Lean mixture/white plugs after Pertronix (1 Viewer)

[nachohouse]

I’ve got a 1970 1F and stock carb (rebuilt 4-ish years ago by Jim C I’m told). Installed a Pertronix II and Flamethrower coil a little over a year ago. Starts right up and runs great, the exhaust smells way less rich than it did with the stock ignition.

I just pulled the plugs to check things and cylinders 2-5 look a little lean/white. Cylinders 1 & 6 had a nice caramel color and no fouling.

Timing set around 12ish deg advanced (harbor freight timing light dialed to +5ish). No manifold leaks that I can detect, a little soot by the exhaust ports on 2+3. I sprayed brake clean while it was running around the manifold and base of the carb and had no change in idle.

Is this anything to worry about? Do I need to change to richer jets or do anything to fatten the mix? Anyone else with an electronic ignition have this? Thanks for the help.

Edit: Forgot to mention I capped the vac retard, so running with only mechanical advance.

 

[Rocky_LC]

I have seen Pertronics advance the timing about 3* over what was set with the points, just by installing the module.

If you haven’t re-checked the timing after the install, I’d suggest that first.

Rocky

 

[charliemeyer007]

#5 could run lean from bad vacuum booster. You could have a manifold/carb gasket leak - easy enough to test with a spray can of WD 40 with a pee tube. Quickly and lightly spray the gasket surfaces interface on a cool engine that is idling smoothly - when you hit a leak the RPM's will kick right up. Put a big hemostat on the break booster hose, does the rpm change? how about the vacuum gauge?

 

[Grayscale]

Copper top - NGK BPR5ES?

 

[nachohouse]

I have seen Pertronics advance the timing about 3* over what was set with the points, just by installing the module.

If you haven’t re-checked the timing after the install, I’d suggest that first.

Rocky

Thanks, yeah I rechecked before I posted still in the 12-14 deg ballpark.

 

[nachohouse]

#5 could run lean from bad vacuum booster. You could have a manifold/carb gasket leak - easy enough to test with a spray can of WD 40 with a pee tube. Quickly and lightly spray the gasket surfaces interface on a cool engine that is idling smoothly - when you hit a leak the RPM's will kick right up. Put a big hemostat on the break booster hose, does the rpm change? how about the vacuum gauge?

I was pretty thorough with the brake clean around the manifold and carb gaskets. I even used my propane torch as well to be sure. No change in RPM. I don't think it's the brake booster because I hook my vacuum gauge to into that hose and the idle is no different with the booster hooked up vs. hooked-in to the vacuum gauge.

I've got a Remflex manifold gasket on the way so I'm just going to try that to be sure. What's the best way to check the base of the intake manifold for a crack without separating the exhaust & intake manifolds. Is there a way?

 

[nachohouse]

Copper top - NGK BPR5ES?

Denso W14EX U-Groove. Should I change plugs?

 

[Mark Jennings]

To correctly read the plugs, get a new set, gap as required then, find a nice straight section of road…..install the new set and make two WOT runs….one way ‘till you run out of RPM and back….gotta’ keep your foot in it, minimize idle and part throttle. I like to do this on gentle uphill runs, puts a higher load on the engine and hotter combustion temperatures.

Then pull the plugs and read…..use any of the Google picture charts to determine fuel mixture, oil burn, preignition, etc….

Now. this will tell you if you’re running rich/lean ONLY on the main jets or, as you mentioned, a potential manifold leak….idle and part throttle, if the carb is clean, should be fine.

 

[Grayscale]

Denso W14EX U-Groove. Should I change plugs?

Those are correct heat-range. Keep them.

 

[Pighead]

Is this anything to worry about?

I don't see a problem yet, but I'd keep an eye on it for the next 10 or 20 years

 

[Grayscale]

The suit on the exhaust ports on 2,3 is concerning. Exhaust in the engine bay is a health concern for the driver. Are you running the stock manifolds?

 

[pb4ugo]

What the op describes sounds perfect.

How do I "read" a spark plug? - NGK Spark Plugs

Learn how to analyze your engine's overall operating condition just by looking at your spark plugs. Find this and other DIY tips on our resource page.

ngksparkplugs.com

 

[nachohouse]

To correctly read the plugs, get a new set, gap as required then, find a nice straight section of road…..install the new set and make two WOT runs….one way ‘till you run out of RPM and back….gotta’ keep your foot in it, minimize idle and part throttle. I like to do this on gentle uphill runs, puts a higher load on the engine and hotter combustion temperatures.

Then pull the plugs and read…..use any of the Google picture charts to determine fuel mixture, oil burn, preignition, etc….

Now. this will tell you if you’re running rich/lean ONLY on the main jets or, as you mentioned, a potential manifold leak….idle and part throttle, if the carb is clean, should be fine.

This is a cool idea, I’ve got another set of plugs so I will try this and report back.

 

[nachohouse]

What the op describes sounds perfect.

How do I "read" a spark plug? - NGK Spark Plugs

Learn how to analyze your engine's overall operating condition just by looking at your spark plugs. Find this and other DIY tips on our resource page.

ngksparkplugs.com

Yeah this does seem like I might be doing okay. The plug pics in my Haynes manual makes things seem more ominous.

 

[nachohouse]

What the op describes sounds perfect.

How do I "read" a spark plug? - NGK Spark Plugs

Learn how to analyze your engine's overall operating condition just by looking at your spark plugs. Find this and other DIY tips on our resource page.

ngksparkplugs.com

Yeah this does seem like I might be doing okay. The plug pics in my Haynes manual makes things seem more ominous.

The suit on the exhaust ports on 2,3 is concerning. Exhaust in the engine bay is a health concern for the driver. Are you running the stock manifolds?

Yep stock manifolds. It’s pretty minimal on the top of the gasket. The gasket doesn’t look too old (I only acquired the rig 3 years ago) so I just chalked it up to wear-in soot since there aren’t any loud leaks or problems with it running or missing.

 

[Mark Jennings]

I’ve also noticed over the years that the fuel you buy plays a good part of reading ‘OLD’ plugs….what I’ve seen with the advent of 10% ethanol….is a ‘Hard Ash’ build up on the plugs. Unleaded fuels, non-ethanol and ethanol laced, typically are sooty, leaves the tail pipe black….

Two things I dislike about ethanol laced gas is 1) it will absorb water and if you are not routinely running a tank dry or draining it seasonally….rusty tank syndrome. Then 2), lower vapor pressure…the stuff will vapor lock at lower ambient temperature, e.g. lower engine bay temperature.

What I do like however, the ethanol acts as an octane booster, so you can run a tad more advance in the timing and….more timing gives a perceived improvement in throttle response….

So when you do your WOT runs, make sure it’s the fuel you generally run. Read the plugs as the old racers did….take some pic’s, then pull those same plugs at 3k miles and read again…to me ash is a tell-tale of fuel impurities.

And finally, another fun thing to do, is borescope the cylinders, borescopes are pretty inexpensive now…..mine was $50 from Amazon and I’ve stuck it every car I own…..then again, you may not want to see what’s there…..….but it does have cool factor.

My #6 on my ‘68 F, looks like a vertical score….(piston top to the left)….

 

[Grayscale]

Sometimes installations are kinda compromised by buggered up threads on the head studs. If you can't get a clean pull upon disassembly, the cast iron of the exhaust manifold, or steel header can mar the male-end of the stud thread. Using a die to clear the thread interference from the head stud will be important if you are threading anything back onto the stud (like a double-nut-technique for stud removal/replacement).

Having clean threads is important for manifold(s), as the torque is making a seal for intake vacuum and exhaust.

I don't think that male threads can be restored with dies, as the die usually takes some of the critical thread-root, and plating with it (as the factory never cut threads, but rolled the material to shape). Steel has this interesting property called 'grain-flow.' I kept the original studs for further service, even though I expect them to be much more subject to fatigue/failure. Post-installation, I checked the torque values after some thermal cycling. I've experienced no issues getting a gasket to set for the intake and header.

Maybe the improper manifold stud torque setting is a condition that your F-engine is dealing with? I used copper anti-sieze and the factory torque specs.