capt den Posted April 12, 2023 Report Share Posted April 12, 2023 i know there are threads on this, but i am unable to search them.anyway, my plugs look pretty good for being in 2 years.compression is 100 on all except #4 which is 75. put oil in and it went up to about 85.guess i have a valve issue in that cylinder. this test was cold.only one plug was sooty and that was the one plug that was an ngk BR6S. i do not know why i had one plug different. all the others are autolite 306. this engine burns some oil so i think i need a hotter plug.anyone know the autolite number for the hotter plug? asking my local parts store would probably not get the correct answer.the ngk plug seems to have fared the worst so i want to stick with autolite. thanks dennis Quote Link to comment Share on other sites More sharing options...
DJK Posted April 13, 2023 Report Share Posted April 13, 2023 15 hours ago, capt den said: i know there are threads on this, but i am unable to search them.anyway, my plugs look pretty good for being in 2 years.compression is 100 on all except #4 which is 75. put oil in and it went up to about 85.guess i have a valve issue in that cylinder. this test was cold.only one plug was sooty and that was the one plug that was an ngk BR6S. i do not know why i had one plug different. all the others are autolite 306. this engine burns some oil so i think i need a hotter plug.anyone know the autolite number for the hotter plug? asking my local parts store would probably not get the correct answer.the ngk plug seems to have fared the worst so i want to stick with autolite. thanks dennis Increase in compression by adding oil is usually an indication of worn rings. The higher the number the hotter with Autolite plugs. Quote Link to comment Share on other sites More sharing options...
Sam Buchanan Posted April 13, 2023 Report Share Posted April 13, 2023 Here is a link to a plug comparison chart: https://www.autolitesparkplugs.com/heat-range-conversion-chart-2 However, look at this note about Autolite plugs which complicates things: Where is Autolite? Autolite's numbering system does not have a standardized heat range identifier. The last digit in an Autolite part number represents the heat range within a plug family. For example, take the 254x plug series. Autolite has 2544, 2545 and 2546 available. 2544 is the coldest plug in that plug family, and 2546 is the hotest. However, according to an Autolite reference chart, Autolite 86 has the same heat range as 2244 and Autolite 303 is a hotter plug than 2974. Therefore, it is impossible to chart an Autolite heat range hierarchy, let alone a standardized comparison to other spark plug brands. Quote Link to comment Share on other sites More sharing options...
greg g Posted April 13, 2023 Report Share Posted April 13, 2023 Have the same set of AC45r plugs since 2006 when my 230 was rebuilt and installed. They have 55k miles on them. I have pulled them 3 or 4 times to check them and re gap them to .33, they appear like new. I believe the second digit indicates heat, I believe they go 42 to 49 in the range. I have a auto set of Autolites in my travel box but I don't remember their number. 303 maybe. I recommend rhe AC's without reservation. 1 Quote Link to comment Share on other sites More sharing options...
9 foot box Posted April 13, 2023 Report Share Posted April 13, 2023 To answer your question, looks like a 308 is the next hottest. Quote Link to comment Share on other sites More sharing options...
Paulo Windsor Posted April 13, 2023 Report Share Posted April 13, 2023 Hello from Portugal. I use on my 47 Chrysler ngk B4 since 1991 and work very well. Only change once because rust on them. ? Quote Link to comment Share on other sites More sharing options...
capt den Posted April 14, 2023 Author Report Share Posted April 14, 2023 thanks for all the info. i guess 308 will be best. looks like it only comes in resistor. i do not know why i would use resistor versus non resistor. just curious about the compression. it only went up about 15# with oil. does that indicate worn rings in that cylinder? a shame that one cyl. is low, but i will live with those numbers. i will try the dollar bill test. dennis Quote Link to comment Share on other sites More sharing options...
Los_Control Posted April 14, 2023 Report Share Posted April 14, 2023 I'm married, I never have cash in my wallet I did use a piece of notebook paper cut into the size/shape of a $1 bill. For my truck. That thing fluttered so bad that within 20 seconds the paper ripped in 1/2 ..... Until I can take it out for a nice long drive ... then diagnose I refuse to do anything with the motor. It runs well & plenty of power as is. The dollar bill test is quick & dirty, will tell you if you have a valve problem, will not tell you which cylinder. Quote Link to comment Share on other sites More sharing options...
capt den Posted April 14, 2023 Author Report Share Posted April 14, 2023 these old flatties tend to keep running,even somewhat poorly, but they keep going.they keep oil pressure and that is a big part of a worn engines ability to keep going. once we have owned one for a while we know it's best running sound. then we know when it is asking for help. mine runs smooth but i knew something was amiss. the compression test shows a weak cylinder, but it will stay that way for the forseeable future. i am 74 and doing an engine rebuild is not out of the question, but not something i look forward to. in my younger days i could have the engine out easily. when the weather starts getting cold and i do not drive it much then it will get more thought. for my cooling issue i have a shroud from a 54 new yorker and i have a possible 6 blade fan in my future. i saw an ad for a car for sale and they mentioned a high density radiator. anyone ever hear of that? my rad. was recored and flows perfectly. i am not sure if it is 2 or 3 tubes. maybe i need a new aluminum 4 row core. i know my issue is crap in the block, but i have flushed it with various products[including beet juice], pulled the core plugs and rodded where i could. you cannot get to the other side of the block, so there must be crap there. electric fan was no help. 100degree days in stop/go traffic is a no no. runs hotter than it should at other times also. guage is good. i am going to get an infra-red thermometer to see where it gets the hottest and maybe that will help pinpoint something. the 6blade fan and shroud should help[assuming the one i have a lead on comes through] .just as an aside, with all the junkyard i have dealt with lately i am giving french lake a 10. very pleasant and professional. keep them running, dennis Quote Link to comment Share on other sites More sharing options...
Los_Control Posted April 14, 2023 Report Share Posted April 14, 2023 Hello Dennis. For what it is worth, I have ACDELCO R45 plugs in my engine ..... Years ago I heard some quality issues with Champion plugs. I actually have a new set of Champions around, was what I did my first start on .... As soon as I could I replaced them with the ACDELCO ... now the Champions are spares if I ever need them. I have no facts to backup the quality control issue .... just something I heard on the internet so assumed it was true. .... I have ACDELCO in all my vehicles. I have ran NGK plugs & think they are a quality plug. I'm just assuming here. Someone you or the previous owner had a plug foul out. The particular parts store did not have the same plug you were running, so they sold you a NGK of the same heat range as a replacement. Now you are having problems again with the same cylinder .... The plug is bad & fouled .... I'm suggesting that it is not a brand of plug .... A hotter plug could help. Just a problem with that cylinder. Years ago we use to be able to buy a anti foul plug adapter ??? All it was is a extension that raised the plug 1/2" higher .... getting it away from the oil. Anyway you go, you have a opportunity to pull the head & investigate whats going on. Back in the day it was pretty common to pull in a car at the local service station, pull the head & drop the pan .... Replace the rings & bearings & send it back out ..... If you need a valve job this could turn into a 2 day job ..... they did not remove the engine from the car. .... Unless it was needed. I have no idea what a engine gasket set cost today .... It used to be around $100. A small price to pay to pull the head & see what is really going on. Might be simple, might be major .... A small price to pay $200 & labor + a weekend, to take a look. If it is a easy fix .... fix it. Is a major ordeal, slap the head back on & run it .... decide what you want to do with it. Quote Link to comment Share on other sites More sharing options...
Dave72dt Posted April 14, 2023 Report Share Posted April 14, 2023 Somewhere around thirtyfive years ago Champion plugs had a streak of failed plugs. Half of them straight out of the box wouldn't fire so mechanics grew very leery about using them and it's a habit that's hard to break. I'm one of them but common sense says Champion couldn't still exist if it didn't recognize and fix the problem. Some people have had a bad run of luck with NGK's. All of them have had bad runs and quality issues at one time or other. Those non foulers are still available from Dorman. You can find them occasionally on the HELP! shelf. They were never more than a Band-aid fix. Some of the other tricks were to open up the plug gap or pull the plug wire off the plug and fasten it a bit away from the plug so it would have to jump the gap to try to get a hotter spark to that plug. Quote Link to comment Share on other sites More sharing options...
capt den Posted April 16, 2023 Author Report Share Posted April 16, 2023 i also heard the champions have a bad rep. had one go bad on a boat once. 2 cyl. engine, lost one cyl so i could still limp home on one. my boat mechanic used only NGK. i put new autolite 308 in my 265 chrysler today. runs just fine. dennis Quote Link to comment Share on other sites More sharing options...
Sniper Posted April 16, 2023 Report Share Posted April 16, 2023 I've been running Autolite forever with no issues I can remember anyway LOL Quote Link to comment Share on other sites More sharing options...
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