Greetings.
1980, Olds 98. 350 quadrajunk. I've replaced; carb, egr valve, all vacume lines, brake booster/master cylinder, vacume modulator on trans, plugs, wires, cap, rotor, water pump, intake manifold gasket, and prob some other small misc. things. The car has 80,000 miles. I can't seem to get it to stop from hesitating from a stop once it's warmed up. Seems to lag until you push the gas hard enough to open the secondary's on the carb. Also idles a little ruff when warmed up. Exhaust smells like its sucking too much air, almost sweet smell. Any ideas on where to go next ? Thermac system? Trying to keep as original as possible. Any help would be appreciated.

 

What is your timing set at? Have you adjusted the mixture screws? Is it a reman or the factory carb rebuilt? That carb has an adjustable part throttle mixture adjustment. Adjust it up one turn at a time if it still is there, if the above is already adjusted.

 

did you check to see if that exhaust flapper by the doughnut gasket is open they like to rust in the closed position

 

Timing is set to spec. The carb was factory rebuild. I'm hesitant to mess with the fuel mixture screw but I'll give it a shot. Thank you for your reply.

 

I'm sorry I don't know what you mean. Are you speaking of the air filter assembly? Part of that old thermac system in the snorkel? I'm intreaged. Please elaborate. Thank you for your responce.

 

its a heat riser valve located on the drivers side exhaust manifold where the pipe meets if you have one it is either spring loaded or vacuum controlled and it closes to let hot air recirculate back to motor when cold but almost always rusts in the closed position to heavily restrict flow

 

Thanks again. Will check tonight.

 

Check for vacuum leaks as well.

 

What factory? Rebuilt carbs are infamous for needing adjustment (at best) or being completely ruined (at worst). Seriously, unless the carb was rebuilt by one of the handful of enthusiast shops around the country, it is likely junk.