My motor is running rough at higher rpm,s (2000-4500ish). When its in neutral it runs good, it misses a little but when there is a load on it (driving it) it runs a lot rougher. you can hear a misfire and feel a bad vibration. im thinking vacuum advance is not working correctly but i don,t know how to check it. any other suggestions or advice would be greatly appreciated. Motor Info 302 .060 over KB Pistons 10.7to1 Compression Comp Cam Big Muther Thumper Cam .491 .476 Lift 107 deg Comp Cam Lifters, Push Rods, Magnum Steel Roller Rocker Arms Prostar Aluminum heads Weiand Stealth Intake Holley Street Avenger 670cfm Vacuum Secondary GM Style HE Distributor 2Hrs of run time on fresh rebuild On a side note. this forum has been fantastic, you guys have been great and have a vast knowledge on mavericks,always polite and have helped us out immensely. hopefully we can get this running so we can get to the roundup and put some faces to the names
Yes flat hydraulic lifters, i used the comp cam's break in additive and followed the break in procedure. im going to pull the valve covers today and check things out, see if there is something noticeably wrong, i don't here anything but im going to check anyway
disconnect the vaccum pot completely..plug the hose.. and see what it does. You may have the carb misadjusted and/or the ignition advance curve may be such that it's causing a lean misfire. Adding advance from the pot may just be adding insult to injury at this point. What is the initial advance set to right now? Does that carb(new or used?) have power vavlve blowout protection built in?
I always go so far as to pull lifters and check out the current mating between the cam/lifter lobe just to be sure as well. Even the slightest galling now.. can rear its ugly head many hundreds of miles later on when you are floating on the cloud of success. Metal flakes in the oil can wipe the whole motor and make you wish you had double checked surface run in. Even just thinking about this stuff makes me happy I only run full rollers on everything these days.
well ill have to continue the diagnosis in a day ou two, I was driving it to the alignment shop,after about 10 mi. the fuel pump died, its been acting up for a few days,now im thinking low fule pressure might be the culprit...LOL
