exdrag77

I bought my MSD 6AL off a friend so had no instructions for setting up. After reading a bit, looks like I should be running a larger gap than the stock 327 calls for? I'm using Autolite 303 plugs at .035 gap now since that's what the orig motor called for. If you have a 327 and MSD, what plug/gap are you using? I realize I'll have to find the right heat range for my app but looking for a start point.

81VetteFreak

Take the Autolite out and replace with AC R45 or R46 . Run a .035 gap is my reccomendation . They may have a "S" at the end , cant remember . Been along time since My Ole 327 died for good . Miss the engines badly , best smallblock I ever ran .

exdrag77

From what I read, I thought I need a larger gap with the MSD?

i885744

35 thousanths .035" on your feeler gauge. That combo will run great with an msd. Enjoy it!

Ybnormal

I run .045-.050 with my MSD 6A, the extra juice will jump the gap, no problem. I also ran .035 for years before expermininting with the larger gap and it worked fine also. Play with it and see what works best for your application.

YBnormal...drive a vette

81VetteFreak

The larger the gap , the more stress you put on the Distributor and coil . Keep this in mind when you try the wider gap .

I run a Mallory Unilite and I run a .035 gap wth my 327 2:02 375hp heads and R45s plugs .

exdrag77

But do you run a MSD box? The MSD makes a much higher energy spark so I thought I read the gap should be increased?

81VetteFreak

I dont run a MSD box , I run a Mallory Super coil . The MSD isnt putting out any more than my Mallory does .

If you choose to run a wider gap , I would not exceed .045 .

exdrag77

I assume you mean you run your Mallory Unilite distributor with an Accel Supercoil? If that's the case, the MSD 6AL with a Blaster coil is a different system. Much more intense and longer duration spark (multiple spark). I pulled a wire off the coil one time while running before my ignition switch was connected and had about a 3" spark jump! Never had that happen with the Accel dist and Supercoil I used to run way back. Thanks for the info though and I'll probably just experiment a little!

gkull

First of all a friend would not sell you anolog MSD he would throw it away and tell you all the downfalls of using very old technology with random miss fire and imprecise plug in rev pills.

I run my plug gap at .055 I pulled out a set of plugs once that had erroded to over .070 and still ran fine. You have to run quality spiral wires to keep arcing from happening.

There is a scientific way to figure out optimal plug gap. Dyno, G-Tech meter, or stop watch. stop watch is easy. Drive out to an open space. Set your plug gap to .038. Put your car in second if an auto or 3rd if stick and be driving at say 25 mph or something about 1800 rpm. Just stomp on the gas and time the car to redline or what ever you feel safe.

Get out and regap the plugs to .042 or go up in .004 increments. continue to increase the gap untill you see a decline in performance and then regap your plugs back down.

The best peanut plugs I ever used were Bosche Platium 4 tips. If you want the number I could get it for you. It's all I ever used in my 186 double hump P&P heads

exdrag77

I bought that 6AL about 15 years ago so it was high tech at the time! That would explain the random miss I have at low RPM that I haven't been able to track down. I am now actually learning things about tuning I didn't know when I was 18!

Anyway, I do have a G-Tech RR meter so will have to give your gap selection suggestion a try. Also, if you find the Bosch number you used, that info is also appreciated. Thanks for the help!

gkull

I was just razzing you about MSD 6a or 6al boxes. It's better than not having anything.



I've always bought new ideas in plugs. Like split fire, u-grouve, platinum, 4 tips.

Your standard plugs to me just get to quickly eroded when used with high powered modern ignitions. So platinum or iridium is a requirement.

I have never used a G-tech. It would be a fun to just to get some measurements.

gkull

years ago I had a killer .060 over destroked 350 with a 3.25 forged crank.

It had @210 cc heads with 2.055/1.6 valves, solid cam, single plane, with 750 double pumper, heads milled to 58 cc so with flat tops the compression was 10.8. Set the rev limiter red at 8000 rpm. Good time motor. It saw time in drag racing and in circle track cars.

.060 overbore comes out to about 337 or so ci. I later ran it for a couple of years with a 2X4 tunnel ram with 660 center squirters in a 53 ford pickup street rod. It was still running years after I sold it.