Look at my plugs detonation?

[loudvolvo]

Timing is 34* at 3000rpm with vac advance plugged off. these two spark plugs worry me. I've always heard a slight ticking sound but thought it was a loose rocker arm, now i fear it could be detonatoin

this is the #6 plug

these two are the #8 plug

I'm going to put the timing back at 32* to see how it does. I know i had too much timing because the motor didn't want to start when hot and when i took out 2* it started fine. btw these are the plugs recommened for these heads (procomp) and all the other plugs are your normal chalky grayish tan color any suggestions?

 

[purple barney]

wow :shock: is the motor getting hot? its odd to have two cylinders running that lean whats your compression? what type of fuel? you should be able to run 36 to 38 total on a sbc with no problem. it on the even side only. have you done a compression test?

 

[barnym17]

That kinda looks like a fuel problem, additives and such.

 

[loudvolvo]

If it was a fuel problem wouldn't more than 2 plugs look like this? I run 93 or 91 in it, what the highest octane thats available. Would some good quality octane booster help at all? I had my timing set ~37* and the motor was slugish to start once it warmed up. I took some timing out and its fine now. I just feel like i should be able to run more than 32. I guess i could throw some colder plugs in. Should i put them in every cylinder or just these 2?

 

[barnym17]

It should affect all cylinders but ditrubution is rarely equal in an engine you usually have to tune for the leanest cylinder.Did it run better at 37 degrees? the slow crank is easy to fix.

 

[loudvolvo]

It should affect all cylinders but ditrubution is rarely equal in an engine you usually have to tune for the leanest cylinder.Did it run better at 37 degrees? the slow crank is easy to fix.

other than the starting problem it ran a lil better in the top end, felt like it had a lil more. But at 32 it still is strong as hell

 

[rock]

What you think is 32 degrees timing may be 42 on someone elses timing light. Just speaking from experience. Also with the vaccum pluged you have to make sure the springs and weights in the distributor are also "Wide open" and swung out so there is no extra advance available. Its possible that your weights are not fully open at 3000 rpm. Just a thought. Dont be suprised if the intake lobe on those cylinders is going bad and not allowing the valve to open fully, causing a lean condition.

 

[lurchsmalibu]

Would upping the carb jet size be an option? Has that been experimented with?

What is the plug numbers your running?

 

[Mike Allred]

Your plugs don't appear lean or detonated -- just chalked up with additive contaminants. I'd clean em up, fill up the tank with a different brand of decent fuel and run er' at 36 degrees. Detonation looks like black or gray specks. You're growing white fuzz on those plugs.

 

[Anonymous]

Your plugs don't appear lean or detonated -- just chalked up with additive contaminants. I'd clean em up, fill up the tank with a different brand of decent fuel and run er' at 36 degrees. Detonation looks like black or gray specks. You're growing white fuzz on those plugs.

x3 (there was a similar post above)