Don't forget when your foot is in it there will be zero slack in the chain even IF it has a 15* deflection as you say. A loose chain will vary timing at an idle NOT at WOT. Will you even notice a diff. in performance with a replacement chain (unless it's REALLY bad) which in my opinion is HIGHLY doubtful. 1st. is do what others & myself have said & DO a health check of the engine. Follow advice & TRY not to over think. Just my humble opinion. Tom T. P.S. A dyno session would probably uncover some of these gremlins your having. Could be $$$ well spent to find some answers before spending $$$$ you just don't have. At one point in time I was 19 also & money didn't fall out of trees, then or now. Just another thought.
So, I'll bite. Sounds like a fuel delivery issue. Maybe everyone is barking up the wrong tree. So, the biggest problem is that the OP did not post the problems that made him decide that he had the solution. If you want an internet solution, you really need to start at the beginning. If I were this person, I would start over from the beginning.
Yeah, using the KISS principal. Keep it simple stupid. You'd be surprised of HOW MANY things are discovered just starting from the beginning with just the basics.
On the KISS front, I'll give you an example that I learned from a few years ago. I had an F150 with a fresh engine, but it always had a terrible intermittent miss at idle. Light throttle, it'd run like a champ, back to idle it'd pop out the exhaust, but not all the time. It also had some pretty stiff brakes, which will come into play in this story later. I did everything I could think of to fix it. Changed plugs, changed wires, changed cap and rotor, ignition module, coil, played with timing, rejetted the carb, compression checked good, leakdown tested at about 8% on all cylinders, blahblahblah....lots of time, lots of money. Finally just accepted it and drove for a year or so like that. Then one day, I decided to take care of the stiff brake pedal and installed a new brake booster. When I removed the old one, I found it had a crack on the seam on the back of it, causing the brake pedal to be stiff. Well, guess what? After that, the truck then ran like a champ with no misses, no hiccups, no anything. All it needed the whole time was for me to find the vacuum leak, which just happened to also be the cause of the stiff pedal because the brake booster was leaking.
What's making me want to do this is driven by wanting more performance. Its a fully street-driven, weekend cruiser stock Riviera with HEI and a dialed Q-jet. Engine is healthy aside for its tendency to stop pulling at 3750, chirps the tires from everything above 2k-4k. Very nice idle, idles at 25mph, 750 in drive. Just picked up a used 219/238 at .050 cam with 109 LSA and matching lifters and will purchase new gaskets/timing set. Hoping to throw that in with the exhaust crossover drilled with a 1/16 hole on each 3/4 freeze plug. Would it be worth it, after checking General engine health, to throw a stage 1 pump on it? I'm on the younger side and trying to figure this out and basically need to ask more questions than I answer.
Put a $12.00 stock fuel pump on it with a clothespin on the choke butterfly and go for a ride. Its either not getting gas or has a bad choke pull off letting the engine suck the choke plate closed at WOT. Then theres issues like a worn pump cam up front, bad vent/collapsing fuel hose at the tank. ws
I will probably start with that, or try to starve the engine of gas with sustained heavy throttle to make sure it is fuel related.
@LARRY70GS I tried to send this in conversation. Pending input of others (though I totally agree with Larry) I will follow this when I put it together right. +4 advanced 219/238 @ .050 109 LSA Scott brown grind
