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Post by floridaslingshots on May 24, 2011 13:43:59 GMT -5
This engine acted the same before i got it rebuilt, I gave SE my motor without the coils, rockers and carb so this has nothing to do with their work i feel they did a fine job on the rebuild and my problem is on the parts that bolt on the engine ..my engine burned a piston in the front hole toward the front of the car. i sent the engine to get rebuilt. I got the engine back rebuilt from SE and the rear cylinder exhaust is cold to luke warm while at idle or slightly above. The front cylinder exhaust is hot to touch. compression is good. the plugs i pulled at the rear always pulled wet. front plug dry. Spark is good. I tried another coil and unplugged the diode. same result. i installed intake and stack gaskets new Again. My fuel pressure is 6 to 7 lbs. , a little high. If i pull the plugs and turn the engine over it spits raw unburned fuel out the plug hole on the rear only. I'm gonna check and set fuel pressure tonight and do a leak down test . I had so many problems , oil leaks, handling problems, i may be trying to fix something that isnt broke. I replaced the needle in the carb and turned on the fuel pump on while holding the carb in my hand .. no leaks, needle holding at 6 lbs. pressure. Also when i pulled off the muffler end the rear pipe started to heat as normal ?? It scares me to think that this is normal especially after i burned up a piston before on the front cylinder. If the fuel pressure was to much , you would think it would wet both plugs. Well Before i start again tonight my thoughts are, Fuel Pressure, Carb, cracked intake, valve timing. I read an older post on cold cylinder , i wanted to see if there was any more info from anyone.. Any help would be appreciated Thanks, Mark
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Post by cokesbury on May 24, 2011 20:30:05 GMT -5
What are your valves adjusted at? What are the temps after a run?You can't go by the temps at an idle,they are setup to run at higher rpm,s. What jets are in the carb? 6 lbs is high we run 5 to 51/2.Start with the basics. Let me know what happens.
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Post by hammerdownpower on May 24, 2011 20:44:31 GMT -5
Try a different carb if you already ran without the diode wire. A clogged carb will cause this as i've had it happen to me. Car fired up and ran fine since the fuel from one barrel mixed somewhat into the other cylinder. But one of the orifices was clogged so throttle response was sluggish. Turns out someone had swapped jets and busted the tiniest piece off inside when they reinstalled it and it was blocking it. Same can be true for a spec of dirt. If you dont take the carb completely apart you really don't clean it.
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Post by floridaslingshots on May 25, 2011 7:44:13 GMT -5
Alright, this is what i found.. I did a leak down test..Good I did a compression test ...Good Spark i knew was good. I started the motor and adjusted the fuel pressure to 4.5 - 5lbs. The motor seem to run great. There was heat in the front cylinder and i had almost the same heat at the rear cylinder. I ran the motor for a few minutes shut it off and did a plug check, both plugs clean. I restarted the motor ran it for 15 or so minutes then condensation was building on the intake. heat still felt good. Then A LOT of condensation started running down the intake and carb on the outside. The cylinder slowly started to cool off almost to where i could lay my hand back on the pipe. I pulled the plugs again and on the rear cylinder found 2 beads of what i think is water coming from the condensation build up. So i think the excessive condensation is starting to mix in with the alchohol in the intake and almost fooling the plug and cooling the cylinder. I also think the engine will be fine running under racing rpms with the engine at full operating temp. I could watch the condensation work its way down the intake but only on the rear because the front cylinder runs a little warmer with less cooling air at idle. Does this make sense? i'll run it in warmups tonight and recheck it. The lower fuel pressure i do believe helped also. The outside humidity has been high here in PA and in Florida my car use to sit in a 100 degree trailer. when you get use to seeing things a certain way for a long time , something out of the normal can mess you up i guess.
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kdarc9
Junior Slingshot
Posts: 6
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Post by kdarc9 on May 25, 2011 11:40:50 GMT -5
You will notice condensate on your intake and carb housings when you run motors up here in the northeast. Methonal loves moisture and will suck it out of cool air. I try not to run my motor at a idle much for that reason. I tape my fan screen up to warm my motor quicker to about 200 degrees before going out for my race. I also change my oil every week faithfully. Some weeks it looks perfect coming out and sometimes it looks like a weak coffee milk shake! I have no explanation for this as I never change my carb jets. I have always assumed it was air moisture in the air on race night that contributed to the milky oil. On real humid nights I drop the oil before my feature and run fresh oil for my feature. I suspect your car will run fine on the track once you get some temperature into the motor. I would clean the carb good as suggested above. Burning a piston is mostly from lack of fuel in a cylinder. Good luck!
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