Spark plug gap with MSD
 

I have an 87 with MSD ignition and a blaster coil I removed the plugs and they were black so I cleaned them up and want to reinstall them. I know that my car is running rich and will address that too. When I researched the gap I found it should be around .050 I am using the Bosh plugs with the electrode at the side of the center electrode not on top of. When I try to gap the plugs placing the feeler guage between the side and center electrodes the center electrode bends at about .028 and it just does not look right to me. My question is do I use different plugs or gap these at .050 and not worry about the bent electrode? What type of plugs do those that have MSD use? Engine is mostly stock all smog stuff removed B&B Exhaust and as I said MSD K&N air filter
Thanks
Mike

You could phone MSD. I did this for mine when i change mine. I lost the paper i wrote it on... whoops.
They were very helpful. I don't believe it was as large as .050

What would happen if you didn't increase the gap ie. run an MSD with standard plugs?

I have the original instructions from when the PO installed it and it says to start at .040 and increase by .05 till it is tuned right up to .060. It runs good with the standard gap but I am wondering if I am defeating the purpose of the MSD for not using the larger gap

I have Bosch W4CS silver tip plugs gapped to .040" with MSD6AL on my 930 running up to 1.1bar on 93 octane pump gas with WMI and havn't tried a bigger gap.

Works great like that, never missfires and seems to me like the bigger plug gap with fatter CDI spark would give better ignition than the smaller stock gap. That may only be wishful thinking though.

With the expensive OEM Bosch 3dpo plugs you can file the sideways ground electrode down to increase gap but you can't go back to a smaller gap once thats done.

You can get a plug gapper from Summit that not only gaps but aligns and bends the electrode so it has a perfect gap across the face not just at the tip. They are cheap and worth the entry fee.

Also not some plugs with their pointed design are difficult to gap past their preset design.

Start at .05 larger then stock without any other changes. MSD will not clear up a black plug.

Started with NGK-V Power-7-R5671A-7 Gapped at .035...Worked will in the beginning-started missing and one of the plugs-porcelain cracked. :(

Tried (1-step colder than the ngks) Denso-U Groove W24ESR-U- Gap stock out of the box- .028-.030.
Best plug so far for me.

Walt

Wanna930 I have a few different feeler guages wire ones blade ones and the solid circle one bt the side electrode does not move only the center electrode bends which leads me to believe these plugs can only be set at the factory settings. Walt do you use MSD?

Currently have MSD6AL & MSD black expoxy coil...so far so good...

Alot of the guys on the forum have it over .035 and above..with no problems.
My car didn't like it. Constantly get frustrated just to make it drivable and stable at 1bar...(trial & error)

My car has SC-CAMS-7006Turbo, HKS Fuel Enrichment-(safety) ...blah-blah..-top end rebuilt...

Car is just happy with a $1.50 copper plug right out of the box..Nothing else to do.. :)

Walt

The MSD can fire some pretty big gaps, but it really depends on how good of condition the high voltage side of your ignition system is. Remember, a spark will jump the path of least resistance, which could be a bad plug wire, or a carbon tracked cap or rotor. I've used MSD's on several cars and have seen some that wouldn't go past 0.035, and some that would easily go over 0.040.

That said, a 930 with an ignition system in good condition is probably good for 0.035-0.040.

Thanks for all of the help guys I know the plugs that are in there are very expensive so I guess from what I am understanding I do not have to open the gap that much. I will leave it as is clean up the plugs real well and adjust the AFR

So leaving the plugs at their standard gap won't actually damage the plugs it is just not using the spark to it's full potential.

On a different supercharged car I owned with MSD, I gapped the plugs to 0.025".

It ran a lot better than the gap MSD recommended for N/A cars.

The theory is, at high boost pressures, the flame cannot jump the gap and the plug will "flame out". This was so true on my other car when it would bang out at high RPM.

I had MSD on my other car and I had them gapped at 0.045
Going more than that made the spark jump from the wires (they were not brand new)
Apparently MSD does not really like (need) expensive plugs, the regular Bosch ones are perfect for the MSD.