Went to accelerate, then I noticed the carb spitting out the air cleaner and had a engine clunk at 1/2 engine rotation speed. Still hitting, but also spitting out the carb and idled smooth... With the clunk.

I have been looking for motivation/inspiration to test fit my 500 Caddy/4l80 combo
Looks like I have a reason now.

 

Way to have a valvetrain problem!!!!!!! Don't forget to post your 416s in the classifieds.

 

When this happened, i had just worked a 12 hour day. I am now thinking it's nothing more then a slipped timing chain. Might have it torn down by tomorrow evening.

 

I doubt the chain being a tooth off. These mid '80s chains aren't as bad as early 70s chains. They still stretch, but nowhere near as much.

 

they don't stretch, but the garbage plastic teeth still like to shear...

 

Oh yes they do stretch. Dramatically. I've changed them on my own late '83 L69, and my own '91 LO3, among others.

 

sorry, i didn't quite type my whole thought process, lol...what i was meaning to type was "they may not stretch like the 70's chains, but the garbage plastic teeth like to shear more often"

 

ahh, gotcha.

 

I'm not sure why these engines don't have a tensioner, seems like that might be important. Are the teeth really made of plastic?

 

no, they're covered in nylon. And if you use a good aftermarket chain, you don't need a tensioner. I've seen a Manley double roller chain go 90,000 miles and have less than 3 degrees worth of stretch in it after all thaose miles. Similar story with Cloyes Street Roller sets I've used in my own engines.

 

Yanked everything down to the timing chain. I see a double roller in excellant condition
The distributrer is exactly 180 degrees away from #1.
Tomorrow I yank the valve covers and take a peek. I can't imgine what is wrong now. The way the engine was spitting back through the carb, I would have placed a bet on the timing chain. Unless the coil was firing late for some reason.

 

Is the any way the ECM could be causing late firing making the engine spit back up the carb?

•edit• nevermind, I forget about the noise

I think I shall name this engine "Toast"

 

.

 

My expert noob opinion is that a valve seat recessed causing thr pushrod to break. I noticed the top of the valve was higher then the others. Using a straight edge acroff the tops of the valves confirmed it.

Oh,well...time for a late model engine swap

 

i'm in favor of this notion.

 

Unfortunatly, this needs to be done asap as this car is my DD. So this might go carbed out of convience.