Dead Cylinder question 350 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jbristo67 · 03-01-2009, 07:25 PM

I have a 350 that has a dead cylinder compression wise. It is a crate motor with about 20000 on it. The guy that had it before me put a new cam in it and just never finished it up. What could be causing this Problem Any ideas??? The motor runs. I dont think it should be anything big. I was thinking maybe a head problem or push rod

stllookn · 03-01-2009, 07:30 PM

It could be a flat lobe on the cam. What was the compression in that cylinder? Did you take the valve cover off to check the movement on the rocker arms on that cylinder? This would be a good second step.

jbristo67 · 03-01-2009, 07:33 PM

Thanks for the direction I will get after it

**1970cstblazer** · 03-01-2009, 07:38 PM

Most probable is a valvetrain issue. Worst case could be a hole in the piston.

jbristo67 · 03-01-2009, 08:23 PM

How do I go about trouble shooting a valve train issue

67_C-30 · 03-01-2009, 08:45 PM

Did you ever take the valve covers off to see if all the valves were moving the same amount? Have you done a compression check to see which cylinder it is? We just a need a little more info to help you properly.

cparman · 03-01-2009, 08:56 PM

pull valve cvr and check movement of rockers to ck for worn cam lobe.

If you can put compressed air in the cylinder and listen to where it is going. IE if you hear it hissing thru the carb I would suspect an intake vavle problem. Thru the exhaust, and exhaust valve problem. Thru the valve cover would indicate a ring problem

jbristo67 · 03-01-2009, 09:01 PM

Quote:

Originally Posted by 67_C-30

Did you ever take the valve covers off to see if all the valves were moving the same amount? Have you done a compression check to see which cylinder it is? We just a need a little more info to help you properly.

No a buddy of mines dad is the one who did the compression check. I havent gotten my hands on the motor yet. My buddy was just wanting to sell it to me for a 100 and with as low miles as it had on it I thought it could be a really good deal on a good motor if it was nothing major.

jbristo67 · 03-01-2009, 09:03 PM

Quote:

Originally Posted by cparman

pull valve cvr and check movement of rockers to ck for worn cam lobe.

If you can put compressed air in the cylinder and listen to where it is going. IE if you hear it hissing thru the carb I would suspect an intake vavle problem. Thru the exhaust, and exhaust valve problem. Thru the valve cover would indicate a ring problem

See thats the thing its a new cam that has never been run

67_C-30 · 03-01-2009, 09:06 PM

Quote:

Originally Posted by jbristo67

No a buddy of mines dad is the one who did the compression check. I havent gotten my hands on the motor yet. My buddy was just wanting to sell it to me for a 100 and with as low miles as it had on it I thought it could be a really good deal on a good motor if it was nothing major.

Oh OK. Worse case scenario, its probably a cam and set of lifters, unless they just killed it. You said they changed the cam, and if they did not set the valves correctly or use a break in oil or zinc additive, it could be wiped out lobe. Today's oil is ****, and even people that have been building engines for years can wipe out a cam if they don't know about zinc being taken out of today's oil. It probably worth the $100 all day long regardless if it not cracked.

grayw0lf · 03-01-2009, 09:25 PM

Pass that engine up.

Do you happen to have your friend's name & number handy?

**El Jay** · 03-01-2009, 09:29 PM

Quote:

Originally Posted by cparman

pull valve cvr and check movement of rockers to ck for worn cam lobe.

If you can put compressed air in the cylinder and listen to where it is going. IE if you hear it hissing thru the carb I would suspect an intake vavle problem. Thru the exhaust, and exhaust valve problem. Thru the valve cover would indicate a ring problem

With that particular cylinder's piston at TDC.

jbristo67 · 03-02-2009, 06:08 AM

Quote:

Originally Posted by grayw0lf

Pass that engine up.

Do you happen to have your friend's name & number handy?

You just mad me lauph out loud

68 longbed · 03-02-2009, 08:52 PM

Quote:

Originally Posted by grayw0lf

Pass that engine up.

Do you happen to have your friend's name & number handy?

juniors used cars BR-549

03-01-2009, 07:25 PM	#1
jbristo67 resident oilfield trash Join Date: Jan 2009 Location: Lubbock TX Posts: 1,465	Dead Cylinder question 350 I have a 350 that has a dead cylinder compression wise. It is a crate motor with about 20000 on it. The guy that had it before me put a new cam in it and just never finished it up. What could be causing this Problem Any ideas??? The motor runs. I dont think it should be anything big. I was thinking maybe a head problem or push rod __________________ 1967 SWB C10 396/400 factory air factory tach (sadly had to send to a new home) 1986 Honda 70 Fourtrax 1991 Chevrolet K5 blazer 2wd 1982 Mastercraft Pro Star 190 Stars and Stripes 2002 Chevrolet Tahoe 2011 Nissan Armada Last edited by jbristo67; 03-01-2009 at 07:27 PM.

03-01-2009, 07:30 PM	#2
stllookn Saving 1 truck at a time! Join Date: Aug 2001 Location: Kent, WA Posts: 6,465	Re: Dead Cylinder question 350 It could be a flat lobe on the cam. What was the compression in that cylinder? Did you take the valve cover off to check the movement on the rocker arms on that cylinder? This would be a good second step. __________________ '68 C20 Longhorn 50th Anniversary 400/TH400 '68 C20 Longhorn 50th Anniversary 468/TH400w/buckets '72 C20 Halfhorn (Longhorn w/o cab and front clip) '69 Flxible Cruiser (look up ugly in the dictionary)

03-01-2009, 07:33 PM	#3
jbristo67 resident oilfield trash Join Date: Jan 2009 Location: Lubbock TX Posts: 1,465	Re: Dead Cylinder question 350 Thanks for the direction I will get after it __________________ 1967 SWB C10 396/400 factory air factory tach (sadly had to send to a new home) 1986 Honda 70 Fourtrax 1991 Chevrolet K5 blazer 2wd 1982 Mastercraft Pro Star 190 Stars and Stripes 2002 Chevrolet Tahoe 2011 Nissan Armada

03-01-2009, 07:38 PM	#4
1970cstblazer All stock and staying that way Join Date: Jul 2003 Location: Elkland, PA Posts: 1,692	Re: Dead Cylinder question 350 Most probable is a valvetrain issue. Worst case could be a hole in the piston. __________________ 1970 K/5 Blazer CST 4WD, Medium Bronze, 93k ACT. miles, 350, 4 speed, rear positraction, 16.5" x 8.25" HD wheel option, tilt, tach, vacuum, AM/FM, manual throttle...Dad ordered and purchased new 4/70. Currently frame off restoration finally getting close to completion.. 1972 Cheyenne Super 20 2WD, DK Blue/White, 90K ACT. miles, 402, TH400, 4.10 open, tilt, tach, vacuum, A/C, AM/FM, manual throttle.. A mostly original paint never rusted Texas survivor... 2017 Sierra 1500 SLT 4WD, Black, 45k miles, 5.3, 6L80E, 3.42 LS, 20" polished wheels, everything but moonroof and 6.2... 2019 Canyon SLT 4WD, White, 62k miles, 3.6, 8L45, 3.23 LS, 18" wheels

03-01-2009, 08:23 PM	#5
jbristo67 resident oilfield trash Join Date: Jan 2009 Location: Lubbock TX Posts: 1,465	Re: Dead Cylinder question 350 How do I go about trouble shooting a valve train issue __________________ 1967 SWB C10 396/400 factory air factory tach (sadly had to send to a new home) 1986 Honda 70 Fourtrax 1991 Chevrolet K5 blazer 2wd 1982 Mastercraft Pro Star 190 Stars and Stripes 2002 Chevrolet Tahoe 2011 Nissan Armada

03-01-2009, 08:45 PM	#6
67_C-30 I have a radical idea! Join Date: Jan 2005 Location: Sweet Home Alabama! Posts: 6,513	Re: Dead Cylinder question 350 Did you ever take the valve covers off to see if all the valves were moving the same amount? Have you done a compression check to see which cylinder it is? We just a need a little more info to help you properly. __________________ '67 C-30 Dually Pickup 6.2 Turbo Diesel, NP435 ‘72 C-10 SWB , 350 4bbl, TH350 '69 C-10 SWB , 250 L6, 3 OTT '69 GMC C3500, dump truck, 351 V6, NP435 '84 M1009 CUCV Military Blazer 67 C-30 Turbodiesel build thread http://67-72chevytrucks.com/vboard/s...d.php?t=254096 My trucks http://s226.photobucket.com/albums/d...ediafilter=all Member of the 1-Ton Club!

03-01-2009, 08:56 PM	#7
cparman sharp as a marble Join Date: Jan 2007 Location: atlantic beach,florida Posts: 1,082	Re: Dead Cylinder question 350 pull valve cvr and check movement of rockers to ck for worn cam lobe. If you can put compressed air in the cylinder and listen to where it is going. IE if you hear it hissing thru the carb I would suspect an intake vavle problem. Thru the exhaust, and exhaust valve problem. Thru the valve cover would indicate a ring problem Last edited by cparman; 03-01-2009 at 08:58 PM.

03-01-2009, 09:25 PM	#11
grayw0lf Registered User Join Date: Apr 2004 Location: Clanton, AL Posts: 1,253	Re: Dead Cylinder question 350 Pass that engine up. Do you happen to have your friend's name & number handy? __________________ 85' CUCV M1009!!! The newest addition! 6.2diesel, Th400, NP208, & only 36k miles! 70' C-10 LWB Fleetside - Looking good these days! 05' Dodge Neon 88' Winner Escape Sport 1750 - 4.3v6 94' Seadoo SP 84' Honda TRX200, bare nekkid. Just a frame & tires. Always looking for another project or any good deal!

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