Spark Plug

[Ricks70Duster340]

Now have about 150 miles on my new engine and pulled the #1 plug. Looks rich to me so went a step smaller on the jet but got surging so went back. Timing is 18* at idle and max 30* at 3000. Plugs are NGK-BKR5E-11. Not sure if I need to go a step hotter on the plugs?

 

[A56]

Personally I would consider slightly tweaking the air fuel mixture before changing plugs. My 2 cents

 

[Ricks70Duster340]

Personally I would consider slightly tweaking the air fuel mixture before changing plugs. My 2 cents

Not sure how I would be able to do that when I went down 2 sizes on the primary side of my rods and the engine surged so had to go back to base.
The picture does not show it but only the top 1/3 of the insulator is white while the rest is black. There are about 2 threads that are black too. Maybe I could get a better picture from the side if needed.

 

[Newbomb Turk]

Now have about 150 miles on my new engine and pulled the #1 plug. Looks rich to me so went a step smaller on the jet but got surging so went back. Timing is 18* at idle and max 30* at 3000. Plugs are NGK-BKR5E-11. Not sure if I need to go a step hotter on the plugs?

View attachment 1716319214

30 is probably high at that rpm.

Vacuum advance?

You may need to change the metering rods to keep it slightly fatter at a cruise.

 

[Murray]

Engine is not broken in yet. 150 miles is not enough time to start tweeting spark plugs. For 150 miles the plug looks fine.

 

[RustyRatRod]

Engine is not broken in yet. 150 miles is not enough time to start tweeting spark plugs. For 150 miles the plug looks fine.

I'd leave it just AS IS until it's completely broken it. Its tuning needs will change.

 

[Bewy]

It depends what the engine was doing just before the plugs were pulled. Was it idling? That could explain the carbon, while at cruise the A/F might be correct.
Alum heads? Use NGK 4s.

 

[Hysteric]

Now have about 150 miles on my new engine and pulled the #1 plug. Looks rich to me so went a step smaller on the jet but got surging so went back. Timing is 18* at idle and max 30* at 3000. Plugs are NGK-BKR5E-11. Not sure if I need to go a step hotter on the plugs?

View attachment 1716319214

That's a resistor plug right? Try a BP5ES.

 

[Ricks70Duster340]

30 is probably high at that rpm.

Vacuum advance?

You may need to change the metering rods to keep it slightly fatter at a cruise.

I am using Trickflow 240 heads, Performer Intake, Edelbrock 800 AVS2 carb (stock jets/rods/springs), TTI headers, Blueprint Engines Ecoil, Progression Ignition distributor. Cam is Oregon Cams 237/246 .050”, .558”/.579” lift(1.6), 110. The engine starts quickly and idles nicely without a choke. Off-idle and low speed response is excellent. Attached is a screenshot of the timing table I'm using. These are the parameters I used to make up the table:

Idle speed: 780
Idle timing: 18
Max RPM timing: 30
All in RPM: 3000
Max vacuum advance: 6
Start vacuum advance at: 85 KPa
Max Vacuum advance at: 20 KPa
Rev limit: 5500

 

[Newbomb Turk]

Ok, if it idles cold without a choke it’s pretty rich.

Looking at your timing it looks better than it sounds. As long as you are in the mid 20’s for timing (at WOT) around peak torque you are fine.

It looks like it could take more timing at light loads (cruise).

I think I’d work with cruise timing and see if it will take more timing there (like adding vacuum advance) and then I’d work on the carb.

Your timing looks better than it sounds lol.

 

[Ricks70Duster340]

Ok, if it idles cold without a choke it’s pretty rich.

Looking at your timing it looks better than it sounds. As long as you are in the mid 20’s for timing (at WOT) around peak torque you are fine.

It looks like it could take more timing at light loads (cruise).

I think I’d work with cruise timing and see if it will take more timing there (like adding vacuum advance) and then I’d work on the carb.

Your timing looks better than it sounds lol.

Thanks, will give that a try. Still have to feather the throttle a bit when cold, but not nearly as much as I've had to do in the past with other engines.

 

[Newbomb Turk]

Thanks, will give that a try. Still have to feather the throttle a bit when cold, but not nearly as much as I've had to do in the past with other engines.

With your heads you should be able to get 40 or so degrees at a cruise. They probably won’t take much more than that because the chambers are very nice.

That would certainly help at a cruise.

 

[Bewy]

Idle timing is waaaaaaaaaaaaaaay too low. As a test/trial, try advancing to 30-35*. Rpm will increase, idle will be smoother & more vac.

 

[Bewy]

And....from Edel

 

[Ricks70Duster340]

With your heads you should be able to get 40 or so degrees at a cruise. They probably won’t take much more than that because the chambers are very nice.

That would certainly help at a cruise.

I am certainly not against increasing the cruise timing, but am very concerned about over-timing causing problems. As I've recently read (from another poster) someone ended up with engine damage from over-timing and he reported that he could not hear any detonation.

 

[Newbomb Turk]

I am certainly not against increasing the cruise timing, but am very concerned about over-timing causing problems. As I've recently read (from another poster) someone ended up with engine damage from over-timing and he reported that he could not hear any detonation.

Certainly detonation can happen with too much timing. And it will kill parts.

At low load, part throttle the engine will take more timing. How much more timing and when it occurs has to be tested to know for sure.

What I'm sure of is a quick curve and vacuum advance don't usually play well together.

At and around peak torque is where you run into big detonation issues. Lets say you make peak torque at 4500 and peak power at 6000. Then bring the timing all in by 3000. Unless the timing is retarded a bunch all that timing below peak torque is killing power.

If you then add vacuum advance and you add all that timing at peak torque you kill even more power and if you aren't into detonation you are very close.

If you keep the timing reasonable around peak torque chances are you won't have enough timing at peak power so you lose power there because you can't add any more timing without getting into detonation or you are already detonating and its now worse.

Saying all that, you need to correct the curve so that at WOT and peak torque you have the proper amount of timing so you can add vacuum advance.

 

[CRUZE 418]

Have you checked your fuel pressure? Had this same issue with my Sixpack, it was too much fuel pressure. Regulator cured that, 7.5 down to 5. Now I can get down to fine tuning. Not saying that all of the above isn't important, but this was my problem.

 

[Bewy]

You have to be careful with vague/generalised statements where detonation is blamed for engine failure......