Twin plugging 2nd plug position ?

For those who couldn't care less how their 356 left the factory!
Message
Author
User avatar
Nigel Cousins
356 Fan
Posts: 70
Joined: Thu May 29, 2008 7:14 am

Twin plugging 2nd plug position ?

#1 Post by Nigel Cousins »

Hi
I am at the point on my engine project where I am going to machine the heads for the 2nd plug. Having reviewed many posts and photo's there seems to be two options for the plug position. I am looking for feed back on which is the better position.

Option 1
Version 1.tiff
Version 1.tiff (6.8 KiB) Viewed 5742 times

Where the plug exits in between the push rod tube, this would need me to use one of precision matters removable tubes to get out the plug.

or Option 2
Version 2.tiff
Version 2.tiff (7.2 KiB) Viewed 5742 times
Where the plug exits in the centre of the head

Thanks for your time and I look forward to your replies

Nigel

User avatar
Vic Skirmants
Registry Hall of Fame
Posts: 9279
Joined: Tue Oct 27, 2009 5:02 pm
Location: SE Michigan
Contact:

Re: Twin plugging 2nd plug position ?

#2 Post by Vic Skirmants »

A customer once sent me a set of heads for his project that would have required pushrod tube removal to service the bottom plugs. This was before Ron's tubes were available. I refused to use them.

Erik Thomas
356 Fan
Posts: 403
Joined: Thu Jan 14, 2010 4:55 pm
Location: Rhode Island

Re: Twin plugging 2nd plug position ?

#3 Post by Erik Thomas »

I know they used twin plugs on the aircraft engines. I would like to see how they did it there. With modern plugs, they last a long time, so it should not be a massive issue.

Edwin Ek
356 Fan
Posts: 1898
Joined: Sat Jun 21, 2008 11:16 am
Location: Santa Monica, CA

Re: Twin plugging 2nd plug position ?

#4 Post by Edwin Ek »

Erik Thomas wrote:I know they used twin plugs on the aircraft engines. I would like to see how they did it there. With modern plugs, they last a long time, so it should not be a massive issue.
Interested also.
#6386

User avatar
C J Murray
356 Fan
Posts: 9161
Joined: Fri Oct 23, 2009 7:24 pm
Location: 30MI WEST OF PHILA
Contact:

Re: Twin plugging 2nd plug position ?

#5 Post by C J Murray »

Twin plugs, from a performance standpoint, are a waste of time. They are a great addition if you want more places for cracks to start.
'57 Speedster
'59 Sunroof
'60 Devin D Porsche Race Car
'63 Cabriolet "Norm"
'67 911 S Original Owner
'03 Ferrari 575M
'09 Smart Passion

User avatar
Glen Hamner, Jr
356 Fan
Posts: 491
Joined: Thu Mar 27, 2008 4:16 pm
Tag: '63 S/R project, '80 911SC, '11 Cayenne
Location: San Antonio environs, TX
Contact:

Re: Twin plugging 2nd plug position ?

#6 Post by Glen Hamner, Jr »

Hi Nigel,

Normally I would post a personal note but you have not listed your e-mail for such communications. Your interest is valid and has considerable value in improved combustion of the F/A mixture, its will also increase the life of your pistons/rings/cylinders. Have you found the answers you are seeking? If not, drop me a personal note. glen, Boerne, Texas
hamnerhaus@yahoo.com

Conrad Carter
356 Fan
Posts: 436
Joined: Tue Aug 05, 2014 9:54 am
Tag: Let's be careful out there!
Location: Durham, NC

Re: Twin plugging 2nd plug position ?

#7 Post by Conrad Carter »

On modern 2 plug heads aren't plugs located on axis 90 degree from valves centerline and equidistant from this centerline? I.E., neither plug is in center of the combustion chamber. I could be wrong and am NOT an expert on the subject.
Conrad

User avatar
Craig Richter
356 Fan
Posts: 1305
Joined: Thu Dec 15, 2011 9:01 pm
Location: San Miguel de Allende/Traunkirchen

Re: Twin plugging 2nd plug position ?

#8 Post by Craig Richter »

Hello Mr. Hammer,
Please do not be reluctant to post more of your thoughts on twin-plugs here on our forum. Of course silence is your right, and I apologize if my asking is somehow offensive; but many of us old f-r-s are very interested in such theoretical discussions, and we would love to hear more from you.
 

User avatar
C J Murray
356 Fan
Posts: 9161
Joined: Fri Oct 23, 2009 7:24 pm
Location: 30MI WEST OF PHILA
Contact:

Re: Twin plugging 2nd plug position ?

#9 Post by C J Murray »

Craig Richter wrote: Wed Oct 16, 2019 1:57 pm Hello Mr. Hammer,
Please do not be reluctant to post more of your thoughts on twin-plugs here on our forum. Of course silence is your right, and I apologize if my asking is somehow offensive; but many of us old f-r-s are very interested in such theoretical discussions, and we would love to hear more from you.
Craig, what brought on this comment? Of course people should speak freely, on both sides of a point of view. Sometimes that is referred to as "having the courage of your convictions". I find it odd that today some people equate a difference of opinion as "hate speech". Passion is good. Twin plugging is not though.
'57 Speedster
'59 Sunroof
'60 Devin D Porsche Race Car
'63 Cabriolet "Norm"
'67 911 S Original Owner
'03 Ferrari 575M
'09 Smart Passion

User avatar
Martin Benade
356 Fan
Posts: 12181
Joined: Wed Nov 23, 2011 10:52 am
Location: Cleveland, Ohio

Re: Twin plugging 2nd plug position ?

#10 Post by Martin Benade »

Don’t aircraft engines use twin plugs primarily as a backup? On the other hand I remember being on a DC3 as a ten year old and as they warmed it up my father pointed out that they were testing the magnetos. We heard it slow noticeably when they shut off one set of plugs. He was familiar with WW 2 aircraft. If it slowed, maybe the second set of plugs was accomplishing something. My 356 is fine with single plugs however. It was great having a physicist for a father!
Cleveland Ohio
62 Cabriolet
56 VW
02 IS 300
04 Sienna

User avatar
Craig Richter
356 Fan
Posts: 1305
Joined: Thu Dec 15, 2011 9:01 pm
Location: San Miguel de Allende/Traunkirchen

Re: Twin plugging 2nd plug position ?

#11 Post by Craig Richter »

Cliffy, I just wanted to know what Glen has to say. I've known your take on this for a long time, and I used to be a mag-checking pilot, so understand Martin's point. Maybe all this PC stuff is just making me talk weird.
 

Mark Schumacher
356 Fan
Posts: 148
Joined: Wed May 21, 2008 9:15 am

Re: Twin plugging 2nd plug position ?

#12 Post by Mark Schumacher »

Nigel
I have a twin plug engine with heads done by Walt at Competition Engineering. They are drilled similar to your version 2. I can get at the plugs but on the left bank the plugs face forward and are pain to get at. Right bank not as bad. I would opt for version 1 and Ron’s push rod tubes if I did it again.
FWIW, my engine is a 1883cc and has fairly mild compression (9.4:1), .040” deck height, a Elgin 7208 cam. I have run both single plug with a RS0012 distributor and a twin plug “Scorcher” model E4VW from Australia. Both ignitions have advance curves developed by John Benton. Weber IDF40 with 34mm Venturi carbs. Heads massaged by Walt.
I prefer the twin plug. Much better throttle response and seems like flatter torque curve. Blast to drive. This is a seat of pants assessment. I run a few DE events/yr. The twin plug pulls out of the apex stronger. No difference in top speed on the straight. However the twin plug is a PIA. I blew out a lower plug once, probably forgot to tighten it. Had to Timesert the hole. I run heater boxes and it was pain to get that right. More things to go wrong. For me it’s a good trade off as I enjoy working on the car.
I hope this seat of pants assessment helps
Mark

User avatar
Wes Bender
356 Fan
Posts: 4861
Joined: Wed Aug 27, 2008 10:54 am
Location: Somewhere in the Gadsden Purchase, USA

Re: Twin plugging 2nd plug position ?

#13 Post by Wes Bender »

I'm in the Craig/Cliff camp. I wouldn't put twin plugs in my engine, but I'd sure like to know something more definitive about them...... I can understand shortening the burn time in high revving engines, but is that the only benefit? Maybe Ron will chime in with his experience.
Some days it's just not worth chewing through the restraints.....

neil blaber
356 Fan
Posts: 183
Joined: Sat Jun 08, 2013 10:40 pm
Location: melbourne, oz

Re: Twin plugging 2nd plug position ?

#14 Post by neil blaber »

have you spoken to jake raby? pulled from the samba:-

''I built a twin plug 1915 T1 last year for Herbie Blash, Chief Tech Inspector for the FIA (F1) that made 165HP with 155 TQ on pump gas (89 octane) at 11.5:1

He loves the car, it went into a Beck Spyder''

that would have been in 2008, full thread here:- https://www.thesamba.com/vw/forum/viewt ... sc&start=0
instagram - neilblaber

User avatar
C J Murray
356 Fan
Posts: 9161
Joined: Fri Oct 23, 2009 7:24 pm
Location: 30MI WEST OF PHILA
Contact:

Re: Twin plugging 2nd plug position ?

#15 Post by C J Murray »

'57 Speedster
'59 Sunroof
'60 Devin D Porsche Race Car
'63 Cabriolet "Norm"
'67 911 S Original Owner
'03 Ferrari 575M
'09 Smart Passion

Post Reply