Plugs keep foiling up

kennyhbh · #1 (**permalink**) 05-31-2013, 06:53 PM

After 50 or so miles the plugs are foiled up. So bad i had a hard time getting home tonight from a car show. I just got the car ,so have no history its a Roush 402 sr. So far change out the plugs , adj floats,trimming ,. When engine has fresh plugs engine runs real strong! Starts right up ,water temp is good, but when plugs go bad, back fires after let foot off the gas, here it missing,ect. Any suggestions..

Tommy · #2 (**permalink**) 05-31-2013, 07:12 PM

Kenny,
When I had my engine rebuilt with higher performance in mind, the builder installed a set of cool plugs to assure there was no pre-ignition or detonation that could have caused real damage. These plugs lasted longer than yours (about a thousand miles) before fouling, but I got tired of messing with them. So I looked up the heat range data on them and got a set one step warmer. They have worked fine with no fouling. .... If I were you, I'd try plugs one step hotter and see if that helped.

bobcowan · #3 (**permalink**) 05-31-2013, 08:27 PM

What plugs are you using, and what do they look like when fouled?

kennyhbh · #4 (**permalink**) 06-01-2013, 04:28 AM

running auto-craft 605

Gaz64 · #5 (**permalink**) 06-01-2013, 04:29 AM

A little more info on the engine would be helpful.

Foiled? You mean fouled, with fuel or oil.

Fouling from excessive richness, weak spark or too cold heat range?

What spark plug are you using? Compression ratio? Cam profile? Carburetor?

RICK LAKE · #6 (**permalink**) 06-01-2013, 04:47 AM

Kennyhbh Ken are you running an MSD setup?? If yes check the cap and rotor. The center of the cap probe is carbon and may have cracked off. You will get spark but ugly. Check rotor end for burn and make sure the steel point is tight in rotor cover. How do you have the coil mounted. If it is an oil filled one you want the coil vertical and if possible not mounted on the motor.
Next would be to check the fuel pressure regulator to too high a pressure. NO more than 5 psi is needed to run a motor. When you start running 6 psi and high the floats start to bounce and cause flooding when driving. Do you have black smoke coming from pipes? If so what color does it look. As others have said, gas is black, blue is oil, white is water. I would make sure you also that the correct PCV valve in the motor. It could be sucking oil instead of oil mist in motor. Leave pcv valve off motor and road test add rag to keep oil from sparying on motor and is if spark plugs go bad again. If not we need to check valve and possible blowby from the rings in the motor. May have a bad motor. I have seen bad camshafts and distributor gear problems in Roush motors. Pictures would really help here. Final checks make sure you the the correct gap for the plugs in this motor. Get a spark tester and make sure the spark is bright and strong. If you have a spare plug and vice grips and wire to ground plug you want that nice spark with the motor running. Start with fuel pressure first. Good luck. Rick L.

bobcowan · #7 (**permalink**) 06-01-2013, 08:48 AM

I'm not familiar with Autocraft. Do you man Autolite? If so, the 605 is a pretty standard copper core plug, with a #3 heat range. That plug is used in a lot of stock late model engines, and has a slightly shorter reach than you would expect (by 1mm) for a SBF.

As you increase the performance and power output, you usually decrease the heat range. Usually, 1 heat range per 75-100 hp.

But, getting back to the original question, what do the plugs look like when fouled? Are they oil or fuel fouled? A picture would be nice. I'd also like to see the back of the strap.

Also, what gap are you using? I'm not sure what static compression that engine has, but the gap should probably be something like .035"'ish.

Dwight · #8 (**permalink**) 06-01-2013, 09:01 AM

with the newer gas we burn today you will not get the same tan tailpipe color that we did in the 60's plus ethanol in our modern fuel it makes reading plug a lot harder.
Here is a good link to plug reading.

sparkplugreading

kennyhbh · #9 (**permalink**) 06-01-2013, 12:40 PM

Hi guys. change the plugs still having the problems. gap 55 . running msd. change out the cap and rotor . swap in a different 6al msd box . wont hold a idle have to keep pumping pedal keep it running, at higher rpm i can here it miss fire. side pipes are black carbon. also the plugs that i took out weren't filled with carbon.

bobcowan · #10 (**permalink**) 06-01-2013, 01:15 PM

Quote:

Originally Posted by kennyhbh

Hi guys. change the plugs still having the problems. gap 55 . running msd. change out the cap and rotor . swap in a different 6al msd box . wont hold a idle have to keep pumping pedal keep it running, at higher rpm i can here it miss fire. side pipes are black carbon. also the plugs that i took out weren't filled with carbon.

Gap is too big. Bring it down to about .035" or so.

So probably not too rich, and probably not oil fouled.

But you might consider going one heat range colder if they foul out that quickly with a smaller gap.

You could also consider cutting the ground electrode back like in a racing plug.

Gaz64 · #11 (**permalink**) 06-01-2013, 01:37 PM

Quote:

Originally Posted by kennyhbh

Hi guys. change the plugs still having the problems. gap 55 . running msd. change out the cap and rotor . swap in a different 6al msd box .
wont hold a idle have to keep pumping pedal keep it running, at higher rpm i can here it miss fire.
side pipes are black carbon. also the plugs that i took out weren't filled with carbon.

What carburettor?

Sounds like one or more blocked idle air bleeds.

Some pics would be nice.

As Bob has said, plug gaps are too big.

Never heard of your plugs either.

kennyhbh · #12 (**permalink**) 06-01-2013, 01:41 PM

We're are these idle air bleeds.

Got the Bug · #13 (**permalink**) 06-01-2013, 12:56 PM

What do the plugs look like? Are they wet in any way? Any coolant loss lately?

You might want to try doing a compression test.

CHANMADD · #14 (**permalink**) 06-02-2013, 09:51 AM

If the carb is right, its not going to change by driving down the road.......I would do a leak down test.....sounds like you're burning oil.......doesnt need much to foul.........the other .......MSD..........I still cannot fathom why anyone uses that............The plug gap still sounds a little big........the wider plug gap has kinda the same affect as advancing the timing...........hence the foul-up.........

kennyhbh · #15 (**permalink**) 06-02-2013, 10:22 AM

Hi Chammadd, I did notice that i burning little oil. How do i leak down test? and what will that tell me. I like i said the plugs were dry, just carbon on them. thanks

Gaz64 · #16 (**permalink**) 06-03-2013, 01:31 AM

Quote:

Originally Posted by kennyhbh

Hi Chammadd, I did notice that i burning little oil. How do i leak down test? and what will that tell me. I like i said the plugs were dry, just carbon on them. thanks

Ken,

Can we see pics of your plugs please?

kennyhbh · #17 (**permalink**) 06-03-2013, 02:55 AM

Hi Gary , send me your emial I will send some pics this afternoon.you can post on this if you want. Thanks Kenny

Gaz64 · #18 (**permalink**) 06-03-2013, 03:17 AM

PM sent.

CHANMADD · #19 (**permalink**) 06-02-2013, 10:51 AM

The oil becomes Carbon once burnt..........You'll need some help for a leak down test......

CHANMADD · #20 (**permalink**) 06-02-2013, 10:57 AM

An easy ..old school way to check if its the rings.........hold at a steady 3000 rpm for fifteen seconds.......then blip the throttle........not girlie style.......like a man you know a blip right to the floor.......white smoke coming outa pipes.......means rings......not gospel..... But if that produces smoke then do a leak down