engine gone bad
Thread Starter
Pro
Joined: May 2004
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From: caraquet N.B Canada
engine gone bad
Last week my engine started to run extremely rought. Today i checked and i got two cylinder that dont work. I have check the compression and it seem fine. I also check the fire and it's fine too. Also check my carb and look ok. I even remove the valve cover to check if the valve were working fine . Because a few years back i had a broken valve spring and was running rought also.With those pre-computer car i always tought that with those combo working fine it should work fine. If someone could help me i would be please.
Last edited by den(thevetteman)78; Oct 27, 2007 at 10:00 PM.
Pro
Joined: Jul 2005
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From: Holtwood PA
Last week my engine started to run extremely rought. Today i checked and i got two cylinder that dont work. I have check the compression and it seem fine. I also check the fire and it's fine too. Also check my carb and look ok. I even remove the valve cover to check if the valve were working fine . Because a few years back i had a broken valve spring and was running rought also.With those pre-computer car i always tought that with those combo working fine it should work fine. If someone could help me i would be please.
Team Owner
Joined: Aug 2006
Posts: 24,125
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From: Columbia Missouri
this should be in the tech forum..but, check timing check for spark at the plug, maybe plugs went bad (fouled out?)if the compression is good and theres no knocking and banging in the bottom, the engine is probably ok, I would start with the ignition..how did you know 2 cylinders aren't working??
How do you know for sure you have two cylinders out? It's hard to see in there. 
Thread Starter
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Joined: May 2004
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From: caraquet N.B Canada
this should be in the tech forum..but, check timing check for spark at the plug, maybe plugs went bad (fouled out?)if the compression is good and theres no knocking and banging in the bottom, the engine is probably ok, I would start with the ignition..how did you know 2 cylinders aren't working??
The first thing we did was changing the plugs,after we remove one plug wire at a time and notice that after removing the 2 and 5 the engine was not changing sound. so remove the plugs and notice that they were wet. vwe did a leak test around the intake and at the bottom of the carb.
Race Director
Joined: Jul 2004
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From: Scottsdale Arizona
Paul says cylinders 5 and 8 but looks like you've edited this out. Are these the two that are missing? If so, very unlikely to ve a vacuum leak unless something really significant happened.
First off, make absolutely certain that you have spark to those cylinders, then make triple sure that you have the right firing order. Super easy to make this mistake.
First off, make absolutely certain that you have spark to those cylinders, then make triple sure that you have the right firing order. Super easy to make this mistake.
Thread Starter
Pro
Joined: May 2004
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From: caraquet N.B Canada
Paul says cylinders 5 and 8 but looks like you've edited this out. Are these the two that are missing? If so, very unlikely to ve a vacuum leak unless something really significant happened.
First off, make absolutely certain that you have spark to those cylinders, then make triple sure that you have the right firing order. Super easy to make this mistake.
First off, make absolutely certain that you have spark to those cylinders, then make triple sure that you have the right firing order. Super easy to make this mistake.
Race Director
Joined: Jul 2004
Posts: 12,696
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From: Scottsdale Arizona
I'd start by making sure that it wasn't the manifold vacuum port for the tranny and headlamps. This is the fitting that sticks up from the intake behind the carb. A simple way to test this is to pull the two (I think its two n the 78) hoses off and put a small piece of hose from one to the other. If the car still runs rough, spray a little WD-40 at the threads where the fitting connects. If the rev's come up, you've found the leak.
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Pro
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From: Holtwood PA
did you check the spark at the cap end or at the plug end?? you can get a cheap tester that the plug cap plugs onto and the it clips to a ground...it sounds to me like the plug is not firing...if it's wet that means that fuel is getting there and is not igniting
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From: caraquet N.B Canada
We did check it at the plug end with those tester and the spark was real strong. So thats why we don't know what could cause it to run like that. The only thing he could think left, it's that it dont have enough gas who goes into those cylinder to fire them up . He have another carb i will try it to see if it's not the carb.
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From: Holtwood PA
We did check it at the plug end with those tester and the spark was real strong. So thats why we don't know what could cause it to run like that. The only thing he could think left, it's that it dont have enough gas who goes into those cylinder to fire them up . He have another carb i will try it to see if it's not the carb.
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From: Holtwood PA
Instructor
Joined: Dec 2004
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From: Carlisle Pa.
Same problem but cylinders #2 and #8
New dist. cap, wires and plugs.
compression is good in all 8.
Good carb. and no vac. leaks.
i'm thinking intake gasket or headgasket.
I have to finish clutch in the 85 then i start the tear down of the 72.
New dist. cap, wires and plugs.
compression is good in all 8.
Good carb. and no vac. leaks.
i'm thinking intake gasket or headgasket.
I have to finish clutch in the 85 then i start the tear down of the 72.
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From: Holtwood PA
hey neighbor...yeah I got the front clip off mine..need to find a shop that can straighten the fram for next to nothing...(not to hijack)...let me know I'll try to help if I can..have a pretty well epuiped shop in Paradise