Guest Posted November 28, 2000 Share Posted November 28, 2000 OK, Got a problem, need advice. I believe I have a burned exhaust valve. The car idles rough, then starts to backfire but not a loud sharp backfire, more of a muffled pop. I checked the dwell and timing and they seemed to be good. I have a new timing chain (5mo old) brand new coil, cap, rotor, wires and plugs. I plan on pulling the valve covers off when the engine cools down tonight and look for any obvious valve train signs. Is there any obvious way to troubleshoot this without a compression gauge? What signs will I get if a cam lobe is worn down? I dont think its a blown head gasket and I don't think its a ring problem. The car has never used oil and doesn't run hot. I started having this problem a few days ago on the interstate when the car started running rough while accelerating. Today it has stumbled, not idled smooth and quit on me twice. Still no cooling problems or oil loss. Thanks for any help Link to comment Share on other sites More sharing options...
Guest Posted November 29, 2000 Share Posted November 29, 2000 it sounds like a broken valve spring to me is popping going down the road and does it feel like its missing.unless the lobe is flat you wont be able to tell if its bad with out take a mic to it and checking the lift on it.a comp test is a good place to start though i would go that route first that would help you find the bad cyl.but if its the vavle spring you should see it i hope this help ya let me know how you make out chris Link to comment Share on other sites More sharing options...
Guest Posted November 29, 2000 Share Posted November 29, 2000 Pulled the covers off last night. Nothing broken. Valve train appears to be operating properly. Going to Recheck and reset the lash today. I just put an edelbrock 1405 600cfm manual carb on yesterday and last night doing some tuning I found that the idle circuit was adjusted very rich. So I played with it a little and got it to run a little better. Maybe the carb was causing it to miss and choke out? So I plan on spacing the carb today by about 1/2 inch at the base. I heard the edelbrock carbs don't react to heat as well as the other ones but I gotta tell you, its a worl of difference from the holley. Kevin, I suggetst the edelbrock power package with the rpm air gap intake and 600 cfm edel carb. Anyone on the board live around Erie PA. Moving there on the 5th of Dec. I gotta get the old girl ready to go. Link to comment Share on other sites More sharing options...
Guest Posted November 29, 2000 Share Posted November 29, 2000 I've heard that bent pushrods can also cause this problem. It would make sense being the rpm's your running going down the highway. Did it start this after a hard acceleration? I assume it popping out the exhaust? Carb? The only way I know how to check your push rods is to take them out one at a time and find a perectly flat surface and roll them to see if there bent. Also look for cracked rocker arms. Some time not so obvious. I'd do this the same time I checked the push rods. Take the Rockers off to do a thorough check. I had a similar problem one time after installing an Accel HEI distributor. I done everything you could possably do or tweek in adjustments from curve kits to carb spacers you name it. The minute I put an old GM HEI distributor back in it straightened it out. It appeared to be something in that new distributor. Never found out what it was. I kept the old HEI in there. Link to comment Share on other sites More sharing options...
Mike Hall Posted November 29, 2000 Share Posted November 29, 2000 If you have a non HEI distributer? I would try a new set of points and condencer that is under the rotor.If the points have even a little wear or arcing on them this could cause this. Link to comment Share on other sites More sharing options...
Guest Posted November 29, 2000 Share Posted November 29, 2000 Thanks guys, way ahead of ya on the pushrods. Didnt find any bent ones but did find one rocker arm with a small hairline crack where the pushrod seats. Could be possible that I'm losing some much needed force under higher rpms. I'll bet the neighbors wished I had your modified covers since I smoked them out last night!!!! Link to comment Share on other sites More sharing options...
Guest Posted November 29, 2000 Share Posted November 29, 2000 Hey, been there, done that! You get the strangest looks from people when the oils flyin and smokin! I'd say that rocker arm is the culprit. I bet once that little burger heats up that crck will expand? Link to comment Share on other sites More sharing options...
Guest Posted November 30, 2000 Share Posted November 30, 2000 i would check the plugs if it was running rich i bet one is fouled out i used to have this happen a lot it would foul a plug and miss and backfire.chris Link to comment Share on other sites More sharing options...
Guest Posted December 1, 2000 Share Posted December 1, 2000 OK..Here's what I did. Replaced the cracked rocker and the pushrod. I found that the nut on the adjacent rocker was worn and would also back off so I went ahead and replaced that arm, rod, bushing and nut. Just for good measure I also replaced the points and condenser. Pulled the plugs, none fouled, set the lash again and all appears to be well. I think she's ready for the move. Thanks guys, sometimes it gets frustrating when the old girl won't cooperate. I don't think she likes having new stuff in her belly!! Making the trip from CT to PA on Tuesday. Link to comment Share on other sites More sharing options...
Guest Posted December 2, 2000 Share Posted December 2, 2000 Good luck on your move. Hope it's trouble free for you. Link to comment Share on other sites More sharing options...
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