Re: Cam break in is done!....Now more questions!
[Re: Kern Dog]
#1492884
09/03/13 03:17 PM
09/03/13 03:17 PM
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Joined: Mar 2008
Posts: 5,746 Ontario, Canada
Dodgem
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master
Joined: Mar 2008
Posts: 5,746
Ontario, Canada
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Just a faster curve on the 14 advance with lighter springs will hold it off the stop so say idling in gear at 28 (so 9 mechanical advance in) with another 5 mechanical advance to go as rpm comes up. without driving you can test how it will respond to more in gear idle advance by advancing it till you have 28 in gear and fiddle with idle see how it likes it I know this would be 42 total but at this point your not driving just finding a nice idle. Then you tailor you advance springs to get it to idle at that advance but still have your 33 to 36 total.
Last edited by Dodgem; 09/03/13 03:26 PM.
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Re: Cam break in is done!....Now more questions!
[Re: Kern Dog]
#1492886
09/03/13 03:26 PM
09/03/13 03:26 PM
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Joined: Mar 2008
Posts: 5,746 Ontario, Canada
Dodgem
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master
Joined: Mar 2008
Posts: 5,746
Ontario, Canada
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Just a faster curve with lighter springs will hold it off the stop so say idling in gear at 28 (so 9 mechanical advance in) with another 5 mechanical advance to go as rpm comes up. without driving you can test how it will respond to more in gear idle advance by advancing it till you have 28 in gear and fiddle with idle see how it likes it I know this would be 42 total but at this point your not driving just finding a nice idle. Then you tailor you advance springs to get it to idle at that advance but still have your 33 to 36 total.
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Re: Cam break in is done!....Now more questions!
[Re: Kern Dog]
#1492888
09/03/13 04:09 PM
09/03/13 04:09 PM
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Joined: Mar 2008
Posts: 5,746 Ontario, Canada
Dodgem
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Ontario, Canada
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At present you may (probably) not getting any advance at idle just what you set to. It takes more RPM's to start stretching the stiff springs to get some of that 14 mechanical advance. But put lighter springs in and idle rpm should be enough to allow some stretch and some mechanical advance. so say if you put the lightest springs in that came with your dizzy 950 rpm may allow dizzy to advance lets say 8 deg so that will give you 19 + 8 = 27 advance at 950 instead of it sitting at 19 total in both cases is still 33. so one light spring may do it maybe needs too it's trial and error. But as i said you can at idle turn dizzy till you get say 27 then mess with idle if it's good then tailor your advance springs to get you there after turning dizzy back to where it was.
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Re: Cam break in is done!....Now more questions!
[Re: Kern Dog]
#1492890
09/03/13 05:02 PM
09/03/13 05:02 PM
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Joined: Jan 2003
Posts: 5,444 Indiana
YO7_A66
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Indiana
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""It was running PIG rich in gear!"" On your next drive, after the engine is up to running temp, find a quiet parking spot and apply your emergency brake (or have a friend apply the brake) with the tranny in D. Then spend some time tuning your metering screws to achieve the highest vacuum reading while readjusting your idle after each adjustment (if needed). You should be able to tune it in D (13's or so) if you have enough initial timing.
"" It was dropping in the 11.0 range but it was still pinging."" Was it pinging while showing 11.0 or did it ping under accel before it hit 11.0?
What was your leanest reading while you were out driving?
1970 YO7 A66 [Canadian Export] F8 Challenger 340 (Currently in shop for stroker assy.)
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Re: Cam break in is done!....Now more questions!
[Re: Kern Dog]
#1492891
09/03/13 06:54 PM
09/03/13 06:54 PM
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Joined: Jul 2007
Posts: 1,526 North Carolina
cjskotni
pro stock
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pro stock
Joined: Jul 2007
Posts: 1,526
North Carolina
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Quote:
Thanks, Dodgem.
I just drove the car after putting the air cleaner on. It was running PIG rich in gear! It was dropping in the 11.0 range but it was still pinging. Huh? I expected the addition of the air cleaner to richen it up some, but now it looks like I'll have to go back at least 4 jet sizes to get close. I'm amazed though that it still pinged. I would think that an over-rich condition would have stopped that by a longshot. I'm going to pull a plug and check the cranking compression. Before the cam swap, I was at 185-192. This cam has a later intake closing, so I really expected it to reduce cylinder pressure so it would NOT detonate given the same tune as with the '509 cam.
I am not surprised that you may need to jet down some as you are 4 jet sizes over what I am running on my 500 stroker. However, I wouldn't worry too much about the carburetor tuning yet.
As mentioned before, you need to get your base timing down. I would give it as much base timing as possible before you start getting the kick back on the starter and then back off a degree or two. This should also yield a higher vacuum reading at idle which you will want to maximize. Once you do that, you then need to set the idle screws (also for max vacuum). Then set curb idle...probably relatively high for the cam you have...maybe 900-1100 RPM's or so?
Next you can deal with the jets and use your sensor to nail down the optimum size(s) to use. My dyno guy seemed to like to see around 13 or so under WOT...closer to 14-14.5 under lighter load.
I am guessing that you may still have the pinging problem and this may take some experimenting to fix. You may have some cooling issues from earlier posts...fix them so the engine is running <195* or so. You should be able to get that motor to advance to 34* or so without pinging...if not you may need to think about better fuel. Yeah you can dial back the total timing to keep it under 30* but this seems to be a band-aid and not a true 'fix'. You may find you will need to blend in some race fuel to get her happy. :-(
Either way, I wouldn't want to dial the timing way back which affects vacuum and how well the engine runs just to avoid the pinging if a gallon or two of race fuel per tank might fix ya!
Otherwise, you ma look into a thicker head gasket and see if you can shave a little off the compression but I think the engine temperatures being kept in check will go a long way here.
Does the motor still die after 15 minutes or is that been fixed? You had some other issues I seem to recall....
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Re: Cam break in is done!....Now more questions!
[Re: cjskotni]
#1492892
09/03/13 09:43 PM
09/03/13 09:43 PM
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Joined: Feb 2010
Posts: 18,493 Granite Bay CA
Kern Dog
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Striving for excellence
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Striving for excellence
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Posts: 18,493
Granite Bay CA
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The closer I get, the further away I am.
Earlier I wrote that after the cleaning of the air bleeds and the UPjetting to #90 primaries, I was running waaay rich. It still pinged. I didn't run it to full throttle to see the A/F readings because of the pinging. It wasn't rattling nearly as bad as it has in the past, but it was there. I came back and went back to the #88 jets. The A/F numbers leaned out a bit but it was still rich under load around 12.5 to 13.5. It still pinged as well. The opinions I get on this brand of carburetor range from either guys with no comment to guys saying they are junk. Almost everyone that complained about them says they picked up speed and reliability with a Holley. Tomorrow I'll put my 750 back on for a road test. If it still runs rich or detonates with this totally stock, UNmodified carb, I'll have to look elsewhere for the problem. I suspect that the Demon is a POS though. After I put in the #88 jets, the idle in Park A/F numbers really leaned out and the IN GEAR idling almost went full lean past 17.0. Its as if I am dancing around a goal that the carb isn't equipped to meet.
Oh, regarding RACE gas: The entire point of changing to this cam was to achieve a later intake closing, reduce cylinder pressure and increase detonation resistance. Running race gas shouldn't be necessary. I checked one cylinders compression today and gor a 173 reading. That hole showed 188 with the 509 cam.
Last edited by Frankenduster; 09/04/13 05:53 AM.
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Re: Cam break in is done!....Now more questions!
[Re: Kern Dog]
#1492895
09/04/13 03:57 PM
09/04/13 03:57 PM
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Joined: Apr 2012
Posts: 18,880 -
RSNOMO
Moparts Torchbearer
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Moparts Torchbearer
Joined: Apr 2012
Posts: 18,880
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Quote:
Oh, regarding RACE gas: The entire point of changing to this cam was to achieve a later intake closing, reduce cylinder pressure and increase detonation resistance. Running race gas shouldn't be necessary.
Beyond all that you've been through here...
Have you tried a good shot of 110???
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Re: Cam break in is done!....Now more questions!
[Re: RSNOMO]
#1492896
09/04/13 04:09 PM
09/04/13 04:09 PM
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Joined: Feb 2010
Posts: 18,493 Granite Bay CA
Kern Dog
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Striving for excellence
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Granite Bay CA
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I ran some 110 leaded with the 509 cam setup. It ran fine with zero detonation. The thing is, a few years back, it ran fine on 91 with the same timing. Maybe some of that is due to the ethanol in the fuel, but I wonder if most lies in this carburetor.
Converter stall speed? Sorta hard to tell. Its a 9 3/4" unit that was built to be a 3000 stall. I didn't like the lazy way it felt so I had the builder cut it open and change a few parts inside. It stalls lower than that now. When I'm stationary in gear holding the brake, it will start spinning the tires on concrete at around 2200 or so. Asphalt would probably be higher.
Last edited by Frankenduster; 09/04/13 04:14 PM.
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Re: Cam break in is done!....Now more questions!
[Re: mickm]
#1492903
09/04/13 07:18 PM
09/04/13 07:18 PM
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Joined: Jul 2007
Posts: 1,526 North Carolina
cjskotni
pro stock
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pro stock
Joined: Jul 2007
Posts: 1,526
North Carolina
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I agree here. I think with a 10.7:1 compression, you will have your work cut out for you to run this on pump gas...especially with the ethanol swill we have available today. Even with the aluminum heads, I think you are going to have a temperamental engine if you don't spike it with some race fuel. It's also possible maybe your compression ratio is a tad higher than you calculated. The rule of thumb I hear is 9.5:1 max for iron heads and add a point for aluminum heads so you are a little past the border. I am sure somebody here will chime in that they run more than that on pump gas but every engine build is different. I agree with your logic on the cam choice but maybe not enough cam to bleed it all off? If this were my motor, I would start with a head gasket change. I used the thick FelPro's on my build (.055" compressed) which helped bring my calculated compression down almost .2 points from the thin gaskets. With thinner gaskets (.039"), I would have been closer to a 10.6:1 which kind of made me worry about being in the same boat as you. If the AF ratio isn't way lean @ WOT, then you really have two more things to try and fix here. Verify the engine is NOT running hot and/or lower the compression. I would try to avoid retarding the timing any more than 31* total and that is too retarded in my opinion. You will get there and your car will burn rubber (reliably) before you know it!
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