krash kendall
Active Member
Yeah, I was fixing the parking brake and gave him a creeper to play with. Next thing I new he was rolling under beside me. My wife took the shot. He's 3 1/2.
Still can't figure out why my 351c is vibing at 3k rpm
- Thread starter DarkoStoj
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You can't run it without the flywheel. How would you start it ? The horizontal bar is called the "Z" bar. And no it won't cause a vibration. Check to see if your vacuum advance is working. Also try spraying around the intake with carb cleaner for vacuum leaks. If all else fails I'd suspect the balancer or flywheel. The clutch & pressure plate could throw it off if they're not zero balanced.DarkoStoj said:
D.Hearne said:
My mallory unilite distributor doesn't have a vacum advance canister, how do I check the timing to make sure everything is good in that department?
All the gaskets are new and installed properly on the intake, so everything should be good there, but I'll give it a shot anyway.
The balancer was replaced with a good unit. The old one was spun, and absolutely TOAST.
The only thing I can come up with is that either the pressure plate isn't balanced to 0 properly, or the flywheel isn't balanced to 28oz properly.
I just hope that if I do go through all that work, that fixing the balance on the flywheel & changing the main bearings with give me a good motor again. I really don't want to go through all that to only end up with a motor that has low oil pressure and burns oil.
Check the advance with a timing light. What was the oil pressure like ? With Clevelands, it's rather low at idle and picks up to around 60-80 at mid to upper rpms. This is due to the right side lifter gallery also being the main gallery. If the pressure sender is at the rear behind the intake, the pressure is lost at idle from the leakage around the lifters.
D.Hearne said:
The oilpressure guage is a mechanical one that is right behind the intake like you said(you can see it in the picture). When I start it up I get around 60psi cold, then when it warms up I get about 20psi at idle. While cruising on the highway at around 4,000rpm (no over drive and 3.89 gear) my oil pressure is at about 30psi. I burn through about 2 quarts in 2 weeks to a month's time. It does smoke a little occasionaly, but its not the smoke that billows. It resembles the smoke of a car thats driven without warming up. If I am cruising down the highway and hammer it, there is a big cloud of smoke behind me right after the secondaries open...does that mean anything?
The car also seems WAY slower then it should be. It has 3.89 gear with a detroit locker, open chamber 4v heads, pop up pistons, solid flat tappet cam thats pretty lopey at idle, 1.7 roller rockers, and a edelbrock performer intake with a 600cfm edelbrock. I always assumed it was the intake and carb being mismatched to the motor, but I don't really know anymore. I hate putting money into the motor and changing things if I don't know the motor is good. Because if its about to go, I'll just put in a Windsor.
30 psi hot is way too low. I'd check the bearing clearances. And install a high volume oilpump.Run no less than 20W-50 oil. You could also have a port mismatch causing the oil consumption. That Edelbrock intake might be for 2 bbl heads and isn't covering the 4 bbl ports. Check the part # and look up to see if that's the intake for 4 bbl ports. I know they made 2 different ones for 2 bbl vs 4 bbl heads.
D.Hearne said:
It is a 4bbl intake, but I did notice the ports are still considerably smaller than the ports on the 4bbl head, but i'd assume they line up.
My theory right now is the flywheel/pressure plate is out of balance, which caused the vibration, which caused the premature wear on the main bearings. I just don't know if it would be worth it to pull the motor, get the flywheel checked, and change the main bearings if there is still a chance the motor is no good.
Given that you said your vibe is present in neutral but more prominent in gear, I took this to mean 'under load' it is more severe. Usually U-Joints are the primary thing suspect for 'under load' variations in vibration... but this obviously does not follow in neutral. The flywheel theory would also not apply as the vibration would be constant intensity in neutral and under load. My thought process took me forward of the flywheel to a potential static/constant miss. I just kind of skipped over checking bad wires, spark plugs, and carburetor tune for one reason or another and went straight to taking a stab at a compression test for a suggestion.DarkoStoj said:
Just a thought.
I don't think you understood me. Both intakes I'm refering to ARE 4 bbl intakes. BUT one fits 2 bbl heads and is a 4 bbl intake. The other is a 4 bbl intake that fits the 4 bbl heads. With all the other mismatched parts there, it sounds entirely possible that you've got the wrong intake for your heads. This would explain the vibration at 3000 and the oil consumption, it's possible that you've got a vacuum leak from the port mismatch that shows itself at that point.DarkoStoj said:
WORTH
Dirt-Old 20+Year Member
DarkoStoj said:
Yes it does, unfortunatly I can't tell you what it means. A pulsating vibration is caused by 2 items vibrating out of sync. Which may or may not help in your search for the vibration you have. If you have ever been in a twin engine boat you would have experienced this first hand. You can sync the 2 engines by feeling this pulsating vibration. When you finally get them both running at the exact same rpm the pulsation goes away and the engines appear to smooth out. Unfortunatly I'm not a scientist and I have no idea why this happens.
Getting to YOUR problem, you've got a lot of very good input here in this thread, but one thing has been painfully overlooked and that is the fact that all engines vibrate. The reason we have rubber engine, tranny,exhaust hangers, ect. is so WE don't feel this vibration when we're in the car. I have chased a few vibrations in my 30 years of auto repair that ended up being incredibly stupid things. The problem that gave me the most problems and took me the longest to finally find was a brocken bracket under an A/C compressor on an old Mercedes.
Unfortunatly for you, your pretty much on your own here because there is no way you can reproduce what your feeling for any of us to help. It's like trying to describe a sound, can't be done.
The only thing I've seen in this post that I didn't agree with was your clutch cross arm. Someone said that couldn't be the problem, but it could. If it is metal to metal it CAN telescope a vibration to you.
And of course there is still the possibility that you DO have a vibration that shouldn't be there.
What WORTH is describing here isn't a vibration, it's "Harmonics" And like he said, all engines produce it.WORTH said:Yes it does, unfortunatly I can't tell you what it means. A pulsating vibration is caused by 2 items vibrating out of sync. Which may or may not help in your search for the vibration you have. If you have ever been in a twin engine boat you would have experienced this first hand. You can sync the 2 engines by feeling this pulsating vibration. When you finally get them both running at the exact same rpm the pulsation goes away and the engines appear to smooth out. Unfortunatly I'm not a scientist and I have no idea why this happens.
Getting to YOUR problem, you've got a lot of very good input here in this thread, but one thing has been painfully overlooked and that is the fact that all engines vibrate. The reason we have rubber engine, tranny,exhaust hangers, ect. is so WE don't feel this vibration when we're in the car. I have chased a few vibrations in my 30 years of auto repair that ended up being incredibly stupid things. The problem that gave me the most problems and took me the longest to finally find was a brocken bracket under an A/C compressor on an old Mercedes.
Unfortunatly for you, your pretty much on your own here because there is no way you can reproduce what your feeling for any of us to help. It's like trying to describe a sound, can't be done.
The only thing I've seen in this post that I didn't agree with was your clutch cross arm. Someone said that couldn't be the problem, but it could. If it is metal to metal it CAN telescope a vibration to you.
And of course there is still the possibility that you DO have a vibration that shouldn't be there.
