R45XLS spark plug alternative?

[Larry T.]

I have a NOS set of 45XLS (non-resistor) plugs. Is there any downside to running these versus the R45XLS? Any upside?

Larry

[Joe L.]

Re: R45XLS spark plug alternative?

I have a NOS set of 45XLS (non-resistor) plugs. Is there any downside to running these versus the R45XLS? Any upside?

Larry

Larry-----


Possible radio interference is the only down-side of using the non-resistor plugs. You could install them and see if any significant such problem is created. If there is none, you're "home free". If there is unacceptable radio interference, change the plugs. I think the chances are great that there will not be significant problems created.

[Larry T.]

Re: R45XLS spark plug alternative?

Thanks Joe, to be honest with the one speaker and side pipes it is almost impossible to enjoy the radio anyway.

Larry-----


Possible radio interference is the only down-side of using the non-resistor plugs. You could install them and see if any significant such problem is created. If there is none, you're "home free". If there is unacceptable radio interference, change the plugs. I think the chances are great that there will not be significant problems created.

[Duke W.]

Re: R45XLS spark plug alternative?

All '66 models had non-resistor plugs as OE. Resistor plugs may reduce radio interference, but it may not be perceptible as long as all the other RFI suppression devices are installed.

Resistor plugs dissipate some energy, so non-resistor plugs are preferable for more reserve spark energy to resist fouling as long as radio interference is not a problem.

Duke

[John D.]

Re: R45XLS spark plug alternative?

Are there any concerns with piston to plug cleaance with the XLS plug ?

[Larry T.]

Re: R45XLS spark plug alternative?

I also have a set of 43N plugs. I know those were original equipment, should I use them in lieu of the hotter and longer 45xls? For performance only, without regard to originality.

Thanks,

Larry

All '66 models had non-resistor plugs as OE. Resistor plugs may reduce radio interference, but it may not be perceptible as long as all the other RFI suppression devices are installed.

Resistor plugs dissipate some energy, so non-resistor plugs are preferable for more reserve spark energy to resist fouling as long as radio interference is not a problem.

Duke

[Jack H.]

Re: R45XLS spark plug alternative?

Typically, the extended reach profile isn't an issue, but this REALLY depends on the internal specifics of the engine in question. If it's been 'tricked out' with non-stock pistons, there 'could' be a clearance issue.

The BW to tell is to measure and/or mark the plug(s) and turn the engine over by hand to see if they 'kiss' piston dome(s) in the event you question your specific engine configuration...

[Duke W.]

Re: R45XLS spark plug alternative?

Heat range "3" is too cold for typical road applications. I beliieve the 45XLS or R45XLS are generally accepted as a good replacement plug, but I'll have to leave it to other BB owners to verify that there are no interference issues.

Save the 43N set for judging.

Duke

[Larry M.]

Re: R45XLS spark plug alternative?

A 43 "heat range" plug will foul quickly on the street. A 44 heat range plug is not much better. The best one for us to use for street driving is the 45.

This is based upon MANY years of experience by MANY Corvette owners. I remember making this spark plug heat range change back in 1967. It's not a new finding.

There are exceptions to this, but they are relatively few.

Larry

[Paul H.]

Re: R45XLS spark plug alternative?

I have experimented with all 3 heat ranges in my 68 427/390. Go with the 45XLS. They last and the car seems more responsive. I like the 5 heat range in small blocks as well. It just works.