![]() ![]() How did you get your cylinder pressures? how specifically did you test it? I ask, because anything near or over 200 really needs serious octane. its not hard, its just following specific steps. PLUS a further 10 degrees from the vacuum advance mechanism, making a total timing of 46 degrees for me. your MSD has this same capability if needed. To exploit this leaner condition, the vacuum advance mechanism "adds timing." Typically, most small-block Ford engines with a compression ratio of 9.5:1 will, in most cases, respond well to 36 degrees of ignition timing (initial timing plus the mechanical advance) many of us well above the standard 10 or 12 initial, I think I ended up with 18 on my 427 stroker - I just had to limit my mechanical advance to 18 as well for a total of 36. In addition, the scavenge effect in the exhaust port needed to expel the spent exhaust gases from the combustion chamber dilutes the oxygen levels with unburned fuel and slows the burn rate. These leaner, low-load mixtures are the result of slower air velocities, which cause lower volumetric efficiencies (poorer cylinder filling). Leaner air/fuel mixtures, those that occur during idle and light throttle loadings, have a shorter burn time than rich air/fuel mixtures. While cruising at light throttle loads, igniting the charge early is exactly what occurs on a fuel-efficient hot rod with vacuum advance ignition timing. The mechanical advance involves some springs (magic!) I never have messed with. Or if your distributor is jumping still with the vacuum advance unplugged. Don't get stranded!īy doing this you should get a chance to see if your vacuum advance is doing something strange. Beware if your timing gets advanced it may be difficult to start your car. Trying a few degrees here or there is entertaining though. To really fine tune it I believe a vacuum gauge is best. Drive the car a little and see how it does. If your idle goes to 800 or 900 rpms I wouldn't worry about it. Your timing will probably bump up a little. Rev the engine and see if the mechanical advance built into your distributor raises the timing into the mid 30's eventually Unplug the vacuum advance and plug the vacuum port or line Let me know if I skip any steps or do things wrong myself. Guys, I am not a pro by any means but maybe the way I don't do this all the time makes me think about the individual steps. I really think the first thing to do is set the timing to a normal level then make adjustments. If the car turns over more slowly when it is hot, reduce the idle timing by 3 more degrees. if it pings it may have too much total timing or total timing may be coming in too soon. Tell us what rpm total timing is reached.ĭrive car. Retard the timing by 3 degrees from this point. With the engine running and warm, advance the distributor until it stops building rpms or starts to run slightly rough. I would plug the vacuum advance and leave it plugged for now. if your converter is stock then run a 2400 with these and your tires will roast and these are not real huge cams but they are pretty stout. With your set up i would look at an xe274h or 270h. ![]() ![]() it is a crime to even advertise a cam that small as a "performance" cam. Your car will never feel fast with that cam because it is so small so timing will not improve it much. I would run a slightly cold plug with that much compression. "I have to roll on the throttle to get the car to move out without incident." Sorry to hear about your sluggish performance. Is my distributor f'd, any thoughts as to what the problem might be? This retard behaviour seem to happen more at 10 to 12 degs, with the initial timing set higher at 18 or so the advance seems to pickup off of idle more constantly when throttle is applied? The distributor does not seem to alway settle back down to initial timing setting and the initial timing retards to almost Zero degs when a little bit of throttle is added for a couple of seconds then the timing advance curve kicks back in then it proceeds to stop retarding timing and starts advancing. I backed down the initial timing about 13 degs and 34 total. Total timing was about 40deg at about 4000ish rpm. When I check initial timing with my light it checked in at about 18deg idle. Roller Cam Crane Cams rocker Arms 3 11746 030 over, not exactly sure on compressionĮdelbrock camshaft # 2182 204° / 214°. All cylinder pressure measured between 180-200psi on a cranking compression test. I had a shop do a compression test a couple of months ago. Sluggish in lower RPMs, seems like I have to roll on the throttle to get the car to move out without incident. The car does not seem to be performing to it capabilities. I have a mildly built 351w that I wanted to adjust timing on. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |