spark plug help

[herminator]

My L-82 had R45TS plugs in it when I got it last year so I replaced them with the same (it hadn't been running in 16 years). Now I look in the book and see that the stock plug is a R44T. What is the difference between the two? Do I want to use any particular brand/number plugs because I have some mod's? BTW, I have a fouled plug and that is why I am looking at them again. Plug wasn't fouled before new intake and carb were put on but all cylanders had 145-155 compression before switch (haven't checked them again since).

 

[Vette79]

My L-82 had R45TS plugs in it when I got it last year so I replaced them with the same (it hadn't been running in 16 years). Now I look in the book and see that the stock plug is a R44T. What is the difference between the two? Do I want to use any particular brand/number plugs because I have some mod's? BTW, I have a fouled plug and that is why I am looking at them again. Plug wasn't fouled before new intake and carb were put on but all cylanders had 145-155 compression before switch (haven't checked them again since).

Stock Cylinder Heads or something newer? If they are newer Cylinder Heads then the manufacureres web site should have a specs page where it will reference or suggest what spark plugs to use. Spark plugs come in different lengths and heat ranges which definitely have an impact on performance, etc. What do the plugs look like? Dark and oily covered, a white film, smell like fuel? Where they gapped properly? I use sparkplugs.com as a reference.

 

[herminator]

Stock Cylinder Heads or something newer? If they are newer Cylinder Heads then the manufacureres web site should have a specs page where it will reference or suggest what spark plugs to use. Spark plugs come in different lengths and heat ranges which definitely have an impact on performance, etc. What do the plugs look like? Dark and oily covered, a white film, smell like fuel? Where they gapped properly? I use sparkplugs.com as a reference.

Stock heads which were resurfaced and beehive springs not too many miles ago. the one plug is dark/oily looking. No major fuel smell. Expect the owener went one hotter than stock due to mod's (engine blocked, balanced). Maybe there is a head gasket problem? Not showing any other signs though but what else would cause plug to foul like that?

 

[Vette79]

Stock heads which were resurfaced and beehive springs not too many miles ago. the one plug is dark/oily looking. No major fuel smell. Expect the owener went one hotter than stock due to mod's (engine blocked, balanced). Maybe there is a head gasket problem? Not showing any other signs though but what else would cause plug to foul like that?

I'm certain others here will respond to this question as I would be speculating. My guess would be the valve stem seal. Oil leaking past the valve into the cylinder fouling the spark plug.

 

[Hib Halverson]

My L-82 had R45TS plugs in it when I got it last year so I replaced them with the same (it hadn't been running in 16 years). Now I look in the book and see that the stock plug is a R44T. What is the difference between the two? Do I want to use any particular brand/number plugs because I have some mod's? BTW, I have a fouled plug and that is why I am looking at them again. Plug wasn't fouled before new intake and carb were put on but all cylanders had 145-155 compression before switch (haven't checked them again since).

Well...one thing is the 45 is a full heat range hotter than the 44 and you NEVER go hotter with a modified engine; you go colder. With the old AC heat range numbering system, the bigger the number, the hotter the plug.

The "TS" rather than just the "T" means the 45s were tapered-seat, projected-tip plugs and the 44s were tapered-seat, standard-tip.

It sound like this engine is modified to some extent so I'd be using an AC 2 or 3 heat range or equivalent, rather than a 4 or a 5.

IMO, the best spark plug on the market right now for performance use is the Denso Iridium power. Admittedly, the Densos are pricey but, if you want to use them the ITF20 would be a good choice for street high-performance use and is what I use in my cast-iron-head, 71 Big-Block. If the application is a show car and not high-performance, the IT16 might work better. BTW, with Denso, the numbering is the reverse of old-AC, ie: the bigger the number the colder the plug.

 

[herminator]

I'm certain others here will respond to this question as I would be speculating. My guess would be the valve stem seal. Oil leaking past the valve into the cylinder fouling the spark plug.

You're prob. right. Actually thought of that as I was driving shortly after sending by last message. Thanks for your input.

 

[LLC5]

Stock heads which were resurfaced and beehive springs not too many miles ago. the one plug is dark/oily looking. No major fuel smell. Expect the owener went one hotter than stock due to mod's (engine blocked, balanced). Maybe there is a head gasket problem? Not showing any other signs though but what else would cause plug to foul like that?

I would start with the basics first, 1)complete compression check of cylinders, 2)complete cylinder leak down of all cylinders. Resurfacing the head adds higher cylinder pressures and can sometimes cause oil blow by past the rings, and worn valve guides as stated previously can cause oil fouling problems.

 

[herminator]

I would start with the basics first, 1)complete compression check of cylinders, 2)complete cylinder leak down of all cylinders. Resurfacing the head adds higher cylinder pressures and can sometimes cause oil blow by past the rings, and worn valve guides as stated previously can cause oil fouling problems.

If oil blow by, I guess I will be looking at valve job or upgraded heads in the future. I was hoping to put off new hypo heads for about 1K miles, is that reasonable? Will I simply replace the plug from time to time milk it along or are there other possible problems that could surprise?

 

[Hib Halverson]

If you have "blowby" you're looking at an engine overhaul and nothing less.

If the oil use is from the valve guides, you can fix that with a proper "valve job".

If the engine hadn't run in 16 years and it's fouling a plug, I'm gonna guess that the cylinder walls are rusted. If that's the right guess, the only solution is an engine overhaul.