simple spark plug question...I think
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Instructor
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From: Boston ma
simple spark plug question...I think
does anyone have any experience or results with the a/c rapid fire plug in hp small block ? I would like to try them in my fuelie if there have been good results. if so which one have you used RF 4 ?or RF 7 ? some sites say there is no application for a hp mid year smallblock running 11-1 pistons
Or does everyone recommend staying with ac 43 or 44's
Thanks
Or does everyone recommend staying with ac 43 or 44's
Thanks
Last edited by fuelie65; Jan 28, 2007 at 03:12 PM.
Team Owner
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From: Greenville, Indiana
does anyone have any experience or results with the a/c rapid fire plug in hp small block ? I would like to try them in my fuelie if there has been good results. if so which one have you used RF 4 ?or RF 7 ? some sites say there is no application for an hp mid yera smallblock ??? running 11-1 pistons
Or does everyone recommend staying with ac 43 or 44's
Thanks
Or does everyone recommend staying with ac 43 or 44's
Thanks
Maybe this will help:
http://www.acdelco.com/html/faq_plugs.htm
http://www.idavette.net/tech/acplugs.htm
I choose to use AC R45S (or other brand equivalent) in my SBC's. They've worked well for me over the years, especially with the demise of leaded gas. One of them is a '63 fuelie.
If your point ignition would fire the wider gap, it may be of some benefit. I doubt it will do so reliably. Why pay $4 for a plug when you can often get by for less than buck?
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Instructor
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From: Boston ma
Thanks Mike,
I saw one of those site..that is where it showed no application for a 375 hp sb I think you are right on not spending the extra buck...the car only runs about 100 miles a year !!
So you are running a 45 ( hotter plug ) in your fuelie with good results, with these new fuels ?
Steve
I saw one of those site..that is where it showed no application for a 375 hp sb I think you are right on not spending the extra buck...the car only runs about 100 miles a year !!
So you are running a 45 ( hotter plug ) in your fuelie with good results, with these new fuels ?
Steve
Burning Brakes
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From: Corona CA
I happen to really like the Rapid Fire plugs. My car is a 365HP and I think I used the RF#4, but I would have to check and even then if I were you I would install them, then hand turn the motor to be sure you don't smack the electrode. I don't know that they are any longer than other plugs I have run but it pays to be careful.
What I liked about the RF plug was that the motor idled noticeably better. I have tried some un-scientific tests like changing out a week old set of champions (recommended by the maker of my aftermarket ignition) for the RF and found the RF to be smoother. Also my motor was not totally stock with an aftermarket cam that has some idle issues. I can't say they are WORTH IT, but compared to say Gasoline, or synthetic oil paying an extra $20 bucks for plugs once a year didn't seem to be a big issue.
What I liked about the RF plug was that the motor idled noticeably better. I have tried some un-scientific tests like changing out a week old set of champions (recommended by the maker of my aftermarket ignition) for the RF and found the RF to be smoother. Also my motor was not totally stock with an aftermarket cam that has some idle issues. I can't say they are WORTH IT, but compared to say Gasoline, or synthetic oil paying an extra $20 bucks for plugs once a year didn't seem to be a big issue.
Racer
Joined: Feb 2005
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From: coral gables miami
AC R45 is your safest plug with higher compression so as not to close up the gap present with 45S plugs because of the extended tip. The OEM plug of #44 is no longer serviced by AC and a #43 would be too cold for normal service therefore the only logical alternative is the 45 series. High dollar designer spark plugs are just that, "high dollar" and no better than OEM plugs. Just cost more and horsepower does not make any difference. 
Last edited by gofastvette; Jan 28, 2007 at 04:14 PM.
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From: Inverness FL
St. Jude Donor '07
Thanks Mike,
I saw one of those site..that is where it showed no application for a 375 hp sb I think you are right on not spending the extra buck...the car only runs about 100 miles a year !!
So you are running a 45 ( hotter plug ) in your fuelie with good results, with these new fuels ?
Steve
I saw one of those site..that is where it showed no application for a 375 hp sb I think you are right on not spending the extra buck...the car only runs about 100 miles a year !!
So you are running a 45 ( hotter plug ) in your fuelie with good results, with these new fuels ?
Steve
which reminds me to ask; do those of you running Rochester FI notice that there is a fuel wash 'color' change on your sparks plugs? what i mean is, is one side of your plug's porceline a lighter color than the other side?
Bill
Last edited by wmf62; Jan 28, 2007 at 04:18 PM.
Team Owner
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From: Greenville, Indiana
I happen to really like the Rapid Fire plugs. My car is a 365HP and I think I used the RF#4, but I would have to check and even then if I were you I would install them, then hand turn the motor to be sure you don't smack the electrode. I don't know that they are any longer than other plugs I have run but it pays to be careful.
What I liked about the RF plug was that the motor idled noticeably better. I have tried some un-scientific tests like changing out a week old set of champions (recommended by the maker of my aftermarket ignition) for the RF and found the RF to be smoother. Also my motor was not totally stock with an aftermarket cam that has some idle issues. I can't say they are WORTH IT, but compared to say Gasoline, or synthetic oil paying an extra $20 bucks for plugs once a year didn't seem to be a big issue.
What I liked about the RF plug was that the motor idled noticeably better. I have tried some un-scientific tests like changing out a week old set of champions (recommended by the maker of my aftermarket ignition) for the RF and found the RF to be smoother. Also my motor was not totally stock with an aftermarket cam that has some idle issues. I can't say they are WORTH IT, but compared to say Gasoline, or synthetic oil paying an extra $20 bucks for plugs once a year didn't seem to be a big issue.
I admit, I know little more about these plugs than what I've read today. If you are running an aftermarket ignition that will reliably fire fire a plug gap wider than the stock .035, you should notice an improvement in the idle with the Rapid Fire. Stock point ignitions are not designed to fire a .045 gap and it's my understanding that's what their design gap is. If you adjust it down to .035, I'd think you'd lose any performance advantage. I think part of the higher price on these and similar plugs merely represents the increased cost of materials they put in the plug to resist point erosion from a hotter spark than a stock point ignition will deliver. That doesn't mean it will last any longer in your engine. Plugs in carbureted engines usually crapped out because of lead and other deposit fouling, not because of gap wear. Since the gasoline has been cleaned up, gasoline deposits are no longer an issue.
Team Owner
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From: Greenville, Indiana
i'm running the Autolite equivalent of an AC 46 in order to keep some of the deposits burned off.
which reminds me to ask; do those of you running Rochester FI notice that there is a fuel wash 'color' change on your sparks plugs? what i mean is, is one side of your plug's porceline a lighter color than the other side?
Bill
which reminds me to ask; do those of you running Rochester FI notice that there is a fuel wash 'color' change on your sparks plugs? what i mean is, is one side of your plug's porceline a lighter color than the other side?
Bill
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From: Greenville, Indiana
Thanks Mike,
I saw one of those site..that is where it showed no application for a 375 hp sb I think you are right on not spending the extra buck...the car only runs about 100 miles a year !!
So you are running a 45 ( hotter plug ) in your fuelie with good results, with these new fuels ?
Steve
I saw one of those site..that is where it showed no application for a 375 hp sb I think you are right on not spending the extra buck...the car only runs about 100 miles a year !!
So you are running a 45 ( hotter plug ) in your fuelie with good results, with these new fuels ?
Steve
The only problem I have with the ethanol fuel is the same as others. Sometimes on a hot restart, it will blubber and flutter around and then clear out in a few seconds. It's of no consequence to me.
My engine has the .125 dome pistons, .019 deck and the (I think) .038 blue Felpro head gaskets. The heads are stock for the application and not milled. Stock mechanical curve, use the '64 SHP vacuum can hooked to manifold vacuum and 12 degrees intial lead. The car runs fine on 91 octane mid-grade gasoline.
Burning Brakes
Joined: Jun 2005
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From: Hinesville, GA & Oswego, NY
Rapid Fire Plugs
Tried rapid fire plugs on the last tune-up, of my 60, 283, 270hp, ran great for about 3000 miles, then picked up real bad secondary break-up, put the scope on it and it all lead back to the plugs, replaced with a set of R45S plugs and have had no more problems.
Race Director
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From: Taylor Michigan
Horsepower or engine size do not make any difference in sparkplugs. It`s the condidions that they are used in that determines the heat range. As a general rule all early Vettes used AC 44 spark plugs. So did most of the entire line of GM cars. A AC 46 plug was basically a 6 cyl plug of which GM made thousands until the 1955 V8 and then 44`s were used for the 8 cyl`s. The only problem for people now owning those Vettes of yesteryear is that very few individuals can supply that knowledge unless they grew up in those surroundings.
Burning Brakes
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From: fighter pilots make movies, bomber pilots make history
I switched to the RF 7 a couple of years ago. I like the AC 45S very well but its seems the RF 7 is marginally better about clearing deposits
Joe
Joe
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From: Inverness FL
St. Jude Donor '07
Drifting
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From: Allen Park Mi
i bought a stock of AC46 from ebay last year...
i have about 40 plugs that are new in the box...
i installed them in my Z28...my 64Fi, and my dual quad 64 421 superduty pontiac.... after months and miles, they look as new as they did when I put them in.
Jerry bramlett told me that the 46 AC would be the last plug i'd ever have to buy for my GM cars... and so far, he is right on.
io think i have a few 44 and 45... they are all non resistor and have the Green AC logo and green bands.... so not only do they work great (after 40 years) but they look as they should.
if you do an ebay search, you'll probably find them for no more money than a set of rapid fires... and they'll be what should be in your car.
Aaron
i have about 40 plugs that are new in the box...
i installed them in my Z28...my 64Fi, and my dual quad 64 421 superduty pontiac.... after months and miles, they look as new as they did when I put them in.
Jerry bramlett told me that the 46 AC would be the last plug i'd ever have to buy for my GM cars... and so far, he is right on.
io think i have a few 44 and 45... they are all non resistor and have the Green AC logo and green bands.... so not only do they work great (after 40 years) but they look as they should.
if you do an ebay search, you'll probably find them for no more money than a set of rapid fires... and they'll be what should be in your car.
Aaron
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From: Greenville, Indiana
Put a set of extended tips in you engine with a little dab of dum dum on the end. If it's been contacted, that'll tell you your clearance. Or you can just crank it up. That soft tip won't hurt the piston.
Use any major brand with a gap your ignition can jump and a heat range your engine likes and you'll be fine.
Racer
Joined: Feb 2005
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From: coral gables miami
I first heard of this perceived problem in early 1963. A buddy had a '62 fuelie that he said he couldn't run the extended tip in because of piston interference. I think this was just about the time the extended tip was released. Anyway, since then I have run the extended tip plugs in a fair number of domed piston SBC's and haven't had any problem with them hitting.
I heard of many others that have "heard" of problems but I'm still looking for that guy that has had.
That soft tip won't hurt the piston. {this is not the issue}
Use any major brand with a gap your ignition can jump and a heat range your engine likes and you'll be fine.
I heard of many others that have "heard" of problems but I'm still looking for that guy that has had.
That soft tip won't hurt the piston. {this is not the issue}
Use any major brand with a gap your ignition can jump and a heat range your engine likes and you'll be fine.
My initial encounter with the issue was on my 61 FI piece. Not a simple car to replace plugs on. In fact none of the FI Vettes are easy. The GD shielding and air cleaner had to be removed after the car was started and then warmed up for a few moments. The engine got hot, those manifolds are now burning hot and the plug shields cut hands even when the engine is not hot. Too do a job twice under those conditions taught me not to use any suffux "S" plugs ever again in my FI Vettes. I know others have stated that they have used the "S" plug with success, but I only use the single OEM shim for head gaskets as was original. 
Team Owner
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From: Greenville, Indiana
Well you can quit lookin, i`m right here and one of those that has had! My initial encounter with the issue was on my 61 FI piece. Not a simple car to replace plugs on. In fact none of the FI Vettes are easy. The GD shielding and air cleaner had to be removed after the car was started and then warmed up for a few moments. The engine got hot, those manifolds are now burning hot and the plug shields cut hands even when the engine is not hot. Too do a job twice under those conditions taught me not to use any suffux "S" plugs ever again in my FI Vettes. I know others have stated that they have used the "S" plug with success, but I only use the single OEM shim for head gaskets as was original.
My initial encounter with the issue was on my 61 FI piece. Not a simple car to replace plugs on. In fact none of the FI Vettes are easy. The GD shielding and air cleaner had to be removed after the car was started and then warmed up for a few moments. The engine got hot, those manifolds are now burning hot and the plug shields cut hands even when the engine is not hot. Too do a job twice under those conditions taught me not to use any suffux "S" plugs ever again in my FI Vettes. I know others have stated that they have used the "S" plug with success, but I only use the single OEM shim for head gaskets as was original. 
Why do you change plugs on a hot engine?
Melting Slicks
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From: DFW
They hit my pistons (350/327 with steel shim head gaskets). Indexing worked, but too much trouble and I went back to non-S plugs. It was not by much, and I suppose a composite head gasket might make the difference.