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Tue May 01, 2012 1:26 pm

I'm having an issue with the engine. It is making a noise and vibrations at higher rpm. Its a 1971 bay with a 1776cc engine, dual carbs solex H40/44EIS, it has electronic ignition, and manual transmission.

the noise starts at 2400 rpm, it is idling at 1200 rpm with no issues. i disconnected the fan/alternator and ran the engine for a minute without them and the noise is still there. there is a lot of vibrations that can be felt in the floor when driving. also it dose not matter weather the clutch is engaged or not.

Below is a video if the engine and the buzzing sound when it revs up.

In the last three days I replaced the vacuums lines to the break booster, tuned the carburetors and did valve lash, as well as timing.

Any help will be greatly appreciated, I'm kinda at a loss.

http://www.youtube.com/watch?v=nL0d1M567VQ

Tue May 01, 2012 1:38 pm

hmmm, that's a tough one.

So you say it does it without the fan/alt belt on so that would rule out the fan or something caught in the fan. I would check with my hand to see if anything is stuck in the fan (engine off or course) anyway. :)

My next guesses would be cam gear rivets or bolts hitting the back of the oil pump, and then a loose flywheel or clutch.

hth

Jeff

Tue May 01, 2012 2:07 pm

you will have to use your senses to find it. Do you feel it in your feet more, your butt, your ears, with the windows up or down, your feet, shifter, on turns more etc. - when you are moving or standing still etc. Could be anything.

Tue May 01, 2012 3:12 pm

Does the engine speed change when you pull each plug wire out of the distributor cap one at a time?

Tue May 01, 2012 4:21 pm

At idle, the speed drops only when I pull the wires for cylinder 3 or 4. There isn't a change when I did it for cylinders 1 and 2. Dose that mean I should do a compression test?

Tue May 01, 2012 4:30 pm

Yes, and also confirm the carb is working on that side, missing cylinders or running on 2 or 3 makes a shake similar to what you describe.

Wed May 02, 2012 1:17 am

^2 sort of.

no change on 1 and 2 means that side isn't firing. check for plugged idle jets on that side, and maybe re-check your valve adjustment on 1 & 2.

reset your timing after.

If you pull the plug wire and hold it about an inch from the dist cap is there any change? If so, could be a bad plug.

I should read more thoroughly.

Jeff

Wed May 02, 2012 8:41 am

So I pulled the spark plugs on cylinders one and two and they looked ok, not black but they were a light brown.I did a compression test and both cylinders had 100PSI. The idle jet was just cleaned three days ago with the tune up. I took off the air filter and opened the throttle and can see the main jet squirt fuel in. as well as the butterfly valve open.

I'm going to do a continuity test on the wires this morning and replace the spark plugs. Then do valve lash and timing again. Just for kicks and giggles. hopefully that helps.

Thanks for all the input.

Wed May 02, 2012 10:55 pm

Its Fixed!!!!

This morning I replaced the spark plugs and wires. The plugs were uniform in color, brown. But the wires where really bad one of them even came apart as I changed it. I then started it up and it still made the vibration noise. But I noticed that the alternator was slightly rotating with the vibration.

I then pulled the the alternator and fan. Turns out the fan and shrouding was busted. so I'm not sure if it was one thing or the other or the combination of the both, but she's running much better now. Thanks everyone for your input. Below is a link to some of the pictures I took.

https://picasaweb.google.com/105715608126221756350...directlink