There are seven things to check:-
1.If your idle jets are smaller than 65 (0.65 mm) and the car boggs offline, then the first thing to check is the carburation. The progression from idle to the main cicuits chipping in is important with a 38 Weber. They have very small 27 mm throttle venturis, so it has great low end air speed. The cam and carb look like a good choice, but if the carb is wrongly jetted, then that's the first thing to check!
2.If there is lots of compression (10:1) and the cam has 50 thou lift figures under 210 at 50 thou on the exhast, then it most likely won't be a problem. This means the engine has good effective compression. The litmus test for this is how much compression the engine has in psi when cranking. If it's quite high, above 130 and below 185, then its likely to be able to idle quite well.
3. The idle vaccum should be above 15 inches of Hg at about 800-900 rpm. If its 10-15, it'll be lousy, and the cam is too big.
4. Wild cams in a poorer breathing head are not an issue as much as it is with very deap breathing heads. If the air speed is quite high because of small ports and a fairly restrictive intake, then quite wild cams are able to be used. Ford couldn'r use any thing wilder than a 270 degree cam in a 351 Clevleland because the combination of huge ports and a long duration cam made them lousy to drive with poor idle vaccum. 289's and 427's, with fairly small ports, could cope with huge duration cams with autos. Same with your 200. Poor off idle torque (twisting force too low compared to stock) is a function of a big cam with poor air speed. Bigger the ports, lower the air speed.
5. The torque converter may already be fairly loose anyway. As soon as you increase torque, you get a higher stall speed than stock. If a stock 200 with a 252 total duration cam has 160 lb-ft of torque at 2200 rpm, then then a worked 200 with a 272 duration cam may have 205 lb-ft at 3000 rpm. But at 2200 rpm, it'll still have great dollops of low-end torque. It's all to do with the neat thing sixes do that V8's don't. They always like to slog at lower revs more than V8's do.
6. Our sixes have short rods which produce better effective compression. Since the stock I6 has less than 8.5:1 compression to start with, any cam upgrade is often grouped with a compression upgrade. This is whats happened with yours.
7. If you have tuned all the rest of this stuff right, then your only other option is to consider an offset keyway or special cam sprocket and chain to degree the cam back a little. Most stock cams work well were the dots are on the timing teeth. Often, high duration cams need lots of work on getting the timing advanced or retarded by a degree or so. It makes a massive difference to how the car runs at the low-end.
