Stopping the knock: Lower compression and ported heads...

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I didn't expect that anyone was waiting on the edge of their seats, I just thought I'd relay what has happened.
I appreciate reading when someone finally fixes a problem they had been working on.
 
I was able to drive the car today. Good news...NO detonation at all. I'm running a mix of about 90% 91 octane with what 110 leaded was left in the tank since before the teardown. It was also only 50 degrees out.
I still think that with 91 octane at 100 degrees I should be fine. There are still a few details to work on though. It feels a bit rougher at idle and the idle vacuum is certainly lower. I may need more initial timing. I'll probably need to go with smaller jets since I'm running in the 12.0 to 12.8 range at part throttle. (According to the Air/Fuel guage) Power feels pretty good but the secondaries don't seem to be opening fully. It doesn't seem as loud at WOT as before.
With work taking up as much time as it has, it is hard to get as much done on the car as before. I was unemployed from March to early September so I was able to get much more done back then.
 
...It feels a bit rougher at idle and the idle vacuum is certainly lower...
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Ports are bigger in volume, and compression is lower...these are the manifestations of those input conditions.

I may need more initial timing.
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...probably...but you didn't quantify your initial since reassembly either. Did you recurve your dizzy yet to limit your total advance?

I'll probably need to go with smaller jets since I'm running in the 12.0 to 12.8 range
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Time to drive with a friend and map it.

Power feels pretty good but the secondaries don't seem to be opening fully. It doesn't seem as loud at WOT as before.
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Quite likely all related...

It feels a bit rougher at idle and the idle vacuum is certainly lower. I may need more initial timing. I'll probably need to go with smaller jets
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...time to start back to square 1; minus your detonation...hopefully.
 
Before I pulled the heads, I mapped 2 MP electronic distributors. I put in the heaviest springs included in the tuning kit I bought. Both distributors were set to 14 degrees of total advance. One started advancing a few hundred RPMs off of idle and reached full advance by 2200-2300 RPMs. The other started advancing about 400 RPMs off of idle and reached full advance at about 2400 RPMs. The goal there was to try to delay or slow the curve to be "all-in" just shy of the converter stall speed. That didn't work out as planned. I may have had luck if I used heavier weights spec'd for a different distributor. Rusty Rat Rod repeatedly posted that I needed to delay the timing curve but I felt that he was barking up the wrong tree. My experience was that even when I was rolling along at 3000, 3500 or 4000 RPMs, the engine knocked when I floored it. What would it help to delay the advance to 3000 rpms if it knocked at any point AFTER that? It seemed like a pointless effort to keep jacking with the timing curve.
I figured that there would be some tuning after the fact. I don't mind. I have a bunch of jets and power valves here.
This weekend I hope to check cranking compression. I'll report the findings when I do.
Another topic:
Even before all this, with the 509 cam in place, I've been annoyed with the part throttle performance. The high stall converter makes the car feel lazy at part throttle. It responds when I lean into it and the converter winds up, but I'd prefer a tighter feel. The problem is, the bigger cam needs a higher stall converter. The car reacts faster when in direct drive (3.91 gears) compared to when the GV is engaged ( OD final drive of 3.05)
I don't know if I need a better converter or if a smaller cam and tighter converter. For now I'll tune what I have and see if it is good enough to live with.
 
No. I didn't say to delay the timing curve. I said LIMIT IT. You have to limit the curve by welding up the slots. 14 degrees advance could well have been too much and been the trouble all along. Initial is usually in the 20 degree area. Add in the 14 mechanical and that's 34*. Even more if initial was over 20. Usually high compression big blocks like only 30-32* total. That's what we kept trying to get through to you was to LIMIT the curve. Not delay it. Big difference. Plenty of people run more static compression with aluminum heads same as you on pump gas. There was no reason you could not have. You simply chose not to listen for whatever reason.
 
RustyRatRod said:
No. I didn't say to delay the timing curve. I said LIMIT IT. You have to limit the curve by welding up the slots. 14 degrees advance could well have been too much and been the trouble all along. Initial is usually in the 20 degree area. Add in the 14 mechanical and that's 34*. Even more if initial was over 20. Usually high compression big blocks like only 30-32* total. That's what we kept trying to get through to you was to LIMIT the curve. Not delay it. Big difference. Plenty of people run more static compression with aluminum heads same as you on pump gas. There was no reason you could not have. You simply chose not to listen for whatever reason.
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:cheers:
 
RustyRatRod said:
No. I didn't say to delay the timing curve. I said LIMIT IT. Usually high compression big blocks like only 30-32* total. You simply chose not to listen for whatever reason.
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Probably because some advice contradicted other advice.

30-32 degrees? Come on, man! I haven't read from many that thought 30 degrees was optimal for their big blocks no matter the compression. I knocked on 31.
Say what you want about high static CRs being tolerant of pump gas, but having 190 + cranking numbers means that it wasn't going to happen for me. My early CR numbers of 10.7 to one was closer to 11.0 to one when I went back and again measured the head gasket thickness, the piston-to-deck heights and the chamber volume. Sure, the guys that tried to help by suggesting using a "bigger" cam thought it might work and maybe it would have if I went even bigger than I did. Trouble with that is that in trying to tame the engine to tolerate dog piss gasoline, I would also make it less fun to drive in 90% of the type of driving that I do.
I have made several mistakes in my life, as have everyone else. Regarding this car and the engine, all I really want is a great street engine with plenty of low to midrange power. I don't need it to click off a 10 second 1/4 mile timeslip and I'm not interested in impressing people with the lopey cam. I'm not pleased with the feeling of a loose high stall torque converter that is required when using a big cam like this. I am aware that the bigger cam was a band aid to stop the detonation.
Sometimes I wonder what it would have been like to have a milder engine that makes less power but also gives less trouble.

I've driven the car a few times since getting it back together. The idle vacuum is lower than it was at the same rpm as before. Before it was just under 10, waivering between 8-10 in neutral. Now its around 7 to 7 1/2. I bumped the timing and saw the rpm and the vacuum numbers go up. The best vacuum came in with the initial timing set to 28 degrees. I didn't drive it because that would have put my total timing to 42 ! Silly observation, but does this mean that I might benefit from a narrower advance curve? Something like 5-7 degrees past the initial? Sledgehammer runs locked out timing. I'm guessing that means that at all rpms, the timing stays the same. Is this even for street use? If so, how well does that work? I ask because I have almost no interest in straight line drag racing this car. I enjoy distance street driving, cornering and maybe even autocross. These types of use are not often at WOT where tuning may be easier to do.
 
Frankenduster said:
My experience was that even when I was rolling along at 3000, 3500 or 4000 RPMs, the engine knocked when I floored it. What would it help to delay the advance to 3000 rpms if it knocked at any point AFTER that? It seemed like a pointless effort to keep jacking with the timing curve.
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Now I realize that all of the advice given here is done free of charge, but I have asked the ABOVE question before and RRR has not responded. I have reread the threads I started and it was mentioned several times that I needed a slower and later advance curve. RRR was one of the members that suggested it. I have asked before how a "full advance delay to 3000 rpms would help".
I will write it again in as plain English as I know.
If I floored the car from idle, the car knocked. When i floored it from 2000 rpms it knocked. When I tried running the car at any road speed in either 1st or 2nd gear, rpms of 3000, 3500, 4000 rpms, at light throttle, THEN tried to floor it, the car would detonate.
I interpret this to mean that whether the spark timing was all in by 2200 rpms or 4000, the engine knocked. Delaying the point at which it was all in made no difference. If my thinking is wrong, I surely would welcome a clear explanation.
 
Franken, you may benifit from a timing curve coensiding w manifold vacuum advance. If you run high initial to get it snappy off idle, limit your total mechanical to +10 then the vac adv at part throttle will improve torque at part throttle and remove its advance under hard throttle. Don at fbo is a big proponent of this method from what i understand.
 
Frankenduster said:
Now I realize that all of the advice given here is done free of charge, but I have asked the ABOVE question before and RRR has not responded. I have reread the threads I started and it was mentioned several times that I needed a slower and later advance curve. RRR was one of the members that suggested it. I have asked before how a "full advance delay to 3000 rpms would help".
I will write it again in as plain English as I know.
If I floored the car from idle, the car knocked. When i floored it from 2000 rpms it knocked. When I tried running the car at any road speed in either 1st or 2nd gear, rpms of 3000, 3500, 4000 rpms, at light throttle, THEN tried to floor it, the car would detonate.
I interpret this to mean that whether the spark timing was all in by 2200 rpms or 4000, the engine knocked. Delaying the point at which it was all in made no difference. If my thinking is wrong, I surely would welcome a clear explanation.
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you have a thick skull, delay and limit are to different things. you delay (retard) or advance the curve to come in faster or slower. Limiting timing is adjusting slots or keys so the total mechanical timing is more or less.

Real world example.

Stock slants are usually timed 0-5* depending on the year at idle, but run much better with 10-16* initial timing. by increasing the idle timing you have also increased your total because mechanical and vacuum adv ADD to initial. So when I curve my dizzy's I set them for 14* initial, remove the heavy spring for a light one for about 2300 all in curve. Now being I play with mine the stamped number isn't correct but I see how much advance the slots allow, usually 10* to much. so after welding the slots I LIMIT my total timing to 30*. Now with the can (currently a VC-208) I get another 22* for 52* of advance when the vacuum can is in full force.

Understand?

Rice Nuker said:
Franken, you may benifit from a timing curve coensiding w manifold vacuum advance. If you run high initial to get it snappy off idle, limit your total mechanical to +10 then the vac adv at part throttle will improve torque at part throttle and remove its advance under hard throttle. Don at fbo is a big proponent of this method from what i understand.
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that's how the chevy guys do it. By doing that you are effectively loosing your vacuum advance benefit. By using ported vacuum your dizzy curve controls everything all the time. Your initial timing is always where you want it, and your total timing is tailored to your spec. Now by using ported the vacuum can can add MORE timing at cruise conditions, where it couldn't before because it was already maxed out because you don't want to pull the dizzy apart. Its a lazy way to do it...
 
Rice Nuker said:
Franken, you may benifit from a timing curve coensiding w manifold vacuum advance. If you run high initial to get it snappy off idle, limit your total mechanical to +10 then the vac adv at part throttle will improve torque at part throttle and remove its advance under hard throttle. Don at fbo is a big proponent of this method from what i understand.
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and for the most part big motors I set the dizzy for all in by about 500, basically is just a start retard.
 
Franken sorry you are frustrated and having troubles still.... I am locked out timing at 34* however the higher the intake valve closing ABDC on the cam the better. Eddie Miller who just set the fastest NA pass ever on dragweek at 8.5x on pump gas 93 in his duster and he claims he is at 14.2 to 1.
 
-Sledgehammer- said:
Franken sorry you are frustrated and having troubles still.... I am locked out timing at 34* however the higher the intake valve closing ABDC on the cam the better. Eddie Miller who just set the fastest NA pass ever on dragweek at 8.5x on pump gas 93 in his duster and he claims he is at 14.2 to 1.
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i know of a couple of motors on pump junk running 15:1, they have big cams and water until they swap carbs and run alky.
 
My closed chambered 10.7 compression 360 ran fine on 91. I was in the bay area too. Even on cold days.

Frankenduster said:
Probably because some advice contradicted other advice.

30-32 degrees? Come on, man! I haven't read from many that thought 30 degrees was optimal for their big blocks no matter the compression. I knocked on 31.
Say what you want about high static CRs being tolerant of pump gas, but having 190 + cranking numbers means that it wasn't going to happen for me. My early CR numbers of 10.7 to one was closer to 11.0 to one when I went back and again measured the head gasket thickness, the piston-to-deck heights and the chamber volume. Sure, the guys that tried to help by suggesting using a "bigger" cam thought it might work and maybe it would have if I went even bigger than I did. Trouble with that is that in trying to tame the engine to tolerate dog piss gasoline, I would also make it less fun to drive in 90% of the type of driving that I do.
I have made several mistakes in my life, as have everyone else. Regarding this car and the engine, all I really want is a great street engine with plenty of low to midrange power. I don't need it to click off a 10 second 1/4 mile timeslip and I'm not interested in impressing people with the lopey cam. I'm not pleased with the feeling of a loose high stall torque converter that is required when using a big cam like this. I am aware that the bigger cam was a band aid to stop the detonation.
Sometimes I wonder what it would have been like to have a milder engine that makes less power but also gives less trouble.

I've driven the car a few times since getting it back together. The idle vacuum is lower than it was at the same rpm as before. Before it was just under 10, waivering between 8-10 in neutral. Now its around 7 to 7 1/2. I bumped the timing and saw the rpm and the vacuum numbers go up. The best vacuum came in with the initial timing set to 28 degrees. I didn't drive it because that would have put my total timing to 42 ! Silly observation, but does this mean that I might benefit from a narrower advance curve? Something like 5-7 degrees past the initial? Sledgehammer runs locked out timing. I'm guessing that means that at all rpms, the timing stays the same. Is this even for street use? If so, how well does that work? I ask because I have almost no interest in straight line drag racing this car. I enjoy distance street driving, cornering and maybe even autocross. These types of use are not often at WOT where tuning may be easier to do.
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There's a guy on The Hamb with an early Hemi that has over 13:1 and runs on 93. So it can be done. Of course, comparing a Hemi chamber to a wedge chamber is somewhat unfair, but it can still be done nonetheless. The key is learning what other people have done, listen to those who've done it and replicate it.
 
For the last 8 months I have really stepped it up in the efforts to make this car a better driver. I have made some good moves and some mistakes. I have taken some advice on some stuff and made my own decisions on others.
The decision to lower the compression by using the thicker head gaskets wasn't supported by everyone. Many thought it was a bad way to go. I am happy to report that the car runs better than I expected.
There is more tuning to do to get the Air/Fuel readings closer to ideal. In all the testing since getting the car running again, I've not heard a single incident of detonation. The car runs strong at WOT andpart throttle. I'm getting closer to making it run better at low speeds with the tuning changes. Yesterday I pulled off the MP Chrome ECU and installed the Rev-N-Nator box. I bought it in Sept of 2012 and ran it a short time back then. I had to limit the timing to 29 degrees total because it was even more sensitive to detonation than any of the other ECUs I tried. Backing off the timing put my initial timing setting at 15 degrees which made the car feel lazy off idle. Now with the almost 1 point less compression, the engine is more tolerant of running more spark lead. Now that I know how to adjust the timing curve in the MP electronic distributors , I think that I can make the Rev-N-Nator work to its potential.
Driving the car tonight, it felt really strong. It felt great at light acceleration and at cruise. It was responsive at every RPM level. I'm running 91 octane exclusively and the car hasn't knocked at any time. It feels stronger than I can ever remember in the whole time I've owned the car.
As I wrote, there is still more to do but I think I am on the right path. I want to thank the many FABO members that chimed in. RRR, 805Mopar, Sledge, Rice Nuker, TXStang and numerous others.
Keep reading and responding. I appreciate the advice and responses from anyone willing to help.
 
have you tried very cold plugs? my 11.25 360 iron head runs good on 93, 205 cranking psi
 
EL5DEMON340 said:
have you tried very cold plugs? my 11.25 360 iron head runs good on 93, 205 cranking psi
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My 12:1 360 in my valiant had the exact same cranking pressure. It didn't like 100% 93 without some timing removed but it did run on it. Didn't matter cause I almost always ran a mix with Cam2.
 
My cranking #s were in the 188 range with the 509 cam and 191 average with this Lunati cam. I had what sounded like detonation in both cases using 91octane gas. When I pulled the heads to have them ported and to install thicker head gaskets, none of the pistons showed any signs of detonation. They did have carbon buildup which I cleaned off, but there were no pits, divots, markings or cracks anywhere. I am told that detonation results in marks that look like the work of an icepick. I had none of that. In fact, the pistons looked almost like new after cleaning.
This was confusing to me. Every time I went full throttle and heard what I thought was detonation, I didn't just keep my foot in it. I lifted off of the gas. My point is that IF the engine was knocking, I stopped it before any damage occured. On the other hand, if the engine was never detonating, what the heck was I hearing ???
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Related or NOT related ??
In May of last year I decided to replace the K member. The replacement one was fully welded at all the seams and had additional supports for the steering box. When I had it back together, the LH header sat closer to the steering box. At idle, there was one tube that would lightly contact it. It didn't make any noise at idle from the contact. At higher rpms as the engine smoothed out, is it possible that the knocking noise was from this? Personally I doubt it because the engine lifts the left side under a load. I know this is a long shot.
 
It does result in piston damage.......but it takes some TIME to do it.........OR rather quickly under severe load. I've given all of my theories about your detonation, only to be rejected and mocked via PM so I'm not contributing to that anymore. It was detonation. That's my opinion. It's also my opinion it was not caused by too much compression. But you could put that together through all of my posts.......hopefully.
 
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