Detonating 493 and what I did to stop it.

[Kern Dog]

Strange thing: Adding the Rev-N-Nator ECU made my A/F ratio go rich at cruise. I would have expected the thing to make the engine run cleaner due to it being a "better" unit.
I welded in the H pipe. I would have done an X but I don't have a way to make one of those. Anyhow, the exhaust tone quieted down some. It sounds less raspy than before at idle and at freeway speeds. I like that but I'm not finished yet.
The soggy feel at part throttle still annoys me. This is the result of using a high stall torque converter, OD gearing and a "race" oriented camshaft. If I ease into the gas at freeway speeds, the car feels lazy. If I lean into it harder, the car responds great.
I think that I am to the point where the rough idle and high rpms are too much for me. I want instant throttle response. I want to tap the gas off idle and start moving right away. This means I'll likely be switching to a smaller/milder camshaft. If that means that the car runs out of breath at 6000 rpms, who cares? I have 3 speeds in the trans and the GV overdrive. The GM BOP and Cadillac engines had long stroke cranks and they made huge torque numbers. they often only had 3.42 gears or taller to move those 5000 lb behemoths around, too. A milder cam means I could use a stock type stall rated converter and maybe switch to a 3.55 diff. I think I'm ready to have a more streetable car instead of a 6500 rpm dragstrip engine.

[Challenger340]

Strange thing: Adding the Rev-N-Nator ECU made my A/F ratio go rich at cruise. I would have expected the thing to make the engine run cleaner due to it being a "better" unit.
I welded in the H pipe. I would have done an X but I don't have a way to make one of those. Anyhow, the exhaust tone quieted down some. It sounds less raspy than before at idle and at freeway speeds. I like that but I'm not finished yet.
The soggy feel at part throttle still annoys me. This is the result of using a high stall torque converter, OD gearing and a "race" oriented camshaft. If I ease into the gas at freeway speeds, the car feels lazy. If I lean into it harder, the car responds great.
I think that I am to the point where the rough idle and high rpms are too much for me. I want instant throttle response. I want to tap the gas off idle and start moving right away. This means I'll likely be switching to a smaller/milder camshaft. If that means that the car runs out of breath at 6000 rpms, who cares? I have 3 speeds in the trans and the GV overdrive. The GM BOP and Cadillac engines had long stroke cranks and they made huge torque numbers. they often only had 3.42 gears or taller to move those 5000 lb behemoths around, too. A milder cam means I could use a stock type stall rated converter and maybe switch to a 3.55 diff. I think I'm ready to have a more streetable car instead of a 6500 rpm dragstrip engine.

It would seem that by now ?
.... that you are fairly conversant with all aspects of DCR as it relates to detonation and fuel requirements.
So fill ur boots with the smaller Camshaft if you are so inclined.

The one question I have, is what makes you sure that you currently have a 6,500 rpm Dragstrip Engine ? or, that the new "smaller" Camshaft you are planning will make peak power anywhere even close to 6K ?
I guess what I am asking is.... have you ever Dyno'd this Engine... as in an ENGINE DYNO.... to SEE the actual peaks ?, with Lambda, EGT, A/F, Fuel Metering,, etc., etc., for tuning ?
or,
what are your 6,500 and 6,000 rpm numbers based upon ?

just curious, but HOW LONG have you been chasing this DETONATION problem ?
I did not go back and re-read your entire commentary on this problem, but if may also ask at this late date ?... what were the Flow numbers on your Ported Edelbrock Heads used on this 493, and more specifically..... what is your final "Intake Port CC Volume", as it relates to chasing this confounding detonation problem ?

To Wit here;
Just checking to be sure here ?......but have you have been chasing DCR/Camshaft/Detonation problems all along, with un-ported stock Edelbrocks on this 493 ?  

[Kern Dog]

In 2006 I had the car on a chassis dyno. It had the 292/509 cam in it then. I had the same Performer RPM intake, 850 Demon carb, 2" TTI headers as I still have. The cam was degreed in and set 4* ADV. The car peaked at 369 HP at 5350 and the torque was in the 490 range at around 3100 rpms. I clearly recall the HP numbers but not the torque #s. As many other first time dyno test participants, I was disappointed and annoyed. The car detonated even back then, but the 4* ADV had the cranking compression at 200 ! Later I moved the cam back to straight up ( What I call dot-to-dot). The cranking #s came down to an average of 188 and the car stopped knocking. Many miles later, the detonation came back. (Probably as carbon built up on the pistons)
I have not had the car on a dyno again to verify the results of the changes.
I picked the 6000 & 6500 rpm number out of thin air....I may be being conservative as to "over-revving" the engine. Oil pressure is always good. I have no valve float. Even at 6000 the engine is still gaining at a fast rate. Who knows, this engine may still be making  power past 6500. I just feel nervous running it that high.

Your last question: How long have Ibeen chasing the detonation?
Since the original assembly in 2004 I have been dealing with it from time to time. It was only evident at WOT so I could have simply driven around forever at 3/4 throttle or less and never had a problem. When I had it on the chassis dyno, the operator tech recurved the distributor and eliminated most of the knocking. Later in 2006 I switched cams and added thicker .060 Cometic head gaskets. The detonation stopped completely but the new Comp cam went bad. I replaced it but the second one went bad as well. I decided at that time to save a few $$$ and put the 509 cam back in. It turns out the 2 failed cams pushed lifter shavings through the engine. I had some valve stem wear and had to pull the heads. I didn't have the money for another pair of Cometics so I used some Fel Pro gaskets I already had. The engine ran fine again until carbon built up again.

[Kern Dog]

To recap the events of the past year:

After a 1000 mile round trip last Spring, I decided to get serious about eliminating this detonation problem. I had pulled the engine in 2011 to hone and rering it, so the long block was sound. Plenty of people suggested i replace the MP 292/509 cam with a modern grind with a later intake closing. A guy on FABO suggested a Lunati solid flat tappet that he liked. I installed one and my detonation problems got worse. I later discovered after digging that the Lunati had an IVC that was 1.5 degrees earlier than the 509. The cam swap was a backwards move!
I tried recurving the distributor, jetting the carb, checked fuel pressure, retarding the timing and race gasoline. The only time it did not knock at WOT was with 110 leaded gas and one other time when I retarded the timing to 20* total. I had 191 average cranking compression, almost 11.0 CR and a dynamic CR of 8.29. I tried the suggestions of those I deemed to be smarter than I. Finally I defaulted to using thicker head gaskets again. While the heads were off, I had them ported. I did not have them tested on a flow bench. The pistons (once cleaned) showed absolutely no signs of detonation. This may be because each time I heard the engine knock, I always lifted off of the gas immediately.
I'm now down to 10.07 CR, a dynamic of 7.61 and the engine does not knock. Currently I'm pondering how to get it to feel more responsive at freeway speeds around 2500-3000 rpms. I think with a 4 degree advance of the cam and widening the lash a bit, the car will feel a bit more snappy. I'm also leaning toward getting a tighter torque converter.

[heyoldguy]

There are only a few people who have responded to your threads and know how to put a complete package together to do what you want successsfully. Bob does. If Challenger340 offers advice, don't mix his recommendations with anyone else's advice. You have received information from too many sources that haven't really been there and done that. I told you once before, select one person who knows what they are doing and let them advise you.

[Cooter]

I'm convinced with my iron headed 440 @ 10.8:1, that even todays "premium" fuel is just sh*t.
Mine has nowhere near the overlap of your cam but still a bit and it rattles.
Put true 100 octane in tank and no knock.
I even calculated out the .040 'quench' BS...still rattles. Even with aluminum heads, best to play it safe and stick to 10:1 on iron heads, and no more than 10.3:1 or so with aluminim heads.

Newer cars can get away with it due to electronics, but old school motors just can't.

[Challenger340]

You still, really, have NOT answered the most important question regarding the useage of Edelbrock rpm heads on a 493, as it relates to your entire DETONATION problem !!
Which I suspect, is only compounded with bigger Camshafts ? because if the Port Fawks up and goes sonic at "x", no amount of bigger and tuning will fix it.

Having them supposedly "ported", without any idea of Flow or CC Volume of the Intake Port means absolutely nothing, again, related to the DETONATION PROBLEM.

You can Tune until the Cows come home, jetting, play with DCR/Camshaft, etc., etc., attempting to get around the Detonation, which sounds like you did here ?
And unfortunately,
it will all be for nought, as you found out..... because, THAT ain't the problem, as if you haven't already figured that out by now ??
The PORT is the problem !
(light bulb going on here )

Get your Heads in somewhere WITH A FLOWBENCH !
IMO,
You can NOT run 250 cfm Edelbrocks anywhere even close to attempting mid range DCR/pressure Calcs on 91 Octane on a 493.
and IMO,
THAT HAS BEEN YOUR WHOLE PROBLEM ALL ALONG !!!

And as heyoldguy said, and very well put I might add, get one guy who KNOWS WHAT HE IS DOING helping you... stick with it.
Come to think of it...
If you are going to continue with the Edelbrocks....   might be a REALLY good idea to get your Heads over to heyoldguy for some Porting, Flow Data, before going any further with anything !

I am OUT,
my apologies if I have offended in any way,  by the manner in which I have presented this... NOT my intent !!
IMO, just needed to cut to the chase here  The PORT is the problem... always has been !

[Kern Dog]

I don't understand anything that you wrote. Your posts remind me of this really smart Carpenter I worked with that was always willing to help others, yet spoke over everyones head. I appreciate that you responded, but after reading it twice, it still isn't that clear to me.
Ports being the problem? Considering that this is the biggest inch/biggest money engine I've ever built, I'll readily admit to not knowing everything that there is to know about making it all work to its potential. The reference to intake ports may be correct, but I have never heard anyone else mention that. I don't see how intake ports have anything to do with detonation.
I have ran it with several different combinations since 2004. The only instances where it didn't knock was when it was ran with lower static compression. Once with .060 Cometics in 2006 and the way it is now.
I thought the Edelbrock heads were rated at 291, not 250. Regardless, they are supposed to outflow any stock head except for the Max Wedge heads. In all the responses in all the threads that I have started, several guys claim to run 906s and 452s that surely flow less than stock Edelbrocks. The guy that ported mine is a friend of the Machinist that I use. He is an old school guy that probably has no access to a flow bench. I've never had heads ported before so I went on the word of the Machinist that hasn't steered me wrong before. Maybe the heads aren't "documented" to flow any better than before. I'm not pulling them off the car to get validation of flow numbers.
The car isn't knocking anymore. THAT was the main goal. Now I'm casually working on improving the street manners.

[Cooter]

See the problem IMO Red 70 with guys that know more is we tend to get really frustrated when people will choose to listen to the furthest possible opinion on their problem. It's the Internet and when a question, or response is asked/given on a forum it took me years to get over the fact that some folks will pick and chose the stupidest reply to follow cause they simply do not like the guy that while correct, he's an ass.

What I hate to see are those that simply reply "just send your sh*t to me, pay me, and I'll get you right"...
These types clearly do not understand that this is the Internet and people want/ask for FREE advise, NOT A SALES PITCH . Hense, my signature.
while I replied in the beginning that I felt the only way your gonna get it to stop pinging is lower the static compression, you chose to do all sorts of stuff before finally lowering compression.
yet, I'm sure their are a few here that might be able to get your motor to NOT ping, but if they are gonna want to charge for their help, I'm sure you feel the same as me, they can eat sh*t and die. We are here to help, not pad some douche's pocket. I don't care how many times he's been there, done that. If your not willing to help for free here, GTFO.

What you just experienced is what I've delt with for about 10 years on another board. People there clearly could see I'd been where they are, yet refused to stick with one person's advice and were all over the place. What I had to learn was some people have to get hit by that perverbial train. They refuse to listen. It stopped bothering me about 4 years ago. Some threads I read and while pissed poor attempts are made to make me look as if I didn't call it, the knowledgeable can clearly see a reply that's worded different, but the same EXACT thing I told them. They wanna go round In  circles, f*ck em. Let em.
this does frustrate the knowledgeable, but it took me a long time I to understand, no matter how many you help, people are NOT gonna listen every time. I wasn't even attempting to charge for my services either.

When the knowlegable feel frustrated, they tend to blow you out the water with tech. Talk as you've whitnessed here, or they know the answer you seek and since they can't run a business, they just refuse to help you and will watch you struggle.
there's a special place in hell for these types IMO. Carry on, and if you figure out some other way of cutting back on the ping, let us know, cause we like results and are appreciative.

[Cooter]

Don't belive me? Take a look at the "Charger Build Question" thread.....

[Challenger340]

I don't understand anything that you wrote. Your posts remind me of this really smart Carpenter I worked with that was always willing to help others, yet spoke over everyones head. I appreciate that you responded, but after reading it twice, it still isn't that clear to me.

Look, and excuse me ....
But, I am stating it as best I can here ?
Trying to explain a concept... is never easy ?

In the SECOND SENTENCE of my reply, I put it as plainly... and simply... as I can ?
I Said...
"if your Port FAWKS UP.... and goes SONIC....  no amount of Tuning with fix it"
To clarify.... in my experience....
When a port can NOT maintain, or keep up.... to transfer the Air/Fuel Charge from the Intake into the Chamber... that A/F Charge "quality" suffers, resulting in erratic Flame Fronts, typically heard as ping.... ping.... ping.... due to poor A/F charge quality in the chamber..... after the Fuel having been SEPARATED FROM THE AIR in the port.
The Port going SONIC, refers to the audible noise heard on a FlowBench when this happens... basically, a separation of the AirFlow in the Port, including separation of the Fuel Molecules from the Air, an IN-EFFICIENT Port.

IMO,
Your Head "Ports" are insufficient for the application, either due to Size, Shape, Flow, or Efficiency, and it is resulting in very poor quality Air/Fuel being presented for Ignition in your Chambers.
In my experience,
You can NOT Tune around this condition, you NEVER WILL Tune around it, there is NO WAY to Tune around it.

IMO,
THAT has been your problem all along here, consistent with the symptoms

* Thick-Gooey Carboned residued Piston tops.... that's the lower ended Oils that do Not burn well.... separated from the upper end aromatics in the fuel(they do burn)...... which crack off in the distressed IN-EFFICIENT Ports when going Sonic.
It rips the fuel itself apart, for lack of better descriptive here.

* Glazed Cylinder Walls, something is lubricating from ABOVE the rings now isn't it ?
I will bet I could SHAVE with the underside of your 2nd Rings which will be sharp as a razor !

* The Engine is over sensitive to Fuel Octane quality far beyond "normal" DCR ranges for lower Octane Fuels ??

* Tuning "irregularities" seen wide-band.... where it seems to AVALANCHE, or "over react" all of a sudden to changes one way or the other ? under the wrong conditions for normal explanation ?

I am NOT trying to speak over your Head.... no mileage in this for me ? But honestly here.. have you not SEEN all of the above ?
But,
I also can NOT use up gunga bandwidth trying to explain thermal dynamics and airflow over the internet ?

IMO,
GET YOUR HEADS FIXED !

Good Luck with the Engine
Bob.
 
 

[cudaken]

Greg, while sometimes Bob and Cooter may not have the best Keyboard manners I do respect there ideas.

I have had a few Cam 2's and I do understand what Bob is telling you. I had a local Mopar expert port my 346 heads for the blower motor. Before he gave them back (he worked in is garage at home) he took them to have them bench flowed by his friend. Told me the gas and air was not mixing right and had to play with them a little more. He said it would make the A/F mix lean, and with a Blower it is a bad thing. 

I all so think what Bob is stating is there is a differences between Flow and Air Fuel Mixture. Am I right Bob?

Cuda Ken
   

[Kern Dog]

Look, and excuse me ....
But, I am stating it as best I can here ?
Trying to explain a concept... is never easy ?

IMO,
GET YOUR HEADS FIXED !

Good Luck with the Engine
Bob.
 

Thanks Bob for responding. I do understand you better now. As I wrote before, the engine isn't knocking since I changed to these thicker head gaskets. I am not going to remove the heads again anytime soon. The engine ran great before with the Edelbrocks UNported with .060 Cometics and it runs great with ported heads and these .075 Cometics. I appreciate your concern, but if the goals I had have been met, I see no reason to fix what isn't broken.
Oh, the cylinder walls are fine, my cranking compression is a 191 average and each cylinder is within 3% of each other.

[Kern Dog]

I replied in the beginning that I felt the only way your gonna get it to stop pinging is lower the static compression, you chose to do all sorts of stuff before finally lowering compression.
I must admit that your advice wasn't what I wanted to hear but it did make the difference.


Carry on, and if you figure out some other way of cutting back on the ping, let us know, cause we like results and are appreciative.

Again, your advice was correct. The car has been ran several times since I got it running again and it does not knock on 91 octane. Warmer weather is coming but but I hope I'll stay knock-free.
I hope that threads like these serve as a guide for others to read. Maybe some of my mistakes can be avoided by others in the future.

[Challenger340]

I all so think what Bob is stating is there is a differences between Flow and Air Fuel Mixture. Am I right Bob?

Cuda Ken
   

EXACTLY Ken,
and Thanks for putting it so simply.

[Kern Dog]

Strange thing: Adding the Rev-N-Nator ECU made my A/F ratio go rich at cruise. I would have expected the thing to make the engine run cleaner due to it being a "better" unit.

I wrote this a few days ago. Today I went out to resume tuning. I was curious about why the car was running richer than it was before. I replaced the #84 primary jets with #83s. I adjusted the 4 idle mixture screws to get the in gear idle #s to the 14.4-14.8 range then went for a drive. The A/F numbers were a little leaner than before but I had expected there to be more improvement. back at home I pulled the Rev-N-Nator and installed the MP Chrome ECU. The numbers didn't change much. if at all. It was then that I realized that I had retarded the timing 3 degrees with the REV unit as per their instructions. I reset the timing and the A/F #s improved. I realize now that the ignition timing change was responsible for the change. I didn't know that timing had such an effect on the readings.
The car really scrams. The lazy part throttle feel seems to have diminished. It feels much more snappy. I'm going to add vacuum advance to see if the A/F at cruise improves even more. I expect it to help.

[Kern Dog]

Today I finally checked the cranking compression.
Before with the Fel Pro .039 head gaskets and nearly 11.0 to 1 compression I was at an average of 191. Now with the 10.07 to 1 ratio my average went down to around 160 !
I checked every hole twice. I had the battery charger on the battery to maintain an even charge. I was amazed that the cranking numbers dropped off so much compared to before.
I decided to start playing with the lash to see what effect it had on the cranking psi. Wow, what an eye opener! The Hot Lash specs are .020 IN and .022 EX. I normally set them .006 tighter (.014 & .016) when cold to account for the expansion of the aluminum heads. This time I set them cold to .022 IN and .024 EX. That is .008 wider spec. This raised the cranking compression to an average of 170.
I haven't driven the car yet. I figure I'd see how it feels after the lash adjustment. If it feels more responsive down low I might leave it as is as long as it isn't knocking.
I was really surprised to see what an effect the lash really had on the cranking compression

[Kern Dog]

On another site, a Mopar guy thought I may be heading for trouble with the wider valve lash setting. On his advice, I called the Lunati tech line. Their guy agreed, saying NOT to go more than .004 past the published spec.
I decided to try advancing the cam 4 degrees instead. This is supposed to move the power band lower in the rpm scale.
I finished up today. The timing was reset to account for the 4 degree cam advance. It fired up quickly and once it was warmed up, it seemed to idle smoother. I did go back and relash the LH bank to the spec on the cam card. I figure it makes more sense to do one change at a time so I'll know exactly what effect each change has. It was raining this afternoon so I have yet to road test it.
I didn't put a vacuum guage on it. I just didn't think of it until I started writing this just now. The idle speed went up about 100 rpms.
Along with trying to make the car more civilized, I'm still working on the Air/Fuel ratio tuning. Now that I have the MP Chrome ECU back in I'll probably go back to using vacuum advance. I'm sure that will improve the burn cycle at idle and cruise speeds

[Cooter]