Aussie Gremlin

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   Back to the track last night with the new timing settings, did run a PB of 115.03 mph on the first run, which is about 1-2 mph more than usual although had traction issues all night, so didn't improve the ET at all. I think I may have suffered from brain fade and completely messed up the front shock settings in that regard.
I still feel that it is behaving like having a rev limiter set at 6,200 rpm, because it just doesn't seem to want to rev past that point and it does feel like it it breaking down. At this point I've changed valve springs, rocker arms and fixed an obvious issue with the timing curve, so I'm a bit stumped. Plugs, leads, ignition module (Holley coil driver) perhaps?

Tempted to pull the Hyperspark distributor out and put the old Pertronix one back in just to eliminate that possibility.

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WesternRed Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5799	Post Options Post Reply Quote WesternRed Report Post Thanks(0) Quote Reply Posted: May/07/2021 at 10:09pm
	Back to the track last night with the new timing settings, did run a PB of 115.03 mph on the first run, which is about 1-2 mph more than usual although had traction issues all night, so didn't improve the ET at all. I think I may have suffered from brain fade and completely messed up the front shock settings in that regard. I still feel that it is behaving like having a rev limiter set at 6,200 rpm, because it just doesn't seem to want to rev past that point and it does feel like it it breaking down. At this point I've changed valve springs, rocker arms and fixed an obvious issue with the timing curve, so I'm a bit stumped. Plugs, leads, ignition module (Holley coil driver) perhaps? Tempted to pull the Hyperspark distributor out and put the old Pertronix one back in just to eliminate that possibility.
	I've finally given up drinking for good...........now I only drink for evil.

WesternRed Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5799	Post Options Post Reply Quote WesternRed Report Post Thanks(0) Quote Reply Posted: May/09/2021 at 5:38pm
	Plan B, ditch the coil driver module, I have ordered the Sniper CDI box and coil, hopefully that sorts it out.
	I've finally given up drinking for good...........now I only drink for evil.

WesternRed Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5799	Post Options Post Reply Quote WesternRed Report Post Thanks(0) Quote Reply Posted: May/12/2021 at 5:14pm
	I'm still not convinced that the coil driver is completely at fault here, but it is time to do some more wiring:
	I've finally given up drinking for good...........now I only drink for evil.

WesternRed Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5799	Post Options Post Reply Quote WesternRed Report Post Thanks(0) Quote Reply Posted: May/21/2021 at 12:40am
	So I got the CDI box and coil installed, finalised the setup in the ECU and fixed the distributor reference angle, which was set incorrectly. Hit the track on on Wednesday night and with some good air managed some quick runs, several 11.7's, but didn't quite beat the 11.6 from a couple of weeks ago. Guess what, the rev limitation is still there, it just won't go past 6,200 RPM. So clearly the coil driver wasn't the issue and the nice new fancy pants CDI ignition wasn't the answer. Looks like I'm back to the drawing board, the Holley forum isn't helping much either, but I do have a couple more things to try in the setup. On one of the burnouts, I had it nailed and the RPM actually flatlined at 6,200 so it really is just like having a rev limiter set at that point (it's actually set at 6,500). One of the things to try will be setting the limit much higher to eliminate the possibility that it might be coming in early. I'm struggling to think that any mechanical issue like floating the valves would be so consistent, but I may be wrong?
	I've finally given up drinking for good...........now I only drink for evil.

Dave Z Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Nut Joined: Jul/02/2007 Location: Massachusetts Status: Offline Points: 300	Post Options Post Reply Quote Dave Z Report Post Thanks(0) Quote Reply Posted: May/21/2021 at 3:28am
	We had been fighting the same problem with one of our cars. I'm convinced now that it's the lifters. Dave Z

WesternRed Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5799	Post Options Post Reply Quote WesternRed Report Post Thanks(0) Quote Reply Posted: May/21/2021 at 3:30am
	Could be time to go solid.
	I've finally given up drinking for good...........now I only drink for evil.

WesternRed Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5799	Post Options Post Reply Quote WesternRed Report Post Thanks(0) Quote Reply Posted: May/21/2021 at 8:22pm
	Maybe this is telling me something: As the RPM flattens out at the top end of the run, the MAP signal also starts jumping around, particularly with spikes on the high side. If say the lifters were pumping up due to valve float and holding the valves open a little longer, you might start to see the pistons pumping air back into the intake. The ECU also seems to be pulling fuel out but the AFR remains relatively steady. Bit more data from the same run, you can clearly see the fuel flow drop off at the end of the run: I have learnt that I will need to do some work on the target AFR table within the system as I am currently running the simple setup option, which is causing the target to jump around with small changes in the MAP value.
	I've finally given up drinking for good...........now I only drink for evil.

WesternRed Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5799	Post Options Post Reply Quote WesternRed Report Post Thanks(0) Quote Reply Posted: May/24/2021 at 9:32pm
	I have determined that even with the new valve springs, I only have 82 lbs on the seat and 310 lbs open at 0.542” lift, might explain a little bit of valve float at 6200 rpm. Edited by WesternRed - May/26/2021 at 5:07pm
	I've finally given up drinking for good...........now I only drink for evil.

WesternRed Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5799	Post Options Post Reply Quote WesternRed Report Post Thanks(0) Quote Reply Posted: May/26/2021 at 5:15pm
	So I happened to have a set of 0.065" valve spring shims laying around, stuck them in to give me an extra 27 lbs of spring pressure now 113 lbs on the seat and 341 lbs open. Turns out that is worth an extra 200 RPM or so before I get valve float and it ran a new PB straight off the trailer, although only but 0.005 sec. Did run a string of 11.6 passes on the night cumulating with 11.606, mph was up 1-2 as well all helped along by some great air on the night. It was great to finish our season on a high, now I have until September to do some work on the car.
	I've finally given up drinking for good...........now I only drink for evil.

1982AMCConcord Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jul/13/2012 Location: Kenosha, WI Status: Offline Points: 1287	Post Options Post Reply Quote 1982AMCConcord Report Post Thanks(0) Quote Reply Posted: Jun/01/2021 at 10:28pm
	That's fantastic Darren! Glad to see the shims helped! I've really enjoyed seeing you push the Grem Puppy further with every little change. Congrats on finishing the season strong. Looking forward to seeing the work you do in the off season.