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Discussion Starter #1 (Edited)
'73 CORONA 18RC


I was looking into a coil w/o external ballast. I did some research but mostly got info from Rockauto searching and tech people @ NGK. Heres what I found and wanted to run it through here to see if anyone had these experiences.


My application calls for NGK coil #48774 w/ external ballast(external ballast is required so that it reduces the 12V down to 8-9V so it doesn't burn up the points (is this continuous or only when it is started up!..IDK, could find that info). So, here say, says better performance is obtained w/internal ballast, so I found (through NGK techs) NGK coil #48863 has a internal ballast. I'm having a little problem of backfiring while cruising and let up off the gas(no exhaust leak, but it also may be due to valves not closing,timing chain in need of changing)...so taking this one little step at a time.
 

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rock crawler
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I remember having that backfire issue with my 83 like 30 yrs ago, when it had the original 22R in it.
I can't remember for sure what I figured the cause to be, maybe running rich, timing, or an issue with the fuel cutoff solenoid. The 22R has a pointless ignition FWIW.

And I've never had that problem with the 22R in my 84, and don't remember ever having that with the 22R in my 81 Corona.
 

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You say: "may be due to valves not closing". Does this mean you havn't adjusted the valve clearances since you got the vehicle?

spark plug gaps, point dwell angle, and ignition timing must also be set correctly. And distributor cam lobes lightly greased.
 

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Discussion Starter #4 (Edited)
You say: "may be due to valves not closing". Does this mean you havn't adjusted the valve clearances since you got the vehicle? https://www.youtube.com/watch?v=zMaIB0QWpmU

spark plug gaps, point dwell angle, and ignition timing must also be set correctly. And distributor cam lobes lightly greased.

Does this mean you havn't adjusted the valve clearances since you got the vehicle..yep did it.. first time when I got it (7 yrs ago) and then about 3 yrs ago(but they where all in spec so I didn't have to adjust'em


spark plug gaps..NGK #1233 set @ .032
point dwell angle..i have an Old sears dwell meter that still is working good


Timing, well as far as I can tell, because my 18RC Toyota service manual (old 30 yr old green book I have) shows the 2 notches on the crank pully but not the degree, so I assume one is for the TDC (0) (verified) and the other is 7 degrees before TDC, its setting @ 7 and stays steady when adjusting. In "D", with vacuum line pulled and plugged.


When I checked out the timing chain, the guide pad,sprockets and tensioner all were within specs(7 yrs ago). it could be time for a changing though, but IDK..all looked fairly new at the time.
 

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Discussion Starter #5
ok, so heres what I found out :My coil w/ external ballast put out 2.86 Volts to the points..my problem was backfiring when letting of the gas pedal and poor performance when the webers 2nd barrel was engaged(created hesitation)




Replaced that coil with NGK coil #48863 w/ internal ballast, that put out 6.0 Volts to the points...that eliminated 95% of the backfire and when the 2nd barrel was engaged...well....it hauled arse!


I went step by step to eliminate any other problems first (new: plugs,points condenser, cap rotor, plug wires) but found that none of them cured the hesitation and backfire


.
 
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