tomsbuick Posted July 9, 2017 Share Posted July 9, 2017 ;) Greetings Reatta owners. I realize that in the tutorial there is a section on how to change over the Ignition Coil to AC Delco but i wish to keep the Magnavox. I bought a replacement Magnavox but before installation my question is should there be a thermo gasket (i did not get one) between the unit and the mount heat sink plate? I read also they use a thermo paste between the unit and the plate? I have not taken the old one off yet. I guess it plugs in (spray down with wd-40 at bolts and were it mounts). Any Suggestions? Link to comment Share on other sites More sharing options...
Frogware Posted July 9, 2017 Share Posted July 9, 2017 Interesting...any particular reason you are staying with the stock ICM? Just curious. Link to comment Share on other sites More sharing options...
DAVES89 Posted July 9, 2017 Share Posted July 9, 2017 The mounting plate is the ground. I used sandpaper to clean up the plate then replaced the ignition module/coil pack. No need to do anything else. Link to comment Share on other sites More sharing options...
Ronnie Posted July 9, 2017 Share Posted July 9, 2017 No gasket between the mounting plate and the ICM for sure. I think the paste might be good for heat transfer but I don't recommend it. If I remember correctly the ICM uses the mounting plate as a ground. If so the paste might interfere with that. Just clean the mounting plate really good so you will get good heat transfer from the ICM into the plate. Link to comment Share on other sites More sharing options...
tomsbuick Posted July 17, 2017 Topic Author Share Posted July 17, 2017 On 7/9/2017 at 5:18 PM, tomsbuick said: ;) Greetings Reatta owners. I realize that in the tutorial there is a section on how to change over the Ignition Coil to AC Delco but i wish to keep the Magnavox. I bought a replacement Magnavox but before installation my question is should there be a thermo gasket (i did not get one) between the unit and the mount heat sink plate? I read also they use a thermo paste between the unit and the plate? I have not taken the old one off yet. I guess it plugs in (spray down with wd-40 at bolts and were it mounts). Any Suggestions? I replaced the original coil with a aftermarket Magnavox type but i did some testing with my multimeter and found the secondary coil ohm resistance is different- the original tested 12.9-13. and the new coil tested 6.9. Anyone know if this new coil is safe to use? :huh: Link to comment Share on other sites More sharing options...
retired mechanic74 Posted July 19, 2017 Share Posted July 19, 2017 The coil has a primary and a secondary side. The primary is controlled by battery voltage input, the secondary side is controlled by pulse out puts. If my memory serves me correctly. The ohm of a coil is the controlling factor as to how much electoral charge is sent to the spark plug. The less resistant the hotter the charge, more resistent, the less of a charge. It would seem to me that if you to put more power to the spark plug the sooner it will break down. I myself would stay with the recommended coil, unless of course you plan to race the car at Inde. Link to comment Share on other sites More sharing options...
harry yarnell Posted July 20, 2017 Share Posted July 20, 2017 " the more power to the plug, the sooner it'll break down." What kind of logic is this! Link to comment Share on other sites More sharing options...
retired mechanic74 Posted July 20, 2017 Share Posted July 20, 2017 " the more power to the plug, the sooner it'll break down." What kind of logic is this! It causes more heat to the electrode at the end of the plug. If this wasn't a problem then you wouldn't need any resistance at all. Spark plugs are rated by their heat range get one hot enough and it can burn a hole in the piston. That is a simple explanation and I'm not going to elaborate, but a complete study of Ohm's Law could help to explain it. In other words the specific resistance is there for a reason. Link to comment Share on other sites More sharing options...
DAVES89 Posted July 20, 2017 Share Posted July 20, 2017 Tough crowd... Link to comment Share on other sites More sharing options...
tomsbuick Posted July 20, 2017 Topic Author Share Posted July 20, 2017 Tough crowd... Link to comment Share on other sites More sharing options...
2seater Posted July 21, 2017 Share Posted July 21, 2017 This what the book says regarding the standard coil system: The secondary resistance, across the two terminals, should be 10-13k ohms. I measured the two coilpacks I had handy, the first is installed : 13.2k, 12.9k, 13.12k right on the high limit. The shelf coilpack: 11.85k, 11.85k, 11.74k, pretty well in the middle. I am pretty sure the one on the car came from a vendor at a Buick Grand National event many years ago, billed as "hi-performance" and has approx. 55k miles on it. The other is the take-off from the car with about 70k miles. Now this is just supposition, but perhaps the higher resistance value is due to the number of wire turns in a higher turns ratio coil?? I am by no means knowledgeable on this subject but generally lower resistance allows more current (amperage) to flow. Link to comment Share on other sites More sharing options...
tomsbuick Posted July 21, 2017 Topic Author Share Posted July 21, 2017 Link to comment Share on other sites More sharing options...
Frogware Posted July 24, 2017 Share Posted July 24, 2017 Okay...with all this talk about coils, spark gap, resistance, etc... I am beginning to wonder about my setup. Since I have changed mine out with the newer delco (D555) coils and ICM I have noticed that my acceleration has been a bit sluggish. From a read I found it is suggested that the D555 coils not be used with FI engines, if so long term results could be catastrophic! It was suggested that the D576 coils be used instead, but that may not work for our cars. I am not running any races either, but I want my car to last for as long as possible. I know there isn't much if any actual specifications on these coils other than what Padgett has given us but it would be nice if we had a little more. Say if we decided to change out the ICM what else would we need to change (ie; spark gap)? And is the D576 setup better than the D555 or worse. Anyway if I am asking to much sorry, but at least let me know if I need to change my spark gap or just go back to the Magnavox setup. Thanks! -Scott Link to comment Share on other sites More sharing options...
DAVES89 Posted July 24, 2017 Share Posted July 24, 2017 I use the AC #14 with a .060 gap on AC Delco Ignition Control Module with coils from a 1992 Pontiac Transport with the 3.8 motor. This coil pack set up was used as late as 2006. I will as part of maintenance clean the IAC [idle Air Control], and the MAF [Mass Air Flow] sensor as well as the butterfly and MAF housing. I then use Sea Foam through the plenum. Now on the Red with the rebuilt motor all this was done prior to install so I am probably 50,000 miles away from doing it again. Link to comment Share on other sites More sharing options...
Ronnie Posted July 24, 2017 Share Posted July 24, 2017 The D555 coil is the proper coil for a 1991 Reatta with the 3800 fuel injected engine. The D555 is the correct coil that fits a 1992 Pontiac Transport that is referenced in Padgett's ACDelco Upgrade article. It will work fine in any Reatta engine when paired with a matching ICM. I have ACDelco Rapidfire spark plugs (14s I believe) gapped at .060" but .045" would work without damaging the engine too. I've had it on my '88 model Reatta for about 5 years and it works perfectly. I don't know where you got the information that it wouldn't work properly with a FI engine but I don't agree with that. Bottom line is if you feel better about running the Magnavox system you should stick with it but I feel the Delco setup is superior. Link to comment Share on other sites More sharing options...
Frogware Posted July 24, 2017 Share Posted July 24, 2017 Thanks for the info I really appreciate it. As for the information I made an error, it was from a Camaro forum and upon further reading I mistook the acronym FI as meaning Fuel Injection, but they were referring to Forced Induction/Super Charged. Sorry my bad :( Last month I cleaned the MAF and such but haven't done the Sea Foam, I will do that next to see if that cleans up the acceleration a bit. If that doesn't work maybe I have one of the coils going bad so I may have to check the resistance. Thanks Link to comment Share on other sites More sharing options...
retired mechanic74 Posted July 25, 2017 Share Posted July 25, 2017 Okay...with all this talk about coils, spark gap, resistance, etc... I am beginning to wonder about my setup. Since I have changed mine out with the newer delco (D555) coils and ICM I have noticed that my acceleration has been a bit sluggish. From a read I found it is suggested that the D555 coils not be used with FI engines, if so long term results could be catastrophic! It was suggested that the D576 coils be used instead, but that may not work for our cars. I am not running any races either, but I want my car to last for as long as possible. I know there isn't much if any actual specifications on these coils other than what Padgett has given us but it would be nice if we had a little more. Say if we decided to change out the ICM what else would we need to change (ie; spark gap)? And is the D576 setup better than the D555 or worse. Anyway if I am asking to much sorry, but at least let me know if I need to change my spark gap or just go back to the Magnavox setup. Thanks! -Scott I wouldn't be as concerned with the spark gap as I would be with the heat range of the plug. Standard coil pack standard plugs more likely will get you another 100,000 miles out of the engine. Mine runs fine, and if someone beats me off the line at a light? OK cop will get him instead of me. And plus I get 30 miles to the gal. Link to comment Share on other sites More sharing options...
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