I developed a problem with 455 engine where it started out the engine was running a little rougher than it use to. A little while back while drag racing I was shifting from 1st to 2nd and then accidently went back to 1st and over-reved the engine. It seemed to be running a little rougher than but I didn't hear any engine nosies so I thought it was ok. After about 5 -10 mins of running with the fan on after starting from cold, #3 cylinder header pipe is starting to glow red. What I think is really weird is the glowing starts about 5 in. down from the header flange. I would have thought that the engine would have to be running lean for this problem to occur. The spark plug on that cyl. doesn't look real lean (white). I have pulled the roller rocker arms on that bank and looked at those and the pushrod - looks ok. From what I can see the valve springs look ok. I thougt maybe the valve might be bent/burnt and plan on doing a compression check or leakdown test. Any other suggestions other than tearing it down?
I had a problem with a glowing header in an Olds 455 that had an old 850 DP carb on it. It also idled rough, so I went through the carb. After the rebuild and resetting the floats, the glowing stopped. I hope your problem is as easy as mine was. Marc
I would definitely do the compression check and I would double check the valve springs to be sure they are all solid and closing the valves. A single break may be easy to overlook. I broke a valve spring with out knowing it (and then broke it again, and again which was when the valve keepers fell out! I knew it then because the rocker arm slide off to the side and the push rod was hitting the valve cover) I changed all the valve springs at that point! I was fortunate that valve didn't drop into the cylinder. A compression check can still be tricky, I had a burned exhaust valve on a Chevy that I didn't pick up with a traditional compression check.
I did a compression check on the engine (cold) with the throttle wide open, 5 rotations of the engine and got 150 -160 psi on all cylinders except cyl #5 which was 180 psi. I felt this compression is fairly normal for the relative large duration cam that I am running and 9.7 compression ratio. I am more curious why 1 cylinder is higher than the rest. The spark plugs are all tanist color, even cylinder #3 that shows that hot pipe. Any other suggestions?
I am not an expert by any stretch and I am sure there are much more qualified members on the board so I hope they will respond to you. I don't know how to do this but I would check to see if there is some sort of leak-down test you could do to see how well the cylinders hold the compression. I would still be looking at a bad exhaust valve if I were having the problem you describe. I had a skip in my Chevy (250 straight 6) and I did a couple of compression tests that didn't pick up anything noticable, so I changed the distributor to a HEI, and rebuilt the carb (because it had a studder at take off). It wasn't until I blew the back of the muffler out (probably from a rich exhaust with one lame cylinder) that I could really hear the true exhaust tone and realized I had a bad valve. As bad as the valve was, I couldn't didn't detect the real problem until I could really hear the engine without the back plate of that muffler. Good luck.
Is it your '70 or '71? I was always told that beginning with '71, hardened valve seats were used due to the decreasing use of lead in gas. So anything prior to '71 was susceptible to burning the valves/seats if used hard on unleaded fuel. My Chevy that had the problem is a '70. After re-reading your post, do I understand that it is also running rougher than before the glowing header?
Carl, It is very possible that you have bent/burnt an exhaust valve, possibly by floating and smacking a piston when over-revved. Before tearing anything apart, I would put #3 at TDC with both valves closed and put some air press in that cyl. See if you can hear leakage. OR, if you have leakdown tester, even better way to check for slight leaks. Good luck!! Don't worry about the seats, Buick used way higher nickel content in their heads than chebby did. Stock valves, I would worry about those.ou:
The latest update is I did is to put air into cyl#3 and listened for any leaks. I could not detect any leaks in the exhaust, but did hear some leakage thru the rings. I talked to TA performance about my dilema and they told me that it could possibly be a valve problem or a phasing issue with the spark - retarded timing! Unfortunately I had aready pulled the head off to look at the valves. I wanted to get it resolved as soon as possible and if I needed a valve, I want it now. Anyway the exhaust valve doesn't look burnt and isn't bent. It was good in a way because what I saw on that cylinder is that it looks like the firing is happening in the header pipe instead of the combustion chamber - that exhaust port is almost totally clean as compared to the others being blackish and sooty. Dave at TA told my about the MSD distributors need to be phased to fire the spark correctly and at the right time. At this time I think I may have this problem with that distributor. I will know probably tomorrow on the outcome. It sounds like it is matter on hooking up some wires correctly otherwise the timing is retarded and could fire on an open exh. valve. I guess at this point I don't know what else it could be. I will hope for the best!
I wonder if it could be cross-fire in the plug wires? Sounds too obvious I know but I just don't get why its ONLY #3. Or is it? What is the timing set at? Tell more about your ignition setup. MSD Distrib., MSD 6AL box? Have you ohm'd the plug wires? Phasing the rotor is fine, but it affects all 8 cyl equally. HMM...o No:
Carl, I am glad to hear it is not a valve problem. I am sorry you had to pull the head to determine this. I hope you had more reason than the opinions I offered regarding the valve as the possble cause and my experience. I hope you can sort it out and have luck with the ignition system.
For what it's worth..... I had a low 12 second Monza that I put quiet mufflers on once. About 3 or 4 of my header pipes glowed red after about 3-4 minutes of idling. I quickly removed the mufflers and the problem went away. :gt: Don't know if this has any relevance to your dilema, but thought I'd offer it anyways. o No:
I got the heads back on and started the engine. The #3 pipe still would start to glow after about the same amount of time. I remembered that I had blocked the fuel return port on the fuel pump so I hooked it up again and leaned out the idle mixture screws a bit, thinking that maybe it was running too rich. I don't know if it cured the problem or why it should, but from what I have seen so far the pipe is not getting red. If fact we put a heat sensing gun on all the pipes and #3 was not any hotter. Go figure! So for right now I am driving it and observing to see if it happens again. Thanks for the responses that I got!
