Topic: spark plug change? going from Points to HEI
in Forum: C3 Engines
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Former Member
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Willow Grove, PA - USA
Joined: 10/27/2006
Posts: 232
Vette(s): 1974 Stingray Coupe LS4 454 Dark Brown Metallic with Deluxe Saddle interior
I am adding a HEI Tach Drive Dist to my 74 to get rid of the points ( yes, keeping the original dist and rebuilding it for future)
74stingray454 2007-02-23 18:40:15
It currently calls for R44t's, does changing the dist to HEI matter in regards to Gap and heat range or is that all determinted due to compression and such?
I was going to keep the R44ts and run the HEI... but I thought I had better ask here and see if there is any sound advice to be had.
thanks fellas, Jim
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Frederick, MD - USA
Joined: 9/8/2003
Posts: 3398
Vette(s): 1969 convertible L71 427/435 4-speed black interior
Keep the same plugs. The HEI gives you a more consistant and reliable spark and consistant timing. Some year HEI systems called for a wider plug gap. I'd check with some custom engine builders if that would be necessary for you. Depending on the year too wide gap may result in pistons hitting the electrode.
Lifetime MemberDuncanville, TX - USA
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Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
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#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
You can run the same plugs, but gap them wider. Instead of .030", gap them at .045" to start with. I've seen specs on HEIs that have the gap at .060" or more, but that's just not needed. .045"-.050" should do the trick. 
You could go to the "extended tip" plugs, if needed, to get the larger gap, but I believe the R44ts plugs will take up to a .050" gap with no problem.
You could go to the "extended tip" plugs, if needed, to get the larger gap, but I believe the R44ts plugs will take up to a .050" gap with no problem.
Joel Adams
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Former Member
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Willow Grove, PA - USA
Joined: 10/27/2006
Posts: 232
Vette(s): 1974 Stingray Coupe LS4 454 Dark Brown Metallic with Deluxe Saddle interior
Thanks Gunslinger and Adam,
74stingray454 2007-02-23 18:59:42
I was looking to run the Delco Rapidfire #10 ( cross references the R44t and R44TX),
I have had a set of Rapidfires in my Monte SS for 4 years and noticed smoother idle and slight better performance since day one... the Rf's have a good vote from me... so I wanted them in my Vette too...
Lifetime MemberDuncanville, TX - USA
Joined: 11/8/2003
Posts: 20213
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
The R44TX is the extended tip plug...
Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
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What is the best HEI system for our cars. I'm sure some are better than others. I have not had any problems with points but HEI sounds like a good idea.
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Frederick, MD - USA
Joined: 9/8/2003
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Vette(s): 1969 convertible L71 427/435 4-speed black interior
There's a number of different things you can do to upgrade your ignition system. You can buy a Pertronix conversion kit that installs in your stock points distributor...it's probably the least expensive way to go.
You can get an aftermarket distributor with tach-drive, but tach-drive units are pretty expensive.
About the only aftermarket distributor I hear people have less than positive things about is the Mallory Unilite...it tends to blowout with voltage spikes.
The Pertronix is probably the easiest and most cost effective way to go. With the savings you can buy an MSD 6 series capacitive discharge ignition box and mount it behind the passenger side of the dash where it can't be seen.
You can get an aftermarket distributor with tach-drive, but tach-drive units are pretty expensive.
About the only aftermarket distributor I hear people have less than positive things about is the Mallory Unilite...it tends to blowout with voltage spikes.
The Pertronix is probably the easiest and most cost effective way to go. With the savings you can buy an MSD 6 series capacitive discharge ignition box and mount it behind the passenger side of the dash where it can't be seen.
I run the Crane XR-1 set up in my Vette. Been in there 4 years, no problems. I did gap my plugs to .040. I run Champion Plugs in everything I own. I do turn some high RPM's too!
Dave
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Willow Grove, PA - USA
Joined: 10/27/2006
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Vette(s): 1974 Stingray Coupe LS4 454 Dark Brown Metallic with Deluxe Saddle interior
I picked up a NEW tach drive HEI dist off eBay from a supplier who says he supplies to Mid American and Ecklers.....
Ill post my impressions as soon as it comes in..
Jim
in Forum: C3 Engines
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