Engine fouling spark plugs

[Alive65]

Hey fellas'
The stroker in the elky is ruining spark plugs, it's been steadily getting worse for the passed couple weeks. Dad thinks its loading up from the cold weather which makes since, it looks like a sludge from gas, no oil has been in the combustion chamber. But this problem has only been recent and it has been cold for a while now. He thinks I should park it but I don't want to, this car is my pride and joy, I am also pretty happy that I have the only hotrod with a race motor that still drives around during winter in our small town, cheers to the elky! Here's what is making me wonder that it could be other problems too, I don't want to say this because I know how foolish it is.. But I have one cutout on my drivers side and full exhaust on the passenger because I wanted to see how we'll I liked them before committing to doing both sides, the cutout has a slight leak which causes uneven back pressure, the passenger side spark plugs looked worse than my drivers. Also, I had to put 91 ethanol gas on the way back home on a long trip because i could not find a gas station with 93, used an additive to make up for it. It started getting worse after that. And if it was the cold weather... When we rebuilt the carb the race (lean and rich adjustment?) was turned out 5 turns where the previous owner had it set, we set it to two turns which was edelbrocks suggested tune, if I leaned the motor out a bit for this colder air could I help fix this problem? The spark plugs and plug wires were replaced in September. The car has been in the shop for the passed couple days, while I was taking care of the spark plug wires I also patched up the oil pan, took off the heater core( 2nd one in a couple months) changed antifreeze and some other maintenance stuff. Any suggestions on this topic would be greatly appreciated, suggestions on leaving it parked until warm weather will be taken into account as well, I would just hate to do it but if it keeps me from going through spark plugs and hurting my motor because it doesn't want to fire than so be it. Thanks guys!

[FlatBlack65]

...oh boy, where to start....

[Alive65]

Originally Posted by FlatBlack65

...oh boy, where to start....

I know, I think I've pushed my luck. I'm just trying to find a way to keep it from doing this so soon again, I may lean it out and check my spark plugs in a month to see if it takes care of the problem, and change my exhaust to how it was, it's fun, but I not practical in a town where everyone can know everyone. Sometimes it's better to have a quieter car to play in, any suggestions? It acts like its running too rich to burn everything in the chamber because I usually drive like a grandpa

[Keyser Sose]

Pics of the plugs would help a LOT. Barring that, I'll give it a shot.

exhaust: If that cutout is open, it will make a LOT of difference, and I can give you a good example that I saw myself on a flow bench. I once ran across a small shop in a small town, and they guy there was doing research (under contract) for S&S for harley head work and exhaust systems.

He was bouncing up and down he was so excited when I ran into him. He just needed to tell someone what he had JUST discovered, so he told me, before he burst.

On harley shovelheads (this was the summer of '91), everyone likes the slash cut drag pipes. He showed me one of those on his flow bench (thru a modified head). Then he put another pipe on the flow bench, same diameter and length, but cut off square on the end. The square cut pipe showed a 19% improvement in exhaust flow! Then he put the slash cut pipe back on, and ran it again, but this time added smoke/dye into the airflow. The slash was allowing the exhaust pulse to start spilling out on the short side of the slash, while still constricted on the long side. This was slewing the entire pulse off to the side. It was also creating a LOT of turbulence right at the end of the long side of the slash, further constricting the flow. (btw, I went straight home and cut my slashes off with a hacksaw)

You are doing the same thing with that cutout. Since it is either a 90* corner, or at least a 45* (or so), you are seriously disrupting the flow of the exhaust. I stayed there for about 3 hrs and that guy was showing me all kinds of neat stuff on that flow bench, but the bottom line is this....

Your exhaust acts just like flowing water as it goes thru the exhaust. bends and "slash cuts" in the system create eddies, turbulence, backflows (remember anti-reversion headers?), and all sorts of things that interfere with the smooth (thus quicker, and more power) flow of the exhaust system.

That's why a short (in front of the axle dump) exhaust system flows better that one that runs full length. Even if mandrel bent, those curves to get it over the axle cause disruptions to the flow. If they're not mandrel bent, all those little creases in the curves just massacre the flow thru that area. Full length pipes are about noise management, not power.

So basically your heads are flowing at different rates, but you only have one carb, so one side is gonna load up.

You need to decide on one way or the other, make both sides match, and then tune the carb to that. I'd be willing to bet that if you put it on the track, you prolly lost close to .10 sec or even more by mixing the exhaust system like that.

You are also correct that the colder weather will make the fuel mixture denser, so leaning it out is the right direction to go.

this will give you something to think about and a place to start.

[Alive65]

Thankyou Keyser! I meant to cut my Frankenstein mod off the car last time I was at our shop but did not have the time to, time to turn the elky back to normal. I just wanted to see what it would sound like and make sure it had enough flow to prevent it from backfiring before I went all out and got the nice electric cutouts. It was a nice curve and in a spot where I figured most of the flow would be off of it but it was enough to make a difference. I hardly ever ran around with it open, only when I was showing what it might sound like with nice cutouts on it to a couple friends or something, but wasn't for sure if it would be forcing that much back because it does have a small leak It sounds cool as hell, but was just supposed to be a temporary test, thankyou though, I appreciate the insight! cool story about the flow bench I might add

[woody31]

Also check the heat range on the plugs...go with autolite plugs gapped @.045

[Alive65]

Thanks woody, I think I had them set around .04 to .045, but I cannot remember what kind of plugs they were and I was just looking at them yesterday.. My brain is a very unorganized file system

[Muljo777]

Are you sure your thermostat is closing? You mentioned changing the heater core. Was this due to no heat? If your stat is wide open your engine might be running way too cold. The choke would stay on and give you a rich mixture. Something to check. Good luck.

[dstinch]

Hello. One more thing to look at., If your tune up is good for your motor what heat range plugs are you running? You say race motor but mostly drive easy, maybe a hotter plug will help. Colder temps mean denser air and should run leaner. (i think) My little blower motor is jetted on the rich side and when i had autolite 103s it ate plugs. Switched to 105s and it helped a lot. I also run a afr gauge to make sure i'm not going lean at wot. Good luck.

Don

[dstinch]

Did not see Woody31 post before i posted.

[Alive65]

Thanks guys, thermostat is fine,just keep getting cores with leaks around the fins, gets to 180 back down to 160, actually checked that today, but the choke has had problems before, I didn't even think about that until you suggested, and thankyou for the info on spark plugs, the tune is very nice, I don't know much about them yet but both sides were loaded up with junk, the passenger was just worse than the driver, I will check into getting those

[woody31]

i should have been more specific in my reply,,autolite 25 is what i run,,,,may try those,,they seem to run better in my motor than a/c delco ,,,,wore out 362 9=1 comp. ratio ;;;280 comp cam,,,ect ect ect....

[Alive65]

My compression is maybe around the high 10 or 11:1 range, roller cam, needed a vacuum pump to have functioning brakes.. It does not like 91 octane and doesn't fire right whenever I have had to use it( 2 or 3 times) but I know dad got nice spark plugs when he bought them but I just don't know how much spark they put out. I'm headed out to the shop tomorrow and I'll take a peek at them again and it looks like I've got some reading and thread searching to do, but thanks for all the help everyone. I like asking questions before I start picking and choosing, I can do some amazing things with bodywork and fabrication, but I never got the chance to really play with a motor

[JJLT1]

the race (lean and rich adjustment?) was turned out 5 turns where the previous owner had it set, we set it to two turns which was edelbrocks suggested tune,

what does that mean?? what kinda carb?? what kinda choke?? check the choke..

[woody31]

Originally Posted by JJLT1

what does that mean?? what kinda carb?? what kinda choke?? check the choke..

in the firdt post you mention edelbrocks reccomendation....imho...they are junk,,,especially with todays ethanol based fuels,,,,soundslike it has gummed up inside..i had the same issue with my edelbrock a while back,,,a quick call to SEAN MURPHY INDUCTIONS solved that issue thanks to a new stage 2 qjet,,,at the very least , start with a complete tear down of the carb,,make sure it is spotless,,,pay close attention to the power plungers,,,in the end i hope you get it lined out but i would bet a call to smi or mountain man carbs is in your future,,good luck..