magnummopar
Well-Known Member
when 6I and 6 E are opening/closing, check intake #1 at TDC and see what the lifter preload measures at rocker. What was valve guide clearance?
when 6I and 6 E are opening/closing, check intake #1 at TDC and see what the lifter preload measures at rocker. What was valve guide clearance?
Zinc additive in the oil during break in? Cam lobes get wiped out real quick if no zinc is in the oil during break in.
It looks like you have at least 1 dead misfire. Have you done a cylinder power balance test to identify what cylinders are affected?
Double check the valve adjustments again.
Make sure the power valve in the carb isn't kaput or the wrong calibration as this would make it run too rich.
try 20 to 22 degrees initial, then connect your vacuum advance to manifold vacuum and using your vacuum guage, adjust the idle mixture to the most rpm or highest vacuum...
How does oil get to the backside of the intake valves, loose or tight?
What was the RPM in the video?
do you have another carb to try on the motor?
sounds like it would be worth a try to loosen the valves a little
1/2 turn on preload should be fine, what is adjuster thread pitch, then do the math. how did it drive, did it have good power? is the engine out of balance and vibrating/shaking??
It sounds as though you've tried to be somewhat methodical in diagnosing the problem with how it's running.
You've said that the (mild) camshaft was degreed in when installed which should make a person believe that the cam timing isn't the issue.
You've tried multiple carbs that you said you knew were good. Even if they weren't perfectly tuned I don't think carburetion would then be the problem.
You inspected the camshaft for noticeable wear and didn't see any. Was the cam run previously in another motor? If it is a used camshaft that hadn't shown an indication of problems in another motor I wouldn't think it's improperly ground. If it is a new camshaft there's always a possibility that the cam grinder screwed up. It's not very likely but without measuring each lobe for lift, timing, and duration you can only assume there's no problem with it.
You've checked the spark plug wires for current carrying capacity and firing order along with the distributor cap and rotor for defects. You've checked the ignition timing and verified it's where it should be. My experience with MSD boxes is usually that they work perfectly or don't work at all. It doesn't sound like you've got an electrical problem.
The presence of oil on the backside of the valves combined with the engine running rough may indicate improper sealing of the intake manifold but I'm inclined to think that your engine hasn't had a chance to run long enough to properly break in the new rings and they're not perfectly seated yet. If I'm wrong that would mean that you've probably got an intake leak that's affecting both oil consumption and air/fuel ratios. I don't think that slight valve seal leaks by themselves would lead to the engine running the way it does.
It still seems to me to likely be valve lash but is there any possibility you've gotten really bad fuel?
what dampner are you running? if it has an elastomer in the center of it. mark it with a bright white or yellow across from both sides. see if its moving more than an 1/8" to one direction. they do wiggle some but it could have slipped at initial fire and you never knew it.
is it internal or external balanced? u say you had it balanced but is that with the dampner and flexplate?
id suggest swapping out that junk 6al box for a digital 6. common random misfire is the 6al's regular failure flag.
what is plug gap? you can eliminate plug gap by going dowj to .014 and rule out any ignition fire issues. but once again 6al box with the low rpm multi fire delight is also its freddy kruger for these type of problems.
did you check dizzy engagement for full gear contact? is it a tooth off?
those are the things i consider once ive ruled out carb, valve back lash, lower intake leaks, and dizzy damage.
you could also have had the cam bolt if center single bolt cam back out allowing chain deflection for a rough runner.
cam advance sprocket fall out or come lose if adjusting bolt style not incremental spacer designed.
So with your Vacuum reading is telling me that this is a "HOT" street engine. I probably missed it but what exactly is the true static compression of the motor and also what is the stick in it exactly?
When you say good compression and leakdown what are the numbers?
JW
I too would be interested to see the numbers.
But, I noticed some clues.
you said;
1)I removed the hose from the PCV valve and the engine idled up but still idled very rough. Plugged it with my finger and it idled back down with the still rough idle. (post #1)
2)Tried all kinds of timing. Nothing makes it better. Only thing that makes a change is when I turn it too far one way or the other, then it way out of adjustments. Turned the idle screw in/out, no better.(post #32)
3)It has a hesitation when getting into the throttle while cruising and always has a miss to it.(post#40)