Looks like she is running a bit on the lean side. But it's really confusing.
She runs just fine, starts easy, makes a lot of power, no knocking under load etc. - not a single sign of a lean running engine, at least as far as I know.
I have a ton of advance though - 36 deg. (at 3600 rpm) mechanical and 20 deg. at 15 hg/inch at the vacuum (manifold). But actually if you drive, the Engine loves it, and I think it would be happy to take even more. A guy that actually was racing 235s/261s back in the 50s and 60s told me an 848 head wants a lot of timing , and that's exactly what I see. The more I throw at her, the better she runs - but that white plugs are concerning me.
This is a mild build 261, 848 head, 3/4 cam (Bulldog), overbore, single Clifford intake, headers, flipped pistons, Fish carb.
Other than that P.T. Barnum spark plug having three too many ground electrodes, I don't see a problem. If you're running no-lead gasoline, spark plug color is not an indicator of fuel mixture. The "tan to chocolate brown" color we looked for 50-something years ago became impossible to find once the lead additives got removed. Now plugs will have one of two colors- - - -white or sooty black once the mixture gets WAY too rich. A really lean mixture will cause a shiny, blistery appearance of the porcelain plug tip, and a severely eroded ground electrode. Extremely lean mixtures will also detonate, burn holes in pistons, and burn exhaust valves.
What's a "flipped piston"???????? Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
So I don't have to be worried? That's a consolation Jerry.
Originally Posted by Hotrod Lincoln
What's a "flipped piston"????????
I got this fron Smokey Yunick (some old hot rod magazine artikel he wrote).
Our pistons have an offset pin to reduce piston slap - right?
In a nut shell: If you take the pin out and rotate the piston 180 degrees (so that notch/mark faces backwards instead of to the front) you change the (rod/crank) geometry, which Yunick states gets you some more power and "snappiness".
By reversing the piston, the rod is more upright on the way down (like a longer rod), pushing more directly on the crank, thus, slightly higher torque at certain points in the stroke. You pay for it with some piston chatter when cold though, also probably more wear.
Agreed. Plug looks perfect to me. Keep giving it to her till you see a performance drop off.
I had an Ford FE engine (429) that loved timing. If I set it stock it was a dud compared if I gave it what it wanted. Only failure I had on that thing was a broken fuel pump spring that was sucked into the oil pump impeller at 8K + rpms.
Smokey might have been right about a lot of things, but he's all wet on this one. The purpose of an offset wrist pin is to assure the piston skirt is pressed firmly against the cylinder wall before the spark plug fires. Letting the piston "float" in the cylinder at the moment of plug firing will increase two things- - - -noise, and the risk of breaking the piston skirt as it slams against the cylinder when the combustion pressure hits the top of the piston. Doing race stuff on a street engine is beyond belief- - - - -forged racing pistons are usually made without offset pins, possibly confirming Smokey's opinion, but I've yet to build a racing engine over the past 50+ years that was not totally worn out in less than a thousand miles on the dirt track- - - - -usually a LOT less! Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
