210+ cranking comp, 10.7 CR and '509 cam...Serious mismatched combo!
 

Who the heck knew?
I built this engine in 2004. Back then I was unaware of internet tech forums. I only had the advice from my Dodge dealer and what I read in magazines. Mopar Performance had a 440 based crate engine with a 4.15 stroke that was rated at 500 HP. It used 9 to 1 compression, iron heads and the 292/509 cam. The price was a bit stiff, so I decided to put an engine together myself from a few different sources. I had a 1974 440 that was standard bore. I ordered a 4.15 stroke rotating assembly from Hensley Performance out of Tennessee. The man said their kits would add up to 10.8 compression but he assured me that it would run fine on pump gas. I went with the '509 cam from Mopar Performance thinking that if THEY used it in their crate engine, it must be a winner...PLUS, the engine I was building had almost 2 points MORE compression, so it should be even MORE powerful.
Over the years I have dealt with various problems. Detonation issues, improper tuning, etc. I have often thought that the car should be faster. I have to limit the timing to 31 degrees to avoid detonation on Californias 91 octane gas. I can add 104 or 110 fuel, but that just sucks!
Today i did a compression check and found a high of 220 and a low of 210.
WOW !!
I have read in many places that to be streetable and run on pump gas of 91 octane, an engine needs to be below 190. Well, that leaves me out. I have been active on other tech forums, and the consensus is that with this 10.73 compression ratio, I need a MUCH bigger camshaft. A cam with more overlap AND a later intake closing event will reduce the cranking compression and make the engine less likely to detonate.
I wish that I had a mentor or something when I built this engine years ago.
Also, among the many responses that I have received in my threads I've started, the issue of rocker arm ratio has been covered. I wasn't aware of this until recently, but apparently the stock stamped steel rocker arms that are rated as 1.5 ratio are rarely actually 1.5. I've read that they are often between 1.38 and 1.45. This means that I may have up to 16 different rocker arm ratios in my engine. The '509 cam isn't delivering a true '509 of lift after all.
I ordered a set of 1.6 ratio aluminum rocker arms from Mancini racing. These are made by Harland Sharp exclusively for Mancini. These will not only deliver a consistent ratio, but even MORE ratio. The 1.6 will bump the .509 lift to .543. I don't know exactly how much this will help, but I do expect something. I'll keep you posted.

KD -

Think your problem is the cam itself. The .509 has been around for a lot of decades and was really never considered that great. The detonation is most likely due to insufficient overlap.

I guess you're sure the valve to piston clearance will be adequate with a .543 lift?

Archer

Stock rockers are more than up to the job. Different cam may help ? I would guess your compression is more like 12 to 1 To fix it ?? I would consider going to a large chamber aluminum head if it is in the budget

The math involved with the engine specifications adds up to 10.73 to one. I have checked it numerous times.
The high cranking compression numbers will come down with a camshaft that has a later intake closing event since true compression only happens when both valves are closed. If the intake valve stays open longer, less volume is trapped in the cylinder.
The advantages of the aftermarket rockers have been proven. The higher ratio will translate into a cam that acts larger than it is with stock valvetrain,

Hey Kern Dog, did you degree your cam. I think if its too far advanced it will increase your cranking compression.
Spike.

The cam was degreed when I first built the engine in 2004. Putting it at the dot to dot spot added up to 1.5 degrees retarded so I put it to the 4 degree advance spot. THERE it came in at a true 4 degrees. A LOT has happened since then though...
I had the engine out to deglaze the cylinders and install new rings in 2011. I reused the '509 cam but used a new timing set. I installed the chain and gears straight up which WAS 1.5 degrees retarded last time. Funny thing though...My eyesight is to the point where I need reading glasses to see stuff close up. I have a sneaking suspicion that I MAY have the timing set set up to the advance position!
I have had several people scratch their heads at the cranking compression numbers I reported. One such person was the famous engine guy known as Dwayne Porter.
When I first had some detonation issues in 2005, I did a cranking compression test and had numbers just shy of 230 PSI. This was with the 4 degree cam advance. Dwayne thought my numbers should be in the 195-200 range if the cam was in straight up.
I started installing the 1.6 rocker arms. The hold down blocks had to be filed down a bit to allow free movement of the rockers. I took a few thousands off of them and they move freely now. I installed 3/8" pushrods from Proform but had to stop work. It was 106 in the garage and I was sweating all over myself.
ARCHER: The .543 lift will not be a problem. I had a Comp Cam in the engine in 2006. It had .545 lift and performed fine until it wiped out a lobe.
TVLYNN: I was unaware of the shortcomings of the factory rocker arms until recently. On a stock engine, they work fine, but add 53 cubic inches and a larger cam and you'll need to upgrade to maximize the engines potential. Add to that, the stock stuff is NON adjustable. Some cam manufacturers call for a .020 lifter preload which can be difficult to achieve with a non adjustable setup.
The switch to 1.6 ratio arms will make every valve action consistent. The lift will be higher and there will be some small gains in duration as well.

California gas is different that what is available to the rest of the country

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Today I got the pushrods in and adjusted in the left side. The right side is still the stock parts. I wanted to compare the left to the right for cranking compression numbers. Several people on various tech forums thought that the cranking PSI #s I posted seemed to be higher than this engine should have had, given the combination.
I had 2 guages to use and chose the one that showed the highest numbers. NOW looking at both of them, it is obvious how they gave different readings.

The guage on the left has a needle that starts at 30 PSI ! All along, this guage was reading too high.
I checked all 8 holes again. The left side has the 1.6 rockers, the right side is all stock. The numbers tell an interesting story. Look how close the left side numbers are. No doubt the much more accurate rocker arms have contributed to a more even range. 3 PSI is amazing. NOW look at the right side. Not only are the numbers higher, they have a 7 point spread. That is still decent and well within an acceptable range though.
The left side averaged 186.5 PSI per cylinder. The right side is 193.25. This means the new rocker arms reduced cranking pressure almost 7 points. Getting the numbers under 190 was the goal.
After I finish the right side rocker arms, I'll retard the cam 4 degrees and see what results I get. I'm hoping for a minimum of 5 more points to get me near 180. If I reach that goal, I might be satisfied for a while.
Many have told me that I am leaving a LOT of power on the table by sticking with this '509 cam.

I'd like to drive the car more through the summer and fall. Once the weather turns cold, I usually don't drive the car much, certainly not in the rain. Wintertime is when I make changes that usually take the car out of commission for a few weeks. I may have the heads ported along with having them matched to the intake. I thought about going with a thinner Cometic MLS .027 gasket to increase the quench. At that point, I'll look into replacing the cam. I like the idea of the EDM solids that deliver oil from the lifter directly to the cam lobes. Sure seems like it wouls cut down on camshaft & lifter failures.

The quench should have been built into the motor originally.. WHAT heads do you have ?

The heads are Edelbrock 84 cc closed chamber. When I built the engine originally in 2004 I wasn't involved in any online forums and I didn't know many guys with Mopars. A lot has happened in 10 years.

Good job and thanks for the play by play valuable informations.

Those new numbers must have you excited now.

I could be off base ? Part of the problem? I'm guessing with everything posted... Your original motor was built with the idea of using open chambered heads ?? Edelbrock makes both an 84 closed chamber and an 88cc open chamber head. If you used 84cc heads that would make a big difference in the compression and the quench area of the engine build !

Pretty interesting. The stock steel rocker arms rating of 1.5 ratio often is an exxageration. They have been found to be between 1.38 and 1.45 instead. Consider this: The '509 cam has a lobe lift of .33933. IF the rocker arms had a real 1.5 ratio, you'd get .509 lift. If the rocker arm is as bad as 1.38, your lift is .468 !! If it is as good as 1.45, you'd have .492. The 1.6 rockers being a TRUE 1.6 ratio, give .543. This is a BIG jump and should make a difference.

Sorry if I confused anyone regarding the heads. I had these Edelbrocks on my previous engine, a .030 over 440. They are the same 84 cc closed chambered pair that I bought in 2003.

I hear conflicting opinions on quench when the distance opens up as far as I have. Some think that anything over .050, you have no quench effect. Some, like myself, think that while you may have lost much of it, you STILL have something. Even given my little experience with the topic, my common sense tells me that the closed chambered design still has the tendency to push the incoming mixture from the "quench" side toward the valves and spark plug side, inducing some swirl & mixing. THAT has to be worth something.

Thinner head gasket means higher compression ratio, just keep that in mind

If you are referring to my idea of using the .027 Cometic gasket, here is what I have learned:
The higher compression ratio will be MORE than offset by the improved quench. The theory is that the benefits of quench are improved so much that the rise in compression ratio is almost a non issue. I am not absolutely certain that I will do this, it is just an idea that I am floating around...
Thank you though. Your concern is appreciated.:hello:

NOT WITH THE CLOSED CHAMBER HEADS !!!!! It will just raise the compression !!! It will change with the open chamber heads.
RE DO YOUR THINKING ABOUT THE ENGINE, because you did not build it and have no idea what it is...

I don't know you, but I have some doubts to your post.
Stock rockers are more than up to the job? Read up on that one. Their rated ratio of 1.5 to one has been found to be between 1.38 and 1.45. I have yet to hear of one ever being actually 1.5 as they are rated. Think about that. A '509 cam could really be opening the valve .468 !
The stock rockers are fine for low lift cams. This was one of the considerations behind the Mopar Performance musclecar cam designs. Ever wonder why MP cams had so much duration in relation to lift? It was to allow Mopar racers to retain the stock rocker gear. Sure, it is durable and it lasts forever....UNTIL you want to step up to higher lift or a solid lifter stick.
Some cam companies strongly suggest an adjustable valvetrain be used with their cam kit. Comp cams is one of them. The reason? To set the lifter preload. Pretty hard to do with the stock stuff.
Regarding the compression: I used a few different online calculators and came up with the same number.
A larger chamber aluminum head? The Edelbrock open chamber is 88 ccs. That is the largest cc rating that I know of. the 4ccs wouldn't make a noticeable difference. At around $1500 a set, it surely isn't a cost effective effort.
Something I have heard recently: Some suggested to have the pistons milled .060 on the valve side, leaving the quench side untouched. This, along with a thinner head gasket would lower the compression while improving the quench. The thing is, I am not willing to pull the engine just yet. It is an interesting idea though.
The title of this thread was a bit overstated. I don't really consider the engine seriously mismatched. More correctly, I am just UNDERcammed.
Today I finished the installation of the 1.6 rocker arms and installed new plugs and wires. The engine idles a bit lower and runs a bit smoother. Power is up but not by much. ZERO detonation but I currently have a 50-50 mix of 110 and 91 octane. The real test would be to run it on straight 91. All the reading I have done lately has me anxious to step it up though. the 493 is about 12% larger than a 440, so theoretically the engine needs a 12% bigger camshaft just to stay even. This puts me in the 275 @ .050 range with a 570 lift. This is right in line with some of the cam specs I have heard suggested. I only worry that too big of a cam will make the car sluggish out of the hole.
I'll do more research before I cam it up. I've made enough mistakes by being impulsive.

Sounds like an insult here ^^^
I DID build the engine. What exactly are you trying to say here anyway? Are you familiar with quench at all? An engine with an open chambered head has no quench. An engine with a closed chamber can have quench if the piston to head distance is less than .060.
Read up on quench. It is pretty interesting. The OEMs have embraced the theory. Ever wondered how they are able to run the higher compression ratios on todays crappy gas? It isn't just because of EFI and engine computers. Q U E N C H in the simplest definition is where the piston rises to TDC and pushes the mixture away from the flat part of the head toward the valves and spark plug side. This movement enhances the burn, keeps fuel atomized and cools the piston and head due to the fast movement of the mixture across the cylinder. This effect allows a higher compression ratio to be used without risk of detonation.
The theory is though than once you get past a certain distance, the effects of quench becomes less effective. I've had a hard time pinning anyone down on the exact number, but .060 seems to be near the end.

I am getting close to ordering a cam kit.
Comp cams has their Extreme Energy XE294H hyd flat tappet. It has 250/256 @ .050 Intake/exhaust and my 1.6 ratio rocker arms take the lift to .553/.558 IN/EX with a 110 LSA. This cam has an intake closing 4 degrees later than the '509, more lift, duration and slightly more Lobe separation. I'm also going to go ahead with some thicker head gaskets to lower the compression. I've found that most of the sharp engine guys agree that with the .056 distance that I am currently at, there is very little quench going on anyway.
There are a few .051 head gaskets available from different companies. I've seen different bore sizes as well. My compression ratio with the current .039 head gasket with a 4.410 bore is 10.73. A .051 gasket with the same 4.410 bore size drops it to 10.45. A .051 gasket in a 4.590 bore size takes it to 10.26. I just wonder if there could be a problem with using the bigger bore size if the actual cylinder is still 4.35.

No offense taken. AN open chamber head HAS i big dead zone in the head. The quench area squeese the mixture towards the spark plug. DO you know your quench distance ? from piston top to head at TDC ? How far down into the bore were the pistons ?

As is, the piston is .017 in the hole, the head gasket is .039. This puts me at a .56 quench distance. I've been told that at this point, the qhench is barely effective. This is why the idea of a thicker head gasket seems feasible

You were talking about a thinner gasket and now a thicker one ?? IF you are at .060 I would change the cam first and try it.. Closed chamber heads would be fine with a slightly thicker gasket
The last motor I built was a 360 for my daily driver. stock pistons, Block surfaced .050 for a zero deck and J heads cut to 64cc with 202 valves 284/484 purple cam. Just cruising I could run regular 91 at the track. Needed better gears and converter in street trim would run 14.2 100-101 mph in a 67 Coronet on Parker Ave.

Here I go. First, Kern, I think your on top of your game. There is no big secret, me and my machinist agree at .050" loosing it and creating detonation. He likes .040", some guys are useing .035"-.025", way too tight for my conservative thinking. I'm working on building a 351 Windsor with my ford son and have learned more about these things than I ever wanted to. Some of the SBF guys are talking they run 10.8-11.2 on pump gas with aluminum heads. Too much compression for me. I have been looking at some Porche sites and guys retarding their cams to bleed off some cylinder pressure have created more detonation.

What I know and have learned is it all boils down to Intake Closing ABDC. So the guys who say they are "getting away with it" just have large duration snotty cams with very late Intake Valve closing.

Do you know what your's is now?

Smaller pistons will tolerate very small quench BIGGER pistons less so .. Then we have computers Knock sensors etc to retard timing

Finding the exact specs of a Mopar Performance cam isn't easy. They march to a different beat, that is for sure. For years they refused to publish anything but the advertised lift and duration numbers. In the late 80s/early 90s they decided totell enthusiasts to muliply the duration x .85 in an effort to pacify the Mopar faithful.
The current MP catalog I read didn't specify which cam on theirlists were their OWN cam or one they get from outside suppliers. I've seen cams with identical specs to several Comp cams that I've been looking at.
One Comp cam guy said that Comp Cams sells a copy of the 292/509 cam and it had an intake closing of 47 degrees @ .050. Info like this is nearly impossible to get from any Mopar Performance source. The site I've used to measure static and dynamic compression requires the intake closing number to be @ .050 PLUS 15 degrees.
This stuff is all very confusing. I am used to working on relatively safe, stock stuff. I've rebuilt several engines, but I am quickly learning that the further you deviate from a stock build, the more stuff you need to learn.

I wasn't really on board with the thinner head gasket idea, that was the suggestion of some other people.
The thicker head gaskets idea : Years ago when I switched to a Comp 285 cam, I also switched to the .060 Cometic gaskets. The car ran great, but now that I think about it, it may have done so despite the gasket change.
The current quench distance is .056.

A member on another forum gave me a suggestion on a cam choice. I will go ahead with the cam swap and see what happens.

I say Go VooDoo or Straightline for a cam...

The cam I picked is a bad mamma-jamma! Lunati Street/Strip solid lifter.
261/271 duration @ .050, .576/.600 lift with a .022 lash. 108 LSA. I also ordered a set of those cool EDM lifters that provide a steady stream of oil from the lifters directly to the cam lobes. I've been nervous about wiping out another cam. I've had some mixed luck with cams in the past, but since I learned about the deficiencies of todays oil, I've had better luck. the '509 in my car has almost 3000 miles on it and it is hanging on.
Since day one I felt that this engine should have made more power. Other builds I read about generated over 500 Hp, some were closer to 600. I had my car on a chassis Dyno after the engine had 700 miles on it. It peaked at 369 at 5400 rpms. Even accounting for the drivetrain losses of 20%, I still only made an estimated 442 HP. I understand that some dynos will test higher than others, but even still...369 HP???
I'd like to REtest the car before changing cams. It would be great to have hard data to show the difference.