#8 plug leaner than the others? - Ford Muscle Forums : Ford Muscle Cars Tech Forum

jholmes217 · 09-29-2012, 12:33 PM

I recently switched from a old Weiand 8011 to an Eddy Performer RPM. I've done three or four spark plug checks since the switch. 7 plugs are the nice light chocolate milk color, and #8 plug is almost white still. Is this normal for a Performer RPM, or do I maybe have another issue somewhere?
Engine is a 1969 302 block with 1970 port and polished with 1.94 intake and 1.6 exhaust valves. Compression is 9.3 to 1, and the cam is a Comp Cams 274 hydraulic flat tappet. Carb is a 600 vacuum secondary Holley.

DanH · 09-29-2012, 02:06 PM

swap plugs around or new plug and check the wire is the first test

klutz , you got the answer ? could it a vacuum leak klutz ? or , or

jholmes217 · 09-29-2012, 03:07 PM

I swap plugs to a different cylinder after each check, and the #8 always comes out more white. Same thing if I put new plugs in. I haven't found any vacuum leaks.

DanH · 09-29-2012, 03:15 PM

this a 15426378 order ? if so make sure 7 & 8 wires are not close to each other

FEandGoingBroke · 09-29-2012, 05:41 PM

Swap that #8 Wire with the #4 wire and re-run. If you still have a white plug later check or intake gasket interference or a leak in the gasket over #8.

289hipo · 09-29-2012, 10:16 PM

i had the same prob with my windsor.the white header paint burned off no 4 and 2 header pipes.i changed carbs and that fixed it.very weird.i also checked for vaccume leasks with a propane torch.without lighing torch open valve and go around intake carb and carb spacer

jholmes217 · 09-30-2012, 12:28 AM

Quote:

Originally Posted by FEandGoingBroke

Swap that #8 Wire with the #4 wire and re-run. If you still have a white plug later check or intake gasket interference or a leak in the gasket over #8.

Changed all of the plug wires a couple weeks ago Gary, and still doing it. I will try looking for vacuum leaks again. If I don't find any, I'll try changing the Holley for a Summit 600 CFM carb.

KULTULZ · 09-30-2012, 12:55 AM

Vacuum leak is the most likely cause. Ten dollar vacuum gauge will find it (along with propane method also described).

If the ignition was bad (plug/wire) the plug would read fuel fouled.

It may also be a distribution problem either in the carb or intake plenum. As a last resort, you would fatten the primary jet (1) that feeds the plenum side that supplies #8.

THEXTON THX382 Vacuum Leak Detector Wand-

DanH · 09-30-2012, 07:20 AM

Quote:

Originally Posted by KULTULZ

Vacuum leak is the most likely cause. Ten dollar vacuum gauge will find it (along with propane method also described).

If the ignition was bad (plug/wire) the plug would read fuel fouled.

It may also be a distribution problem either in the carb or intake plenum. As a last resort, you would fatten the primary jet (1) that feeds the plenum side that supplies #8.

THEXTON THX382 Vacuum Leak Detector Wand-

klutz heres a hint , know why the chair your butt and hand is sitting on isnt burnt black ?
there never was a fire , so its still the same color

jholmes217 · 10-02-2012, 08:02 AM

I also have a slight "sputter" at cruise speed that may be related. I did three things roughly at the same time a couple weeks ago. I adjusted the valves (roller rockers), I changed plug wires, and I swapped carbs. I'm thinking the "sputter" and the whitish plug on #8 may be related and caused by the #8 valves not adjusted properly. I was adjusting valves while also trying to watch my kids, so I was interrupted several times and may have done that cylinder wrong. You know how it goes if you have or had little kids. Daddy, I'm thirsty, Daddy I'm hungry, Daddy, I have an owwee. Then you try to pick back up and think "were was I?" I wouldn't trade my kids for the world, but they can be frustrating when you are trying to concentrate or they take a hammer and pound the bumper on your Cobra Jet Mach 1. Lol

FEandGoingBroke · 10-02-2012, 08:58 AM

Might be you're onto something! Get it took care if dag nabbit!

Blulakr · 10-02-2012, 03:35 PM

Do you have a vacuum tee at the back of the manifold?

Keep in mind vacuum leaks aren't always external or near the intake\carb. Any one of the vacuum lines off of a tee or the components they connect to can create vacuum leaks. Leaking brake booster diaphragm, heater controls, trans modulator......