Decided to check my coil with an ohm meter. Primary side was normal. secondary side was 7.8 kohms. Haynes says 8-11 kohms is normal, and if not replace. Went to parts store and checked 2 Standard brand coils with ohm meter and they were exactly the same as my coil........So I guess my coil is ok? Anyone know what the significance is of the secondary side being low like this?
86 F150 302 EFI

 

Can I run a MSD TFI coil with the stock rotor and cap without burning them up prematurely? I'm not looking for a super coil, just one that's a little better than factory. What about the Accel coil? Everthing is bone stock on my truck.
I'm thinking my stock coil with 180,000 miles on it is pooping out when it heats up.

 

You should not have a problem as long as you have a decent set of 8MM wires.. (nothing fancy, just not EL-cheapo).

Watch the teeth on the cap & rotor. If you have a cap&rotor without brass contacts, too much juice will chew them up. I generally get about 15K miles with my Accel Supercoil (with no ballast) and a brass tipped rotor&cap. It would totally destroy a cheap one in a short amount of time.

 

I thought that might be the case. I have new Motorcraft 8mm. But my cap isn't brass, but I think the rotor is. Cap already looks chewed with about 25,000 on it. When you say "no ballast", I'm assuming you mean the multispark box. I didn't want to use this. I just want a little better coil than factory. MSD might be too much. Same as Accel? What about Mallory? And what did you set your spark gap at?
Thanx

 

No ballast means I didn't use that little resistor to drop the coil voltage.

The MSD should be fine. I here Accel is junk from a couple people on this board. I left my gap at stock.. Probably should have increased it a little bit.

 

I used an MSD coil, with the stock cap and rotor. Seemed to have went through plugs faster until I regapped them to .055. This was prior to the "side gapping" I experimented with.

-Kerry

 

Side gapping? I'm intrigued. What is this experiment?

.055 sounds a little big, even with a HO coil. You said prior to doing this you had shorter plug life, how short was it?

I just got a msd blaster tfi coil for my truck, probably put it on tommorow.

 

Side gapping was more popular with people trying to improve performance without spending a mint on "trick" plugs like the bosch+4s or splitfires. The principle is the same: more area open to the air/fuel mix, so you get a more complete burn.

Basically you take a plug, modify the outer "ground" electrode so it sets off to one side (usually accomplished by cutting or grinding). And give it the same gap you would if it were an unmodified plug.

This will make you go through plugs even if you have a stock coil. The standard plug was designed to shoot straight across the gap, not off to one side, this erodes the center electrode quicker than usual. If you use double platinum plugs for the experiment, you're wasting a good plug. Those plugs are only plated with platinum, so modifying the outer electrode exposes the base metal and causes increased gap erosion that way.

Performance wise I noticed a small gain in mpg, but it was noticeable.... about a mpg consistantly. At what cost, well having to take and regap the plugs every 3,000 miles, and you can only regap these plugs a few times with the outer electrode ground off.

We have a few posts archived here about the side gapping experiment... for a while it was quite popular.

Why .055", well the stock coil on my '82 300 was rated at 32-35KV... probably only putting out 25KV at the end of it's life. I was still gapping them at .042-.046 when I put in the MSD Blaster2 coil, and it was rated at 50-60KV, almost twice of the output of the stock coil. After 5,000 miles of the new coil,and a complete tune-up with hign end parts (but I still consider this stock) that were still shelf bought (no mail or special order, in other words), the autolight platinum plugs were shot. The center electrodes on two of the six cylinders were eroded to the point that the little nub on the end was gone (this is platinum), and a pit had to begun to form on the under side of the outer electrode. That tells me that coil was putting out some juice.

I bought six more plugs, this time I splurged and bought the double platinums, gapped them to .080 to start. After several tanks of gas I finally settled on the .055 and retarded my timing a bit further than stock (12 BTDC vs. stock 6 BTDC). The truck performed well, so I left it things that way.

Then I started with the side gapping again.... back to square one. Now my wife's brother-in-law has the truck and everytime he does a tune up I get a phone call.

-Kerry

 

This would be advancing the timing, not retarding..

 

Thanks Kerry, you really cleared that all up for me.

I put my msd blaster coil on today. So far so good. I only went for a short ride with it but it was running good. I recently put on new wires, cap, rotor, and plugs (autolite, not platnum) all top quality. I'll see how the plugs hold up, if they wear I'll open up the gap. I'm also looking for a MSD box to go along with the coil now, so I'll probably have to open up the gap then.

I don't feel like changing or regapping plugs every 3000 miles, so I think I'll stay away from side gapping.

 

Thanks Bob, this ain't my week... do as I say, not as I speak...

Hope your upgrade works well, Nick.

-Kerry

 

Very interesting. Can't decide on a new stock coil or one a little better. I'm thinking Mallory.

 

I hope I didn't goof-up. I just put a Accell super truck tune up kit on my '86 300 (EEC-IV). That consisted of an Accell cap & rodor, new silicone 8mm spiral wires, Accell spark plugs and an Accell super TFI coil. The truck now runs great - it really needed these new parts.

The goof-up part? I gapped the plugs at .042-.043. Is that too small a gap for the Acell super coil - I belive it's rated at 45,000V.

I don't want to burn up the new Accell plugs.

What do you think?

 

Oscar, Just take your plugs out and re-gap them. Did you also put in the multi-spark box, or just the coil and cap and rotor? What did it set you back in $. And how is much better is it running. I'm thinking about doing the same to my 86 302 efi, but don't want to go with the multi- spark, just coil and cap.
My truck runs good but when it gets hot sounds like almost a miss, but it's not, just rough. Like maybe spark isn't enough.

 

The kit I got was about $100 you can order it from Jegs. It really made a big difference.

The TFI coil I replaced was original (17 yrs and 115K miles) and my cap & wires were about 5 yrs old. So it was really past due for a change. The Accel plugs are a dished electrode design - I am not sure how they will hold up, but they seem like a good plug.

I'll pull the plugs and regap to .048-.049 and that should give a little better spark and keep the plugs from burning up.

I did not do the multi-spark box. My system is the EEC-IV with the module on the distributor and feed back carb.

I have read a lot of bad stuff about the EEC-IV on the forum; but, mine runs very well and I have never had a problem.