I think you're confusing yourself. Any RB based stroker (I'm assuming 4.15 crank/500"?) will make that .509 behave like a stocker. So, at 5" if vaccum you have an issue or two. First, the base timing. Unplug the vacuum pod on the dist, and plug the hose. (we'll get back to which port later) Use the timing light to set the static timing to 15° BTDC. That's usually a good place to start. reset idle speed to below 800rpm. If it wont idle, the mixture screws may be off, or the idle speed screw may be out too far (slower). Get it set to 800 rpm, then re-check the base setting. If it has moved, reset to 15° and tighten. then, using a vacuum gage, adjust the mixture screws to the highest reading, then re-adjust speed, and retune mix, etc. When it's as good as you can get, you can increase the idle if you liek it higher. I dont like them over 900 or so unless the cam forces it. In your case, you should be able to run that thing at 800 with no issues and plenty of vacuum (over 10"). Then, rev the egnie slowly by hand and check the timing at 1500, 2000, 2500, and 3000 rpms. Write them down. It should advance from idle to about 2200 depending on the curve Don installed. If it keeps rising, try going to 3200. The total should be no more than 38°, and frankly, I wouldnt ever run that much in a stroked RB anyway. 32-34 total, without vacuum is the range I look for. If you got it, it's fine. If it's higher, I'd verify it's right by FBO. If it's low, you can add initial to get things right. The vacuum advance is meant (on a mopar) to be run off ported vacuum. Not manifold. Your vaccum can is manifold. If you have a Holley carb, its the nipple on the front metering block, pass side. If it's an edelbrock, it's the port to the pass side, on the front of the carb. If it's a Demon and has the ported vacuum source, it's the rearward port on the pass side of the base plate. If you arent sure, at idle, there wont be any signal present. But as you open the throttle, vacuum will come up on a ported source. I have several 500+ inch engines that develop way over 5" of vacuum at idle, and they have cams about 30% larger than a MP .509. If the cam wasnt degreed, the cam is probably not indexed right. If you cant get things better, take a cylinder pressure reading. If it's low, you found the problem.
Topic: 440 Stroker Issues - Not enough vacuum/ Vacuum advance / ignition (Read 10573 times)
