spark plug heat range

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35regal

35regal

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i need spark plugs for a street/ strip motor, 340 , 11.1 compression, eddy mildy ported heads, solid cam 244/252@050, msd 6al, timming all in 1600rpm, 750 dbl pump, 4200 stall, 93 pump. thanks!
 
All post above are about correct n10s are OK in the 10-11 to one area, but cam alltitude fuel mix how you drive are all factor gears etc. Start out in around the N10 range and go colder it the plugs look like they are melting? it is going to take some driving etc to get it just right with your combo..

Spark advance and total make a HUGE diff too.

What are you running for base timing and total advance and when is all in?

Maybe a set for the track and a set for the street is what ihave done.. Most times colder for the track buddy..:)
 
i run 111 race fuel in my car at the track and pump on the street after i turn the timing down and i run auto lite 64 would like to try a colder plug i had 65 and changed at the track to 64 dont know if the car just like the plug or i just did something diff. but it did go a hair faster but i was testing the new motor and learning myself....by the way is that the comp cam 282xs...if so how fast have you been with it...thats whats in my car and ive been a 7.54 with a bad 1.67 60' made a few changes and hope for some drop in et..
 
C130 Chief said:
Most of us run way too hot plugs. Don't be afraid to go WAY colder.
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You want the hottest plug you can tolerate without detonation or melting of the tip. It will keep the plugs cleaner and less likely to foul. There is absolutely no advantage to a cold plug if a hotter one works.

Most folks should be running stock or a step or two colder, certainly not "WAY colder".
 
dartcuda1 said:
I agree I used RN9Y with my 340 and it was .30 over and 12to1 comp. Mark
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Sorry I didn,t see you put eddty heads on the engine.What I did was I seen what the head manufacture said and started with the middle heat range and went up or down from there.I have a big block with indy heads. Mark
 
Autolite 3924's is what i run in my 416 and 360 very happy with the results..i wouldn't run champions in my lawnmower..
 
earthmover said:
i run 111 race fuel in my car at the track and pump on the street after i turn the timing down and i run auto lite 64 would like to try a colder plug i had 65 and changed at the track to 64 dont know if the car just like the plug or i just did something diff. but it did go a hair faster but i was testing the new motor and learning myself....by the way is that the comp cam 282xs...if so how fast have you been with it...thats whats in my car and ive been a 7.54 with a bad 1.67 60' made a few changes and hope for some drop in et..
Click to expand...

Why do you run such a big difference in octane on the same engine?what is the comp on that engine and the engine specs.
 
35regal said:
i need spark plugs for a street/ strip motor, 340 , 11.1 compression, eddy mildy ported heads, solid cam 244/252@050, msd 6al, timming all in 1600rpm, 750 dbl pump, 4200 stall, 93 pump. thanks!
Click to expand...

Autolite AR 3924 is a good starting point but I run NGK plugs cause they have 2 plugs for one heat range in a Champion and Autolite so you can get your heat range more precise I dont waste my time with Champion plugs either.

DSC_3565wtmk[1].jpg
 
i run the race at the track cause i bump the timing up to 36 going to try 38 and pump with it at 32 and the 111 is because thats about the only thing i can get around here except 112/116 we have 100 at the pump at a store out of town but its just a few coins lower than the 111...i do need to try it and see how it react cause it could be better,just never tried it....
340 bored 30 over
j heads mild port work 240/140@500
comp cam soild 520/540 with 1.5 roller rockers
dome tops on eagle h beams
stock stroke 3.31
x-cal intake with hp 950 86/88 jets 31 shooters and 4.5 pv in the front blocked back
mp dist. locked out
727 with 9.5 verta (5000)
4.57 gears with 27/10.5 qtp (changed to 28/10.5 m/t slicks now)
comp 11.5.1 plugs look good will take some pics next time to post for more info on them....
car runs 7.54 1/8th mile with poor 60' 1.67 it leaves good the burn the tire off..(changed the frontend around a little so hope it works better) oh i have 02/03 ss on the back 90/10 front and mp long drag shocks back....????for you did you have to make alot of changes to use the mustange body???or you useing the tube frontend????if so did you still have to make the headers?????got a freind that wants to try it.....did you use a motor plate or fab up mounts??? whats your back susp??? sorry so many ??? and if you can suggest something fo me to try out shoot ill try anything to get it faster,my son gonna get the seat time this yr. so it will be down on weight im 240 hes 160 so that helps hahaah
 
dgc333 said:
You want the hottest plug you can tolerate without detonation or melting of the tip. It will keep the plugs cleaner and less likely to foul. There is absolutely no advantage to a cold plug if a hotter one works.

Most folks should be running stock or a step or two colder, certainly not "WAY colder".
Click to expand...

Agreed 100%

So anyway how do the plugs look on the street and on the track after you pull them out?
 
earthmover said:
i run the race at the track cause i bump the timing up to 36 going to try 38 and pump with it at 32 and the 111 is because thats about the only thing i can get around here except 112/116 we have 100 at the pump at a store out of town but its just a few coins lower than the 111...i do need to try it and see how it react cause it could be better,just never tried it....
340 bored 30 over
j heads mild port work 240/140@500
comp cam soild 520/540 with 1.5 roller rockers
dome tops on eagle h beams
stock stroke 3.31
x-cal intake with hp 950 86/88 jets 31 shooters and 4.5 pv in the front blocked back
mp dist. locked out
727 with 9.5 verta (5000)
4.57 gears with 27/10.5 qtp (changed to 28/10.5 m/t slicks now)
comp 11.5.1 plugs look good will take some pics next time to post for more info on them....
car runs 7.54 1/8th mile with poor 60' 1.67 it leaves good the burn the tire off..(changed the frontend around a little so hope it works better) oh i have 02/03 ss on the back 90/10 front and mp long drag shocks back....????for you did you have to make alot of changes to use the mustange body???or you useing the tube frontend????if so did you still have to make the headers?????got a freind that wants to try it.....did you use a motor plate or fab up mounts??? whats your back susp??? sorry so many ??? and if you can suggest something fo me to try out shoot ill try anything to get it faster,my son gonna get the seat time this yr. so it will be down on weight im 240 hes 160 so that helps hahaah
Click to expand...

I ran SB in dirt track racing and the most would only like 34-36* of timing any more u have way too much octane which is costing you HP.You should run the same timing all the time it will keep you from fouling your plugs out.On your cam what is the dur@ .050 and the lobe separation and what was it degreed at?Did you cc the heads,pistons in the cylinder,head gasket etc.or are you just guesstimating the comp.?With 100 octane fuel you should run that at the track and be fine cause with 111 you will probably go faster with more timing cause it's to much octane with the compression.Also you have way to much carb.
When I ran my 425W5 motor in my 69 Dart(3110lbs) I ran S/S Springs MP drag shocks for a M/T cause I ran a T-brake and Comp Eng 3 way adj front shocks with 6* of pinion angle it ran 9.70's with 1.31-1.33 60fts.

On the Mustang it has QA1 tubular K-member and lower control arms and double adj upper and lower control arms in stock location in the back.I have QA1 10 way adj struts and double adj Afco shocks with coilover springs in the back.Motor is in with motor plate and mid plate and had to make headers to route them the way I wanted and also cause they are 2in primary and 30 inches long.

DSC_3666wtmk.jpg
 
I believe I´ve read that it´s better to start with a colder plug then a plug that is too hot, because of the risks (detonation) with using a plug that is too hot.
 
A colder plug has some advantages. First, it will provide more margin against detonation in cases where the plug is a contributing factor. Second, it is easier to "read" a plug which is running cooler. That is, if the insulator is always bright white it does not necessarily mean the mixture is too lean, rather the plug may be overheating. And third, a plug which runs cooler will last longer, and require less voltage to fire.

Obviously, if fouling is an issue a hotter plug MIGHT help (but may not be the cause of the fouling). I've always had better luck running the coolest plug that will not foul rather than the hottest plug that does not overheat and cause detonation. Not trying to say anyone else is wrong, just offering a different opinion.
 
dgc333 said:
You want the hottest plug you can tolerate without detonation or melting of the tip. It will keep the plugs cleaner and less likely to foul. There is absolutely no advantage to a cold plug if a hotter one works.

Most folks should be running stock or a step or two colder, certainly not "WAY colder".
Click to expand...

Agreed. I have a set of heads sitting the garage that are blacker than hell because of running too cold on a slightly richer tune.

Stock plugs are fine unless you're doing something like nitrous, or it's the middle of summer. Any other time, the stock plugs are fine from my experience. Every egine is different, but the principle is the same.
 
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