| Fred Hanks | -- 09-06-2012 @ 2:30 PM |
|
I have a rebuilt V8 that sat a yr and now when started it runs at idle just fine and when I up the rpm's it backfires at random and runs rough...I,ve used Marvel Mistery Oil 3 tims down the carb and let sit for weeks to no avail ,the cyl is #7,can this be repaired if I pull the intake ?? Thanx,Fred
|
|
| supereal | -- 09-06-2012 @ 5:33 PM |
|
First, run a wet/dry compression test on that cylinder to confirm that a valve is hanging up. If that confirms low compression, both the head and the intake manifold will have to come off. Another good test before you disassemble the engine is with a vacuum gauge. If you see a flutter, it is likely a sticking valve. If you need a vacuum chart, I'll post one. Sticking valves are most often exhausts where the stems have collected carbon. A weak or broken valve spring is also possible, but the valve assembly will have to come out to be sure. This message was edited by supereal on 9-6-12 @ 5:41 PM
|
|
| fla48 | -- 09-07-2012 @ 8:13 PM |
|
I was able to free up a stuck exhaust valve by removing the spark plug, then gently taping the top of the valve with a small rod. The valve seated and I did not have any subsequent problems. Be careful not to use to much force and damage the valve. Beats tearing the engine down first if it is a minor problem. Good luck.
|
|
| 40 Coupe | -- 09-08-2012 @ 3:40 AM |
|
Try the MMO in your engine oil and pull the spark plug and squirt some down the open sticking valve. if the valve is sticking because it is bent MMO will not correct. You may have to repeat the MMO procedure several times over a couple of weeks. It also may be necessary to exercise the valve through the spark plug hole by lightly tapping the valve closed as a last resort. Keep running the engine and driving the car.
|
|
| Esteban34 | -- 10-09-2012 @ 12:37 AM |
|
I have the same problem I hope that last advice is best. adonde vas, estas alli Esteban
|
|
| EFV-8 Club Forum : | https://www.earlyfordv8.org/forum |
| Topic: | https://www.earlyfordv8.org/forum/viewmessages.cfm?Forum=18&Topic=5162 |