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Author
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Topic: 393 problems
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jeffstar
Journeyman Posts: 93
From: Toronto, Ontario, Canada
Registered: Feb 2003
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posted 08-22-2004 11:12 AM
   
The first hint I had was while recording the mechnical advance vs RPM, as I approached 30 degrees, I could hear a subtle knocking sound, it disapeared when I retarded the timing to 25 degrees. Previously it sounded fine with 30 degrees advance. I took it for a little spin, I was just taking it easy abut 3-4000 rpm and I heard one fairly distinct sound like severe spark knock just for a 1/2 second and then it sounded normal again. About 10 seconds later a clacking sound started, like a lifter except louder and it sounded like it was in the bottom end. I shut it off coasted to a stop. 1) Pulled the starter to look inside to see if I could see anything strange around the clutch, can't see much but nothing unusual. 2) Did a compression test, looks good 205-210 all cyl. 3) Started it up again, this is what it does... at idle everthing sounds normal, bring the revs up slowly and at about 2000 rpm I hear a random and quite loud clack once every few seconds sounds like metal to metal something. If you increase the revs say to 2500 it happens more often. The sounds is loud! When you hear it natural response is to back off the throtle because it sounds very destructive. 4) I pulled the dizzy and tried prying the cam back and forth, looks good. 5) I pulled the intake to check the spider, looks fine, I pulled one lifter looks perfect. 6) I checked the cam timing, perfect as per my degree in notes. Next step is to either pull the pan or the motor Any ideas before I do?
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V8 Thumper
Gearhead Posts: 4377
From: Arizona
Registered: Dec 2001
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posted 08-22-2004 10:01 PM
Valve spring bind?------------------
1965 GT coupe, 333ci aluminum headed/solid cammed stroker, four speed, 3.70:1 9" All Blue Oval, no blue bottle
http://mustangsandmore.50megs.com/V8Thumper.html
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jeffstar
Journeyman Posts: 93
From: Toronto, Ontario, Canada
Registered: Feb 2003
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posted 08-23-2004 12:20 AM
Valve spring bind?Please explain
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V8 Thumper
Gearhead Posts: 4377
From: Arizona
Registered: Dec 2001
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posted 08-24-2004 01:57 PM
If at full lobe lift you cannot fit a .060 feeler gauge between the coils of a valvespring (solid lifters), you could have coil bind. ------------------
1965 GT coupe, 333ci aluminum headed/solid cammed stroker, four speed, 3.70:1 9" All Blue Oval, no blue bottle
http://mustangsandmore.50megs.com/V8Thumper.html
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Catmando
Gearhead Posts: 133
From: Vermilion, OH USA
Registered: Jun 2004
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posted 08-24-2004 08:47 PM
Drain oil / cut open your oil filter, looking for metal shavings. I know we're all guessing on the sound. Rod knock? spun rod bearing. See if it occurs with the clutch depressed or not. Maybe something loose on the flywheel / clutch?
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 08-25-2004 12:14 AM
The last time I heard strange tapping noises on a fresh engine was when we found out that the cam had wiped out 3 lobes and lifters. Another time it was a minor crankshaft clearance issue. Another was the rockers hitting the valve covers... With all those moving parts it could be just about anything. Lots of luck.
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1966 Mustang Coupe: Custom glass hood and BIG scoop sits atop a 289 stroked to 331 c.i., Steel crank, rods and girdle, TFS alum. heads, Stealth 8020 intake, Xtreme 268 Solid Roller, Holley 750 HP, long tubes, 4speed, 9" 3.50 posi.
11.86 @ 116 mph (7.62 @ 93 mph)daily driver!
DanH
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jeffstar
Journeyman Posts: 93
From: Toronto, Ontario, Canada
Registered: Feb 2003
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posted 08-25-2004 12:55 AM
BluesteakI am curious about the "minor crankshaft clerance issue" Please explain Thanks, Jeff
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Stang72
Gearhead Posts: 203
From: Arkel,Zuid-Holland,Holland
Registered: Jan 2003
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posted 08-25-2004 07:43 AM
a friend of mine has kind of the same issue with the same rpm-range, only with a 460..with him we have narrowed it down to a collapsed lifter of something else in the valvetrain..maybe it's a lifter with you??? (if your's hydraulic...) good luck and let us know what it was Ben
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scottford351
Journeyman Posts: 90
From: reedsville ohio usa
Registered: May 2003
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posted 08-25-2004 10:48 AM
My past experience with clearence issues in a 393/8 was the oil pan rail on the right rear where the rails narrow down (by the starter). Only after I had the oil pan completely tightened, the end of the rod bolt hit the rolled edge of the oil pan.
This was in a stock rod motor.
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91 LX 398w street/bracket 6.88 1/8 60FT 1.44
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 08-25-2004 05:26 PM
On any stroker motor, the oil pump, oilpan, windage tray, block, or cylinder wall could be touching the crank and/or rods as they start to rev. May not be your problem if clearances were thoroughly checked during the initial mock-up process. Just throwing out some ideas. ------------------
1966 Mustang Coupe: Custom glass hood and BIG scoop sits atop a 289 stroked to 331 c.i., Steel crank, rods and girdle, TFS alum. heads, Stealth 8020 intake, Xtreme 268 Solid Roller, Holley 750 HP, long tubes, 4speed, 9" 3.50 posi.
11.86 @ 116 mph (7.62 @ 93 mph)daily driver!
DanH
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jeffstar
Journeyman Posts: 93
From: Toronto, Ontario, Canada
Registered: Feb 2003
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posted 08-28-2004 12:03 AM
It was a rod bearing!
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Catmando
Gearhead Posts: 133
From: Vermilion, OH USA
Registered: Jun 2004
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posted 08-30-2004 12:49 AM
OUCH!! Hopefully not too much damage.
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jeffstar
Journeyman Posts: 93
From: Toronto, Ontario, Canada
Registered: Feb 2003
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posted 08-30-2004 01:42 AM
Thanks again for all the advice.With some luck I should get the crank back this week (less 0.010 or 0.020) on the rod journals. All the bearings looked kind of crappy from the bearing material circulating. All the other crank journals look surprisingly good. I expected the oil pump to be trash, a lot of crap came out when I pumped the relief valve, but after cleaning it looks almost new, just a few minute pieces of copper embedded into the rotor. This engine uses a hydraulic roller and FORD OEM lifters, I am a bit concerned some of the bearing grit will be inside the lifters. Should I attempt to clean them if so can I just pump wd40 through the hole or should I disassmeble them? Any other advice is welcome Thanks, Jeff
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