Spike60
Here For The Long Haul!
- Local time
- 7:59 PM
- User ID
- 835
- Joined
- Feb 8, 2016
- Messages
- 1,919
- Reaction score
- 16,448
- Location
- Ulster County, NY
Gonna try and answer a bunch of questions all at once here. Most of us are fixated on cylinder kits cause you can mess around with them and see what's going on in there. But there is little discussion on the coils. Many guys ask about 372's, but there's some overlap with other models and much confusion about the speed limited coils. It's not just a matter of RPM's with coils. There are different advance and start curves in most of the blue coils that are tailored to whatever saw they are in. Mostly going to cover the 300 series models, because most of these coils will fit in different saws, but sometimes it's not a saw it should be in. Most of the speed limited coils can still be used, but you just need to pay attention. This might get long winded. 
Starting with the 2 non-limited coils that fit most of these saws. Part numbers are very similar. What is different about the coils is there is one for the smaller flywheel saws like the 346-357 along with the 334T top handle family and even the 455/460 Ranchers which are still using it. Part number: 544 047 001. The second is for the 372-390-575/576 larger flywheel saws; 544 047 101. I haven't always paid attention to this, and the slight difference doesn't seem to matter, but you will notice it when setting the gap. These are bootless from the factory, so they all have to be trimmed and have the boot installed.
372 chassis: There's a stupid amount of 372 coils, because the XT coils are different than the OE stuff. Main difference on the blue speed limited coils is that the OE's went to 13,600 and the XT's only go to 13,300. The 365's all have the same coils as the 372's, so even in the case of the 365 Specials that were supposed to rev to 12,500, they never used a lower RPM coil. No problem taking them up to 13,500 with whatever cylinder you put on them. The XT coils went back and forth with digital advance, and different advance and start curves to improve idling and starting. The newest XT coil has a new start curve that eliminates the misfire that you would get with a half hearted pull on the rope and make you think the coil was going bad. Idle and acceleration also seem better. This coil comes with the boot and is the only one I use on these saws now, and it doesn't seem to matter which carb is on the saw, (not the case with some other XT coils). I prefer it on XT's over the black coil. Husky is coming out with coils that will fire at lower RPM's to make starting easier on some saws. (The new 445/450 have a coil that fires at something like 700 RPM vs 1400 on the older version.) Thing you have to watch for when doing a mix and match is the XT uses a longer coil wire for the taller cylinder. The shorter wire from an OE will rub on the cylinder fins and ground out before too long. This can even happen going the other way as you have an extra bit of wire to hide in there. Always snap it into the little slot on the top cover, and be wary of shoving down to where it might get caught in the flywheel.
346 chassis: Big thing to be aware of here is when converting 350's to 346's because the speed limited coils on the later 350's only revved to 13,000. I've seen guys pop a 346 kit on there and then try and tune it up and end up blowing it up. The 346 OE apparently never came with a speed limited coil, but the NE version was limited to 14,100. Otherwise there isn't much to look for here.
357 chassis: Don't think they ever stuck the blue coils in these saws, so there's not much to worry about here either. Coils interchange with the 346 chassis, but again you've got the different plug wire length to deal with.
390: I can't remember if the 385's ever got the blue coils or not, but safe to say the 385's should have a black coil and the 390's will have a blue one; limited to 13,000. 372XT coils should have about the same length wire, and I want to try the new XT coil in one of these saws.
575/576- Blues coils in these saws are limited to 13,300. The deal with this chassis is that the 576AT has it's own coil which is gray in color. The saw will absolutely run like crap without the gray coil.
The 550's and 562's are actually a lot better in the mix and match department. Just about any carb will work with any coil, which is nice of them as they each have about 5 different coils at this point. You just have to plug them into the CST and update the firmware to the proper coil. The one exception here is on the early 562's with the EL44 carb, as those coils operate at 8MHz and the rest are at 14MHz. Probably make for screwy running saw if it ran at all.
OK, I need a break from this.
Starting with the 2 non-limited coils that fit most of these saws. Part numbers are very similar. What is different about the coils is there is one for the smaller flywheel saws like the 346-357 along with the 334T top handle family and even the 455/460 Ranchers which are still using it. Part number: 544 047 001. The second is for the 372-390-575/576 larger flywheel saws; 544 047 101. I haven't always paid attention to this, and the slight difference doesn't seem to matter, but you will notice it when setting the gap. These are bootless from the factory, so they all have to be trimmed and have the boot installed.
372 chassis: There's a stupid amount of 372 coils, because the XT coils are different than the OE stuff. Main difference on the blue speed limited coils is that the OE's went to 13,600 and the XT's only go to 13,300. The 365's all have the same coils as the 372's, so even in the case of the 365 Specials that were supposed to rev to 12,500, they never used a lower RPM coil. No problem taking them up to 13,500 with whatever cylinder you put on them. The XT coils went back and forth with digital advance, and different advance and start curves to improve idling and starting. The newest XT coil has a new start curve that eliminates the misfire that you would get with a half hearted pull on the rope and make you think the coil was going bad. Idle and acceleration also seem better. This coil comes with the boot and is the only one I use on these saws now, and it doesn't seem to matter which carb is on the saw, (not the case with some other XT coils). I prefer it on XT's over the black coil. Husky is coming out with coils that will fire at lower RPM's to make starting easier on some saws. (The new 445/450 have a coil that fires at something like 700 RPM vs 1400 on the older version.) Thing you have to watch for when doing a mix and match is the XT uses a longer coil wire for the taller cylinder. The shorter wire from an OE will rub on the cylinder fins and ground out before too long. This can even happen going the other way as you have an extra bit of wire to hide in there. Always snap it into the little slot on the top cover, and be wary of shoving down to where it might get caught in the flywheel.
346 chassis: Big thing to be aware of here is when converting 350's to 346's because the speed limited coils on the later 350's only revved to 13,000. I've seen guys pop a 346 kit on there and then try and tune it up and end up blowing it up. The 346 OE apparently never came with a speed limited coil, but the NE version was limited to 14,100. Otherwise there isn't much to look for here.
357 chassis: Don't think they ever stuck the blue coils in these saws, so there's not much to worry about here either. Coils interchange with the 346 chassis, but again you've got the different plug wire length to deal with.
390: I can't remember if the 385's ever got the blue coils or not, but safe to say the 385's should have a black coil and the 390's will have a blue one; limited to 13,000. 372XT coils should have about the same length wire, and I want to try the new XT coil in one of these saws.
575/576- Blues coils in these saws are limited to 13,300. The deal with this chassis is that the 576AT has it's own coil which is gray in color. The saw will absolutely run like crap without the gray coil.
The 550's and 562's are actually a lot better in the mix and match department. Just about any carb will work with any coil, which is nice of them as they each have about 5 different coils at this point. You just have to plug them into the CST and update the firmware to the proper coil. The one exception here is on the early 562's with the EL44 carb, as those coils operate at 8MHz and the rest are at 14MHz. Probably make for screwy running saw if it ran at all.
OK, I need a break from this.
