70 dart 470 ci drag car build.

MOPARMAGA said
We did some testing today again and besides having to find 40 HP that was lost, it was found again at 14 ° initial timing. We backed it up 2 degrees per test from 22. We made back to back 660 HP runs then before we made any changes we unhooked the Dyno exhaust and it picked up 15 HP and 10 ft lbs.
The Dyno exhaust is 5 inch by 12 feet long and big 5 inch semi truck mufflers ..

The exhaust test is Interesting.
When speaking about timing numbers I have found that it is helpful if you include the rpm that the timing was measured at and if the distributor is locked or unlocked. I'm not trying to tell you how you should do it but I'll give you my 2 cents on how I do it. I'm probably telling you what you already know.
When dynoing with locked distributors I noticed that often the timing doesn't stay the same throughout the rpm range. They back up with rpm, some worse than others. If for example you set the timing on a locked distributor at 2000 rpm to 34 degrees, when the motor is revved to 6000rpm the timing might back up to 28 degrees. So when the customer ask me what he should set his timing at do I tell him 34 or 28? Most customers think that a locked distributor doesn't change with rpm.
What I thought would work best for me and my customers is to specify at what rpm the timing should be set at. I was doing alot of 602 crate motors for circle track customers so I'll use these as an example. The first thing was to figure out the rpm range that was most important to have the timing correct. I figured these motor spend most of there time in about a 2200 rpm range. These motors are chipped at 6200 rpm so that sets the top of the working range. That makes the bottom 4000. So I round the middle of the opperating range to 5000 rpm. This means that I use 5000rpm as my timing rpm. I will sweep the timing on the motor to find best average power in the working range from 4000 to 6200 using 5000 rpm as my timing rpm. When I find the number that makes the best average power I tell my customer to set his timing to 35 degrees @ 5000 rpm, as an example. Doing it this way minimizes the effects of the timing variation through the rpm range. Even if the distributor is unlocked this method works pretty good for me. I'm not saying that timing at other rpms should be ignored but this keeps it simple for my customers.
Before I start I will also check tdc and correct the mark if necessary on each motor. Then I will mark the balancer in degrees. After I do the timing sweep I will mark the zero on the tab and the balancer with a paint marker and write the number next to the line so it cant be confused with tdc. I tell my customer if he has a dial back light to set it to zero. With the motor warmed up rev it to 5000 rpm and make sure the paint marks are lined up. When I mark the balancer I extend the line across the front crossing the elastomer strip to the center hub. This makes it easy to verify that the balancer has not slipped when setting timing.
Crap! I made this way too long. Sorry.