Min connecting time at JED?
 

I have a flight arriving at 830pm on Saudia. I need to connect to a Qatar flight at 1015pm on a separate ticket. Is this doable? No checked baggage, only carry on. Both business class if that makes a difference and a US passport.

Just transited through JED but on a through ticket. Should be enough time given the usual subjects IF you are assured to getting the onward flight BP in advance, and the QR flight is from the same terminal. Could be a long walk to the transit point (<1 mn wait last night at ~1830 but JED doesn't get busy until later) and then back to the connecting gate with boarding cut off times, etc. If you have to go landside, you're probably SoL. Just be sure you are eligible for VoA before you even try this.

My experience with JED is that waiting times for transfer (they check your luggage again) are short (say 2 pax in front of you). But with separate tickets you always take that risk that the incoming flight is late, you miss the connection, and then you are on your own with a ticket to Qatar that is invalid since no-show. Must buy a new ticket for a next flight last minute at whatever the price they have, I never was able to connect to airport Wifi in JED and my roaming never properly worked -> if that happens how do you buy a new ticket, they may not allow you to use the direct transfer lane to departures again since you have no ticket anymore, who knows you can only move on > 11 hours waiting which is the maximum time Saudi Arabia allows you being in transit airside, after that you in principle need a transit visa. So indeed, double check you are eligible for VoA (it could even be Saudia refuses to fly you to Jeddah in the first place if your destination with them is JED and you have no way to legally enter the country)).

My experience with on-time performance of SV is very good, so it may work, but think out a plan B just in case that 5% chance on bad luck strikes you.

And indeed, all assuming SV and Qatar use the same new main terminal (likely, but better double check) and you have a BP for the Qatar flight in advance

Looks like both Saudia and Qatar use terminal 1, so I should be okay there. Will just apply for Saudi evisa to make sure there's no hickup.

FWIW, SV's on time performance is helped by low a/c utilisation. The a/c I tracked seem to only fly one round trip per day.

And JED wifi is pretty hopeless. The main airport one requires a SMS OTP code which never came, and it seems you're only allowed 2-3 attempts to get one, and the SV lounge one was hopelessly slow.

You will not be allowed to fly unless you are eligible for VOA or already have visa. Saudia is only required to fly you to Jeddah and is not responsible for your onward connection. If you miss connection for whatever reason and overstay transit time, Saudia will be required to fly you back to your origin and will be probably fined as well for bribing you in without visa.