Cam is in, car is running, now the TUNING begins!

[Kern Dog]

"I call this the 3-2-1 mix. A 3-1-1 mix was too low of octane and would ping some."

Man, Gary, that would be a hassle in a race car, but a nightmare in a street car....I guess I'm too old to have a regime like that just to drive my car.

Hey, if that works for other guys, that is great.
For me, I want 100% streetability. Idling in traffic. Low speed cruising. 100 mph blasts. 1/4 mile runs. Grocery store runs, long road trips, burnouts on quiet roads.
91 octane or less with no overheating, no vapor locking.

 

[Garys1969RR]

"I call this the 3-2-1 mix. A 3-1-1 mix was too low of octane and would ping some."

Man, Gary, that would be a hassle in a race car, but a nightmare in a street car....I guess I'm too old to have a regime like that just to drive my car.

Its not bad, the station I go to has all 3 fuels available all the time. And I have an 18 gallon tank.(or close to that). So I just give them my credit card and get what I need. Also I like to experiment to see what works, what doesn't.

 

[Kern Dog]

I just ordered the Mallory kit part # 29014. It has several springs to alter the advance curve of my distributor. I've read that a two stage curve is helpful against detonation .
Maybe by Wednesday I'll have the parts installed and tested.

 

[Meep-Meep]

Altering an advance curve to make a high compression engine run on insufficient octane is a band aid. I'd just pull the thing apart and start over with 9.5:1 and a longer lobe separation cam. With 500 cubes the end result will be a much more drivable combo and still melt the rubber off the tires on demand.

 

[67Satty]

I don't think going all the way down to 9.5:1 should be necessary because, heck, I'm running that compression with iron heads with no quench with no problems.

I think he should try tuning his distributor first, then try some steel shim .020" head gaskets (giving him .037" quench distance) if that doesn't work.

If it still doesn't work, then put on the thick head gaskets.

 

[Meep-Meep]

Reducing the quench distance by .015" isn't going to do squat in his case. Quench is good, but shooting for .040" when you have .055" is pretty much meaningless.

Even if you are running an open chamber head (906) you still have quench! Just not as much as a closed chamber. You DO NOT have quench if the top of the chamber has uniform distance to the piston top over the entire bore.

The purpose of quench is to squirt all the gases toward the plug (swirl effect) so the flame front can consume a homogenous mixture resulting in a fast burn. It's also important that the flame front gets all the way through to burn all the fuel vapor in the chamber, so if the quench is too tight, or the other side of the chamber is shrouded by a big piston dome, the flame front will have a hard time getting into the tight space to make a complete burn. This is why large dome pistons typically need a lot of lead to get the job done. The best scenario is to zap the plug; burn it all quickly, and move on. A hemi with a centralized plug location is pretty good at this even though these do not have quench. The flame front just has the shortest path to the edge or the chamber from all directions, which is why it requires less total advance (for gas typically 32 deg total rather than 38 for a wedge).

All this talk about quench is only one factor of many when dealing with detonation and only a few are variable. Things like bore size and chamber shape can't be readily altered so you proceed to the lowest common denominator. Fuel requirement for the available compression! Seems to me I have said this before but it falls on deaf ears. I don't claim to be an expert and will do trail and error like anyone else, but I'm not stuck on an ideology of insisting that one variable must work (in this case 10.7:1 compression). Many people before me figured out what works with a BB MoPar so some of that information should be considered a constant because you can't solve an equation with all variables.

 

[Kern Dog]

There are many opinions on this subject .
Meep Meep, I have read your responses and really do appreciate your input. There are no deaf ears or blind eyes on this end of the computer. Your contention that ..."The OPs problem is that the compression is too high for the avaliable octane"....Is certainly a sensible one and probably right.
* Many Mopars guys felt that a bigger cam with a later intake closing would allow a reduction in cranking compression, leading to lower cylinder pressure. This Lunati cam actually does have a later intake closing but somehow I ended up gaining over 3 psi of compression average per cylinder. I was told that the valve lash could be tightened up on the intake side to make the intake valves open sooner and close later. Band aid? Maybe.
* The ignition curve actually is faster than I like. Regardless of whether it cures the problem at hand, it was something that needed to be done.
* There are many guys that speak of running these high compression ratio numbers on premium fuel. I wonder how many of them are trying it with 91 octane. I suspect that the 93 or 94 octane they are using gives them that slight edge.Since my piston to head quench distance is currently .056, switching head gaskets either thicker or thinner can make a noticeable difference. The .027 Cometics move me to .044. If optimal quench is really found between .035 and .045, I'd need a thinner gasket. I have read of guys using .020 steel shim head gaskets on big blocks with aluminum heads. The .020 moves the quench to .037 but also moves the compression to 11.22. No matter how you look at it, thats still almost 11 and a quarter to one. Would quench REALLY offset all that compression when it has knocked at half a point less? It just seems like putting out fire with gasoline.

 

[Sweet5ltr]

My goodness, just buy the thicker head gaskets already! lol You are making this ten times harder than it needs to be... 10:1 will run on pump fuel like a dream, 11.0-11.25+ obviously will not, regardless of the 'quench' effect. You are band-aiding the effects by trying to work with the 'perfect' distributor curve, and the first sign of bad gas you will be at the same point again. I run a straight up, locked dizzy with 32* timing. Trust me, it isn't going to make much of a difference; the first blip of the throttle and you are at full advance anyways.

https://www.flatoutgroup.com/default.aspx

That is the company you need to contact about your custom gasket needs, and exactly what gasket you should use to get down to 9.75-10.0:1.

 

[Meep-Meep]

Since my piston to head quench distance is currently .056, switching head gaskets either thicker or thinner can make a noticeable difference. The .027 Cometics move me to .044. If optimal quench is really found between .035 and .045, I'd need a thinner gasket. I have read of guys using .020 steel shim head gaskets on big blocks with aluminum heads. The .020 moves the quench to .037 but also moves the compression to 11.22. No matter how you look at it, thats still almost 11 and a quarter to one. Would quench REALLY offset all that compression when it has knocked at half a point less? It just seems like putting out fire with gasoline.

Show me some data that suggests that tweaking the quench .015" will solve a serious detonation problem. If you go down that road I believe you will be wasting your time and money. You need to target for 10:1 or less and install a proper cam and set a proper advance curve to optimize the engine in the street driven power band. Everything will work better. Trust me. You want to make the most average power from off idle to about 5000 RPM and 500 cubes is a very good platform to do that with. To hell with high HP numbers at 6500 RPM because you won't even spend 20% of your driving there. It's a street car so build a street car.

 

[67Satty]

OK, how's this for a data point? This was found on the archives of Moparts, data from a real person. I like to build on the knowledge of people that came before, just like you always do with science. There's been so many of these stock stroke and stroker 440s built. Why reinvent the wheel?

"as a 440 with open chamber iron heads and pistons .100 in the hole, it was an 8:1 (if that) pig that detonated on premium. after the rebuild, it's zero deck, .039 quench, 10.33:1 496 that never detonates."

If Gregory C was willing to try a pair of cheap steel shim .020" head gaskets as an experiment, he would find out soon enough. With his pistons .017" down and the .020" compressed gaskets, he'd be at .037" quench. The labor, time and cost would be nothing compared to what he's been going through and if he did this along with correctly curving his distributor for the combo he might have an engine that is realizing the full potential of all the high-dollar parts he has in it (aluminum close-chambered heads, 1.6 rockers, stroker crank, etc...) and probably really scream if he ever took it down a track in a properly set up car.

I don't agree that correctly tuning a distributor is a band-aid, I feel that putting a thick head gasket on a motor with close-chambered heads is a band aid and makes no sense to me. What was the point of ordering the 84cc close-chambered heads if he was not going run an engine with good quench numbers? May as well have ordered the 88cc open-chambered heads and used thick head gaskets to lower the compression and not have all these problems.

He went through all the trouble to change rockers and cam to have enough lift to realize the potential of his good breathing heads, now why not go all the way towards straightening this thing out?

I agree with what you saying about it's a streetcar so build a streetcar but he's already gone down the road of overkill for a streetcar so he may as well go all the way. Let's face it most people, especially those that are never going take their car to the track would have more fun and more money in their pocket if they just put together something like what IQ52 put together for his dyno day. But people get caught up in having the latest stuff...

 

[Kern Dog]

Ahhh..... the differences in bulding a STREET car versus a RACE car!

In 2003 I built a .030 440 for this car. I bought the aluminum heads because I heard that they flowed better and weighed less than the factory cast iron stuff. I was told that the "closed chambered" design made more power, so I went for it. I had these heads on a 9.5 440 with a 284/484 cam. It ran great and I don't recall any detonation. That engine threw a rod at 846 miles. The rod snapped in the middle of the beam. I panicked when that engine blew up and figured the crank was damaged. I found another 440 locally and ordered a rotating assembly. I figured that a NEW crank, NEW rods and new pistons would reduce the risk of another similar failure. I thought that since I was getting a new crank, I might as well get the STROKED crank, right? I decided to use these heads when I built this engine. The 9.5 440 never knocked, so I was a bit skeptical of how a 10.7 ratio would work. The Vendor of the rotating assembly assured me that it would work on pump gas. Maybe in Tennessee their running some great fuel, but here in CA I am limited to 91 octane with ethanol in it. I trusted the words of that vendor. Maybe if everything were tuned to the gnats *** and all conditions were favorable, it would have been fine. That SUCKS though! If I let my guard down on any one issue, the engine pings.
I never chased the high maintenance women because I like a more casual standard of living.
I guess I sorta feel the same way about this. I probably could use a thinner gasket to improve quench. The .020 gasket is .19 thinner than the Fel Pro I am using and MAY help. The problem is that I think I'd still be really close to the edge with it.
In short, this whole thing sorta "snow-balled". I wanted a high performance engine but didn't do enough research on everything. I can bolt anything together but all along I was UNaware of just how precise the tuning has to be with a high compression engine. The stock type builds I have done could run great on low or mid grade fuel. The timing curves were never modified. The carb was never tuned beyond jetting and idle mixture screw adjustments and certainly never with a wideband guage.
The high compression of this engine has made me increase my skills to get it to run right. I'm not against learning, but at the same time I just wanted an engine that runs strong without being so close to destruction all of the time.

 

[67Satty]

So did you not see the example I put in bold of the guy who went from pinging with 8:1 compression with open chambered heads with no quench to 10.3:1 compression with .039" quench and no more pinging? He raised his static compression and stopped his detonation by taking advantage of quench.

 

[Sweet5ltr]

Wow, I usually don't say this, but anyone considering the fact that the 'quench effect' will allow an 11:1CR RB engine run on today's pump gas is being a little bit ridiculous and irrational. Common sense says that it doesn't take a rocket scientist to understand that 10:1 engines are a dime a dozen on pump fuel, and very-very few engines running 11:1 unless they are fuel injected, finely tuned with minimal timing, and have massive solid roller camshafts. If I can run 93 octane pump gas at 10.25:1 (no quench effect...) he can run pump gas at 9.75:1 (91 octane) with 40 more cubes.. It isn't a complicated issue, I would much rather spend $100 on cylinder head gaskets (I mean, how often do you change them!?) and actually drive the car than be on a quench effect at a massive street compression ratio and sweating bullets every time you were at the pump.. Greg, you obviously see their are only two routes to take at this time, I just hope you pick the right one!

 

[67Satty]

I'm going to ignore the silly name-calling and just say that you can't just get hung up static compression ratios, you have to figure out the dynamic compression ratio. A few minutes plugging numbers from cam cards could have saved him a lot of money and trouble swapping out a cam only to see the cranking PSI actually increase instead of decrease but at least he has a cam with enough lift to take advantage of his head flow now. Now I'm just trying to get him to take advantage of the close-chambered design aspect of his heads. So getting excited about a meaningless number like the static compression ratio is what is ridiculous and irrational to me.

I still maintain that he could make it run like it should with just a little more work without resorting to the easy way out and throwing on some thick head gaskets to lower the compression to make it safe. But yes, as I also said a page or two ago, you could just throw the thick head gaskets on it too if you want.

People on multiple threads have been calling on Gregory C to at least try to curve the distributor for the combo he has but it seems as though he hasn't had the time or inclination to do that. That's what I'd do first but I always like start with the easy to get to stuff first and work my way in. I guess maybe that sounds crazy too?

Like so many others on multiple threads on multiple message boards that came before me, I think I'm about burned out on this one.

 

[Hemirunner]

All I will say is I hope you get it figured out and good luck with it.

 

[Kern Dog]

A few minutes plugging numbers from cam cards could have saved him a lot of money and trouble swapping out a cam only to see the cranking PSI actually increase instead of decrease compression ratio is what is ridiculous and irrational to me.

I actually DID do exactly that! This Lunati cam was expected to drop my dynamic CR from 8.9 to 8.13. The numbers on the MP 509 cam must have been flawed. Thats not hard to do when you consider that for many, many years, Mopar Performance staunchly refused to join the rest of the world and list the specs that every other cam manufacturer did: Duration @ .006, Duration @ .050 and Intake closing. I took the MP 509 intake closing spec from a guy on FABO. It showed that the 509 closed 11 degrees earlier. I now feel that info is wrong. I have found that some CR calculators use a weird way of checking the intake closing point. Some tell you to list Intake closing point PLUS 15 degrees. Huh?
Anyhow, I wanted to mention that I did not just jump in with the choice of the cam. I was leaning toward the Comp XE294 because I was still leaning toward a hydraulic stick.


People on multiple threads have been calling on Gregory C to at least try to curve the distributor for the combo he has but it seems as though he hasn't had the time or inclination to do that. That's what I'd do first but I always like start with the easy to get to stuff first and work my way in. I guess maybe that sounds crazy too?


********************************************************************************
I actually have been working out of town the past 2 weeks. I was unemployed for 6 months so I am quite happy to be back to work.
Also, I DID order and receive the Mallory distributor tuning kit. Today I mapped the curve of the distributor before doing anything more. The instructions tell that the distributors are shipped with one purple spring and a brown one. This results in a 2 stage advance curve where the light purple spring allows a fast initial curve, followed by a flatter-slower curve from the stiffer spring. Mine had 2 pink springs in it. I mapped the curve and found that from a 1000 rpm idle, it immediately began advancing at a rate of about 4 degrees every 250 rpms. ALL the timing was in before 2000 rpms.
I took my spare distributor and looked at it. It also had 2 pink springs in there. I changed to 2 orange springs and put the #2 distributor in. The curve starts moving later and ends later. This may help but I'm not betting any money on it.
I took Distributor #1 and put 2 brown springs in it. I didn't try running it yet though. The car still has some 110 Sunoco in it. I need to run the tank down near empty then fill it with 91. Theres no way to know if the ignition curve changes will work with 91 octane unless I am running only 91 octane.
I am doubtful that the changes will make enough of a difference though. Every time I held the rpms steady at any point above 2000 rpms, (remember, that is the point where the advance is ALL in.) the engine pinged at WOT. It just seems that is it is knocking at any point AFTER the advance is all in, then the actual curve isn't the problem.

I screwed up on this post! My words follow the dotted line!

 

[Meep-Meep]

OK, how's this for a data point? This was found on the archives of Moparts, data from a real person. I like to build on the knowledge of people that came before, just like you always do with science. There's been so many of these stock stroke and stroker 440s built. Why reinvent the wheel?

"as a 440 with open chamber iron heads and pistons .100 in the hole, it was an 8:1 (if that) pig that detonated on premium. after the rebuild, it's zero deck, .039 quench, 10.33:1 496 that never detonates."

Not sure if this is a good data point. It seems that too many thing were changed at one time and the big thing was the condition of the engine. Was the engine CC'd and found to be 10.33:1? I CC'd my 440 and came up with 10.1:1. I am running 915's with a flat top piston -.015" in the hole and a steel shim gasket. It pings like crazy on pump 91 with the iron 4 BBL and 750 AFB. Add a splash of 110 and the 4000 lb car runs high 12's. But now I have a 6 BBL and my pinging is gone - and the 6 BBL is lean!! No other changes were made. My explanation is fuel distribution has improved or perhaps I had one very lean cylinder with the 4 BBL and that is now cured with the different intake and a pile of carbs.

If Gregory C was willing to try a pair of cheap steel shim .020" head gaskets as an experiment, he would find out soon enough. With his pistons .017" down and the .020" compressed gaskets, he'd be at .037" quench. The labor, time and cost would be nothing compared to what he's been going through and if he did this along with correctly curving his distributor for the combo he might have an engine that is realizing the full potential of all the high-dollar parts he has in it (aluminum close-chambered heads, 1.6 rockers, stroker crank, etc...) and probably really scream if he ever took it down a track in a properly set up car.

I don't agree that correctly tuning a distributor is a band-aid, I feel that putting a thick head gasket on a motor with close-chambered heads is a band aid and makes no sense to me. What was the point of ordering the 84cc close-chambered heads if he was not going run an engine with good quench numbers? May as well have ordered the 88cc open-chambered heads and used thick head gaskets to lower the compression and not have all these problems.

I never said correctly tuning a distributor is a band aid. I said altering the timing (i.e. limiting or retarding) to make a high compression engine live on insufficient octane was a band aid. Adjusting the compression ratio for the available fuel is not a band aid. This is the proper solution to the problem.

He went through all the trouble to change rockers and cam to have enough lift to realize the potential of his good breathing heads, now why not go all the way towards straightening this thing out?

I agree with what you saying about it's a streetcar so build a streetcar but he's already gone down the road of overkill for a streetcar so he may as well go all the way. Let's face it most people, especially those that are never going take their car to the track would have more fun and more money in their pocket if they just put together something like what IQ52 put together for his dyno day. But people get caught up in having the latest stuff...

His combo will work fine as is if it gets the right fuel; full advance; proper carb, etc... The thing probably will/does run like a raped ape. Nothing wrong with that if he accepts it as is. But he doesn't so here we are.

 

[Supershafts]

C'mon someone better tell gm to put a fat head gasket on there 11.5 to 1 motor they got in the vette right away. Not to mention doing 10.7 to 1 on regular 87....

Quench isn't important, RR isn't important, just throw pistons on rods and get heads bolt it together and hope for the best :huh:.

 

[Sweet5ltr]

C'mon someone better tell gm to put a fat head gasket on there 11.5 to 1 motor they got in the vette right away. Not to mention doing 10.7 to 1 on regular 87....

Quench isn't important, RR isn't important, just throw pistons on rods and get heads bolt it together and hope for the best :huh:.

:laughing4: That's about what it seems like! In no way, shape, or form can you compare a modern LSX (1/2/3/7/9 and beyond) engine to our RB's. GM spent millions of dollars to squeak out every ounce of available power per/cubic inch, and the ECU/PCM automatically tweaks itself (and timing) to the octane of fuel provided. I should know, I have a Z06 Corvette (only a measly 10.5CR though).. My Z' even retards the timing when the coolant temp exceeds 200*.. Don't expect your Orange box to be doing this anytime soon.

Greg, you obviously only have one logical solution. Pray to Mother Mopar that the 'quench' effect will save you at 11:1+ compression or drop down to a reasonable 9.75-10.0:1 'static' ratio by either A) dropping in a completely different set of pistons and tearing the motor apart or B) buy custom gaskets from the link I provided and actually drive your car... I am not saying quench is not important or rod ratio.. They all play a critical part in an engine build, but in this case, the engine is built. Less static/dynamic compression is the only answer now. Quench' won't save a 11:1CR RB on 91 in California.. Maybe a 10.5:1 RB on 91...

 

[Meep-Meep]

C'mon someone better tell gm to put a fat head gasket on there 11.5 to 1 motor they got in the vette right away. Not to mention doing 10.7 to 1 on regular 87....

Quench isn't important, RR isn't important, just throw pistons on rods and get heads bolt it together and hope for the best :huh:.

Well, damn it if GM can do it on the new engine then I can do it on a 60's designed 440. Who do they think they are getting away with 11:1 on pump gas - with all that electronic spark control; knock sensors; port EFI; controlled inlet charge temps; purposely designed combustion chambers, piston tops and camshafts. I mean really! What makes that team of engineers and hundreds of thousands of dollars spent on dynos and R&D equipment including professional data logging software spitting out reports and charts so special? I should be able to add .015" of quench and change the rod ratio by 7% and I can run 11:1 on 91 octane also.