340 Engine Shake

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Road Grabber said:
A lot of great feedback. I just wanted to mention checking firing order on the plug wires and make sure you didn’t throw a weight off your pressure plate.
Did you have the pressure plate balanced?

I had this problem with an imbalanced flywheel and it shook the side view mirror. Also disconnect your belt and do a sort test without turning the alternator. They can produce a very large vibration.

good luck
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Been there with the pressure plate...it does happen...and its a "pronounced" vibration ...I had the car idling in the bay in a shop I worked at, I revved it up, it shook so bad people standing around were like "what the hell...?"
 
UPDATE:

Verified with a mechanical guage and oil pressure is rock solid at 70 psi. Emailed Speedhut for testing instructions, they provided a great write up on the Guages and sender testing.

The shake is still there, but not as consistent now. The shop owner wonders if the system is learning the new setup (cam and heads).

The shop is going to go through the tune and check a few more things. More to come.
 
Have you ever disconnected the gauges yet?
 
Nat said:
don/t you have to drive it for system to learn ?
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Yes, you do. I didn't think that the changes I made would make that significant of a difference to throw it off that bad, especially because it was so intermittent. We don't know for sure yet if it just needs to learn or if it something mechanical (or electrical) causing the issue.
 
RustyRatRod said:
Have you ever disconnected the gauges yet?
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So far, just the oil psi. I suggested to the shop to put that on his list, to eliminate that as a factor. I just dropped it off last night, so he only verified oil pressure with a mechanical gauge to rule out that being an issue before moving forward. No point in trying to fix the shake if the bearings are toast. lol. But we are all good in that dept. so waiting to hear back on what else he discovers.
 
There's different regimes of operation the system learns. It'll learn to idle without driving. It learns pretty quick, but more slowly if it's already learned before. So you need to do a fuel learn reset if anything gets changed.
 
So got another call from him. He said he noticed a tick tick tick right when the shake happens. The shake still isn't consistent. He wants to pull the intake and examine the lifters to be sure one isn't collapsing and then pumping up.

More to come.
 
This may be a little off topic. He also tested the vacuum with a guage and it's spot on with Fitech 10-11in.

Would you expect the vacuum to be that low with this cam? I swear when I talked to lunati on a cam recommendation, they said this one would have good vacuum with the setup I have.

IMG_20220818_164942323.jpg
 
I get 10-11in with a lot more duration (250+ @0.050), but also with a longer stroke.
 
I saw a breather on the driver's side in the video. Do you have a PCV on the passenger side? It could be defective causing a loss of vacuum?
 
66fyssh said:
I saw a breather on the driver's side in the video. Do you have a PCV on the passenger side? It could be defective causing a loss of vacuum?
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I do have a pcv. It's just one from the parts store. I do have a Wagner dual PCV sitting on the shelf. I should give that to him and have him put it in for me. I'm forgot I got it until now.
 
Can't hurt. One more thing you could check off.

plumkrazee70 said:
I do have a pcv. It's just one from the parts store. I do have a Wagner dual PCV sitting on the shelf. I should give that to him and have him put it in for me. I'm forgot I got it until now.
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66fyssh said:
Can't hurt. One more thing you could check off.
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Yea. I tried to search the cam for some.vacuum readings, but they are all over the place. One theme that I have noticed is Lunati lifters are hit and miss. Maybe that's the nature of parts these days. I wanna do it right and do it once so I can drive my car. *Sigh*

I guess I'll wait and see what he finds.
 
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plumkrazee70 said:
So is that a yes, I should see more? Lol.
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I would expect more, but that could be an issue of installed centerline or preload or ignition timing, pcv, etc.

Idling too rich or too lean can cause a misfire too which may result in lowered vacuum. A lean misfire can read rich on an O2 sensor and a rich misfire may cause a lean read.. Sometimes it's counterintuitive.

A compression test could rule out a leaky valve or cam that's going away or a bad lifter. The plugs seem to suggest #3 might have some issues. Headgasket could be at play, or even the slightest exhaust leak could cause a poor afr read and cause issues. Hard to say at the moment.

Will be interesting to see what your buddy finds.
 
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Phreakish said:
I would expect more, but that could be an issue of installed centerline or preload or ignition timing, pcv, etc.

Idling too rich or too lean can cause a misfire too whichay result in lowered vacuum. A lean misfire can read rich on an O2 sensor and a rich misfire may cause a lean read.. Sometimes it's counterintuitive.

A compression test could rule out a leaky valve or cam that's going away or a bad lifter. The plugs seem to suggest #3 might have some issues. Headgasket could be at play, or even the slightest exhaust leak could cause a poor afr read and cause issues. Hard to say at the moment.

Will be interesting to see what your buddy finds.
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I'm going to ask him to do a compression test also. He did say the tick tick tick is coming from cyl #1 or #3 based on his stethoscope.
 
I presume non-stock prods & rockers were used? If so, could the lifters [ some at least ] be bottomed out, which would hold the valves open?
 
My 5.9 Magnum with .215/.223, .517 lift 1.6 roller rockers pulls 15.5*.

10-11 inches may be okay, I have ran into a bad PCV that was intermittently clogging and causing a shake. New PCV fixed it.
 
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