MSD Distributor & Spark Plug Issue
Thread Starter
Instructor
Joined: Jan 2008
Posts: 201
Likes: 0
From: Leroy Township Ohio
MSD Distributor & Spark Plug / Gap Issue
I recently installed an MSD 50K high energy distributor from Summit Racing (not the extremeone but the mid-range decent one for around $175.00) and installed on my 76 L-48. Car has about 80K, had the Rochester carb rebuilt by an excellent shop, installed a dual / no cat's exhaust from CC, and tuned it up pretty well. My question is: I followed the standard recommendations for the stock 350 /1976 which recommends a plug gap of .045". I also like and used the standard AC spark plugs. My question is should I use a different plug to match the new distributor or is the standard AC acceptable and if so, should I gap them at .060" instead of .045"??
Please help. I think the motor is "building up" a little bit / not running correctly and needs some tweeking.
Any thoughts would be great!!
Reddog76
Please help. I think the motor is "building up" a little bit / not running correctly and needs some tweeking.
Any thoughts would be great!!
Reddog76
Last edited by reddog76; Aug 6, 2008 at 03:22 PM. Reason: better description of title
Melting Slicks
Joined: Oct 2002
Posts: 2,317
Likes: 111
From: St Louis MO
Assuming you're talking about the MSD Street Fire distributor, pn 8362, I'd recommend that you set the gap to .060. It will have plenty of kick and will easily fire that gap. If you have a forced induction or very high compression (>11:1), you may want to run a slightly smaller gap.
Thread Starter
Instructor
Joined: Jan 2008
Posts: 201
Likes: 0
From: Leroy Township Ohio
Yes, that is the distributor. This is the stock 350 / L-48 with 8.5 to 1 compression. Do you think I should go to a different plug instead of the recommended stock AC plug? If so, what would be a good plug for the MSD? This is nothing radical, just trying to get a little better performance out of the stock 350.
Do you have an opinion forn the adjustable advance?
It registers approximately 10 full turns for the adjustable advance and for a stock 350, where approximately should the adjustment be? I am around 4 turns out from base setting (turn in clockwise all the way).
Thanks,
Reddog76
Do you have an opinion forn the adjustable advance?
It registers approximately 10 full turns for the adjustable advance and for a stock 350, where approximately should the adjustment be? I am around 4 turns out from base setting (turn in clockwise all the way).
Thanks,
Reddog76
Last edited by reddog76; Aug 7, 2008 at 08:18 AM. Reason: more info
Melting Slicks
Joined: Oct 2002
Posts: 2,317
Likes: 111
From: St Louis MO
Recommended AC plugs are fine.
Check to make sure that the vacuum advance on this engine will supply ~15 crank degrees of advance (there may be an adjustable stop cam to limit the amount of vacuum advance.)
Using a hand vacuum pump, set your vacuum advance to start advancing at ~7 inches of Hg; and to reach full travel at ~15 inches of Hg. Adjust by the turns of the internal screw. (you'll need to test this, I'd hate to guess at the number of turns.)
1. Set your total timing with the vacuum advance disconnected (check this at a high rpm so that the distributor has fully advanced the centrifugal weights) to ~36 degrees BTDC.
2. Select springs such that the maximum centrifugal advance occurs by ~2800 rpm.
3. Reconnect the vacuum advance to full manifold vacuum (works better than ported vacuum).
Have fun!
Check to make sure that the vacuum advance on this engine will supply ~15 crank degrees of advance (there may be an adjustable stop cam to limit the amount of vacuum advance.)
Using a hand vacuum pump, set your vacuum advance to start advancing at ~7 inches of Hg; and to reach full travel at ~15 inches of Hg. Adjust by the turns of the internal screw. (you'll need to test this, I'd hate to guess at the number of turns.)
1. Set your total timing with the vacuum advance disconnected (check this at a high rpm so that the distributor has fully advanced the centrifugal weights) to ~36 degrees BTDC.
2. Select springs such that the maximum centrifugal advance occurs by ~2800 rpm.
3. Reconnect the vacuum advance to full manifold vacuum (works better than ported vacuum).
Have fun!
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
Use a set of AC R45TS spark plugs. These are a tapered seat and correct for a 76 unless the heads have been changed from a 60`s engine. Performance gap is .035. Those wide gaps just dont get it.The parts are new therefore I wouldn`t screw with the distributor just try a little bit more lead and see how it performs.
Tech Contributor
Joined: Jun 2004
Posts: 20,834
Likes: 959
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
And seriously, Mike Ward above has a point (although he could have been a bit more diplomatic). Save your money for the important stuff.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
Melting Slicks
Joined: Mar 2007
Posts: 2,100
Likes: 12
From: Frederick Maryland
The spark plug doesn't know and doesn't care how the spark is generated...points or electronic. All the extra voltage capacity of the bigger coil only comes into effect when something is less than optimum with the plugs or wires. The coil will only put out the minimum voltage necessary to fire the plug. The extra capacity simply gives it the ability to better overcome a worn ignition system.
Since you have an otherwise stock 350, stick with the stock spark plug recommendation as far as application and heat range. You can try a .010 larger spark plug gap and see how it runs. If it runs fine, stick with it, otherwise stick with the factory recommendation.
Since you have an otherwise stock 350, stick with the stock spark plug recommendation as far as application and heat range. You can try a .010 larger spark plug gap and see how it runs. If it runs fine, stick with it, otherwise stick with the factory recommendation.
Thread Starter
Instructor
Joined: Jan 2008
Posts: 201
Likes: 0
From: Leroy Township Ohio
Thanks to all for the replies. I already use the AC R45TS plugs and love AC's these over any standard plug. Just thought I would find out if the "extra" investment of the distributor which is already in the car would benefit from any changes.
Reddog76
Reddog76
8362, distributer, distributor, fire, gap, gaps, ignition, msd, plug, plugs, recommendations, review, spark, street, streetfire
