Were not your HR7 plugs fouled once. NGK plugs only give you one shot, you foul them you throw them. I am a Denso fan.

Yes, they were mostly fuel-fouled with soot traces. I did what I could to clean them on a wire wheel, but they still looked nasty down deep in the insulator pocket.

Frank

I almost think NGK insulators are porous, I have never seen them come back.

A 2.5" exhaust system with a Walker Dynomax turbo muffler was installed this morning...... it has a nice rumble at idle, but gets quite loud when revved. <img src="/forums/images/graemlins/evil.gif" alt="" /> It's not bad inside the cab, but from behind it's much louder than I had hoped it would be. The original catalytic converter was almost completely plugged - maybe age, but probably made worse by running so rich since I installed MS. I need to investigate available mufflers to see if there's a quieter one that will fit AND not restrict flow.

The LC meter arrived - the Diamante coil measures 5.53mH and the Montero coil measures 5.48mH.... so for all practical purposes, the coils are identical, with only the secondary resistance about 5-600 ohms higher on the Montero coil. I'll use the Diamante coil.

If I use 6A as the current, the MS calculator indicates 3.5msec as the desired dwell, so I might need to set it a little higher than the present 3.1msec, depending on what the actual coil current might be. I'll need to figure that out.

Frank

I used to be a Dynomax type and have installed my share of Flowmasters.
The note from the DOHC in my Diamante wagon through a Dynomax sounds like a Honda stretching redline. Common tone up in town. Sounds like ship to my ears.
But the couple of Magnaflow mufflers I have worked with recently have been just about right. I will be installing one on the wagon in the springtime. I have one on my AWD Mirage and it has a wonderful flat note, never whiny or loud. The case on the mufflers is quite stout so welding mounts to then is not an issue.

The shop owner also sells/installs Flowmaster - he thought the Dynomax would be quieter on the truck than the Flowmaster. I had a Flowmaster on a 350 suburban and liked it fine - it had a better note than what I hear from the Dynomax, but then that's a different engine and pipe..... after I get the engine tuned, I may try a Magnaflow if there's a size to fit the space..... it's very tight and won't allow a longer muffler.

Matt at DIY AutoTune has advised me to use 6.5A in the calculator for dwell.... that puts it at 3.9msec.... fairly long. I've read that MS does cut back dwell and spark duration at higher rpms in order to fit both within the available time, so I guess I'll set it at 3.9msec and use the old hand thermometer trick at idle to make sure the coil doesn't get too hot.

Dang - all these mathematical calculators and tools and you still need to have some experience and common sense. <img src="/forums/images/graemlins/lol.gif" alt="" />

Frank

Frank... nice progress <img src="/forums/images/graemlins/kewl.gif" alt="" /> I can't wait to drive it now <img src="/forums/images/graemlins/smile.gif" alt="" />

If you go with a Flowmaster, depending on which one you choose and who is doing the job, change the outlet to the top of the muffler rather than the end of it, kind of like the old Volvo mufflers. This way the pipe can go back right to the axle. If I recall I had a 5 X 9 Flowmaster on my turbo Monti, Do not remember how long but I generally use the longest I can. I angled the inlet and brought the rear up high so it had a straight shot over the axle. Had to add a heat shield over the rear of it. Nice thing about a turbo is the truck only has the cat on it now, still is quiet.

This one sits almost the same as the OE muffler - right under the heat shield next to the shock. I'll try to get some pictures, but it may be a while - should have taken some while it was in the shop today, but didn't have the camera.

Brendan - tomorrow morning it goes on the dyno for a dose of truth serum. <img src="/forums/images/graemlins/wink.gif" alt="" /> I'm still a little anxious about the lack of power on the low end.... hopefully, the tune will help, but I may have to advance the cams and re-tune..... we'll see.

Frank

Magnaflow's have a nice sound. You will have quite a sharp exhaust bark on a s/c motor. I agree with Charlie, my 2.6T with only a gutted cat was very quiet for a straight pipe car. The turbo chops the exhaust pulses up very fine. Magnaflow also has a 3 chamber muffler sort of like a flowmaster now.