Only runs at 54* advance iNITIAL!!
- Thread starter DBSHEA
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My head was ready to start spinning at 45 RPM:santa:
daredevil
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Wrong damper?
67 B-body
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The gap isn't the concern so much. Its where the roll pin lines up when installing the reluctor. There s a point for cw and cc rotation, and this is different between SB and BB engines. They use the same part number for reluctor and provide two different installation configurations depending on application. Improper installation. Will cause incorrect phasing and this results into odd ignition advance levels.....
eric383
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Let me offer a different look at this problem. If you can get it to run good without paying attention to how far it is advanced, why not drive it this way until you decide to rebuild it.
DBSHEA
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This is a fair point, and honestly what I'll be doing until my daily drivers radiator shows up. But it's going to drive me crazy not knowing why it's doing what it's doing.
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I'll check that out this morning, thank you for the tip.
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Elaborate? If the dampner is showing tdc correctly, how can it be wrong?
daredevil
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Only thing that makes sense is cam timing. Cam must e too far advanced so its bleeding off compression too early.Advancing timing 40* ahead probably fires at the most oppurtune compression time.Is motor very low feeling on torque. 40* theoretically would cause valve closed event 25% early turning a 10 to 1 motor in to a 7.5 to 1 motor,piston only 3/4 up to the top. I,d do a compression test and see if numbers are low.
DBSHEA
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Good tip but I checked and it is set up for ccw.
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This being my first mopar and first big block I don't have much to go off of. My mustang is 502/515 tho and I will say, the dodge has always felt like a dog. I chocked that up to low compression 1970s emission rules and the fact that I'm still putzing with the carb and timing. The tires will light from a stop, but she does thunderchug up to speed.
daredevil
Well-Known Member
Some compression test numbers might tell us everything.
bigblock
Well-Known Member
You can check the cam to crank timing simply by pulling the pass side valve cover. Set #1 on TDC firing. #1 and #6 will be at TDC but #6 will be in overlap. Meaning both I&E valves on #6 should be open slightly. If so your cam timing is correct or close enough. Be sure #1 is on the firing stroke.
DBSHEA
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With 1 at TDC both valves shut no load on the push rods, #6 shows both shut with both valves*shut no load on push rods.
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Sounds like your cam timing is off. Years ago a buddy set his cam using the dot method....and he knows better. It fired up but he never could get it to run right. Turns out it was way off and far enough for all of his intake valve to tag the pistons.
I'll ask again... Are you seeing 54* advance with the vacuum can disconnected and the line plugged? I looked but didn't see you address this.
Check this: I just reread your initial post and you said that you had 54* INITIAL advance, not total. Disregard my comments. Mea Culpa...
Check this: I just reread your initial post and you said that you had 54* INITIAL advance, not total. Disregard my comments. Mea Culpa...
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Just because they are dot to dot doesn't mean it's right. My buddy did the same thing...timed the cam dot to dot and it ended up being way off. Do you know if the timing gears were a matched set (but that doesn't mean they're right)? Was the cam ground correctly? I've seen more cams than I care to admit that were not. How about the drive pins? Were they drilled in the right place? There's just too many variables to trust a dot to dot cam alignment. Always but always use a degree wheel to install a cam and then you will know exactly where it's at. I think you mentioned that you did not install it but you are the one that now needs to check it. And yup, it's a pita.
DBSHEA
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Agreed, and I feel like it's the only path forward. It is a matched set from melling. Looks to be a cheapo replacement set. I know nothing of the cam and can't pull anything off the net. Only marks I see are cwc and Ep45.
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A degree wheel and dial indicator is your friend. There's lots of info on the net with specs for different lifts but even that doesn't tell you everything but just knowing the lift and duration will help and you can plot that out. I'm no cam guru but there are several here that know them well and can help you.....I know enough to be dangerous
Tempest 455
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This ^. Only way to know where it's installed.
DBSHEA
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Ok, took me a while because I had to fab up all the equipment to Get this done but here are the numbers. Bear with me, this is my first time degreeing a cam. But I made sure to triple check all numbers. Tdc was measured via piston stop.
Intake opens 20* atdc closes 162* bbdc
Exhaust opens 154* bbdc and closes 25* btdc
Intake duration 142*, exhaust 173*
Intake centerline at 91* atdc, exhaust 111* btdc
Lsa is 158* with 8* overlap
I'm not sure what the factory shaft mounts ratio is but I measured lift at .213 intake and .215 exhaust.
Intake opens 20* atdc closes 162* bbdc
Exhaust opens 154* bbdc and closes 25* btdc
Intake duration 142*, exhaust 173*
Intake centerline at 91* atdc, exhaust 111* btdc
Lsa is 158* with 8* overlap
I'm not sure what the factory shaft mounts ratio is but I measured lift at .213 intake and .215 exhaust.
DBSHEA
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So here's a sketch of my valves. Sorry for the chicken scratch, maybe you guys can help me decipher this. It's OBVIOUS that the cam is off, if the stocker opened up intake 21* btdc and I'm 41* behind that power curve. Stock cam has 38-46* of overlap compared to ny 8?
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