Self-Inflicted Wound

Shurt24

New member
Sep 30, 2019
10
0
1
Little Rock, AR
Hi all, I’m new here, and have come to confess.

I ran my 403 out of oil. I heard a slight ticking, failed to check it in time, and it began running really rough. Got it home, got some oil in it, and that tick turned into a KNOCK.

I fired it up one more time to move it to where I was pulling the motor, and it ran extremely rough. No power, seemed like the entire motor was out of time.

Got the engine out, torn all the way down to the crank, and have seen no obvious culprits. Looks like the bottom a valve is charred. Looks like a piston has been hit a couple times, but doesn’t look like anything major has gone wrong. Not to cause that kind of running issue.

before I pull these bearings, is there anything I can do/check/test?
 
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Olds 307 and 403

Active member
Oct 4, 2018
339
101
43
Melville, Saskatchewan
Did the timing chain skip? Was the motor really hot? Was it a center exhaust valve? The valve could be bent after contact.
 

Shurt24

New member
Sep 30, 2019
10
0
1
Little Rock, AR
Timing chain was solid. Motor didn’t seem to get hot. I’ll get some pictures of the damage I found posted tomorrow.
Thanks for the quick reply.
 

Olds 307 and 403

Active member
Oct 4, 2018
339
101
43
Melville, Saskatchewan
That makes me think stuck valve. Were the heads done recently? A few guys have had center exhaust valves stick. Machine shops put the clearances too tight, they need a minimum. 0028" is my understanding. Those big center exhaust crossovers create a lot of heat. I picked up a set of fresh machined #6 heads. I checked the guide clearance, right around .003" clearance, 0 issues running them.
 

Olds 307 and 403

Active member
Oct 4, 2018
339
101
43
Melville, Saskatchewan
I used snap gauges with micrometers. My guess is your shop set the center guides to tight. Which cylinder has the contact?
 

Intragration

Member
Apr 2, 2019
44
23
8
Chicago
This sucks, sorry you're having to deal with the fallout. I have a buddy, a self-proclaimed "non-car guy". He bought a newer vehicle, because they're "reliable". At some point, I got the impression he hadn't had an oil change in a while. I asked him how long. He said "oh, 20k miles". ?!? Asked how long since he CHECKED it. "Never, don't know how". So I immediately checked it. There was just a little nugget of black tar on the end of the dipstick. Ended up putting 4 quarts in a 5 quart system. No apparent ill effects. (APPARENT) But I guess they ARE reliable. I always feel sick when I wait too long and have to add a full quart.
 
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Olds 307 and 403

Active member
Oct 4, 2018
339
101
43
Melville, Saskatchewan
Number 8 looks oily. Is #2 kind of carboned up? I think some guide measurement is in order.