Vibration....
 

My BDR has a vibration that seemed to be coming from the engine. I had the engine and everything attached to it rebalanced (a long story, the original builder was a real piece of work) so that it all is perfectly smooth.... Except for this vibration which is mostly felt between 2000 and 2500 rpm. This occurs when the car is idling, so it is not the tires (had them replaced and balanced anyhow) and it is not the engine mounts.

Sooo... The theory is now that it might be the side pipes. Could this be a combination of incorrect timing (it is now TDC) with "untuned" exhaust headers setting up a resonance in the pipes? We are at the end of our wits here...

It may be your cam. I have a 347 and around 2000-2500 RPM the valve overlap causes an odd vibration, rumble, or even a whooshing sound. Noises and vibrations are hard to describe. I am not sure how to verify this though. BTW my cam is pretty radical and this started after I installed it.

2000-2500 rpm is not my idea of idling.
Do you mean stationary in neutral? Carbureted hotrod engines generally have some ragged metering transitions without a load on them.
Do you feel the same thing under load when moving?

If you have a fairly radical cam it probably won't run right with the timing as retarded as you indicate.

A little more info on your cam, intake, carburetor, compression ratio, and timing curve would be helpful in providing useful suggestions.

Easy enough to test that - take the side pipes off.

In theory, you can damage the engine by running it without any headers at all. But open shorty headers are used on race engines all the time.

But, before getting excited about something like that, make sure your tune is spot on. You need to do that anyway, so do that first.

Yes i meant stationary, not idle, sorry. The vibration feels the same whether the car moves or not. The engine has a Comp Cam roller camshaft, Edelbrock intake, Holley 650 carburetor, i believe a 9.0 compression ratio. It is a 302 stroked to 347 with an Eagle kit.

Ok i will check with the side pipes off and change the timing and see if that helps. Thanks for the help so far.

May want to first just experiment with the advance. Thats easier to adjust than pulling off the sidepipes and getting them back on. If that doesnt give any insights, then take off the siepipes.

This is going to be a pain in the A$$
 

Eplatvoet First name would be nice. This is not going to be fun but need to remove the clutch first and pull trans. Retest the motor for the vibration, vibration gone, clutch imbalance problem weight fell off pressure plate. Vibration still there, Pull flywheel and make sure it's balanced. Index this to crank shaft and try to rotate and see if vibration gets better or worse. The other thing to check would be the dampener on the front of the motor. Which one do you have?? I have a super dampener with an silicone internal dampener. IF the fluid is cold the motor shakes for 5-10 minutes until fluid is warm. It dampener is rubber ringed, it could have loosened and shifted out of alignment. This will cause the same problem. Dampener is easier to check first. If you have had problems before with this motor, it might need a new roating assembly and align bored of the mains. More info on the machine problems would help. Rick L.

Ok, what we have done so far is pull the clutch, pull the flywheel and the drive shaft. The flywheel, my friends, has a 2x4 piece of 1/4 inch steel welded to it. Without clutch and flywheel the engine showed bad imbalance. The whole assembly was then rebalanced properly. By the way the harmonic balancer also had a weight on it.... When putting the engine back together we also found that the piston and rods had been in the engine the wrong way around... If we hadnt had the vibration issue we would not have found this. Right now the engine runs silky smooth while idling. No vibration. The vibration between 2000 and 2500 rpm is there regardless of engine temperature. First name is Erwin, by the way. And the engine only has 500 miles on it, by the way... I guess the first owner couldnt get it to run, seeing the car was built in 2008....

I would just undo the sidepipe hangers and run it with them not tied tight to the car. Was the whole rotating assembly balanced while it was apart? That is everything that spins or goes up and down.

Is this one on the cars from TA Specialties with the T&L engines that came out of hiding a couple years ago? Just curious.

Externally balanced?
 

Eplatvoet Erwin If you removed just the clutch assembly, there should be NO abnornal vibration at the rpm you are saying. I have always used markings on building motors with arrows and 1-8 for which cylinder each rod and piston go into. Everytime Many years ago when I started to build motors and the engine was on a table or rotating cradle I have installed wrong bank on the wrong side. First thing that happens with this is putting in the first rod assembly on the other side, the crank will not spin easy, any more and binding happens. This may not happen to all motors but happened on 351 windsor. Either way the balance is off. Quick check, what is the end play of the crankshaft?? Hoping less than .010". IS a vacuum gauge on the motor running showing a steady needle at 2,000 rpms and idle of say 800 rpms?? If yes you are back too a bad rotating assembly. I can't see side pipes causing this problem unless hitting the body or frame on revving the motor. A large camshaft shouldn't cause a vibration at 2,000-2,500 rpms. Does the vibration stop above these numbers?? Is the bolt pattern on the back of the crankshaft universal? I would spin the flywheel and retest to see if vibrations gets better, same or worse. IF there is a change, you are back to balancing problem. Find a new machinist. Rick L.

Thanks for the suggestions Rick.
Cashburn, yes this is a TA car with the T&L engine. Do you know anything more about this?

We "experienced" one engine with T&L. The biggest nightmare I have dealt with to date. Glad they finally closed the doors before anyone else got burned by them. I think you already know all this though.

They did not balance anything to the motor, anything that could be bolted on after was done after the fact and often drop shipped such as the carb, flywheel, etc. Who knows if the motor is internally balanced or? I'm sure at the end of their biz life nothing was getting done fully or properly.

Rick is giving you the advice you need for a path to resolution.

I would not like to be anywhere near a flywheel with weight WELDED on to it--------

Ford engines have used two different amounts of unbalance--28 and 50 in oz----and of course that gives you the possibility of having 3 different/wrong weights on both front or rear-----

You could get a new aftermarket flywheel which can come with both the 28 and 50 in/oz wt plus of course be Zero balanced with out either --- then you can run the engine with no weight, 28, or 50 to see if this corrects the problem-------(assuming front balancer is OK)----

And I'm assuming you mean an entire car SHAKE instead of a little noisy exhaust vibration possibly coming from a loose silencer inside the side pipe---------

Yep, i googled them last year and their story is pretty nasty. Lucky me... Do you also agree with taking the flywheel off and getting a new one?

Yes. The only failure we've every experienced with a flywheel was the one from T&L. The ring gear separated from the plate!!!

Alright; changing the timing - no luck. Taking side pipes off - no luck (but an impressive noise). In fact, the vibration sometimes now also shows up at idle rpm, just around 900-1000.
So we have run out of ideas. I don't want this engine to blow up on me so something needs to be done. Rather than trying the 3 different flywheel weights and rebalance the entire deal again we plan on either putting in a new Eagle stroker kit with a new flywheel or perhaps even a new engine and upgrade to a 427.
Thanks to everyone for the help.

I just went through this with a stroked out small block. For the cost of crack checking and balancing old or unknown stuff we were better off with new brand name parts. There's a few package deals out there that come balanced already. Also look into some crate motor options and see if that is an even better value.

Agreed!
What is the best 347 short block option?
Any suggestions for a great 427 out there?