Diputado

Hi folks,

A simple (hopefully) question...just bought a '65 coupe with a '70-72 model 302 running '65 model 289 heads (early ones..no rail-type rockers), a "nice sounding" cam, Holley 750 and Street Dom. intake, headers, top-loader and a 9" rearend. When I got it home, I noticed that it was running Motorcraft BSF-82C plugs...which are fairly "hot" plugs for a 6-cylinder engine. I pulled a couple and they have dry soot, probably from a too-rich mix from that big 750 (new 600 cfm just arrived!).I plan to change these supposedly "hotter" plugs out for BSF-42C, which are the recommended plug (and what I have ran before in similar setups). But before I do....are the 82C plugs actually "hotter" plugs than the 42C (guy at local Ford place said the opposite!), and if so, WHY would anyone be running "hot" plugs in a mildy-built street rod where the BEST gas we can get here is only 91 octane???

guitarman376

v8 or i6? You say both above. Some motors like different plugs, lots of variables to consider.

Derf00

42C is a cooler plug than 82C

Diputado

The motor is a 302. When I mentioned the 6-cylinder I was referring to the fact that those plugs were FOR a 6-cylinder...not an 8. Sorry for the confusion.

I think the guy at the Ford place didn't know what he was talking about. I agree with the response from Derf00...everything I've found indicates the 42C is a colder plug.

That is the question....is there a logical reason someone would run hotter than recommended plugs in a built-up V-8 running on 91 octane pump gas...??

Oh..yeah...ONE MORE mystery with this motor. When I changed the oil, I discovered that the oil breather cap on BOTH valve covers had been completely sealed to the covers with some kind of gray sealant!!! All vent holes were completely plugged. There was NO crankcase ventilation at all. Resulting pressure had oil seeping up from under one of the intake bolt heads, and leaking out the valve cover gaskets. Now, I am about to change the valve covers to a better design (with PCV capability), as well as replacing the intake gaskets. WHY THE HELL WOULD SOMEONE DO THIS??? Doesn't make sense to this Hillbilly...!!

kenash

Hi, regarding the PCV mystery. The PO didn't/doesn't understand the reasoning and value of a good functioning PCV system. I ran a closed system for a long time until I change over to Dual DCOE Webers.
Make the change and enjoy a reduction in any oil seepage.
Good Luck with your project.

Diputado

Thanks, kenash....will keep you posted. Any thoughts, though, on my original question about those hot spark plugs?? (see above).

kenash

Hi,
You've already received a "ton" on the plug question. My simple reply would be to purchase the correct plug for a stock 302. After which, replace (as you mentioned) that "too big" carb with a 600, or so. Then, start the tuning process.
First, document all of your changes. Perform a stock tune, gaps, initial timing, adjust new carb using a vac gauge. If still sooty/rich, dial back the metering rods first.
again, only make one change at a time.
Good Luck!

Al Newman

Just a wild guess, here, but it sounds like the PO was attempting to eliminate plug fouling from that monster carb. That's why he stepped up to the 82's and killed the crankcase emissions from returning to the intake and fouling the plugs. That don't sound too smart, but I wish I could say I didn't try some really stupid things back in the day. It's how we learn if we are too stubborn to listen to others' advice.
Best,
Al

kenash

Actually a very valid comment! +1