Agreed, the NASCAR guys get between 4-6 MPG running WOT... Depends on track and whether they are choking them with restrictor plates... Now in NHRA Top Fuel/Funny Car it's a different story, try something like 40 gallons per mile... That's right, with burn out included, TF & FC use somewhere around 10-12 gallons per run(well maybe a little less now that they've shortened the distance to 1000ft for these cars)...
Ok Gotcha, However have the same issue again, lifter knock, I just don't get it. What is going on that I get them set and it sounds great, runs great albeit for not long and now I'm back to lifter knocking just as bad as it was before or maybe even louder. Something is going on and I don't get it, IM14 or anybody, what the heck is going on? and FYI the motor doesn't smoke a bit, sounds strong, after warming her up I stomped the pedal a couple times sending the needle into the 6k + area and of course I don't know if they quit knocking because the exhaust is so dang loud but I doubt it, I'm sure they are knocking and it also is not running like it did just the other night after I adjusted them and all the knock was gone.
Free reving an engine will kill valve springs and valves, stop doing that! You need a mechanic's stethoscope. You need to see what cylinder/valve starts ticking. Without hearing it, my guess is you have a cam lobe gone and it takes a few miles to wear that little bit more to start tapping again after you adjust things, and the free reving (engine not under load) is accelerating the problem. SPark
Ok Yeah I'm thinking cam lobe also, in the case of free reving, I rarely ever do that however it's because it's pointless mostly but please explain how free reving is hard on a engine that has been brought to operating temp, has good oil pressure and not pushing it past it's mechanical limits, i.e. floating valves etc.? I am asking this question seriously not arrogantly, I have seen guys fire up their car and immediately rev it while it's cold and the oil pressure and temp hasn't even had a chance to stabilize and obviously that is just stooopid but warmed up and good pressure I don't get it?
nevermind Don't bother to answer, as I played it out in my head what is taking place internally, with no load the possibility of the motor actually revving past a safe zone as the tach not actually indicating just how many rpm's really turned due to electrical circuit speed although minor I see how it could pass the safe limit and the hotter the engine power wise the worse it could be......at least that is what I envision, lol
its bad because your engine is not under load, 6 grand in park, is too much, do a compression test, and a vaccuum test, but my guess is a worn cam lobe,
Proper warm up is critical to prolonging engine life and how you treat them during that time does have major impact over the long run. They are predetermined to last xx amount of time and anything you do to accelerate wear obviously shortens that lifespan to some degree. But.. how much lifespan is long enough when correlated alongside the "fun factor"? As power levels climb along with rpm.. engines don't live as long and that's fully accepted by most as par for the course. Aside from many hardcore racers.. I've likely beaten the snot outta more cars than most on this forum and I fully accept slight reductions in lifespan while enjoying the occasional rev contest at lights or at the track. Experience tells us that it;s far easier to use up an engine under load than it is without one and makes complete sense when the physics involved are heavily explored. Maybe ask yourself a few questions before fully forming an opinion on the matter. Do racecars free rev their engines? Do ALL those same cars have mandated tear down because of the added free rev's? Are they able to do it without "breaking or prematurely wearing out" because their parts are so much better/more durable thsn the factory style junk? What happens to an engines reciprocating mass during high-rpm shifts in heavy cars with wide ratio trans/tall gears? Sudden rpm changes can be noticeably more abrupt at that moment than most others when you factor in the time involved. It's like this. Yes some stresses can be exaggerated during free revs.. trans brake launches, improper burnout procedures, spinning tires hard from dirt onto tire grabbing pavement etc. You must imagine the differences between an unloaded and loaded engine to really break it all down. Timing chain stretch/gear wear? Lobe and lifter wear associated with increased velocities/sudden velocity change caused by abrupt "on and off the gas" throttling? Rockers, valve stems/guides, and tip wear? Disty and cam gear? Oil pump/drive shaft? Increased potential for no-load ring flutter? Then there's added stress on the auto transmission to worry about(throwout bearings can be affected too, especially when holding in the clutch). Excessively free revving an engine is tougher on the front pump and gets progressively worse the faster the engine can rev and come back down to idle. In the end.. I definately wouldn't say it's "good for an engine".. but I would also point out that nearly every engine failure I've seen through the years, mine included, occurs during engine loading/unloading. That should give us a bit of insight into the potential for engine damage during free rev.
Engine failure in circle track cars is usually in the unload phase of a lap. Going into a corner will usually blow up the engine, not coming off the corner. You've unloaded the engine in direction "A" (acceleration) and immediately loaded it in direction "B" (deceleration). In drag racing, many will kick the car out of gear after a run and let the engine coast down independent of the car. They get no braking force from the engine. They also don't load the engine in the opposite direction like circle track guys do lap after lap when doing it this way. From my experiences, you will see exaggerated valvetrain wear on the spring retainers, the timing set, lifters and push rods when free reving an engine excessively. I am not opposed to free reving an engine to 3000-4000 or so, you need to when checking throttle response, timing curves and the like. What kills them is red line stuff. The engine accelerates so quickly and then decelerates so quickly you place additional stresses on engine parts that change direction (valves, rods, pistons, rockers, etc). I usually see valves pulled thru retainers as the number one culprit. My opinion, your mileage may vary, SPark
Thanks Thanks for all the input, however I have finally identified the problem, wiped cam lobe and/or lifter, probably both. As I would adjust the rocker until ticking was gone then run motor just a bit ticking came back, adjust it again until gone, run a min ticking back. It became very obvious as the poly lock on that rocker was getting to where it was almost out of thread to tighten into before locking down hence the rocker was moving lower and lower, could look down the row of 8 rockers and all poly locks had maybe 2-3 threads above nut but one, the bad one had almost all of the poly lock sticking out when fully tightened, in fact if I had adjusted it down one more time I don't know if there would have been any thread left to tighten. Sooooooooooooo, guess what time it is? time to pull the lifters and cam, inspect and hope cam bearings are still in good condition and install new cam and lifters and (use break in oil with plenty zinc) while making sure they are rotating in their housing, if the lower end or cam bearings are worn it's going to become a 331
Ouch!.. that's what we were afraid of.. sorry to hear that. Word of caution here. If you repeatedly cinched up the rockers and continued to eat metal along the way.. that motor likely has a lot of trash in its oil pump, galleys, and bearings. Especially if you were out and about cranking on it like you mentioned earlier. I myself wouldn't even plan on dumping money into it unless it's completely torn down and properly cleaned up(hot tanked). Obviously at that point.. if you want to warm it up even more?.. you'll be into some more time and cash to do it. Good luck with it and keep us posted.
