I put the NGK's in the Dan recommended, and I wish I had the memory anymore to remember the numbers, but it is the extended tip. It works great, but I am still dealing with detonation. So, I am thinking I should try a colder plug. The thing is, I really love these NGK's. The car has never run better, or idled smoother. Part of the improvement is other things, but I am looking for colder plug that is still better than the stock ones I just tossed. I want to keep as much of the extended concept in place as possible. Any adivce? What number NGK's would be a colder range of plug to try?

I guess I am like the baseball player who rubs his bat with a certain charm before he goes to bat. In my mind these extende dtip NGK's are the charm. I am a little afraid I will lose something special if I change these plugs out, even though I can say with logic that I can always change them back if I want.

Sam

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Can you back off the boost or timing? Either that add some alcohol/water injection.

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'72 Duster 198 stock cam, 3:23's Hookers on jack stands for 8 years in the driveway
'79 Maxivan 360 Offy Qjet Comp RV cam/rusting in the driveway.
93 D350 160HP Cummins Auto Dually Clubcab needs a injector pump
2005 Golden Couch Buick

All that is on table. I don't want to back off the timing if I can control the detonation with engine temp, spark plug heat range, and or intake temp, which would be the meth injection. All those are being considered. It's just that the spark plug thing is easy to try, reversable, and maybe the first thing to give consideration to. I don't want to take more timing out if there are toher ways to fix the problem. These extended tip NGK's have been the best thing for dialing in drivability, since they work so well under less than ideal tuning conditions. When I first started, the mixture was all way too lean, and most of the time, the NGK's kept right on firing, never missing a beat.

I want to run a cooler thermostat as well. Right now, however, I don;t have a coolant overflow bottle, which means I could not run it at a track if I wanted to. I kind of want to get the coolant overflow bottle thing worked out before I break open the cooling system again. There is no room for one with the current configuration of things under the hood, so maybe I can put it under the fender. Right now, I am happy to just drive it for awhile, and enjoy the fact that is starts reliably, runs smoothly, gets decent gas mileage, and has this enormous untapped potential waiting to be unleashed. I'll get there. But the plugs are first. I hope someone will give me a number to go ask for at NAPA, and am hoping it will not lose any of it's drivability when I change the to a cooler plug without the extended tip.

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I believe Summit Racing has some nice tubular overflow bottles that will fit in tight places. You might have a look there or you could fabricate something with a length of 3" PVC perhaps.

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David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

I just use a 2 Litre pop bottle that snugs between the rad and inner fender....just under the battery. When the bottle gets dirty I swap in a new one for $.25 and turn in the old one to get my $.25 back.

I have never bolted it down because it fits the space so well.

I use a 4 Litre milk jug on my work truck.....

I just swapped a new set of NGK extended tip colder range plugs into my Vortec EFI motor. They are the peanut plugs of course,,,,and look like a good bet for late slants. They list under 99 Chev Vortec.....Ill look up the number later today. They are one heat range cooler than Delco 44s or NGK UR4s.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Just walk into NAPA and tell them you want to go colder. They can do that. Hopefully!

Got room out front of the radiator support on the side to mount a bottle?

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'72 Duster 198 stock cam, 3:23's Hookers on jack stands for 8 years in the driveway
'79 Maxivan 360 Offy Qjet Comp RV cam/rusting in the driveway.
93 D350 160HP Cummins Auto Dually Clubcab needs a injector pump
2005 Golden Couch Buick

Nope. Not only are the extended-nose spark plugs not available colder, most counter staff (at NAPA or elsewhere) aren't knowledgeable enough to reliably provide the right plugs based on nothing but "I want colder".

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

Does your car go faster if you use one from caffeinated cola?
Interesting. I don't find an extended-tip plug for a '99 Chev 1500 pickup with 5.0 or 5.7, but I think there were other Vortec engines that year. Let us know what you put in!

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

On the '69 model. the grill comes back towards the core support, and what space is there is filled pretty much with turn signal housing. Behind the core support is the fuel surge tank, which I could eliminate with a better gas tank, but that is another big project.

The thing that might get me more space now is better management of the fuses, and relays. I was looking under the hood of a Jeep Wrangler yesterday, and their fuse box under the hood looked like a good bet to install on my Dart, thus eliminating alot of smaller, cluttery add ons picked up from Advance auto over the years. The owner of the Wrangler says there are companies that sell after market replacements for the vehicles for sportsers and off roaders who want to upgrade for running through streams and such. So that is something I am looking into also.

Thanks for the tips. It might seem funny to say I don;t want to break open the coolig system to add an oveflow bottle, but right now the upper hose is acting as my expansion overflow system. When it cools off, the upper hose collapses, and then expands again as soon as I start the car. This is why it has never puked anything out on the garage floor. It also is why the cooling system is not as efficient as it could be right now. I am sure it will help to get that upper hose full. I think this is all adding to the detonation problem. Coolant temp, spark plug temp, air intake temp. It is all fixable.

Sam

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That upper hose collapsing on cooldown suggests your radiator cap isn't functioning correctly.

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

NGK TR55GP Stock # 3403

Allegedly 1 range colder and extended tip than the Delco 44s I had been running. Supposedly the Vortec 350s needed a colder plug than the 87-95 models.....something I discovered all by myself. It was cool to find out GM felt the same way.

I have one very brutal day on them (trailering off road in low range 4x4 for 18kms with up to 20% grades) and they seem an improvement.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

H'mm. Those don't look like the tip is extended...

ZFR5N extended-nose gasket-seat:


TR55GP taper-seat:


And, for comparison, UR4 taper-seat:


What's more, the reach of the TR55GP Chevrolet plug is way too long (1/3" too long, in fact) for the '75-up peanut-plug slant-6 head. Not such a good thing to have all those threads protruding into the combustion chamber. It'll increase your compression ratio by taking up space, but the sharp edges of the threads will invite ping, and when they crud up with combustion scunge, it'll be very hard to remove them.

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

GP Platinum plug, 14mm, .708" (18mm) reach, 5/8" hex, tapered seat, resistor, projected tip, long life single platinum, platinum center electrode only, trapezoid (beveled cut) ground electrode, .059"gap

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Yeah....Im the one who destroyed this rare, vintage automobile.....

~shrug~`.....worth figgering out....I guess the lesson is .....not everything that works on a chev will work on a slant....~shrug~

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Couple things:

• 0.708" (18mm) reach is problematic, see my revised post above. The '75-up slant-6 head needs a plug with 0.460" (10.3mm) reach.

•"Projected tip" is the standard electrode configuration. All the standard slant-6 plugs (and those used on most other engines) are "projected tip". The tip configuration of the ZFR5N, which is proving so elusive in a taper-seat plug, is "extended projected tip". For comparison, a non-projected/standard tip looks like this:


•That 0.059" gap is wayyyyyy wide for most any ignition system one might find on a slant-6, and is really pushing it on any distributor-based ignition system. That gap will push peak secondary voltage way, way up, which will eat up caps and rotors and greatly decrease system reliability by dint of encouraging flashover to ground inside the distributor. This kind of gap works OK on distributorless systems as long as the plug cables are up to the task. This problem is mitigated somewhat by the fine-wire centre electrode, which tends to reduce the firing voltage requirement compared to a traditional centre electrode. What kind of ignition system are you running in your Chev?

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