Hello,
I need help with plug selection for my setup. I have a 383 Chevy with World sportmans II heads and a T-76. This is for a street car on pump gas.
thanks

 

I was planning on running NGK TR6's...

 

I'd go with a 8 not a 6

NGK-5671A-8 for SBC users
NGK-5724-8 for for LT1/LS1

For the LT1/LS1 guys you can range from a 8,9, and 10.
SBC guys go from 7,8,9,10, and 11.

The difference is a tappered seat vs a flat seat from LT1/LS1 and SBC.

These plugs are a NGK race style plugs, the TR6's are a street plug.

 

Rick, my car will be mainly street (I'll hit the track maybe twice a year). I will be running a 383LT1 with AFR210's and a T76 Q trim with alky and FMIC. I hope to be around 700rwhp with 93octane and ~15psi. Can you still use NGK's with AFR heads and why the 8's over the 6's and what gap? Thanks.

Jon

 

Thanks for feedback and I'll be waiting for gap also

 

I believe the 6 is a stock heat range.
While the 8 is colder.
Some of the NGK's come with different center electrode sizes and materials.
The race plug is usually the small size and won't last a lot of miles.
I'd look them up and see what the difference is.

 

the tr55's are the stock heat range, the 6 is one colder. So I guesss the 8's are just 3 ranges colder ???

 

All my NGK experience is in the 8,9,10 range in 2 strokes.
If you look up all the different brand plugs by application. You'll find that they are not a direct cross as far as heat range goes.
For instance, I've seen the same plug sold for a 43-45 AC application.
So it's really a 44. Not to big a deal in a stocker. Well maybe not. I read that was the reason they went to the 4 digit #'s on plugs so you got an exact match for emissions reasons. And they cost triple or something.
As far as gap, from what I've read here, it's boost dependent. As long as you have enough ignition. I think it's 28-30 for 15psi and less. With a Digital 6 or similar power.
The main board has more info on this.
I remember one post where someone said they always started at 28 and adjusted as needed. You have to be careful, my R42LTS's came out of the box at 045. To get to 28 would put them at a good angle. Not a big deal at 1hp/ci. But what about 2hp/ci?

 

The R5671A's will not work on a standard iron head like the Sportsman II's.

A R5671A is a .750 reach gasket plug with a standard tip. For a Sportsman II (or most other iron heads), you can use either a R5673 (.460" reach, tapered seat, standard tip) or a R5674 (.460" reach, tapered seat, projected tip). Either one is available in heat ranges from 6 to 10.

 

The TR6 plugs are a tapered plug. They will physically work, however AFR heads are supposed to use gasketed plugs. I've run some Autolite 103's for the past couple years in my AFR heads, however I'm going to switch over to the correct plug this rebuild. I think the BPR-8ES NGK plug rings a bell. I think we need 3/4" reach and a 14mm thread.

 

I refuse to use autolite resistor plugs, I've seen 4 out of a set of 8 come out new, out of the box messed up. NGK's are much better consistency wise but have very soft insulators, which in one way is good (I've never seen a cracked NGK, I'm sure that if you tried, dropped it'¦), but in another it's bad (once you foul them you'll never get them clean'¦ not a problem when you're talking about stock heat ranges, but when you're talking cold race plugs that will get some carbon on them running at anything but WOT this is an issue).

I've run TR6's in my LT1 with spray and was fairly happy with them (worked great, picked up ET even off the spray, but are prone to misfires). I figured that I'd probably want a little cooler then that in my turbocharged TPI so I'm playing with autolite AR12's for the time being (non resistor race plugs. They drop right off the AC heat range chart, like somewhere around a 41 or less and I don't know anyone that makes something that cold in a 'street' plug, translates to an NGK R5674-7 or champion RV9YC)

 

We normally run Autolite AR-13's in our iron head motors.

 

Ira, is that in the camaro? What is the compression on that thing? AR13's are not that cold'¦ they're like AC 42's, basically one step, cooler then stock for most 350's