BAD VIBRATIONS

[JEFFSWHEELS]

I have a bowtie 454 in my WCC roadster. It has a mild cam and stock compression. Heads are aluminum squareport units breathing through a 750cfm holley. All was well until I replaced the stock aluminum manifold with a new edelbrock RPM performer. The motor runs great and likes the manifold except that now I get a distint motor vibration at exactly 2000 and 4000 rpm.
No knocks and everything is tight on both ends of the crank. Anyone had this happen?

From Shakin in Sherwood

[Cobra2]

could this be a resonance problem?

[WestCoastBill]

Hey Jeff, glad to see you joined up. I met you and your wife at the launch point for Hood River. I had to get some work done so I couldn't go. I've still got your business card and I'd still like to see that top you got to see if I think I need one. I'm sure we'll meet up soon now that the weather is getting good. As for your problem, that's a weird one. Only thing that seems logical is that the manifolds external dimensions are differnt. Maybe the aircleaner is vibrating against the hood, throttle linkage meeting something when held at a certain position, or anything else that may have moved with the new intake. Other possibility is that something has gone wrong coincidentaly at about the same time as your manifold swap. Talk to you later, Bill

[pcs50]

Do you have a stock flywheel and harmonic balancer? If you changed them, they should be externally balanced ones for a 454. Just a thought.

[JEFFSWHEELS]

Originally posted by WestCoastBill:
Hey Jeff, glad to see you joined up. I met you and your wife at the launch point for Hood River. I had to get some work done so I couldn't go. I've still got your business card and I'd still like to see that top you got to see if I think I need one. I'm sure we'll meet up soon now that the weather is getting good. As for your problem, that's a weird one. Only thing that seems logical is that the manifolds external dimensions are differnt. Maybe the aircleaner is vibrating against the hood, throttle linkage meeting something when held at a certain position, or anything else that may have moved with the new intake. Other possibility is that something has gone wrong coincidentaly at about the same time as your manifold swap. Talk to you later, Bill

Bill, It's good to hear from you. I would like to hook up too. I am evaluating a motor/trans change to a smallblock 427 and 5 speed and I would like to look at how your setup for clutch pedals and linkage. Shoot me an email and we can setup a sunny day meeting. Tx..Jeff

[Tom Miletich]

Jeff,

I know this is a late reply. I've only been a member for a short time. I have a 454 and had a severe problem after 5000 RPM. I was able to find the problem. It had to do with the cam. If your problem went away with higher rpm it has to be different. I'll watch this thread to see if you reply. Is your 454 a Marine 454?

Tom Miletich

[JEFFSWHEELS]

Tom, thanks for the reply. I found the problem in the carburator. One of the secondary jets had come loose. That was an inexpensive little fix that was a devil to find.

Tx...Jeff