mystery & vague clues

[Jeb Stuart]

I removed the 38 weber and put my 32/36 carb back on.
Started her up and there was a metal sound like the fan was hitting something.
Turned her off and checked around the fan - nothing.
Started her back up and same as above sound that seemed to come from the fan.
Checked again but this time the starter wouldn't turn the engine over.
I am thinking I must have dropped something in the intake.
So - - the clues
As far as I know all nuts and washer are accounted for.
With a socket (thanks forum for the size) on crankshaft pulley nut I can turn it exactly 360 one way until it stops then exactly back 360 until it stops.
Valves go up and down and push rods look OK.
Removed the intake manifold and looked (as best I could) in the intake ports - nothing.
Looked in the spark plug holes - nothing.
Put a magnet in all holes and no loose metal.
Asked the guys at the British car shop in Decatur GA and they were puzzled. Said they can put back together whatever I take apart. However it'd be 2 weeks (which means 3) to get worked in.
So - - where to go from here? Suggestions? Remove the head?

Thanks as always to this forum

 

[Jeb Stuart]

another clue. When it turn 360 it stops when the #3 intake is moving then, the other way, when the #3 exhaust is moving.

 

[RootesRacer]

sounds very much like something went into the intake and is now in a cylinder.

You can tell it its 1/4 or 2/3 by finding the point where the engine binds with will be TDC for that cyl. Anecdotal info however as if this is the case, the head is coming off.

Definitely stop running it.

 

[DanR]

Jeb,

Here are a few comments from a recent post on the Forum under the MODIFIED SECTION: Holley 4160, 390cfm on V6 - "loose_electron"

From: Bill

Sometimes it is necessary to loosen the throttle plate screws a bit and wiggle the plates around while the throttle is closed. That allows the plates to align properly and close completely.

From: loose_electron

That is very useful information! Thanks!



Then DanR (me).

If they are on the car "Don't drop a screw"


From: Bill

No need to remove them, just loosen. But yeah, don't drop a screw.


The reason I made that comment is that I have been there and done that.... I dropped a nut from a Carter AFB down the intake of my 409 way back in the early '60's. Not good if you don't know ahead of cranking the engine.

 

[Tom H]

Likely there is a loose screw in one chamber. As Rootes Racer suggested, find which pistons are at TDC when it stops. Look in the plug holes to see. Once you find which two chambers are likely shine a bright light into the plug holes and see if you can see any dents in one of the piston tops. Maybe you will be lucky and can insert a coat hanger wire and loosen the screw that is likely now stuck into the head. Your description of the sound is very much like I had the time I suffered a broken piston ring and that's the sound I heard while the 1/4" long piece rattled around in the chamber. After about a minute the sound stopped but I was clearly running on 3 cyl after that. When I pulled the head I found the piece of ring stuck in the head. Maybe you can get lucky and avoid pulling the head.

Tom

 

[hartmandm]

There are USB / smartphone inspection cameras that will fit into the spark plug hole.

Mike

 

[RootesRooter]

Sounds like the object got past the valve and fell into the chamber when you were slowly rotating it. Don't start it up. If you haven't located the object by now, bite the bullet and pull the head.
If the object had previously fallen into the chamber you would have known it upon startup. It sounds nothing like a mere fan striking something; it's more like a jack-hammer.