What spark plugs are you running?

fvike · Jun 4, 2006

I've been using NGK 7373 FR5, but tried to swich to colder FR4 plugs. Didn't work well, blew one of them with a backfire. Oh well, back to the FR5s, unless you got some suggestions... So what are you running, and how do they preform ?

65ShelbyClone · Jun 5, 2006

Edelbrock's recommended Champion RC12YC here. I haven't checked them since the engine has been carbed, though. (~1200mi...it used to be in my old '89 GT)

SoCalCruising · Jun 5, 2006

http://forums.stangnet.com/showthread.php?t=518319&highlight=autolite
try this thread, too.

jerry S · Jun 5, 2006

fvike said:
I've been using NGK 7373 FR5, but tried to swich to colder FR4 plugs. Didn't work well, blew one of them with a backfire. Oh well, back to the FR5s, unless you got some suggestions... So what are you running, and how do they preform ?

Frode:

Have a look at this thread too. Scroll down to my post and click the attachment.

http://forums.stangnet.com/showthread.php?t=635371

fvike · Jun 5, 2006

Thanks for the info. I'm having troubles with getting the engine to run, it's eating spark plugs. And of course a open track event next weekend. Gonna try with either Champion RC9YC or NGK FR5. The NGK FR4s only lasted a backfire.

65ShelbyClone · Jun 5, 2006

So.....you're having trouble with them fouling?

fvike · Jun 5, 2006

Yeah. I wonder if the fuel I run has anything to do with it. I'm running 98 octane gas.

65ShelbyClone · Jun 5, 2006

Are they turning black with carbon or are the electrodes growing over with more brownish deposits? Any black smoke when it runs or really poor fuel economy? How high is the compression ratio?

EDIT: I saw that you don't know the exact engine specs in your stangnet garage. Do you know if the octane rating in Norway are the same as the US? 98 seems awful high unless you have over 11:1 compression.

The gas could have something to do with it, but I doubt it would foul plugs so fast.

fvike · Jun 6, 2006

Plugs are black with carbon. It shoots black smoke, but I can also have white smoke, and still black plugs. Seems like idling will dust the plugs.
I think octane rating is different. We can get two types of gas. 95 octane and 98 octane.

I should perhaps get a compression test ?

jerry S · Jun 6, 2006

fvike said:
We can get two types of gas. 95 octane and 98 octane.

These ocane ratings are differrent than the US ratings. There is the PON (Pump Octane Number) in the US and the RON (Research Octane Number) in Europee and the octane ratings are different. 98 octane in Europe is about 94 Octane in the US. What is your compression ratio?

67&05STANGS · Jun 6, 2006

What gap do you have them at? If you now have electronic ignition and the higher voltage coils you can go higher than the .35 gap recommended for stock applications. I alternate between BF32 and BF22 plugs and have them gapped at .45. I have the Pertonix setup with the Billet dist, flame thrower coil and wires. Car runs great and the plugs get just a greyish brown tint to them.

65ShelbyClone · Jun 6, 2006

jerry S said:
These ocane ratings are differrent than the US ratings. There is the PON (Pump Octane Number) in the US

The "pump octane" here is actually the research octane and the motor octane averaged together. Pump 91 typically has a research octane closer to 95-96 and a motor octane in the high 80s. I don't know if race fuels are rated the same way.

fvike - it sounds like your mixture is either too rich or your ignition isn't lighting the fire very well. I'm also wondering about the cold heat range you're using. I have a few more questions:
1. What temp does the car run at?

2. Do you get pinging with lower ocane gas?

3. Where is the base timing set? How much total timing?

4. Does the oil on the dipstick smell like gasoline?

5. Have you tried hotter plugs?

fvike · Jun 6, 2006

Jerry S:
I'm not sure, I need to get an compression test. I know nothing of the internals of my engine. Guessing around 10:1 somewhere. It's quite hard to turn the engine at the crank.

67&05STANGS:
I've always left the gapping alone at stock. Tried one pair of plugs with .50, with some minor improvement.
My ignition system is seriously stoneage. Autolite distributor; PerTronix Ignitor, Accel 8140 coil (The yellow one). Taylor Spiro-Pro 8mm ignition wires.
We did try to route more power to the coil with a wire from the solinoid. Again with some minor improvement.

65ShelbyClone:
1. 190 F
2. Never tried the 95 octane. Only the 98.
3. I have some timing issues. The car won't run with under ca 18 degrees of timing. The car runs best with distributor vacuum clock pushed all the way towards the radiator hose. I'm not sure about the timing exact number ATM, because I've tried so many different combos the last few days. Everything between 18 to 30 degrees.
4. No. However it did last automn. But that was because I had the car at a bodyshop to fix a ding, and they drowned it with gas when they couldn't start it. They just pumped it full, instead of calling me. However, I only drove the car like a mile after that before I changed the oil this spring. The oil is now very nice. Thin and "transparentish".
5. When I got the car, it had NGK FR4s. I've used FR5s since then. Tried with FR4s last time, didn't last 30 minutes. Have ordered Champion RC9YC plugs now.

Thanks for helping guys! :SNSign:

jerry S · Jun 7, 2006

fvike said:
Jerry S:
I'm not sure, I need to get an compression test. I know nothing of the internals of my engine. Guessing around 10:1 somewhere. It's quite hard to turn the engine at the crank.

67&05STANGS:
I've always left the gapping alone at stock. Tried one pair of plugs with .50, with some minor improvement.
My ignition system is seriously stoneage. Autolite distributor; PerTronix Ignitor, Accel 8140 coil (The yellow one). Taylor Spiro-Pro 8mm ignition wires.
We did try to route more power to the coil with a wire from the solinoid. Again with some minor improvement.

65ShelbyClone:
1. 190 F

Thanks for helping guys! :SNSign:

A compression test does not tell you your compression ratio. It just tells you if you have a leak somewhere. If you don't know your CR, then you don't know the proper heat range of plug to put in there and you are really just making a stab in the dark. If you know your pistons and your cylinder heads, you can figure out your CR and then get the right plug.

Your ignition does not sound that bad to tell you the truth.

Be careful with the timing. Too much advance and you could be asking for trouble. Find somebody with a wide band A/F computer and experiment around.

If your car is hard to start, this could mean that your starter is bad. It could also mean that your initial advance is too high. My car was a beyatch to start. Then I found out that the so-called "tuner" locked out my timing at 28 degrees. That made for some hard starts as well as bad fuel economy.

65frank · Jun 7, 2006

chart for NGK plugs

The FR4 is a hotter plug then the FR5. Ask me how I know…

It took me a while to find this chart for NGK plugs when I had a similar problem, but I never trashed a plug so quick..

http://www.ngk.com/sparkplug411_ngk.asp

fvike · Jun 7, 2006

jerry S said:
A compression test does not tell you your compression ratio. It just tells you if you have a leak somewhere. If you don't know your CR, then you don't know the proper heat range of plug to put in there and you are really just making a stab in the dark. If you know your pistons and your cylinder heads, you can figure out your CR and then get the right plug.

Your ignition does not sound that bad to tell you the truth.

Be careful with the timing. Too much advance and you could be asking for trouble. Find somebody with a wide band A/F computer and experiment around.

If your car is hard to start, this could mean that your starter is bad. It could also mean that your initial advance is too high. My car was a beyatch to start. Then I found out that the so-called "tuner" locked out my timing at 28 degrees. That made for some hard starts as well as bad fuel economy.

Jerry, you're onto something there. I've already had my starter out to maintain it, bacause it stopped working, and I borrowed a smaller 260/289 starter, and it had problems with starting my engine. Got my starter back in again now. Also, I've had a friend set up the advance curve for me last year, (because he wouldn't stop whining about it and I'll take help from anyone who offers it.) and other friends tells me his skills isn't always up to par. I might have an advance issue. I had the car on a C/O machine, and it showed lean condition, but a high amount of unburnt fuel in my exhaust. Anyway, I'm off to install my new plugs.
Let us never speak of the compression thingy again. Massive ego damage taken!

65Frank: I thought lower number meant colder. Thanks for clearing that up.

Got a question: What determines plug gapping ?

jerry S · Jun 7, 2006

fvike said:
Got a question: What determines plug gapping ?

several factors but two crucial ones are Compression Ratio and RPM.

according to the instructions that came with my MSD 6AL, the following gaps are recommended

CR up to 10.5 = gap between .050 - .060
CR 10.5 to 13.0:1 = gap between .040 and .050
CR over 13.0:1 = gap between .035 and .045

I would go with the plugs recommended to you by Edelbrock for a CR between 9.0:1 and 10.5:1, these being the

Champion ----------- RC9YC / 2075
Autolite -------------- 3924
NGK ----------------- FR 5 / 7373 OR BCPR7ES / 3330

and gap them at .050. then I would have a look at your timing.

fvike · Jun 7, 2006

jerry S said:
several factors but two crucial ones are Compression Ratio and RPM.

according to the instructions that came with my MSD 6AL, the following gaps are recommended

CR up to 10.5 = gap between .050 - .060
CR 10.5 to 13.0:1 = gap between .040 and .050
CR over 13.0:1 = gap between .035 and .045

I would go with the plugs recommended to you by Edelbrock for a CR between 9.0:1 and 10.5:1, these being the

Champion ----------- RC9YC / 2075
Autolite -------------- 3924
NGK ----------------- FR 5 / 7373 OR BCPR7ES / 3330

and gap them at .050. then I would have a look at your timing.

Thanks! Got the Champion RC9YC plugs today. First the car wouldn't run. Tried a different set of plug wires, and that helped, but was still overly rich. Turned out to be the accel pump that was 3mm open at all times. I never adjusted it when I installed the carb, I just assumed it was right. :Zip2:

Now I got it running good, just a little fine-tuning left. I'm gonna use this weekends oper track event for that. Ignition is still a little high, but I didn't start to fiddle with that again when I got it running. It was late, I went home. Thanks for the help everyone.

What spark plugs are you running?

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