Greetings @95gmcguy,
Those photos will be a big help to us trying to figure out the probabilities of the foreign object's shape
and size are the reason why your engine hasn't yet developed alarming hammering noises from one of your
cylinders? For example, a ball bearing dropped into one of the TBI throats and makes it past the throttle
blade *will* make it to one of the 8 intake valves, and unless it's diameter is bigger than the valve lift, it's
going into the cylinder with ugly consequences.
On the other hand, IF the shape is such that it got lodged at/near the valve stem and couldn't make the
turn around the short side radius of the intake port & into the cylinder, then *Voila* you dodged a bullet.
****
In a perfect world you will remove the least number of engine components in order to retrieve that foreign
object. As others have already suggested, the borescope is the best way to do just that. In a previous
life (thanks to the zero tolerance for leaving a loose foreign object behind anywhere in the aircraft) I've
had the (dis)pleasure of borescoping, sometimes for minutes, other times for hours on end, for *exactly*
the same FOD situation as you are facing. Given this, the following is based upon extensive firsthand
experience:
* The camera head must be small enough to fit through whatever opening you have available. For example,
the 5/8" spark plugs in your BBC actually use a 14mm thread in the head. In turn, 14mm threads require
a ~12.7mm drill bit in order to prep for the tapping process. Ergo, a >12mm camera head diameter is a non-starter.
Keep this in the back of your mind while shopping for your borescope.
* Picture quality is key. When working on aircraft we'd borrow the engine shop's borescope, and the picture
quality was pretty good -- of course, given the $$$$ of their kit, it should be. Point is, I've then tried to use
cheap borescopes in the civilian world back in the day, and it always ended up as an exercise in frustration.
Especially the units where they included everything (camera + display) in the low purchase price.
* In your case, the ability to capture > store > upload your pics so that the rest of the GMT400 community
can see what you are seeing is key. The really affordable stuff doesn't have that capability, so it would be you
with your camera taking pics of the low res borescope display. And thanks to normal ambient lighting this only
ends up taking a marginal image and making it worse.
* Non-articulating camera bodies are OK for taking a look at a home's HVAC ducting, but is not going to
be of much help inside an engine. For example, a rigid camera body that fits through a spark plug hole
can give you a look straight on at the top of the piston, BUT it can't bend itself 180° in order to take a
look at the all-important valves/combustion chamber surfaces.
Given the 4 borescope criteria listed above, you are going to want to want to either borrow, rent, or invest in
a borescope with this level of functionality: Amazon Link
If you followed that link, you'll see that the price of admission is ~$160. Admittedly not cheap, but if
it helps you to find/fix this yourself instead of involving a garage/dealership, then it will have paid for
itself many times over on it's very first use. (!) And everything after that is pure gravy.
NOTE: The
breaking the piggy bank, but in this case I'd rather just open up the engine with no borescope
instead of using a $30 non-articulating unit like this and risk giving myself a bad case of coprolalia: NOT THE ONE TO BUY FOR INTERNAL ENGINE RECON
NOTE: If it's any help, I can't believe how much functionality is in that $160 unit. Years ago the
jet engine shop guys had the no-kidding articulating camera bodies, but the picture quality was so-so,
and the price of admission was astronomical.
****
I was going to give some pointers on the distributor setup, but you are already in good hands, so
I would simply recommend that you get the engine to TDC on the compression stroke for #1 cylinder,
mark where the rotor is pointing as well as a reference mark between the distributor base to the intake
manifold...and then be sure to DISCONNECT the battery. I don't how many times either myself or a buddy
has accidentally prematurely engaged the starter while the dizzy was still out...Fudge! :0)
Hope this helps you with what to look for when trying to find a foreign object somewhere in the
tight confines of your 454. I'm also hoping for clear photos of the 'chipped' area. And not if but
when you find the foreign object really clear photos would be a valuable future reference for anyone
else that might end up traveling down the same path as yourself. And if you either borrow, rent, or
invest in a capable borescope and find it that way, I'll be downright giddy. (Can't help it -- that's the
way I always felt when we'd find that dropped fastener deep in the nether regions of the cockpit
after a lengthy borescope session.)
Best of luck in your search!
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