QuickDart360
Well-Known Member
I am debating whether to run .101 primary jets or .104. 850 thermoquad on a 360 modded motor. Removed choke door/flap. Engine consists of 292 mopar cam. Kb107 pistons, 340 X-heads. 3.91's out back.
Good morning Bewy! I have some 1996 or 1998 metering rods in it now. But I also have a set of 1966 rods and another set of 2005 rods. Which is the best choice?If it came with 98 jets, try 101. As a test, if you get any surging at high speed cruise [ 60 mph or over ], screw IN the screw in the rod hangar, 4 turns. This will richen the cruise without stripping the carb. Reset the screw & go to a larger pri jet.
This combo will almost certainly need three things, because of the cam:
- a lot of timing at idle, up to 40*. Use MVA to add to the static timing. This gets done FIRST.
- increase in IFR, 0.003-5"
- more idle air so that you have 0.020-0.040" of T slot below the blades at idle, in gear. Later TQs have bypass air in the choke air horn that can be enlarged. Earlier models should have the blades drilled; drill the sec blades. Drilling the pri blades encourages nozzle drip because you are pulling more air past the nozzles.
One other detail I forgot to mention is I advanced the cam @ the crank by 4° to get better low end response and it helped. Also my timing is set @ 16° initial and car has been running well like that. This carb that I want to rejet is a carb I bought from a guy on ebay. His name is Steven Sills. He did it well but jetting is different from the old carb I took off. Old car was set up with. 101 jets and .149 rear jets. Also this old carb had the 1966 metering rods. Only reason I took it off was because it started to give too much fuel. Nozzle drip that is. Caused car to stall out after some driving.What I said in post #3 is going to apply, particularly ign timing.
You get the idle timing dialled in first before touching the carb [ centri timing curve & WOT timing comes later.]
Idle timing is realllllllly easy. Set initial to about 12* BTDC, not critical. Disconnect & plug VA. Adjust carb for best idle.
Warm up engine, in gear, engine running/idling, turn dist slowly to advance timing. Idle rpm will increase; keep advancing dist until you get the highest rpm; toggle dist to make sure you have highest rpm. Idle WILL also be smoother. Now check the timing. If it is 45* [ more likely in the 30s ] , then that is what the engine wants for best idle/tip in response/cool running/avoidance of a flat spot. The easiest way to do this is using vac adv connected to manifold vacuum. A dist with an adj vac adv is reqd for this. Most adj VA units have about 30* of travel. So any combination of init + VA can be used to provide the # you got in the test. The reason the rpm increased in the test is because the engine was making more hp from the extra timing.
I suggest you do the above testing & report back with the #s.