BBC plug life
 

I get about 20 runs out of a set of plugs and then misfiring starts to happen. Usually it starts above 4,000 rpm. When this happens, I replace the plugs and it's perfect for another 19-25 runs. This has been a problem for me with different engine combos and ignitions. I have resisted spending the cash it takes to buy a 7AL, but do I have a choice?
This is a foot brake bracket car, restricted a little to run low 10.0's. Current engine is a 427 BBC, 13.5:1, Chevy OC aluminum head, HEI with performance module and MSD coil. Timing is locked at 39 and retards to about 36. Plugs are currently NGK B5ES, I've tried B7's and B9's. Over the years I've used MSD 6 stuff, with and without crank trigger, HEI's and Accel dual points. I've used lots of plug brands and racing gasses. Different carbs, intakes, compression ratios etc.

I've been lucky this year because it's happened with enough time for me to do a quick plug change and it hasn't cost me a race yet. I can't deal with this anymore. Do I need to just shell out the beans for a 7 series?

Re: BBC plug life
 

Buy a 7AL.

Re: BBC plug life
 

An HEI is simply never going to be reliable above 5500 RPM, maybe lower, depending on parts and application. It may run to 6500 for a while. The best we've ever been able to do was 6500 for a while with an MSD module and coil, and a new GM pick up coil. You may find one in a dozen or so applications that people get away with. There's a difference between something someone is lucky enough to get away with and something that is reliable enough to race trouble free.

We run the same plugs all year with a 7 AL-3, a Pro Power HVC coil, an MSD distributor, and Moroso wires. I use Champion RC12YC plugs, and VP C-12 gas. We put that ignition system on 4 years ago to replace a bunch of Mallory stuff, I think we put a cap and rotor on it last year. We put plugs in it when they look like they're starting to get too much residue on them from the additives.

Re: BBC plug life
 

Do I need the -3 or will the -2 plus be okay? This is a no electronics car.
Can I use the HEI for coil and trigger?

Re: BBC plug life
 

Do not use anything from the HEI system. Please, remember that HEI was designed for a time when 5500 RPM was high RPM, and 300HP was a lot.

Buy an MSD distributor and put the Comp poly gear on it, all your distributor problems will go away. It plugs straight in to your box, no place to have a problem.

The MSD 7AL 3 simply has all of the rev limiter features built in. It has a burnout limiter, a stage limiter, and a high side limiter. If you do not need all of that, then consider a different 7AL.

Get the Pro Power HVC coil, it works great with the 7 series ignitions, without problems.

I've been through all of that. We fought the "mix and match" ignition BS for a year, then we took all of the crap off, put a complete MSD system on, and we do not worry about ignition problems anymore. Put in a matched integrated system one time, and be done with it all. No compatibility issues, no guessing, just race. It's a great feeling.

Re: BBC plug life
 

Alan is correct. We have run the same setup for nearly 10 years now. Replaced the distributor once because of a horrendous engine failure but other than that, cap, rotor, and plug wires every year. And usually about 100 runs on the spark plugs, changed out of guilt, lol.

Re: BBC plug life
 

This ignition will be about a grand when we're all done. It might take me a while to round up that much. I guess if I want to dance to the music I'll have to pay the piper.
I'm not thrilled with the Comp gear idea. I had one in my hand a while back and it made me shiver. Then I called Chris at Comp and he told me they have had some failures with it, but not many. I sent it back to Jegs.
I filed a little groove in the HEI housing to keep the gear lubricated. I know the MSD's have an O ring to seal up the distributor. Do you guys modify that at all?

Re: BBC plug life
 

Nope, I don't modify anything. And the Comp gear in the car has been in the car for at least 3 years. We carry a spare, but have never used it.

If you're convinced that you're never going to need 3 RPM limiters, then don't buy the 7 AL-3.

We've got the same Moroso 40 series wires on the car we've had on for 2-3 years. MSD wires would be fine as well.

Re: BBC plug life
 

At the RPM you are running a 6 AL with the big coil will save you money and do the job. Then there are no questions about No-E or footbrake classes. I have had the best all around luck with the -8 plugs w/ extended tips in BB engines. (when properly jetted) Remember the smaller the number in those plugs the hotter the plug. You could be just burning them up with chamber heat or killing them with heat caused Pre ignition/detonation. A cooler plug is always better to keep from glowing and causing pre ignition.

Re: BBC plug life
 

I ran the B9ES plugs then went to the 7's and just put the 5's in on Friday. I cross the line at about 7200 in good air. Will a 6AL work at that RPM and compression?