I read and re-read the forum on spark plugs for the slant 6. I just purchased a 1979 D-100 Pickup w/ 225 1bbl. This truck will be used for handyman jobs(not super sixed or hyper packed).What is the preferred spark plug for my stock application? Thanks!

These:

http://fueleconomytips.com/2005/10/28/spark-plug-magic/

Mike

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Recognized by US Federal Courts as a Fuel Economy Expert!

These:

http://fueleconomytips.com/2005/10/28/spark-plug-magic/

Mike

_________________
Recognized by US Federal Courts as a Fuel Economy Expert!

Mike, I admire your work a lot, and I don't want to seem like I'm attacking you, but I would really like to see you get a lot more rigourous in terms of testing and providing data. OK, you tried modifying spark plugs in this manner and you say they work better that way, but that's just not good enough. Not because I think you're a liar (I don't), and not because I necessarily distrust you (I don't), but because of simple human psychology. We humans are very poorly equipped to perceive patterns and phenomena accurately just based on what we see (or think we see, or want to see). That's why scientists and engineers base their research on data.

So: How do we know spark plugs are better after you drill a hole in the side electrode? Where are your before/after data with the only difference being this spark plug modification? Fuel consumption before/after, dyno pull before/after, emission test before/after...those data are the only way such a modification can be realistically and objectively evaluated so as to determine whether it's a good idea, a bad idea, or an "it depends on other factors" idea. Same goes for the 2-piece intake valves, power grooves in the ports, etc. Sure, the theory sounds plausible, but if you want to find out if it works (and if so, convince others that it works) then you really need to carefully collect and provide single-variable data. Once you do that, there remains much less room for opinions, guesses, and preferences in either direction.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Welcome on the board. For your '79, use NGK UR4.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I have to agree that without real tests any modification is questionable. If it works, it works, not two ways about it. I often hear about things that are supposed to work and know right off they are untested because of some very obvious flaws that are missed by incomplete understanding of what is actually involved. Sure sometimes it is obvious what can be improved, but not always. Here is a plug modification that does help a little, and yes without any data of my own. Quite a few years back when splitfires just came out and were being hyped with unrealistic claims some guys did some dyno tests on this. I honestly cannot remember who it was other than they were members of a Buick club I was in. The modified plugs were just normal AC plugs of the correct heat range that had the ground electrode cut or ground back to uncover half of the center electrode when you are looking straight at the plug from the business end. I believe this is an old factory racing trick. I have tried it and it does run noticably better compared to normal new plugs. But not that much better for the trouble, and only at part throttle as far as I could tell.. The dyno tests back then showed as much or better results compared to the splitfires (a tiny percent of increase). The downsides are the plugs do not last as long, and you have to make sure they are clean after grinding. Keep in mind, engines always run better with new plugs and that contributes to the hype. I would be wary of any mod that would keep the end of the ground electrode from transfering heat back to the head, like drilling a hole in it. The first thing to do with plugs is make sure you actually have the correct heat range.

The closest thing to data I can provide is my experience developing a 3 fuel generator for a company. The fuels were gasoline, propane, and natural gas. The engine was a Chrysler 2.2 coupled to a 20 kW generator. The engine was spun at 1800 rpm. The engine was fresh, as were the normal Autolite 65 plugs. Baseline:
gasoline = 20 kW
propane = 19.6 kW
NG = 16.4 kW

After drilling and indexing the plugs the results were:
gasoline = 20 kW
propane = 20 kW
NG = 19.3 kW

The conversion factor is 1.76 HP per kW. As I recall, this calculated out to over 20% increase in usable power (running on natural gas) at 1800 rpm.

Of course there are the more subjective "seat of the pants" type tests that don't hold much water in a scientific based community, but at least this is something.

Mike

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Recognized by US Federal Courts as a Fuel Economy Expert!

Ok, just for the sake of argument. Why no increase with gasoline? Were the temp and Baromeetric pressure the same for all runs, especially the natural gas ones? Was the temp of the generator field and rotor the same in both natural gas runs, because it can make a big difference in output comparing a cold generator to a hot one. Did it run better day after day?

Interesting idea, mpgmike.
Was there any more data on that test?
Brake Specific Fuel Consumption?
Was there a test with the plugs indexed but unmodified?

_________________
"When you find a big kettle of crazy, it's best not to stir it." - Pointy-haired Boss

1964 Valiant V200, 225/Pushbutton 904
BBD, CAI, HEI, LBP, AC, AM/FM/USB, EIEIO

There might have been increases with the gasoline, but the test load was the 20 kW generator. Our load bank was set up to draw no more than 20 kW as that was the rating of the generator. The reason I even tried the drilling and indexing was because the 16.4 kW on NG wasn't enough. I needed to find a way to get the output within 95% of rating, even on the NG. My intent wasn't to test the viability of the drilling versus the indexing verses the combination, just get the power up to an acceptable level.

As for indexing, nobody will ever get the same results twice. The reason is that the placement of the old plug's electrodes will be different on every cylinder and on every engine. Indexing the outer electrode simply places it in a strategically good location, and a consistent location, in each and every cylinder. My experiences with indexing alone have ranged from "Oh my God! What a difference" to "you did say you indexed them, didn't you?"

The whole process is practically free to try. I'm not selling the plugs, so I'm not giving a sales pitch. Just sharing something that worked well for me.

Mike

_________________
Recognized by US Federal Courts as a Fuel Economy Expert!

That's what the forum is here for!

_________________
"When you find a big kettle of crazy, it's best not to stir it." - Pointy-haired Boss

1964 Valiant V200, 225/Pushbutton 904
BBD, CAI, HEI, LBP, AC, AM/FM/USB, EIEIO

Thanks Dan! NGK UR4 it will be.

I just changed to the autolite 985s in my 73 duster and now the car runs much hotter than before. plugs are gapped to the factory spec of .035 and indexed ( however I did have to leave the washers on to get them to index correctly. any suggestions?

Your spark plugs are not causing your hot running.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Don't run with washers on the plugs.............



See

http://www.slantsix.org/forum/viewtopic.php?t=21933

about half way down on the tool I made for indexing.


and

http://www.slantsix.org/forum/viewtopic ... ht=indexer

for my comments on indexing a slant


and plugs won't make it run hotter

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes