Persistent Detonation
- Thread starter bobs66440
- Start date
2old2fast
Active Member
Back in the day , my parents had a 455 olds that got putted arond town , 'bout once a year it would build up enough carbon you could actually hear the pistons contact the heads , & run on was terrible...... I'd get a quart of atf , put the carb on fast idle & slowly pour atf in the carb till I got to about 1/2 quart , then dump the rest [killing he motor] , let it sit over nite , fire it up in the morning, I'll swear there'd be chunks coming out the back , take it out & run 20-30 miles hard.... it'd be good for another year.... car had 150K miles on it when they finally sold , still ran great...
dave
dave
one finger john
Active Member
Fresh (new) plugs and an hour drive @ 70 or so on the highway. Vary speed & load.
How's the water temp after warming up? How do the headers look? Glowing? Hot is retarded. Don't ask how I know...painful memories. Just sniffing for any clues at this point. Hate to have you tear it down if we can avoid it, but after timing or a bad carb, I think we're down to a bad or offset cam.
SRM1952
Member
I think the most important starting place is to find your true TDC.---If this is wrong all the work you do could be a total waste of time. So thing is very wrong if you ping with 25 degree timing. If you don't know how - there are plenty of info on this , and not that hard to do. This is and on going problem , TDC maybe falsely marked when engine was built. You do know this is a solid lifter cam valve lash .028 .
Steve
Yes, I'm aware. I set the lash shortly after I got the car.
It runs 180-190 all day, any weather. I've never seen the headers glowing.
Mike
Well-Known Member
I always love these kinds of threads. Member A posts about a problem, so Members B - Z all chime in with different ideas and different cures, all within 24 - 48 hours of Member A's initial post. Then, suddenly, Member A falls completely silent on the matter, and nothing else is ever said. As in who knows if the problem was ever fixed, or not? Not a single soul, from Member B, all the way to Member Z will ever learn what the root of the problem actually was, and what Member A did to eliminate it.
Personally, I guess I approach these threads in a different manner than most. To wit -
But check this out. In the very same post, Bob goes on to say -
Now wait, just a flippin' second! How in flip's sake could the car 'run and drive fine', whilst it 'pings like crazy', under a load? Anyone else seeing this? The car runs and drives just fine, isn't that what he said? But yet, he started this thread because the car was most certainly not running just fine.
What's everyone trying to diagnose, and/or fix in this thread? The motor that pings like crazy, or the contradictory motor that runs fine?
Here is yet another example of confusion reigning supreme -
Heck, I jus' gotta know. Bob, did you look at them? If so, what, specifically, did you look at? And what, specifically, did you learn?
John, I've no clue why you suggest installing fresh plugs before the high RPM jaunt. All that is going to do is ruin a fresh set of plugs. Why not run the old plugs, then after the high RPM run, stick the trans in low gear and drive at a high RPM, until the plugs clean off the high speed deposits?
Get with your bad self, @RPM . We've got a real conundrum on our hands here, and there you come along with plain, old, common-sense, trying to throw everyone off the mark.
I'd rather damn myself to perdition than read back through this thread, so someone correct me if I am wrong. I do believe it took us all the way to Post #26 of this thread, before someone questioned the quality of fuel being used.
Here's the one that grabbed me by the shirt front, Ron. He plugs the vacuum advance chamber in and the motor will not idle in gear. Where do you suppose he is hooking up that vacuum hose? I don't think anyone addressed that wee point, either.
And without any readings from a vacuum gauge, what do you think? Is that a vacuum leak I am hearing, or is my hearing going sour? Shows all the symptoms, doesn't it?
No way of knowing if there is enough P:V to be able to pull it off, but wouldn't you like to be able to tighten up that valve lash a couple thousandths, just to see what would happen?
Apologies to the rest of you for the brief aside with RPM. Please, please, let's get back to making everything harder than it has to be.
So. Bob. Did you get this one sorted out? Are you just planning to leave everyone in suspense?
As for the motor being lazy up to 4K, I think you've some under-lying issues. No question about it Harold (may God's eternal light shine upon him) had some really 'peaky' cam profiles. His race stuff was always fast, but it was death on valvetrains, and very, very temperamental about gear ratios. Bottom line, that cam should be showing signs of life, long before 4K.
Personally, I guess I approach these threads in a different manner than most. To wit -
See how it starts? Bob has a motor with a 'problem', that being it 'pings like crazy'.
But check this out. In the very same post, Bob goes on to say -
See? Problem fixed, even before the original post was submitted.
Now wait, just a flippin' second! How in flip's sake could the car 'run and drive fine', whilst it 'pings like crazy', under a load? Anyone else seeing this? The car runs and drives just fine, isn't that what he said? But yet, he started this thread because the car was most certainly not running just fine.
What's everyone trying to diagnose, and/or fix in this thread? The motor that pings like crazy, or the contradictory motor that runs fine?
Here is yet another example of confusion reigning supreme -
Does anyone else wonder what he was going to be looking at? Plugs he admits were sooted up, plugs that have had another 1,500 street miles put on them since, but now, he plans to look at them. And get this - he admits the engine was swallowing oil, but there is no mention of any oil deposits on the plugs.
Heck, I jus' gotta know. Bob, did you look at them? If so, what, specifically, did you look at? And what, specifically, did you learn?
John, I've no clue why you suggest installing fresh plugs before the high RPM jaunt. All that is going to do is ruin a fresh set of plugs. Why not run the old plugs, then after the high RPM run, stick the trans in low gear and drive at a high RPM, until the plugs clean off the high speed deposits?
Get with your bad self, @RPM . We've got a real conundrum on our hands here, and there you come along with plain, old, common-sense, trying to throw everyone off the mark.
I'd rather damn myself to perdition than read back through this thread, so someone correct me if I am wrong. I do believe it took us all the way to Post #26 of this thread, before someone questioned the quality of fuel being used.Here's the one that grabbed me by the shirt front, Ron. He plugs the vacuum advance chamber in and the motor will not idle in gear. Where do you suppose he is hooking up that vacuum hose? I don't think anyone addressed that wee point, either.
And without any readings from a vacuum gauge, what do you think? Is that a vacuum leak I am hearing, or is my hearing going sour? Shows all the symptoms, doesn't it?
No way of knowing if there is enough P:V to be able to pull it off, but wouldn't you like to be able to tighten up that valve lash a couple thousandths, just to see what would happen?
Apologies to the rest of you for the brief aside with RPM. Please, please, let's get back to making everything harder than it has to be.
I think you intended to type that you would think compression would have to be higher, but in my experience, that line of thinking would be erroneous. 10.0:1 in higher temperatures will spell disaster, unless the cam is killing enough cylinder pressure to crutch things. And between you, me, and the gatepost, I don't see that as being the case. Of course, introducing the concept of camshaft specifications having anything to do with compression and cylinder pressures is likely going to stump Bob. I've a shiny, new nickel that says the combination of the wee cam profile and the piston design is going to have Bob chasing his tail, all around the block. And that's after he fixes the other problems he has yet to discover/consider.
So. Bob. Did you get this one sorted out? Are you just planning to leave everyone in suspense?
As for the motor being lazy up to 4K, I think you've some under-lying issues. No question about it Harold (may God's eternal light shine upon him) had some really 'peaky' cam profiles. His race stuff was always fast, but it was death on valvetrains, and very, very temperamental about gear ratios. Bottom line, that cam should be showing signs of life, long before 4K.
Sorry I haven't been able to work on it and diagnose it further in what you consider a timely manner, other things have taken my attention. I wasn't aware there was a deadline. I wish I had the time, freedom and resources to live up to your standards. I did a lot of those things that you mentioned initially but the way you speak to me as if I were a child and how you ask in such a condescending manner, it does not even deserve a reply. And a sincere thank you to those of you who have reached out and tried to help me without trying to make me feel like an idiot. thank you
one finger john
Active Member
Now Bob, don't get all butthurt over this. It's just your turn in the barrel. This is just the current thread that infuriates the professionals here. There have been many others that have been even more frustrating. Does Oino ring a bell. Do a search and read the whole thread.
Asking for free help is fine. Disregarding advice and going your own way, or even worse, taking the advise of the local hot shoe, and the car still runs like doo doo, is like, why am I helping this guy if he wont even try the repair I have suggested?
I have 45 years in domestic & foreign car repair. Screaming Metal, Mike , Ron, George Barnes, the other george, and countless others here have tons of experience to share. We would like to know that our easy to understand instructions are being followed to the letter.
Why dont you park the roadster and the Chev side by side, bring them both up to No. 1 firing and look at the balancers and see if the timing marks line up to their rerspective timing pointers. If they do then see if you have a late model bbc, and swap distributers. Leave the vacuum line off and plugged. Set the timing @ 15* btdc. And see if it runs better.
You haven't done anything to me personally. I talk this way to EVERYONE. Especially in a learning situation. I'm not here to flap my gums.
Get a stiffer upper lip.
Now as for Mike not understanding replacing plugs and then going out for a 70 mph cruise for hour or so to blow the rest of the carbon out then you know what I say? I will gladly sacrifice a set of brand new street plugs to get an accurate reading on what is happening in the combustion chamber. In my opinion, the only way to do it.
Bob, you batted a thousand with the roadster. Not so much with the Chevy. Consider this a learning experience.
John
Asking for free help is fine. Disregarding advice and going your own way, or even worse, taking the advise of the local hot shoe, and the car still runs like doo doo, is like, why am I helping this guy if he wont even try the repair I have suggested?
I have 45 years in domestic & foreign car repair. Screaming Metal, Mike , Ron, George Barnes, the other george, and countless others here have tons of experience to share. We would like to know that our easy to understand instructions are being followed to the letter.
Why dont you park the roadster and the Chev side by side, bring them both up to No. 1 firing and look at the balancers and see if the timing marks line up to their rerspective timing pointers. If they do then see if you have a late model bbc, and swap distributers. Leave the vacuum line off and plugged. Set the timing @ 15* btdc. And see if it runs better.
You haven't done anything to me personally. I talk this way to EVERYONE. Especially in a learning situation. I'm not here to flap my gums.
Get a stiffer upper lip.
Now as for Mike not understanding replacing plugs and then going out for a 70 mph cruise for hour or so to blow the rest of the carbon out then you know what I say? I will gladly sacrifice a set of brand new street plugs to get an accurate reading on what is happening in the combustion chamber. In my opinion, the only way to do it.
Bob, you batted a thousand with the roadster. Not so much with the Chevy. Consider this a learning experience.
John
I do happen to have a pretty thick skin, but I don't respond well to insults and hostility in an atmosphere that I imagine was originally intended to be fun, friendly and helpful. I'm positive there is a wealth of knowledge and help here for one with a "stiffer upper lip", and I do appreciate the effort. I guess it just stopped being fun for me. I apologize if I left anyone hanging. I'll get it figured out. Thanks.
one finger john
Active Member
Oh BTW, if the 396 is an early one, check the distributer for notching on the shaft. If it is, find a "known good part" that you can substitute. A later (say 1968) distributer.
Mike
Well-Known Member
Insults? Hostility?? Oh, dear child, you are terribly, terribly confused.
Here's the rub on this shite. And yes, Bob, threads like this are shite. You claim to have a problem, but after asking for everyone to help with your problem, you take a powder. No demonstrations of gratitude, no explanations for your absence, you just disappear. If this is something you were not going to have time to work on, then why bother starting the thread, until you do have the time? Seriously, I don't get it. Is this a case where it is acceptable to come here and ask other members for advice that you are too busy to be bothered with? It's acceptable for others to look after your problems for you, just so long as that doesn't interrupt your otherwise busy schedule, is that what you are now trying to say? Howzabout you keep in mind it was you started this thread, not anyone else. You started this thread a month ago, then you abandoned it, with nary a word of explanation. (What would that have taken, maybe 2 minutes?) Then you want to toddle in here and crack wise, offering some smart-arse apology for not knowing about some non-existent deadline?!? And then, to top it all off you have the balls to suggest we are the ones being insulting and hostile?!? Pot. Kettle. Black.
one finger john
Active Member
Bob, in all seriousness, see if you can contact Hot Rod Magazine and see if you can get your car into the section where cars with interesting or off the wall problems are show cased (along with the repair shops). How they were diagnosed, how they were repaired and how much those repairs were. The 55 is good looking. Might be worth a shot.
Unless you want to pull the "396" and do a tear down looksee you really don't know what you have. Sounds like the description from the previous owner was kinda vague. Might have been a throw in situation to get the car out of the shop and sold.
Google high performance shop ny area (or where ever you are). Or better yet, go to the YellowBullet web site. Go to the first forum listed and ask for some advice or recommendations. I'm sure they will be helpful.
Oh, and watch out for the cactuses.
John
Unless you want to pull the "396" and do a tear down looksee you really don't know what you have. Sounds like the description from the previous owner was kinda vague. Might have been a throw in situation to get the car out of the shop and sold.
Google high performance shop ny area (or where ever you are). Or better yet, go to the YellowBullet web site. Go to the first forum listed and ask for some advice or recommendations. I'm sure they will be helpful.
Oh, and watch out for the cactuses.
John
Thank you John. I'll look into it.
Mike
Well-Known Member
Similar threads
