SwedeSpeed - Volvo Performance Forum banner
1 - 15 of 15 Posts

·
Registered
Joined
·
151 Posts
Discussion Starter · #1 ·
Hi y'all,

I've recently started doing more of my own work on my 1973 1800ES with B20F Jet-D. Looking through maintenance records from its former shop I noticed it got spark plugs 5 years and 20,000 miles ago. I haven't yet pulled them to check the gaps, but I figure I'm due.

What's the preferred brand and style for this motor? The service manual says Bosch W225T35, which translates to W7BC in current Boschese. Are these or the NGK BP5HS nickel plugs adequate? Or should I go for the pricier iridium plugs, and, if so, why?

Thanks in advance for what will no doubt be a stimulating lesson in spark plug technology.



Sent from my Nexus 6 using Tapatalk
 

·
Super Moderator
Joined
·
9,305 Posts
I use NGK BP6HS in every B18 or B20 and have always had perfect success. I would not use BP5 unless you are fouling badly, and even then they'd be a bit hot, IMO. I would not waste any money on iridiums.
 

·
Registered
Joined
·
7,614 Posts
I use NGK BP6HS in every B18 or B20 and have always had perfect success. I would not use BP5 unless you are fouling badly, and even then they'd be a bit hot, IMO. I would not waste any money on iridiums.
Ditto 100%
 

·
Registered
Joined
·
2,616 Posts
The regular NGK plugs in the 6 heat range are a good choice for the B20. If your car tended to 'eat' plugs I would stick with the BP6HS if you are going for the non resistor variety. However, since you appear to have made it 20,000 mi on one set of plugs, you FI must be running correctly. In that case, you might want to give some consideration to the iridium plugs. The iridium are not going to make more horsepower or give you better mileage if you car is well tuned. However, they definitely will last longer. More importantly, the fine wire plug is more resistant to fouling if you should happen to over-do it with the gas when attempting a start. The fouling resistance means that you can run the slightly cooler 6 heat range (compared to the BP5) and have less problem with unsuccessful ignition. The fine wire electrode also requires less voltage to fire the gap, so if your battery is low or your ignition system is otherwise compromised you have a better chance of getting successful ignition.

I have had the NGK BPR6HIX in my car for about 1 year now. Last time I pulled them (because I was curious) they came out looking pretty much like when they went in (full disclosure, I converted from Djet to Megasquirt with EGO feedback so my fuel mix stays pretty tight). If NGK sold the less expensive platinum fine wire version of their plugs in a format that could be used in the B20E I would use them; however, they don't, and neither does it appear that anybody else does.

None of my local vendors stocked the BPR6HIX so I ended up ordering them from clubplug.ca. Turns out that even with the shipping, the price was a lot lot lower than from the local vendors.
 

·
Super Moderator
Joined
·
9,305 Posts
The fouling resistance means that you can run a slightly cooler heat range
...
I have had the NGK BPR6HIX in my car for about 1 year now. Last time I pulled them (because I was curious) they came out looking pretty much like when they went in (full disclosure, I converted from Djet to Megasquirt
If your 6's burned clean, I don't see the need to move cooler (7's). The last time I tried 7's (no iridium at the time), the plugs did foul. And 5's definitely pinged. Perhaps things have changed since then.
 

·
Registered
Joined
·
2,616 Posts
If your 6's burned clean, I don't see the need to move cooler (7's). The last time I tried 7's (no iridium at the time), the plugs did foul. And 5's definitely pinged. Perhaps things have changed since then.
I have never run heat range 5 in my car. My observation was based upon the fact that the OP was asking about using the BP5 heat range. I was speculating that perhaps he had a fouling issue. The fine wire plugs might allow the use of heat range 6 without having fouling issues; however, if so, much better to address the issue of why there might be a fouling problem.

For my 1971 B20E, the recommended plug was a Bosch W225 T35 which appears to cross reference to an NGK 7 heat range. For hard driving the recommended plug was a W240 T1 which cross references to an NGK 8 heat range (perhaps for extended pedal to the Metal autobahn use!). The recommended plug for normal driving for the 1971 B20B was the W200 T35 which cross references to the NGK 6 heat range. The NGK 6 heat range has always worked well for my mix of driving.
 

·
Super Moderator
Joined
·
9,305 Posts
For my 1971 B20E, the recommended plug was a Bosch W225 T35 which appears to cross reference to an NGK 7 heat range.
Aha - wasn't aware of that, I always thought it mapped to 6. Hmm, maybe that's why the NGK's are better? :rolleyes:

The NGK 6 heat range has always worked well for my mix of driving.
We're all in agreement.
 

·
Registered
Joined
·
151 Posts
Discussion Starter · #8 ·
Thanks, guys. Sounds like NGK 6 nickel is the way to go. What sort of interval should I expect? Manual says 12,000 miles, I believe.

Sent from my Nexus 6 using Tapatalk
 

·
Registered
Joined
·
2,616 Posts
Thanks, guys. Sounds like NGK 6 nickel is the way to go. What sort of interval should I expect? Manual says 12,000 miles, I believe.

Sent from my Nexus 6 using Tapatalk
Depends on your driving conditions. Lots of highway miles - no problem. A lot of urban driving with frequent engine start-ups from cold, maybe not. Check after 1 year and see what they look like. Also, is you engine running well? If not, definitely less than 12,000 miles.
 

·
Registered
Joined
·
151 Posts
Discussion Starter · #10 ·
Depends on your driving conditions. Lots of highway miles - no problem. A lot of urban driving with frequent engine start-ups from cold, maybe not. Check after 1 year and see what they look like. Also, is you engine running well? If not, definitely less than 12,000 miles.
Engine runs really well after valve refit and head gasket about 20,000 miles ago, when the last set of plugs went in. Mostly used for highway driving at full throttle .

Sent from my Nexus 6 using Tapatalk
 

·
Super Moderator
Joined
·
9,305 Posts
Don't forget the owner's manual was written in 1972. The car may not have changed much, but the gasoline formula has. OTOH, a set of 4 regular plugs isn't a lot of $ per 12000 miles.
 

·
Registered
Joined
·
151 Posts
Discussion Starter · #12 ·
Thanks everyone. I went with NGK BP6HS plugs. So far so good. I noticed the previous set was R-type. Not sure it matters but curious if anyone here has noticed a difference between regular and R plugs in this application.

Sent from my Nexus 6 using Tapatalk
 

·
Registered
Joined
·
151 Posts
Discussion Starter · #13 ·
Thanks everyone. I went with NGK BP6HS. So far so good. I noticed the previous set were R type NGK 6s. Any thoughts on whether there's any difference between regular vs R for this application?

Sent from my Nexus 6 using Tapatalk
 

·
Super Moderator
Joined
·
9,305 Posts
R type as in resistor plugs? No need for suppressor plugs in a classic.
 

·
Registered
Joined
·
151 Posts
Discussion Starter · #15 ·
R type as in resistor plugs? No need for suppressor plugs in a classic.
Yeah, that's what I figured. No complex electronics around.

Sent from my Nexus 6 using Tapatalk
 
1 - 15 of 15 Posts
Top