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WesternRed 
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Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5796 |
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 Posted: Feb/18/2021 at 6:54am |
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After a few weeks off due to starter and COVID issues, finally got back to the track to do a proper test on the new front suspension, good track, got 9 runs in total and overall pretty consistent, which is the name of the game I guess, quick summary below (one run is missing because it pushed over the start line):
Did have a little bit of a play with the shock settings, numbers for compression and rebound above, each had 19 settings, 0 is softest, 18 is hardest and starting off around their suggested settings. Did feel that it was topping out, hence the increase in rebound damping as the night went on. Bit hard to pick much difference in the numbers. No PB's but pretty close on both measures, would probably get there with a little bit better air. |
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I've finally given up drinking for good...........now I only drink for evil.
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WesternRed
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Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5796 |
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Posted: Feb/18/2021 at 4:53pm |
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Well it certainly looks like the suspension is working as intended: At rest:  Launch mode:  |
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I've finally given up drinking for good...........now I only drink for evil.
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WesternRed
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Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5796 |
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Posted: Mar/23/2021 at 7:51am |
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Went out again this week and a bit of inconsistency crept back in due not getting off the line cleanly.
One thing I've noticed is that I'm a little down on RPM, starts breaking down around 6300 RPM, where previously it would push through 6500 if I was a little late on the shift. It's got 180 passes on it now, so I'm wondering if it might be time for some new valve springs, currently running Comp 926-16? Doesn't seem to be any evidence of engine misfiring in the data logs that might indicate an ignition issue. I did initially think that maybe I need to swap the Holley coil driver module out for a CDI box.
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I've finally given up drinking for good...........now I only drink for evil.
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WesternRed
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Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5796 |
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Posted: Apr/01/2021 at 9:36pm |
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No comments on valve spring life? I’ve ordered some new ones, so I guess I’ll find out soon enough. My PB was about 2 years ago and I’ve made quite a few supposedly incremental improvements and so far managed to get to within about a tenth of the PB. Weather conditions also play a big part and heading into the best time of year for that here, cool nights and the chance of sub sea level D/A’s.
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I've finally given up drinking for good...........now I only drink for evil.
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WesternRed
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Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5796 |
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Posted: Apr/17/2021 at 5:14am |
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So while I was in there changing the valve springs I found that a couple of my rocker arms were falling off the valve tips and running around on the retainer as discussed elsewhere:
 After messing around trying to get the factory stamped rockers to work properly without success, I gave up and installed the spare set of Harland Sharp 1.7 rockers that I had tucked away:  I was a bit reluctant to use these as it was already pretty tight on piston to valve clearance and now with the 1.7 rockers it has 0.045" @ 7 deg ATDC on the intake and 0.077" @ 7 deg BTDC on the exhaust, not much room for error. I did manage to run a new PB with the new rockers and springs:  Previous PB was 11.74 and basically it has picked up 0.02 on the 60' and 0.07 by 330' which it carried to the end of the track. Conditions were pretty good, D/A 598 ft and 72 deg, so that probably helped. I did think I had broken it on the following run, but it turned out to have just blown one of the header gaskets, which was a relief. So the outcome of all of this is that the new valve springs didn't really resolve the problem I was having in the first lace and the old ones actually tested up pretty much the same as the new ones. It still seems to be laying over at higher RPM, having a bit of a flutter, which is why I thought the valve springs might be getting tired. In the past, it used to cross the line at 6400 rpm and I thought maybe I was pushing it a bit too hard so I changed from a 26" slick to a 28" drag radial to bring the terminal RPM down a touch and it now crosses the line around 6200. This is the data log from the PB run:  What I find interesting is the fuel flow (bottom red line) seems to peak maybe 2/3 of the way through top gear and then drops away, which seems odd. The AFR and MAP doesn't really change, but maybe gets a little more erratic. I am wondering if the ignition system is just running our of steam as it just doesn't seem to want to rev much past 6200 even in the lower gears. I did install the Holley Hyperspark distributor before this season and I am running the coil driver module, which isn't much to look at, previously it had a Pertronix module in a factory distributor. Holley makes a nice HEI box to go with the Hyperspark system and I'm wondering if this might help. I've also got some new plugs to stick in. |
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I've finally given up drinking for good...........now I only drink for evil.
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WesternRed
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Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5796 |
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Posted: Apr/17/2021 at 6:47am |
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Maybe a little more info, here is some other data from the same run:
 It seems that the closed loop compensation is kicking in about the same time the fuel flow rate heads south, might be that it just hasn't learnt this part of the fuel table well enough yet?
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I've finally given up drinking for good...........now I only drink for evil.
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WesternRed
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Posted: Apr/19/2021 at 7:19am |
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So it turns out Inductive Delay is a thing, who would have guessed, timing was about 8-10 degrees short or target at higher RPM, settled on a final value of 170 usec after a bit of trial and error. So is there a logical reason that insufficient timing would make it think it is running rich and start to pull fuel out to compensate? Does anybody think 38 degrees total is too much advance?
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I've finally given up drinking for good...........now I only drink for evil.
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PROSTOCKTOM
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Joined: Jun/20/2010 Location: Indiana Status: Online Points: 2450 |
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Posted: Apr/19/2021 at 8:21am |
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Tom
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Molnar Technologies Full Service Dealer - Crankshafts & Connecting Rods
1969 AMC Rambler Rouge Race Car 1974 AMC Hornet Hatchback, Wally Booth Outlaw Nostalgic Pro Stock Race Car Project |
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DragRacingSpirit
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Joined: May/27/2009 Location: Mo Status: Offline Points: 903 |
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Posted: Apr/19/2021 at 3:19pm |
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What he said
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Best 1/4 mile 8.99, 1/8 mile 5.71, 60 foot 1.27, no power adders
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WesternRed
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Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5796 |
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Posted: Apr/19/2021 at 5:19pm |
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I'm not sure why I overlooked the inductive delay on the Hyperspark setup as it's obviously a critical parameter that is required to sync the timing across the entire rev range. It's like I have been running with a high RPM timing retard, which has to be killing top end power no wonder it is lay over at the top end of the track.
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I've finally given up drinking for good...........now I only drink for evil.
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WesternRed wrote: