plug fouling

chrisellis · Post by **chrisellis** » Tue Sep 29, 2009 3:20 pm

I am using NGK BPR6ES and I keep getting a random plug fouling after a hard run. The Engine is a 4.6 Rover running quad 45dcoe's. 300 miles and a little rich after a r/road set up.

It had a new set and has done 2 x 1/4 mile runs and then the fouling apears on the first cold start afterwards. the plug in question is blackened and reads 124k ohms when cleaned it is fine, is this unburnt deposites, lead or even using the wrong temp plugs

Chris

Post by **Rossco** » Tue Sep 29, 2009 3:31 pm

Always worth trying hotter plugs.

mgbv8 · Post by **mgbv8** » Tue Sep 29, 2009 4:14 pm

Try B8ecs plugs for a start. Quite a good all rounder these are.

Are you saying its the same plug all the time??

Post by **Rossco** » Tue Sep 29, 2009 4:33 pm

mgbv8 wrote:Try B8ecs plugs for a start. Quite a good all rounder these are.

Are you saying its the same plug all the time??

Good choice of plugs.

I once had a RV8 that would foul No2 constantly. Just a quirk.

chrisellis · Post by **chrisellis** » Wed Sep 30, 2009 1:09 pm

Rossco wrote:
mgbv8 wrote:Try B8ecs plugs for a start. Quite a good all rounder these are.

Are you saying its the same plug all the time??
Good choice of plugs.

I once had a RV8 that would foul No2 constantly. Just a quirk.

Thanks guys, I will try diferent plugs.

It is diferent plugs but always one of two, I am wondering if they are randomly the last plugs to fire and by then the dcoe's have flooded them.

stevieturbo · Post by **stevieturbo** » Sat Oct 03, 2009 8:10 pm

If 6's are fouling due to wrong heat range, then you've no mission with 8's, as they are far far colder !!!

More than likely you have an ignition problem. Assuming the carburettors are tuned and working properly. But the fact you have one barrel per cylinder, there could quite easily be a fuelling issue causing it.

chrisellis · Post by **chrisellis** » Sat Oct 03, 2009 8:45 pm

stevieturbo wrote:If 6's are fouling due to wrong heat range, then you've no mission with 8's, as they are far far colder !!!

More than likely you have an ignition problem. Assuming the carburettors are tuned and working properly. But the fact you have one barrel per cylinder, there could quite easily be a fuelling issue causing it.

Trying 4's this week but although the R/Road guys jetted the carbs I think they are far too rich so will experiment.

Chris

Boosted LS1 · Post by **Boosted LS1** » Sat Oct 03, 2009 11:03 pm

4's are to hot. Doesn't a standard sd1 run on 5's iirc? You should be aiming for 6's or thereabouts. I suspect that like Stevie says you have an ignition problem. Is it sooty or oily? Soot is basically carbon, ie unburnt fuel, it's dry to look at. Sometimes you can get oily soot from to much valve guide clearance and that shows up all over the valve stems. Black and wet indicates oil, wet and dirty is just fuel.

chrisellis · Post by **chrisellis** » Wed Oct 07, 2009 11:56 am

Boosted LS1 wrote:4's are to hot. Doesn't a standard sd1 run on 5's iirc? You should be aiming for 6's or thereabouts. I suspect that like Stevie says you have an ignition problem. Is it sooty or oily? Soot is basically carbon, ie unburnt fuel, it's dry to look at. Sometimes you can get oily soot from to much valve guide clearance and that shows up all over the valve stems. Black and wet indicates oil, wet and dirty is just fuel.

It has to be carbon as the plug has a low resistance when dried and measured. I should be able to rule out oil as the valves and guides, pistons, rings and block are all new 300 miles.

kiwicar · Post by **kiwicar** » Thu Oct 08, 2009 2:40 pm

Do you know what AFR you are running? just if it is on 45's I will bet the guy setting it up has aimed at 12.5 to 1, to me this is more than a bit rich on an engine with so little squish area, especially with those loverly long inlet tracts you are probably getting a fair bit of fuel dropping out of suspension. Unless it is jetted on the idle circute to lean out to 14 to 15 to one at idle then you will be running very rich just before you switch off.
I would find an AFR probe to stick up the exhaust and see what it is doing, especially when you come to a stop after an enthusiastic run.
Mike

Eliot · Post by **Eliot** » Thu Oct 08, 2009 6:38 pm

stevieturbo wrote:If 6's are fouling due to wrong heat range, then you've no mission with 8's, as they are far far colder !!!

More than likely you have an ignition problem. Assuming the carburettors are tuned and working properly. But the fact you have one barrel per cylinder, there could quite easily be a fuelling issue causing it.

As stevie says, you really dont want to run 8's unless your fueling is dead on balls accurate. You want to go down to a 5 if anything. But I suspect your carbs are just running way to rich.
Plug your laptop in and bring the mixture down a bit - oh sorry, you cant