The saga continues.
Just in case some of you are JUST tuning in, THIS engine is the first stroked big block that I have ever had. I've built 3 Mopar big blocks, 5 360s and numerous Chevy small blocks. I understand the basics and can fumble my way through a stock or mild engine build. Over the years I have read a lot and learned a few things, but THIS engine has taken me to a new level.
In 2003 I took a high mileage 440 from a 76 Coronet Police car and bored it .030, added the TRW six pack pistons and these very same Edelbrock aluminum heads. I had the 284/484 MP cam. That car was a screamer with 3.91 gears. Unfortunately it broke the #4 rod at 846 miles. I was pissed and figured that if I was going to build another engine, I was going to use NEW rods. What the heck, why not go with a longer stroke too?
If I were to have the engine apart right this moment, I'd probably use a moderate dished piston to get me into the 9.5 to 9.75 range of compression to allow the use of mid grade fuel if necessary. The milder ratio would also be more forgiving in terms of cam selection. Up until a month ago, I wasn't aware that the camshaft had that much effect on "dynamic" compression. I had heard of the term (Dynamic comp) but since all of my previous builds were so mild, the issue never came up. Now that I have an engine that runs beyond the limits of pump gas, I am forced to learn how to deal with it all.
There have been some great posts and responses here, and I want everyone to trust that I have read through them all several times. I didn't want to be the type of guy that drops off his car at a shop and has all the work done for him. I am interested in improving my skills so that I can avoid similar mistakes in the future.
The specs for the cams on the market can be confusing to me. In the 80s when I first started driving and reading car magazines, all I would hear is LIFT and DURATION. Over the years I've seen split pattern cams, LSA, Intake centerline, Duration @ .006, Duration @ .050, Intake closing point....Maybe all this stuff was out there before but only the hardcore racers had access to the info. Today these numbers are more easily found. The problem is, sometimes TOO much information can make the situation ever harder to understand.
Case in point: MOST that mentioned my need for a bigger cam believe that a later intake closing is a possible fix. Fantastic! Now I just needed to know what the intake closing point of the '509 cam so I could compare it to the new cams. Finding specs like this for the MP 509 wasn't easy. maybe I'd need to physically open a box with THAT cam in it and look for a cam card? The MP catalog leaves that info out. Their website doesn't list the intake closing. Member 273 accessed a dyno program that showed an intake closing of 58 degrees @ .050, and while I appreciate the help, I am curious if it is correct. I just spoke with William at Comp Cams and he said that the Comp copy of the MP '509 had an intake closing of 47 degrees @ .050. He said it was an exact copy, so I'd guess all the specs were carried over? The Comp XE294 is the largest Hydraulic flat tappet cam they offer in the Extreme Energy line. It shows a duration of 250/256 @ .050, a .519/.524 lift with 1.5 rockers ( I have 1.6 rockers, pushing lift to .553/.558) and a 110 centerline. The intake closing is 51 degrees @ .050, 73 degrees @.006.
Some members have mentioned that my .056 quench distance is too wide to be effective. They said a thicker head gasket would NOT hurt quench since I'm already out of the effective range anyway. I tend to believe this for a couple of reasons. 1) The 383 and 440 Magnum used open chambered iron heads with 10.0 compression and ran on premium fuel. ZERO quench in those engines. Mine could have 10.27 with .060 Cometic gaskets or 10.45 with the MUCH cheaper .051 composition gaskets. Either will push the quench distance past .068, which is still less distance than a stock 440 Magnum. 2) I actually did try using .060 Cometic MLS gaskets in 2006 when I ran a Comp 285 cam. The engine ran great but wiped a lobe before the warmer weather came along. Hard to know how it would have ran in 100 degree temps.
For now I am leaning toward the Comp XE294 cam and a pair of the .051 gaskets. Sorta like I did before, but this time a bigger cam and a thicker head gasket that isn't quite as thick as the Cometics....
I'll surely report back with the results. Thanks everyone!