Hi all, new to the forum here. Sorry if my first post might be a bit of a dumb one

Been having engine trouble recently in my swap (It's a 1979 first gen mazda rx7 with a 350 swap)
Specs are as follows

4 bolt main 350 bored .030 over
L31 vortec heads w/ springs
comp 268H cam
4barrel 600 edelbrock
aluminum intake
shorty headers
world class T5
ford 8.8 rear end
usually spun out to 5500rpm
initial timing around 10 deg.
usually runs 160-185 op temp
91 octane
stock bottom end

Engine has ran fine for years, was out with a buddy tearing around and at around 4k rpm got a very loud backfire and engine immediately died. Would crank fine but made no attempt to start, seemed to be puffing a bit of white smoke on crank but hard to tell. Sounded like it would maybe fire one cylinder every 10ish cranks. Popped some flames out the carb when trying to start. Coolant and oil seemed fine. Temps were fine. Towed home

At home I pulled the plugs, they seemed a bit fouled and flooded but overall in running condition (probably flooded from so many attempts to start). Compression tested and was over 130 on every cylinder. Inspected the head gasket with a bore scope and it was definitely ok. Checked distributor and it was sparking on all of the plugs I tested. Drained oil pan, no metal. Had 6psi fuel pressure and carb was jetting properly. At this point I'm running out of ideas. The only other thing I can thing of would be a slipped timing chain but it SEEMS that cylinder 1 is at TDC on the balancer. Not 100% sure as it's tough to see but I'm fairly certain. I know most people think ignition with stuff like this but it all seems ok.

What's the next step in diagnosing this thing? I was either going to take off the timing cover or pull heads but the distributor shaft is stuck in really tight and doesn't want to come out.

Any and all help is appreciated because I don't have many people locally to bounce questions off of. I can also provide any other info to the best of my abilities.


Thanks in advance, cheers!

 

Found that the rotor was only turning sporadically, and was slipping for a quarter of the rotation. Was stuck pretty good but managed to get it out with some liberal application of penetrating oil; turns out the distributor gear had completely sheared off 3 teeth! Cam gear also doesn't look great. The bolt holding the dist wasn't 100% tightened down, so I think that might've let it slide up and have a bit of play causing mess of metal that I have now. Tonight I'll drop the oil pan and check out the filter and pump, pour some diesel through it to try to clean it out, and then pull the top end apart

Anyone else ever see this happen to a dist gear?

 

Yea, I've seen distributor gears shear, Plenty of times.

If the teeth on the cam are chewed up, you'll just continue tearing up distro gears.

 

Any idea if it's usually caused by play/slippage on the dist or if I should be more worried about cam related stuff? I'm planning a rebuild but my block's already bored .030, so if the concern is cam walk I'll probably start fresh with a new bottom end. Either way it's definitely coming apart because having those gear teeth floating around in there gives me a very bad feeling and at minimum I'll be doing a new cam

 

So the timing cover holds the cam back.

On the last one I saw, the timing cover actually flexed under high load and the cam would walk forward. Assuming yours is from cam walk, its a matter of having the cam buttons the right size