I'm trying to smooth out the idle on my 74 maverick, 200CI I6 engine. I just bought a dwell meter and it tells me that the dwell is .035. the sticker on the engine says it should be .025. Could this cause slugish acceleration and hesitation on first acceleration? I lowered the idle to 750 RPM like the sticker says and it seems to be too low. I'll try to adjust the dwell, just wanted to know if this is part of the problem. Ok, I am confusing myself I think. Is there a difference between point gap and dwell? The dwell meter was on 35 when i checked it.
AUBMAN82 The point gap should be .027 or 37 to 39 deg. of dwell cam angle. This can be set two differnt ways .1 take a .027 feeler gauge and set the points in dist. with the points rubbing block at the high point of the dist. cam . 2 or use your dwell meter and rotate the engine with the starter motor and set the dwell using a sloted screw driver to move the points untill you get dwell reading of 37 to 39 deg. Also check for side ways play in the dist shaft where the rotor is place to much play will change the dwell . I hope this helps thx jay
Dwell is far more accurate than using feeler gauges. I use the procedure stated above. Dwell will change timing so reset the timing after you set the dwell
Yes there is a big difference between dwell and point gap. The gap on the points (with the cam high point on the rubbing block of the points) should be .017" to .021" regardless of the number of cylinders and the dwell (the number of degrees that the points remain closed) should be higher with the lower the number of cylinders. Correct dwell for a V8 Ford is 28 - 32 degrees (they run best at 28), a six cylinder will use a dwell of 37 to 42 degrees and the four cylinder engines run a dwell of 56 to 64 degrees. The changing dwell actually allows the coil to "charge" to the saturation point at the maximum required RPM and the time between firing is always about the same. If the dwell varies more than 3 degrees at 2000 rpm your distributor needs to be replaced because the bushings are worn. (variation in dwell can also be caused by a worn breaker plate vacuum advance unit) Be sure to check dwell variation with the vacuum advance disconnected and plugged. To smooth out the idle on your 200 is a long process of adjusting carb, timing and dwell. Disconnect the curb idle solenoid. (if so equipped) Set the dwell first and set it toward the low side. Then set your timing. (changing the dwell will change the timing) Now set your idle speed in nuetral to 550-600. (set idle speed with the idle stop screw) Next adjust the idle mixture to get the highest idle speed or vacuum reading you can. Reset your idle speed. Readjust the idle mixture. Keep doing that until you get the idle speed (in nuetral and timed to factory specs) set so that any change in the idle mixture will make the idle drop. Now, adjust the timing so that the car idles at the right speed as set in the specs. (if you have a curb idle solenoid connect it first) For example 600 in drive) Test drive the car when cold until it warms up (about a half hour of driving) if you have drivability problems they will have to be addressed by further tuning. Any change in timing or idle mixture will change the idle speed. Never exceed 12 degrees of initial advance. (rule of thumb which has been broken with good results) Never exceed the factory idle speed because that will cause run-on (dieseling). If you need help with this process get a Haynes manual for your car and follow the steps in it. The Haynes manuals are very good for the enthusiast and do it yourselfers. I have spent over two hours to get the idle set on my wifes 250 inch six . When you get it right lock the adjustment screws in place with some silicone sealer RTV. That way the vibrations of the engine won't change those settings in the week after you get it tuned.
