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MSD 6A w/o increasing plug gap question-

1625 Views 15 Replies 5 Participants Last post by  SyntheticD
My entire ignition system is new and I added a MSD 6A ignition box and coil, Did the Headers, Y-pipe, High flow cat thing.... love it- The question is, If I didnt increase the sparkplug gap what kinda mileage or power am I losing ? Plug gap and timing are stock, if I adjust the gap and timing to the 6 litre tune-up will it effect the smog readout ? I live in california and dont want the F.B.I watching me cause I was trying to have some fun-
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im pretty sure the sixliter upgrade is smog legal, ill have to go back and read the thread again but nobodys ever really brought that up, atleast i havnt read about it yet, i think youll be fine,

the power and MPG increase you will get from the gap and timing bump is noticable, so just give it a shot if you dont like it back the gap and timing down a bit
With the upgrades you have, a increase in plug gap should only increase your mileage, power, and improve emissions. The idea is that the ignition system is making a hotter spark. You can increase the size of that spark and improve the burning of the air/fuel mixture.

Now doing the increase in gap will not suddenly give you 9 sec 1/4 mile times. You may not even notice a difference behind the wheel.
Any power increase I translate to mileage on a truck like this- For power I drive the F-100...... thats POWER-
If you wanna get really technical, no it's not legal to increase plug gap deliberately, as it's a specified measurement on your VECI label. So is ignition timing. But, I wouldn't worry about a ref checking either. Assuming you can have a larger gap AND increase the energy delivered to the spark plug, it should reduce HC levels.

I have a different school of thought on the emission levels vs. the VECI label. Let's assume your vehicle gets 15 mpg and emits 300 ppm HC. How is it any worse if you modify the vehicle, and it gets 17 mpg but emits 330 ppm HC? IMHO, it's not, because you're attaining higher fuel economy AND overall you're actually reducing emissions. The CARB and EPA seem to view it differently, however.
i think theyre just going by increase numbers of ppm HC there sig, i dont think theyll care about increased MPGs:shrug

either way i think you should do it 351w500
Ive seen them check timing- I will at least increase the plug gap....... Does anyone remember what the increase is with the MSD coil and 6a ?
50-55 should work good, you could do the timing and just back it down to 10*btdc before you go for inspection and take it back up to 13-14.5*btdc after you pass, put the plugs at 50-55 and leave em alone
Im gonna do it and just put the timing back at smog time, It seems that keeping the hydrocarbons down is the concern, They dont care if the car gets 2 mpg. I dont see why a MSD 6A is not required on all cars- After my exhaust system was finished, I noticed that with the cats off of the y pipe the '90 bronco exhaust smelled exactly like my '73 ranchero, With the engine still running I slip fitted the cats onto the Y-pipe and the emissions smelled like a new car, just like hot air. Cats do alot and I would not run without them-
deffinetly, the reason vehicle makers dont make their cars really fuel efficeint out of the factory is beyond me:shrug but some think theyre in cahoots with the oil companys to make more money, more efficeint car+less fuel usage=less $$$ for oil companys
No, it's the fact that emissions are still the #1 concern, cars still weigh a goddamn ton or two more than they should, they keep increasing horsepower and engine size despite higher gasoline costs.... it goes on, but in the end it's consumers making poor choices.

Auto manufacturers don't use MSD boxes because they are very unreliable at best, they cost a lot more, they erode spark plugs faster, and don't yield that much benefit over a purely inductive setup. Hell our TFI setups have a maximum 50kV rating. Not to mention that most vehicles now have an ignition coil for each spark plug, with each one independently controlled by the PCM.
i remember a member on here was going through MSD boxes like crazy, hes on like his 3rd or 4th now......who was that??:scratchhe
How many miles should I expect my sparkplugs to last ??? How long do they last on a factory stock '90 351w Bronco anyways ? FWIW my current emissions are, HC are 26 out of a max of 90. -CO is 0.21 of a max of 0.77- NO is 129 of a max of 830. Now with the new exhaust system, Cats, and MSD 6A it might be different- " Post yer smog results" would be a neat therad.....
if your not running too rich change plugs about every 15k as far as gap mine are at .55 on a carbed model and im getting about 10-12 with 32s and a 600cfm holley. MSD makes great ignitions just have to watch the way there installed and always use the anti vibration mounts i have used the same MSD box on 2 vehicles that were DDs for 4 years. without an issue. biggest part of MSD box is Install Location and wiring. keep there wires away from any other wires and watch the battery voltage. under voltage makes them stop working.
To keep the 6A cool I mounted it on the air filter lid, Cut out a section of the upper lid and removed the aluminum plate on the bottom of the 6A and drilled holes in it, Replaced the aluminum plate on the bottom of the 6A and siliconed the 6A to the lid so its air tite, I got the tube off of a truck that allows the air to come from the factory hole beside the drivers headlight, now the 6A gets cool filterd air and any heat that it generates gets pulled into the engine- I MIGHT be able to post pis if anyones interested.
not a bad idea i placed mine on the passenger fender well it never gets hot there plus the pastic helps reduce the vibration from the motor
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