Has anyone had an exploding air box using an MSD unit?

[Reiver]

Just a query as I'm guessing the stronger/extended spark would help in alleviating that episode.
My factory CD box is fine but am thinking of upgrading as sooner/later that will have to happen.
That and Bosch black coils are in short supply.

[timmy2]

Can't comment on the MSD CDI as mine is working fine and I have a spare just in case it goes out and I need to repair it.
If your black coil goes out, the MSD Blaster II coil is a great replacement. Been running strong in my car for 2+ years.

[JohnJL]

i am not sure the msd and exploding areboxes are linked in any direction. the airboxes blow when starting from cold (usually) due to the stagnant air in the intake behind the filter becoming saturated with gasoline vapor. any spark'll do in those conditions.

[pors1968]

Had a MSD on 3L for 10years no problem .Have pop up valve and make sure is not to lean on cold start.

[psalt]

a query as I'm guessing the stronger/extended spark would help in alleviating that episode.


The airbox issue was a fuel mixture problem, not an ignition problem. It is not caused by sparks. The factory's solution was a distribution rail for the CSV and if the engine is tuned properly with no vacuum leaks, it is rarely an issue.

[moneymanager]

If the longer spark should help it didn't help me. I've lost two boxes with an MSD in place. Get the valve. It will help, though it isn't a 100% solution.

[Reiver]

Thanks, I'd read somewhere in the forum of someone stating a weak spark may be a partial cause.

[dicklague]

I am not sure it will help the airbox problem. You will certainly get better spark and multiple spark that should help overall running. And you have the added benefit of a rev limiter that is better than the Bosch rotor one.

I assume the MSDs work well. My experience is with a Daytona- Sensors CD-1 that comes with a matching coil and is well built with PLENTY of power. I like mine a lot and it has made a HUGE difference on my MFI 2.7.

Better idle, revs a lot better and just works so much better. My bench mark is driving the 911 with the Bosch for 100,000+ miles and comparing that to how it works now.

[pors1968]

What year is your airbox .the worst one are the first 73-75 they havent distribution rail inside.

[wwest]

Originally Posted by pors1968

What year is your airbox .the worst one are the first 73-75 they havent distribution rail inside.

my '78 didn't have the distribution rail...

[pors1968]

You should or it reseal and they take it out .It a the one whith big runner.

[timmy2]

I remember reading the distribution rail was added in the early '80's. They are in all replacement air boxes. My original '78 airbox doesn't have one.

[mysocal911]

Originally Posted by timmy2

Can't comment on the MSD CDI as mine is working fine and I have a spare just in case it goes out and I need to repair it.
If your black coil goes out, the MSD Blaster II coil is a great replacement. Been running strong in my car for 2+ years.

Or the Bosch blue coil.

[tirwin]

Thanks, I'd read somewhere in the forum of someone stating a weak spark may be a partial cause.

All I can share is my personal experience with weak spark. When I first bought my '83 I knew jack squat about how the car SHOULD run. The first time I ever sat in the car and started it, it cranked, sputtered and died. The PO told me I had to feather the gas a little bit on startup (wrong - you shouldn't have to do that). Tried again and BANG, backfire. Learned really fast what the pop-off valve is for.

One of the first things I did was change the plugs, plug wires, cap, rotor and oil change. Bought Clewett wires. Just changing those things made a HUGE difference. The rough starting problems were mostly cured. The rest was fuel pressures (WUR adjustment), hooking the O2 sensor back up and adjusting the basic mixture (it was too lean).

Point is that poor spark can be ONE factor, but it's not the only one.