Bad engine vibration

[Phoenix-MN]

Hey guys, (sorry for the long post) I need to pick your brains, this isn't a turbo but the basics should still apply.
I have a NA 3.8 installed in a Porsche 914 It was balanced at a presumed good shop but is no longer in business (balancer, crank, rods, pistons, flywheel and pressure plate). It idles smoothly up to about 2000 rpm and then starts to vibrate badly, shakes the whole car and you can see the steering wheel vibrate. I've tried stock motor/transmission mounts, stiffer stock style mountss and currently HR poly mounts. Vibration levels are the same for all. The engine is built up like this:
3.8 NA .030 over
9.5:1 flat top pistons
Lunatti BM II cam
Harland sharp 1.65 roller rockers
Cloyes double roller timing chain
Holley intake
Holley HP EFI fuel system (also controlling spark)
Shorty headers

I've taken off the drive belts to eliminate any accessories that might be causing the vibration and it doesn't help. The balancer bolt is torqued properly. The vibration is there sitting still clutch engaged in neutral or dis-engaged in neuitral or in gear. Same for driving/moving down the road. I've run out of ideas and am begining to think that it was not balanced properly to start with.
Anybody have any thoughts on what else to check?

Thanks
Paul

 

[mikestertwo]

Has it always done it since day 1?

 

[Phoenix-MN]

Has it always done it since day 1?

Yes, from initial brreakin/start up.

Addition info that I forgot to include in the original post. When the heads were originally done the shop did not cut the guides for the additional cam lift and on start up it destroyed all the seals.
http://www.turbobuick.com/forums/engine-tech/266806-valve-stem-seals-clearance.html
If the lifters (hydraulic) were "bottomed" out would this damage them? They now run quiet and the engine seems to run fine and makes good power (except fot the vibration).

 

[Nick Micale]

Was this car/engine built in the Phoenix, AZ area?

 

[broke]

ballooned converter? just a thought to throw out there.

 

[Phoenix-MN]

Was this car/engine built in the Phoenix, AZ area?

Built in Minnesota by me.

 

[Phoenix-MN]

ballooned converter? just a thought to throw out there.

It's hooked up to a Porsche 901 5 speed transaxle

 

[TurboBuRick]

What centers the trans axle in the crank? Bearing?

 

[S10xGN]

I'd want to pull it and have it rebalanced, can't be doing it any good letting it vibrate like it is. IIRC, even fire V-6 motors are usually balanced at 36% under as opposed to V-8's at 50%...

 

[Phoenix-MN]

What centers the trans axle in the crank? Bearing?

It has a pilot bearing that fits in the end of the crank with a needle bearing center that fits the input shaft of the transmission.

 

[Phoenix-MN]

I'd want to pull it and have it rebalanced, can't be doing it any good letting it vibrate like it is. IIRC, even fire V-6 motors are usually balanced at 36% under as opposed to V-8's at 50%...

Ya, that is what has been in the back of my mind since the begining. I guess I'll just have to "bite the bullet" and pull everything apart and have it gone through again (different shop this time).

Thanks for the input guys

 

[87GNSteve]

If you can pull the engine and take it to a shop with a engine dyno you might be able to determine if it is the engine before you tear it apart.

 

[charlief1]

Had the same issue with my old NA car. After several years of thnking about it I had the wrong flywheel and balancer on it. Check to make sure you have the right parts and they are balanced right. At idle it would rock the car but run like a scalded ape when I put my foot in it. But it produced lots of vibration. The machine shop didn't have a clue how to balance it but it was fun while I drove it.

 

[Phoenix-MN]

If you can pull the engine and take it to a shop with a engine dyno you might be able to determine if it is the engine before you tear it apart.

This may be an optionn. The race shop that I was thinking of going to has a in house dyno and has lots of race experiance (Tesar Engineering, Long Lake, MN)