Guys let me know if its worth spneding the money to put a higher powerd coil in my daily driver 81 its about 260 hp and just looking for a few ways to get s0me more punch out of it cheaply will it help enough to notice???

Vettehead1963

I would think the coil might make the car slightly more reponsive, maybe. You might be able to gap the plugs a little wider with a stronger coil, but I think the change would be mild at best? Anyone else think so?

If you re-gap your plugs you'll feel a (VERY) little something. If you need to replace the existing coil anyway, spend the extra $5 or $10 for a high energy coil.

John

|UPDATED|5/13/2004 8:08:22 PM (AZT)|/UPDATED|

I have observed a high power coil helping in some situations.. but not all

from my personal observations it appears to help when you run your timing fairly aggressive.. on my 350/350 vette i was able to turn the timing up about 3 more degrees with the hotter coil.. although to be honest I also changed to AC Delco rapid fire plugs at the same time so it may have been a combination of the two.

I ran 10 degrees initial timing with points, 12 with hei, 15 with high output coil..

When I cranked it back down to twelve later trying to debug an intermittent ignition problem (would up being the optical pickup on the mallory unilite, I lost two $100 modules in 3 years.. stay away from them) I noticed it ran less peppy, when I put my old hei coil back in it didnt seem to change.. but the old hei coil wouldnt run at 15 degrees initial.. (i didnt try 13 or 14 to see if the plugs made a diff)

also the gain in performance I noticed when was I nailed the pedal on the highway... with the hei coil it would "clatter" for just a moment when the kickdown engaged at any initial timing above 12.. with the high output I was able to goto 15 without this "clatter" but 16 was too much.

so to summarize..

yes it will help.. but you need to retune your engine to take advantage of it.

i would also recommend that if you do this that you get a good set of wires from either MSD or Taylor..

ive used both.. both are great wires, be prepared to spend 50+ but youll notice a significant difference when you use these as opposed to the $14.99 "auto junk"/"crap boys" special.

Thanks for the Info guys as always I get good advice here and enjoy giving advice when and where I can as well

VETTEHEAD1963

There is a point to consider with a coil. It will put out "X" amount of power. Some power is used to start the spark. This is known as initial KV. (1 KV is 1000 volts). Our stock coils are good for about 40 KV. The power used to start the spark is determined by the resistance of the ignition system. Greater cap, rotor gap, greater plug gap, higher resistance wires, all raise the inital KV. This creates a bit of a hotter spark temp at the plug tips. Don't confuse this with heat range of the plug. Two different things.

Once this takes place, the power left over is what is used to maintain the spark. This accounts for how long the spark last, known as burn time. While spark is being maintained, the level is known as burn KV, which is much lower than initial KV.

If you use 20% of the coil power to start the spark, there is 80% left to maintain the burn, and long burn time can light more fuel. But if the KV levels are too low, this is a very cold spark temp, and may not be hot enough to light the fuel well.

If you use 80% to start the spark, it will light hot and well, but very brief with only 20% to maintain the spark. So the spark goes out too quickly and the fuel does not get completely burned, due to short ignition time.

A stronger coil will allow for both of these to happen at the same time. Always a good thing right? Nope. The stronger coil can overpower the insulation in the ignition system. The result is crossfire and shorts arcing where you don't want them to go. Now the car runs worse instead of better.

The positive is that when you put your foot in it, the cylinder has more resistance due to more compressed air around the spark plug tip. This air pressure really makes a big difference. It can double or triple the Inital KV. So now the stronger coil is necessary to get everything out of the engine.

The answer? A bit stronger can always be better. Too much will hurt you. And too much depends on what you do with the rest of the ignition system. You can go with an entire package and really kick it up with no negatives other than expense. One more caution. Some very high output racing ignition systems don't work well on a street driven car. Their performance is great, but service life very short. You don't want to be redoing your ignition every 1000 miles.

In my personal observations, Accell is good for racing, but not street. MSD is a very good high performance street package. Your results may be different.
You could go with a stock ignition and a slightly stronger coil, and Rapid Fire plugs. This seems to be a good combination. It depends on your engine.

One more note. The distributor rotor in our cars is a weak point. They tend to burn through and short to the distributor shaft. If you use a stronger coil, make sure you have a high quality rotor.

I agree with kens recommendation of MSD for street performance..

but dont forget spark plugs wires..

you can get better performance but you need to upgrade EVERY component that carries the spark..

Exactly.
Wires, cap, rotor, plugs, everything. It has to be a system to operate well.

if you want to treat your baby right..

get an MSD pro-billet distributor (possibly tach drive model.. based on year), MSD or Taylor Spiro Pro wires, MSD blaster SS coil, and an MSD ignition controller and some AC Delco Rapidfire plugs.

itll run you about 550$ for the setup, but you can install some of it piecemeal.

this will make a big difference in how she runs..

it will help your mileage too.

the capacitive ignition is much "quicker" than the stock inductive.

also the MSD distributor comes with 4 different timing limit bushings and 4 sets of springs so you can adjust your timing curve to fit your needs..

if your more concerned with pep than mileage.. you can drop the vacuum advance and set your timing agressively with an offset timing light. the vacuum advance lockout kit comes with some of them and only costs about 5$ by itself.

plus if you have an MSD component go out.. send it in and theyll fix anything with any problem very very cheap.
(ive never had it happen... but thats what I hear)

also, this is a reversible change.. you can take your original parts and put them in storage and change back at any time. the only thing you might have to do is either fabricate a bracket or drill some 1/8" holes on the fenderwell to mount the coil and controller. other than that the installation is a breeze.

I found the best price for this stuff was summit-racing.com

Damn, I love this site!... I may not post much, but I sure learn a lot!