SEARCH SCALEAUTOMAG.COM

Enter keywords or a search phrase below:

Spark Plug Wiring Question

4963 views
24 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    January, 2012
  • From: Oak Creek, Wisconsin
Spark Plug Wiring Question
Posted by fseva on Saturday, April 06, 2013 10:48 AM

I've seen some models that have the plug wires going into the valve covers, but most times, I see the wires going in well below the valve covers into the side of the engine!? It would certainly be the easiest to run them into the valve covers, but most of the time, these are some of the showiest pieces of the engine, and if it isn't really prototypical to send the wires here, that would save having to butcher them. Any suggestions would be appreciated.

Frank

  • Member since
    June, 2012
  • From: Podunkville USA
Posted by gloozalot on Saturday, April 06, 2013 11:12 AM

Fseva, the only time you would send a plug wire to the valve cover would be for a "hemi" engine or that style.  everything else goes into the head.  Google some engine pics and you will see the difference.

To Err is human, to blame it on someone else shows management potential.  

 

 

  • Member since
    January, 2012
  • From: Oak Creek, Wisconsin
Posted by fseva on Saturday, April 06, 2013 5:32 PM

gloozalot

Fseva, the only time you would send a plug wire to the valve cover would be for a "hemi" engine or that style.  everything else goes into the head.  Google some engine pics and you will see the difference.

I have a diecast car here - a '40 Ford hot rod, and the plug wires go into the flat piece at the top of each side of the engine and the "nailheads" are clearly visible everywhere there is no plug wire connection. As I'm pretty sure this isn't a "hemi" type engine, what makes the nailhead similar to a hemi (or that style) so that this breaks the rule? Or are these not considered "valve covers"?

By the way, I did a google search and all I got was companies trying to sell me a wiring "harness", and lots of diagrams but no photos of what you're trying to explain. Since I don't have all day to search for what I'm interested in, perhaps someone else knows where decent photos of fully wired engines can be found???

Frank

  • Member since
    March, 2010
Posted by 70CudaTJ on Saturday, April 06, 2013 7:12 PM

You're probably talking about a V8 flat head or maybe a fancy Ardun OHV conversion flathead, if you're talking about a '40 Ford Hot Rod....that's my guess. Post up a pic?

The "nail heads" are the head bolts/studs.

Frank, Google search "Flathead V8", I just did and got about 1000 images. Or just try "Ford V8...Chev V8....Buick 'Nailhead' V8...etc etc etc

  • Member since
    February, 2010
Posted by ace-garageguy on Sunday, April 07, 2013 8:10 AM

You've got some terminology wrong, first off. A "nailhead" is a nickname for a Buick V8 that has smallish valves, reminiscent of nails, hence "nailhead". The nailhead is identifiable by its vertical, narrow valve covers. Here you can see the exposed plug wires. Some versions of the nailhead have plug-wire covers on the sides of the heads that look like narrower valve covers too.

What you're referring to as a "nailhead" , though perfectly understandable as it looks like it has nails all over it, is in fact a "flathead", meaning that the combustion chamber makes for a head that is flatter INSIDE than an OHV-style engine. Flathead engines do not have valve-covers...the plug wires run to the plugs which are screwed into the cylinder heads.

Mopar Hemi engines are another different design entirely, and DO have large valve covers to enclose the rocker shafts and arms. The plug wires on these run to tubes that run down through the valve cover, and to the plug which screws into the head. The Ardun conversion for flatheads mentioned above used hemi-style heads, and looks rather like the Chrysler Hemi pictured below.

Some versions of this engine will have covers for the plug wires attached to the tops of the valve covers, but the wires run to the same places under the cover as on the photo above.

The best thing you can do is research images for each particular engine you're building, as they are all slightly different and have different wiring and spark-plug placement, due to design differences internally.

Plan your work, work your plan.

Measure twice, post once.

  • Member since
    January, 2012
  • From: Oak Creek, Wisconsin
Posted by fseva on Sunday, April 07, 2013 10:36 AM

ace-garageguy

Thank you so much! You've hit everything I needed to know and I'm very appreciative, especially for the wonderful photos! (I also like the fact that you understand the meaning of "community")

Frank

  • Member since
    January, 2012
  • From: Oak Creek, Wisconsin
Posted by fseva on Sunday, April 07, 2013 10:47 AM

70CudaTJ

I think the problem I was having is asking a general question and then using a specific example of an alternative question. I was really only interested in a simple explanation of where to send my spark plug wires - into the valve covers or the head. It would also help if I had a better general understanding of combustion engines - that'll have to wait until I have the time to devote to it. Thanks!

Frank

  • Member since
    January, 2005
  • From: Cape Coral Florida
Posted by BigTallDad on Monday, April 08, 2013 10:31 AM

fseva

70CudaTJ

I think the problem I was having is asking a general question and then using a specific example of an alternative question. I was really only interested in a simple explanation of where to send my spark plug wires - into the valve covers or the head. It would also help if I had a better general understanding of combustion engines - that'll have to wait until I have the time to devote to it. Thanks!

Without trying to sound like a smartaleck you might want to consider buying one of those "Visible V8" kits.

"In order to teach a dog, you must first be smarter than the dog" P.R. Ferguson

  • Member since
    January, 2012
  • From: Oak Creek, Wisconsin
Posted by fseva on Monday, April 08, 2013 10:39 AM

BigTallDad

Without trying to sound like a smartaleck you might want to consider buying one of those "Visible V8" kits.

That's ok, dad... I've already considered that, but for what I'm really interested in right now, I'll have to save my money and use it to buy car kits and related. I think I can get enough general knowledge of engines by researching them on the web.

Frank

  • Member since
    January, 2005
  • From: Cape Coral Florida
Posted by BigTallDad on Monday, April 08, 2013 1:26 PM

In all honesty, working knowldge of an internal combustion engine (key word there is internal) is not 100% necessary for model purposes. My only suggestion is to avoid what I call the "hair part" approach to plug wires; that's where all the wires on the left side of the distributor cap run to cylinders on the left side of the engine and likewise on the right side. It's sad when a model builder goes that extra step only to do it incorrectly.

Of course there are some engines where order is academic:

those that have the wires exiting the distributor cap via a shroud

those that have the wires running through a tube

Ford flathead V8s did both of the above.

 

 

"In order to teach a dog, you must first be smarter than the dog" P.R. Ferguson

  • Member since
    January, 2012
  • From: Oak Creek, Wisconsin
Posted by fseva on Monday, April 08, 2013 5:35 PM

BigTallDad

In all honesty, working knowldge of an internal combustion engine (key word there is internal) is not 100% necessary for model purposes. My only suggestion is to avoid what I call the "hair part" approach to plug wires; that's where all the wires on the left side of the distributor cap run to cylinders on the left side of the engine and likewise on the right side. It's sad when a model builder goes that extra step only to do it incorrectly.

Whoops! I've been doing it that way because it's so much easier! Promise me you'll never look at my wiring too hard!  Embarrassed

Frank

  • Member since
    November, 2007
Posted by eastown on Wednesday, April 10, 2013 8:40 AM

But then again there is a "Crossfire" dist. cap, where that's exactly how they  come out of the cap, four right side wires to the passenger side, four left side to the drivers side.

 Bob

  • Member since
    January, 2005
  • From: Cape Coral Florida
Posted by BigTallDad on Wednesday, April 10, 2013 2:09 PM

eastown

But then again there is a "Crossfire" dist. cap, where that's exactly how they  come out of the cap, four right side wires to the passenger side, four left side to the drivers side.

 Bob

I believe the crossfire cap is for magnetos, not conventional coil-type ignition.

"In order to teach a dog, you must first be smarter than the dog" P.R. Ferguson

  • Member since
    November, 2006
  • From: Miamisburg, Oh.
Posted by willieman on Wednesday, April 10, 2013 3:18 PM

 I googled the issue, found em, but only for GM HEI .          

Wiliie

Ya gotta stand for something or you'll fall for anything...........

  • Member since
    January, 2005
  • From: Cape Coral Florida
Posted by BigTallDad on Wednesday, April 10, 2013 3:28 PM

The GM HEI (High Energy Ignition) had the coil built into the distributor cap, thus no external wire for the coil. HEI still relied on a firing order, not a hair part. At least that's the way my '76 Gran Prix with HEI was wired (1-8-4-3-6-5-7-2 )

"In order to teach a dog, you must first be smarter than the dog" P.R. Ferguson

  • Member since
    November, 2006
  • From: Miamisburg, Oh.
Posted by willieman on Wednesday, April 10, 2013 3:32 PM

 Check google my friend.

Look for crossfire dist. caps.Cool

Wiliie

Ya gotta stand for something or you'll fall for anything...........

  • Member since
    January, 2012
  • From: Oak Creek, Wisconsin
Posted by fseva on Wednesday, April 10, 2013 4:02 PM

Here's what Queen's Automotive had to say, "Crossfire Distributor Caps are a simple, effective solution for the tangled mess created where the ignition wires are connected to the distributor. By rerouting the connections between the inner and outer terminals, we are able to keep the necessary firing order your engine needs inside while straightening out the spark plug wires outside. This means that your spark plug wires for the left bank of the engine all exit on the left side of the distributor in order, as well as the right side. No spark plug wires cross, ANYWHERE!"

Crossfire Distributor Cap

While the firing order is still the same, it certainly doesn't look like a regular distributor. So, thanks guys for coming to my defense, but that's not the way mine looks!

Wink

Frank

  • Member since
    November, 2006
  • From: Miamisburg, Oh.
Posted by willieman on Wednesday, April 10, 2013 4:15 PM

fseva

Here's what Queen's Automotive had to say, "Crossfire Distributor Caps are a simple, effective solution for the tangled mess created where the ignition wires are connected to the distributor. By rerouting the connections between the inner and outer terminals, we are able to keep the necessary firing order your engine needs inside while straightening out the spark plug wires outside. This means that your spark plug wires for the left bank of the engine all exit on the left side of the distributor in order, as well as the right side. No spark plug wires cross, ANYWHERE!"

Crossfire Distributor Cap

While the firing order is still the same, it certainly doesn't look like a regular distributor. So, thanks guys for coming to my defense, but that's not the way mine looks!

Wink

Same pic I found, but, trust me, "they" made these back in the day, I've seen em.

In the end, it's YOUR model, build it to suit YOU   :)

Wiliie

Ya gotta stand for something or you'll fall for anything...........

  • Member since
    November, 2007
Posted by eastown on Friday, April 12, 2013 9:58 AM

 Purchased one of these "Crossfire" caps 18 months ago. Have two of  them now and they work perfect.

 The second one I have had in use for over twelve years.

 Bob

  • Member since
    March, 2012
Posted by GTX6970 on Friday, April 12, 2013 11:48 AM

How spark plus wires are routed , where the start and where they end depends entirely on the engine your building.

  • Member since
    March, 2008
  • From: roanoke, va
Posted by 2ndtimer on Friday, April 26, 2013 9:47 PM

You've probably already done this. Do a google search for any specific engine (ex: Chevy 409, ford 289, etc). Then click on "image" Lots of photos appear, and you can pick the best ones.

  • Member since
    October, 2010
  • From: Citrus Park, Florida
Posted by Too Old on Saturday, April 27, 2013 8:39 AM

Sorry BTD ,  but such an animal does exist .  This is in Jeg's catalog made by Accel for $45.99 ,  it's called a Corrected Cap .  The old "Crossfire caps had problems and I refused to install them on customer's cars .  I bet Accel fixed the problem and maybe that's part of the reason for the name !

TooOld

A.K.A.  BOB.

" In case of war all rivet counters will be shot ! " - Winston Churchill

  • Member since
    January, 2005
  • From: sunny Sydney, Australia
Posted by nottheband on Saturday, April 27, 2013 6:03 PM

I'm coming in late on this, but thanks everyone for this info, it's beaut to have so many photos and details in one spot.  Great photos ace garageguy, we can never get too many.  Cheers

Steve

  • Member since
    January, 2005
  • From: Cape Coral Florida
Posted by BigTallDad on Saturday, April 27, 2013 7:33 PM

Too Old: Does that "cap" work only for the HEI systems on GMC? Those had the coil as an integral part of the "cap", hence no wire (from the center) to an external coil.

My point is, and regarding the original question, the Crossfire is an exception, rather than the rule.

"In order to teach a dog, you must first be smarter than the dog" P.R. Ferguson

  • Member since
    October, 2010
  • From: Citrus Park, Florida
Posted by Too Old on Sunday, April 28, 2013 7:07 AM

BigTallDad

Too Old: Does that "cap" work only for the HEI systems on GMC? Those had the coil as an integral part of the "cap", hence no wire (from the center) to an external coil.

My point is, and regarding the original question, the Crossfire is an exception, rather than the rule.

BTD ,  You're right ,  they are an exception .  I haven't seen one installed for years and I've never seen one of the Accel caps installed !   It does look pretty nice though ,  I might try one on my current project .

 According to the Jegs catalog it will fit most 1974 - 1990 GM V8's with a HEI distributor .  Accel also has a Corrected Cap for V6's and for standard ( non-HEI ) V8 and V6 distributors .

TooOld

A.K.A.  BOB.

" In case of war all rivet counters will be shot ! " - Winston Churchill

JOIN OUR COMMUNITY!

Our community is FREE to join. To participate you must either login or register for an account.

SEARCH FORUMS

FREE MONTHLY NEWSLETTER
By signing up you may also receive reader surveys and occasional special offers. We do not sell, rent or trade our email lists. View our privacy policy