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#1 |
Senior Member
Join Date: Jul 2004
Location: Sweden
Posts: 833
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Engine smoking
What do you guys think the problem is with my engine.
I bought this 73 454 that was supposed to be OK a while back. Put my newly rebuilt (new guides and new teflon seals) 72 402 heads on it and yesterday I started it for the first time. It ran good but smoked from the left exhaust pipe. Then suddenly it stárted to run on 7 cylinders and a mecanical noise came on. I took the engine out of the truck and found a very oily exhaust port on #5 cylinder. Is it a bad oil ring/piston ring or what do you guys think? Thanks in advance. Mats.
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Mats.. ---------------------------------------------------- 1971 Cheyenne Super Custom Camper 475CBB/TH400/AC 1992 Silverado Sport Truck 1988 Silverado 2500 Ext Longbed 4x4 2001 GMC Sierra SLT 4x4 1990 Chevrolet K3500 1965 Pontiac Grand Prix 1980 Z 28 350/4-speed/AC/T-top 1980 Camaro Coupe V6/3-speed 1979 Buick Century Wagon |
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#2 |
Registered User
Join Date: May 2006
Location: Jonesboro, AR
Posts: 916
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Re: Engine smoking
The last time I had a problem like that, #1 or #3 cylinder dropped a valve. Thankfully it didn't trash the piston.
See if either of the retainer cups move side to side on #5. With those symptoms you will have to pull the head regardless of what it is. |
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#3 |
Senior Member
Join Date: Jul 2004
Location: Sweden
Posts: 833
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Re: Engine smoking
Thanks 71 tahoe,
I will check the retainer cups. Mats
__________________
Mats.. ---------------------------------------------------- 1971 Cheyenne Super Custom Camper 475CBB/TH400/AC 1992 Silverado Sport Truck 1988 Silverado 2500 Ext Longbed 4x4 2001 GMC Sierra SLT 4x4 1990 Chevrolet K3500 1965 Pontiac Grand Prix 1980 Z 28 350/4-speed/AC/T-top 1980 Camaro Coupe V6/3-speed 1979 Buick Century Wagon |
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#4 |
Account Suspended
Join Date: Sep 2005
Location: Monroe, WA
Posts: 3,815
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Re: Engine smoking
Did you run the engine prior to installing the new heads? Agree with checking the heads as noted...but I'd also consider a worn cam lobe (easy to check) or...the engine wasn't as OK as communicated and you've got a bad cylinder - a compression/leak down test will tell you if that's the case.
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#5 |
Registered User
Join Date: May 2006
Location: Jonesboro, AR
Posts: 916
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Re: Engine smoking
Also, how did the plug look? How long did it run and what RPMs did it turn. There may be some distortion in the picture but if you hold a straight edge on #3 exhaust it looks straight. If you do the same to #5 it looks like it's bent. If the new guide was installed at an incorrect angle it could have had enough resistance to let the valve come in contact with the piston without the retainer letting go.
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#6 |
Senior Member
Join Date: Jul 2004
Location: Sweden
Posts: 833
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Re: Engine smoking
I didn't run the before I installed the new heads, and when I started it I ran it for about 5-10 minutes. All cam lobes look OK and so do the valves and the rest of the heads.
I took the whole engine apart and found a stuck oil ring expander/spacer on #5 piston. It was overlapping at the ends and had slipped in to the slotted hole in the piston side. The cylinder wall looks and feels OK but I will take the block to a machine shop to have it measured. Thanks for your comments and advices.
__________________
Mats.. ---------------------------------------------------- 1971 Cheyenne Super Custom Camper 475CBB/TH400/AC 1992 Silverado Sport Truck 1988 Silverado 2500 Ext Longbed 4x4 2001 GMC Sierra SLT 4x4 1990 Chevrolet K3500 1965 Pontiac Grand Prix 1980 Z 28 350/4-speed/AC/T-top 1980 Camaro Coupe V6/3-speed 1979 Buick Century Wagon |
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#7 |
Active Member
![]() Join Date: Jul 2007
Location: Centrally located between Houston, Austin and Waco. BCS area.
Posts: 7,947
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Re: Engine smoking
Hey, 68 50th, thanks for the update. Too many times we have a problem and get opinions/advise and no one knows finds out what fixed it...
My 69 has been fouling the plug on cylinder #1 and I've always assumed it to be the valve guides. I may have to take a deeper look inside the tired, old 350... |
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#8 |
Account Suspended
Join Date: Sep 2005
Location: Monroe, WA
Posts: 3,815
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Re: Engine smoking
Rats
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#9 |
Senior Member
Join Date: Jul 2004
Location: Sweden
Posts: 833
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Re: Engine smoking
I went to the machine shop yesterday to have the engine checked.
The oil ring issue on #5 cylinder didn't damage the damage the cylinder wall. We measured all pistons and cylinders. Cylinders was glazed and just honing and new rings would give to much piston play so the engine will have a 060 over bore (was 040 already) and new pistons.
__________________
Mats.. ---------------------------------------------------- 1971 Cheyenne Super Custom Camper 475CBB/TH400/AC 1992 Silverado Sport Truck 1988 Silverado 2500 Ext Longbed 4x4 2001 GMC Sierra SLT 4x4 1990 Chevrolet K3500 1965 Pontiac Grand Prix 1980 Z 28 350/4-speed/AC/T-top 1980 Camaro Coupe V6/3-speed 1979 Buick Century Wagon |
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#10 | |
Registered User
Join Date: May 2006
Location: Jonesboro, AR
Posts: 916
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Re: Engine smoking
Quote:
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#11 | |
Senior Member
Join Date: Jul 2004
Location: Sweden
Posts: 833
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Re: Engine smoking
Quote:
Yes the ring gap orientation was like that, I also noticed that when I took it apart. I have the "How to rebuild Big Block Chevy Engines" book by Tom Wilson, there is a good explanation for where all the rings gaps should be.
__________________
Mats.. ---------------------------------------------------- 1971 Cheyenne Super Custom Camper 475CBB/TH400/AC 1992 Silverado Sport Truck 1988 Silverado 2500 Ext Longbed 4x4 2001 GMC Sierra SLT 4x4 1990 Chevrolet K3500 1965 Pontiac Grand Prix 1980 Z 28 350/4-speed/AC/T-top 1980 Camaro Coupe V6/3-speed 1979 Buick Century Wagon |
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#12 |
Account Suspended
Join Date: Sep 2005
Location: Monroe, WA
Posts: 3,815
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Re: Engine smoking
Ouch. So are you doing a complete bottom-end overhaul then?
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#13 |
Senior Member
Join Date: Jul 2004
Location: Sweden
Posts: 833
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Re: Engine smoking
Yes, I will do a complete overhaul. Bore, pistons, crank grind, all new bearings, new cam, lifters and cam drive, new oil pump and the heads was done already.
Hopefully everything turns out fine next time I start it up ![]()
__________________
Mats.. ---------------------------------------------------- 1971 Cheyenne Super Custom Camper 475CBB/TH400/AC 1992 Silverado Sport Truck 1988 Silverado 2500 Ext Longbed 4x4 2001 GMC Sierra SLT 4x4 1990 Chevrolet K3500 1965 Pontiac Grand Prix 1980 Z 28 350/4-speed/AC/T-top 1980 Camaro Coupe V6/3-speed 1979 Buick Century Wagon |
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