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Registered
Join Date: May 2008
Location: Cincinnati, Ohio
Posts: 112
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Carb Air Flow
I have a 1970T with a 69E engine and 40IDS carbs. The car was sitting for quit a while when I bought it and the engine was out. At this point, I've been working on it for 1.5 years and mechanically, it's pretty sound. The issue that I having comes in two forms. 1. The carb barrel for cylinder #3 only flows at about 3 bars. All other barrels are synched to 9 bars. If I adjust the airflow screw, it does not help. The carbs were rebuilt over the winter time and each half was soaked in carb cleaner for 3-4 days. The second issue manifests itself in a hissing sound that appears to come from cylinder 1 or 2. The sound gets louder when I go underneath the car. Searching the forum lends me to believe that it could be a small piece of carbon stuck between the valve and the seat. Cold this be the answer? I would appreciate any help. The car pulls very strong above 2000 rpms so, I would think it's not a bent valve.
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08-07-2009, 05:52 PM
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Registered
Join Date: May 2008
Location: Cincinnati, Ohio
Posts: 112
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Suggestions Please??
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08-08-2009, 07:46 AM
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Evolved
Join Date: Jan 2007
Posts: 3,338
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Starting point - I would run a compression check on all cylinders, you may find # 3 is lower than the rest.
____________ A piece of carbon ' remaining in place ' between valve and seat, after an engine has run for any amount of time, is very unlikely. Think: valve rotating slightly/pounding against the seat, the heat involved, vibration, air flow, etc. Carbon CAN build up on the valve stems just ABOVE the seat and in the cylinder heads. That is why at least twice a year, EVERY car/boat/truck/mower/weed- eater I own gets: warmed up to temp, air filter removed, RPMS increased, and plain tap water sprayed from a bottle ( ala Windex ) into the intake ...several times, just to the point of killing the engine, then let it return to RPM speed ... and repeat. The water, during the combustion cycle, turns to steam and helps assist blasting away any carbon deposits. Get one of those stethoscopes to listen under the car to try and locate the hissing source. That sounds like a possible exhaust leak.
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Don't fear the reaper. Last edited by Mo_Gearhead; 08-08-2009 at 08:05 AM.. |
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08-08-2009, 08:02 AM
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Registered
Join Date: May 2008
Location: Cincinnati, Ohio
Posts: 112
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A friend came over today and said that it sounded like an exhaust leak. I'm going to pull the headers over the next week and order gaskets to see if that fixes the problem. I forgot to clarify, cylinder #3 pulls 3 bars at idle and 10+ when I rev the engine. Is that still possibly a compression issue? Thanks for the advice.
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08-08-2009, 01:29 PM
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Registered
Join Date: May 2008
Location: Cincinnati, Ohio
Posts: 112
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I pulled the headers and replaced the gaskets. The hissing sound is still there. I bought a compression tester and the results are as follows.
Cylinder # Results 1 60 2 155 3 140 4 145 5 145 6 145 Obviously, I have a problem on #1 which would explain the leak. The test was done with the engine warm and cylinder #1 would not even hold pressure. So, is this a possible valve issue or p&c? What's the next step, a leakdown test? If it is a burnt exhaust valve, could the head work be completed on the left side only since the right side appears to be fine. Or, would it better to complete work on both sides since I have it out of the car anyway? Suggestions please and thanks. |
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08-22-2009, 04:47 PM
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Alii&Maui
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Make sure the valves are adjusted right. Number one cylinder might be too tight.
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1982 SC Coupe SCWDP#0087 KCSSL#0082 |
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08-22-2009, 05:49 PM
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911SC
