I could sure use some help. I have a vibration in my 69 Z 302 which I can not figure out. I feel it when sitting still or driving, clutch in or out from 1500 to 4500RPM (and prob would continue on up) It is very noticable through steering wheel,peddles, rear view mirror, shifter. Here is what I've just completed. Frame off restoration, DZ has been bored 30, new pistons, cam/lifters, valves / springs/ align bore checked, crank and rods cracked checked, crank turned 10/10. Timing chain / gears, bearings. Pretty much the works!
Everything from the balancer to the clutch has been balanced too. All machine work bya profesional racing shop. The vibration was in the car before I started the work but not too noticable till over 4000 RPM.
So, Ive spent a ton and done everything I can think of and still a vibration. HELP! Thankx, John

What kind of engine and trans mounts do you have - rubber or poly? If the trans mount is rubber, has it separated? What did you use for subframe-to-body mounts? Remove the fan belt and start it up and see if the vibration is still there (to eliminate water pump/fan/alternator).

I agree with John, sounds like a cooling fan. Are you using a clutch type fan? I had a 67 that drove me nuts and it was the fan.

on my 68 the bellhousing to crankshaft was off center about .020 and would shake your teeth out centered it and is smooth now .just a thought.jeff

Hey, thanks for the ideas. I have removed the belt which had no effect on the vibration. (Good idea though). The engine and trans mounts are the ones that were on the car when I got it. They are black (rubber?). I'll check the trans mount to see if it is split. I put new sub frame mounts on which are not poly. They are black (rubber?).
The idea about the bellhousing being off center is an interesting one. How would one determin that?

you would have to remove the transmission and clutch and pressure plate reinstall the bellhousing with out clutch and pressure plate take a mag base dial indicator and put on fly wheel set dial indicator up on the bore of the bellhousing and zero indicator turn engine stop every 90 degrees or quarter turn write down readings + or - what ever you get divide that number by 2 and thats the amount to move bellhousing.hope i didnt leave any thing out.hope this helps .jeff

Try removing your crank pulley. Mine was out of round and contributing to vibration.

Kevin

Good point on the pulley. I just found my crank and water pump pullies slightly bent and out of round. Good excuse for a Zoop's set. I've found and replaced rims, tires, u joints, pinion bearing, tranny mount, motor mounts and driveshaft. All owere old and all were contributing to vibration. I just found a rear brake drum with a piece of the edge broken off so it too is replaced. What a journey.

Good idea on the crank pulley. I'll try anything at this point. I've even considered pulling the engine again and taking it to the dyno shop. I'd like to check out the HP, but would be interesting to check the vibration as well.
Redcam, I understand what you are saying. How did you correct the problem? John

my bellhousing dowel holes were cracked so i took a spiral sand paper role and ground out the amount that i needed to move it in the directions i needed to.i thought since the bellhousing was junk any way why not try it .not alot of ponys under the hood any way.and working good so far.jeff