I plan to run the same cam that was in the 505, now with lower compression pistons. The problem still leads me to think I got a tank of 87 octane out of the 91 pump. I wish there was a way to test the octane level of the fuel in the tank now.
210 to 215 is a 93 octane range in a 505. Judging by those compression numbers and the .050” cams specs I am going to guess that is a custom XFI HR cam. If that is correct, those cams are very aggressive off the seat and pump a lot of compression for there size. The 240 heads have very efficient ports, if you keep with that cam (and I am correct on which cam it is) in a 505, the compression needs to be dropped to 9.4 to 9.6 for 91. The TF240s are very efficient ports, with that cam, I doubt you will even miss the compression with your 505.
I'm a novice at all of this and learning as I go. The carbon build up is something I often forget. If the motor is tuned well and no detonation or pinging, I suppose with miles over time there will still be carbon build up? I just looked back at my records and my 10.2:1 motor with aluminum heads measured 175psi cranking pressure. On the edge? I was hoping for 100K miles out of the motor, which is why I did a milder build. Maybe wishful thinking...
You can run in the 12's with a near stock engine. You can run in the 11's with a moderately modified 440. I'm not trying to be demeaning and it's your car and money, but sometimes we don't work as smart as we should on a dual purpose car. Anyhow, i wish you the best!
175psi isn't a killer. Carbon build up with a poor tune up can be be. Poor assembly technique is usually swept under the rug. Poor parts combo is a killer. Doing your homework leads to longevity.
the good thing with my motor is that it was assembled by one of the most knowledgeable and experienced mopar engine builders I've met and he's a personal friend. It's on me for selecting the pistons ahead of the cam instead of the other way around.
Pistons need to match the combustion more so than the cam match the pistons. The top of the piston is the floor of the combustion chamber. This must match up for the engines intended use.the good thing with my motor is that it was assembled by one of the most knowledgeable and experienced mopar engine builders I've met and he's a personal friend. It's on me for selecting the pistons ahead of the cam instead of the other way around.
to the OP - hoping your motor rebuild goes well and your car is on the road again soon
I see people doing that, running in the 12's with mild cars. The vast majority of them are running high 13 low 14 on stock 440's. It is much easier to do with an automatic. I could never master the clutch with the 505. Stock clutch was a smoke show. I put in a dual friction clutch which was all off or all on. At the line one of three things would happen. Imediately blow of the tires letting the clutch out 3000 rpm. Slip the clutch more to not blow off the tires and leave slower and while smoke the clutch. Or blow off the tires at the 1 to 2 when I lay in to it. 12.8 was with slicks which did launch better. But dumping the clutch at higher rpm just blew off the slicks or bogged the engine. And they did a nice smoky 2nd gear burnout in the water box.
When i was younger i was a die hard 4spd guy. One of the secrets to feathering the clutch is the disc. The thinner the wafer spring between the front and back of the disc the gentler the engagement. Performance or race discs usually don't have the kind of flat spring that is condusive to gentle starts. But, it does boil down to what are you going to do with 600+lbsft of torgue and will you manage it. Control the torque and then the body starts tearing. Almost like a dog chasing it's tail.
BSB67 did. I could have but lost patience. It's very doable with no lumpy cams, loose converters, big tires, headers/open exhaust.
Definitely an area of personal opinion. If i was given a bone stock 78 new yorker mill( meaning longblock w/o cam) I'll show you a 12. Yes that would include a 280-290 cam, intake and headers. Good gears, decent converter and tires that stick obviously. We already know these cars run 14s if everything is as produced.
