Plug selection/gap with 327 & MSD...
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Instructor
Joined: Apr 2004
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From: Mansfield Ohio
Plug selection/gap with 327 & MSD 6AL...
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.
Last edited by exdrag77; Oct 19, 2004 at 12:47 AM.
Instructor
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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 .
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From: Mansfield Ohio
Originally Posted by 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 .
Racer
Joined: Nov 2001
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From: Huntsville AL
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
YBnormal...drive a vette
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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 .
I run a Mallory Unilite and I run a .035 gap wth my 327 2:02 375hp heads and R45s plugs .
Last edited by 81VetteFreak; Oct 19, 2004 at 09:42 AM.
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Instructor
Joined: Apr 2004
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From: Mansfield Ohio
Originally Posted by 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 .
I run a Mallory Unilite and I run a .035 gap wth my 327 2:02 375hp heads and R45s plugs .
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Instructor
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From: Mansfield Ohio
Originally Posted by 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 .
If you choose to run a wider gap , I would not exceed .045 .
Team Owner
Joined: Apr 1999
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
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
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
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Instructor
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From: Mansfield Ohio
Originally Posted by 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
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
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!
Team Owner
Joined: Apr 1999
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
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.
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.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
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.
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.
