. That was one of my thoughts too.

[@Shmokingwheels21]

Hey man do you what could be wrong with my idle ? I posted a video and I’m trying to see what’s wrong w my engine but don’t know

[@CarGuyV8]

Is it a fuel injected tbi 350? Hard to tell from the video. Is it surging or are you hitting the gas?

[@Shmokingwheels21]

@@CarGuyV8 no I’m even on the gas peddle it’s idles like that then like 20 mins in driving , I accelerate and she waits then launches hard and after that she just shuts off at stop lights sometimes

[@CarGuyV8]

@@Shmokingwheels21 Sounds like either a vacuum leak, or a sensor is way out of wack

[@Shmokingwheels21]

@@CarGuyV8 do yk what sensor it might be if it ain’t the vacuum leak?

[@CarGuyV8]

@@Shmokingwheels21 IAC or TPS