v6 spark plug gap settings - Alfa Romeo Forum
You are currently unregistered, register for more features.    
 
Thread Tools
(Post Link) post #1 of 14 Old 07-02-10 Thread Starter
Status: No more GTA
AO Silver Member
 
pcbuild2k's Avatar
 
Join Date: Oct 2007
Location: United Kingdom
County: Cheshire
Posts: 1,496

Member car:

156 JTS

v6 spark plug gap settings

i was just looking up spark plugs and gap settings for my car (156 2.5v6)

i was curious to find the settings for PFR6B plugs to be 0.7mm for the 2.5 then just under that was the settings for the gta, same plugs but 0.9mm, i then checked the gt 3.2v6 and that has the same 0.7mm as the 2.5

can anyone shed any light as to the reason for this?

would there be any advantages of using the 0.9mm settings from the gta on 156 2.5 and gt 3.2?

to confuse things more the 3.2 gtv has 0.8mm settings

info from here NGK ALFA ROMEO SPARK PLUGS
pcbuild2k is offline  
Sponsored Links
Advertisement
 
Status: -
AO Platinum Member
 
David C's Avatar
 
Join Date: Aug 2003
Location: London, England
Posts: 29,969
A PFR6B has a 0.7mm gap.

They ARE NOT re-gappable.
If you want a 0.8mm gap, you spec a PFR6B-8.
If you want a 0.9mm gap, you spec a PFR6B-9.

The V6 are spec'd with PFR6B, so all have a 0.7mm gap.
David C is offline  
(Post Link) post #3 of 14 Old 07-02-10 Thread Starter
Status: No more GTA
AO Silver Member
 
pcbuild2k's Avatar
 
Join Date: Oct 2007
Location: United Kingdom
County: Cheshire
Posts: 1,496

Member car:

156 JTS

any idea why the specs for the plug gap are different for the different models?

gt 3.2 gtv 3.2 and gta 3.2 all have different gap settings? why is this?
i could understand if it was just different for the 2.5 and 3.0

does it affect the way the engine performs? would owners of non gta 3.2 engines benefit from the gta gap settings?
pcbuild2k is offline  
newalfisti
Status: - Update
Guest
 
Posts: n/a
Good luck finding the truth, i spent endless hours when i changed mine and nobody has a clue. NGK said that the plugs are not gapped to a spec bu they have a generic gap of 0.8mm and that they CAN be gapped to the correct value for every application(originally they come with a 0.8mm gap the NGK person claimed).
The specialists(they know who they are i won't name them) didn't have a clue what the gap should be. German websites IIRC were saying that 0.7 is the right gap for the GTA and UK site was saying that 0.9mm is the right gap for the GTA.
Having said that i expect that the main difference between 0.7 and 0.9mm gap on a GTA would be the idle quality and emissions and there would be no performance difference.
Alfa romeo had no i
 
Status: zzzzzzzz
AO Platinum Member
 
symon's Avatar
 
Join Date: Dec 2005
Location: United Kingdom
County: Oxfordshire
Posts: 37,068
When I did my plugs, I just removed the old ones had a quick glance at the gaps on the new ones to make sure they looked roughly correct, then I put them in.


The car runs fine.
symon is online now  
Status: -
AO Platinum Member
 
David C's Avatar
 
Join Date: Aug 2003
Location: London, England
Posts: 29,969
Same here.
David C is offline  
Status: zzzzzzzz
AO Platinum Member
 
symon's Avatar
 
Join Date: Dec 2005
Location: United Kingdom
County: Oxfordshire
Posts: 37,068
Well the only reason I checked them visually was in case they had been dropped or something silly.


I didn't want to out the car back together and have a missfire because the plug gap was closed.
symon is online now  
(Post Link) post #8 of 14 Old 08-02-10 Thread Starter
Status: No more GTA
AO Silver Member
 
pcbuild2k's Avatar
 
Join Date: Oct 2007
Location: United Kingdom
County: Cheshire
Posts: 1,496

Member car:

156 JTS

Quote:
Originally Posted by symon View Post
Well the only reason I checked them visually was in case they had been dropped or something silly.
always been somthing i have been concerned about, they must get a few knocks being thrown around the parts department and delivery vans etc. the last time i changed the plugs on the v6 i had spent a dark evening on the driveway removing the plenium chamber only to find i didnt have my feeler gauges with me, needing the car for work the next day i just bunged the new plugs in and put it back together,

recently i changed the plugs in a mates focus for him, and the so called pre gapped plugs varied between 0.7mm and 1.2mm

this jogged my memory about never checking the gaps on mine so after deciding to change the plugs again ( 40k since last change ) and get the undoubtedly bad gap settings correct this time i tried to research the correct settings but just came out more confussed than before

i will probably just go with the 0.7mm but was just wondering if there was any advantages/disadvantages with having a larger 0.9mm gap, seems i may never know
pcbuild2k is offline  
(Post Link) post #9 of 14 Old 08-02-10 Thread Starter
Status: No more GTA
AO Silver Member
 
pcbuild2k's Avatar
 
Join Date: Oct 2007
Location: United Kingdom
County: Cheshire
Posts: 1,496

Member car:

156 JTS

Quote:
Originally Posted by newalfisti View Post
Having said that i expect that the main difference between 0.7 and 0.9mm gap on a GTA would be the idle quality and emissions and there would be no performance difference.
the main reason i was wondering what the difference would be is that surely emissions, fuel economy, idle and performance (difference bettween a strong and weak spark dependent on the gap)

if you get the gap too small or too large the spark wouldent be totaly efficient resulting in unburnt fuel, hence the need to change the plugs every so often as the spark gets weaker giving less power, worse emissions, worse fuel consumption etc.
pcbuild2k is offline  
Status: -
AO Member
 
GavinH's Avatar
 
Join Date: Jan 2007
Location: Ireland
County: Sligo
Posts: 509

Member car:

156 V6, GTV V6

Sorry about digging up an old thread, but does anyone know what is the tolerance range for the gap? I measured the plugs in my car and they vary from 0.7mm to 0.75mm. Is a +/- 0.05mm variation acceptable?
GavinH is offline  
Status: SOLD my 156!
AO Gold Member
 
gazza82's Avatar
 
Join Date: Jan 2003
Location: United Kingdom
County: Buckinghamshire
Posts: 9,110
Quote:
Originally Posted by pcbuild2k View Post
... they must get a few knocks being thrown around the parts department and delivery vans etc ...
Not if they are still correctly packaged. Mine came with small cardboard tubes over the ends to stop the ends being hit.
gazza82 is offline  
Status: -
AO Member
 
scociu's Avatar
 
Join Date: May 2009
Location: Romania
County: Bucuresti
Posts: 308
Any updates on this matter?
I've just bought some Denso Iridium IK20 5304 spark plugs, and they seem to have a 1.1mm gap. I wonder if, and how, will this affect the performance of the car.
scociu is offline  
Status: -
AO Member
 
Join Date: Apr 2010
Location: United Kingdom
County: Glasgow
Posts: 546

Member car:

2004 gt 3.2 v6

In my experience the PFR6B and PFR7B can be re sized.
When i had the tuned impreza I would decrease the gapping size on the plugs, which was advised after a certain level of mapping.
I would always check the gapping size when buying plugs as they are never all the same.
I doubt on a N/A engine there would be much difference in decreasing the gap size, maybe after remapped a fair bit.
mellinator2k is offline  
Status: -
AO Member
 
Join Date: Apr 2010
Location: United Kingdom
County: Glasgow
Posts: 546

Member car:

2004 gt 3.2 v6

Think the name referred to when decreasing the gap size, trying to increase timing is "one step colder"
Been a while since I did all that though
mellinator2k is offline  
Reply

Go Back   Alfa Romeo Forum > Supported Alfa Romeo Models > Technical & Vehicle Assistance > Engines (TS, JTS, JTD & V6)

Tags
gap , plug , settings , spark

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Forum Replies Last Post
Alfa 147 Spark Plug torque settings Worky Alfa 147, 156 & GT 7 09-07-18 07:06

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome