hotrod66bluestreak

Had this same problem in my 66 coupe, changed up all the stuff you guy's are talking about & it turned out too be my motor mounts had harden up over time & all the vibartion was going in the car. Put new ones & it runs smooth now.

chrisboss429

Are you using a 28oz damper/fleplate on a 50oz roller motor, that'll make it shake like a wet Chihuahua? Just a thought, hate to heat of bearing failure?

umfan92

I fear this is the problem. But I don't understand. You say the vibration was going into the car. Does that mean that after you put new mounts, the motor still vibrated, but you just couldn't feel it? Did the engine run smooth after you put on new motor mounts?

Yeah I made sure to use 50oz. damper and flywheel. I had an 85 302 HO that I suspsected had the wrong damper so I made sure to get the right one for this engine when I built it up.

umfan92

Update: As it turns out, I was interpreting the tachometer incorrectly. Apparently not only do you have to switch it to 8 cylinder (which I did), but you also have to multiply the reading by the number of cylinders (in my case 8 of course), unless you hook it up to the coil wire. I didn't even know you could hook it up to the coil wire.

So after hooking up my timing light, vacuum gauge, and tach, I began tuning/timing. I got it to idle pretty close to 800 (the gauge jumps around from 790 to 810 to 830 to 780, it did the same thing on my mom's VW Golf so I know it's the gauge not the engine). I set the timing to 12 degrees BTDC and adjusted the carb idles screws. It idles pretty nicely now but it still vibrates.

It's not the same shake as before. Before it would have a little kick every other second. But now it's a constant vibration. I'm not sure if it's normal because it's an HO or not. I was told that it should still run smooth. Also the vacuum gauge oscillates slightly, less that 1/2 an inch of Hg. I know that high performance engines are supposed to do that, but is this high performance enough to cause that?

If it's not normal, what could be causing that? Could it be the ignition system? Or motor mounts? I don't know.

1slow67

Is it possible that the firing order is off?

jojobanks

post a vid of what your vac gauge is doing. It sounds like you just need to advance your timing a little bit, but that's a tough call considering you're already at 12*btc

umfan92

My firing order is set to the HO firing order, same as the 351 I think. 13726548 (I wrote that down from memory so if it's wrong, that's just my memory, it's correct on the engine, double, triple, and quadruple checked).

I'll try to post a video of the vac gauge tomorrow. It's exactly like scenario 3 of this website http://www.secondchancegarage.com/public/186.cfm only it doesn't move that fast. It's a slower oscillation.

jojobanks

it might be completely normal AFAIK as I haven't messed with the HO 302s much, but your motor is still stock. Guess you'll need someone more familiar with your specific motor to actually chime in and let you know what's up.

umfan92

Here's what my vac gauge is doing now. The number isn't correct, it's actually higher than that, but just look at what the needle does.

http://www.youtube.com/watch?v=BYYp2...ature=youtu.be

jojobanks

that looks perfectly healthy to me. Depending on what your vacuum really is, you may want to try adjusting your carb/timing to raise it a little more. On a stock cam/stock compression you should have no problems hitting 20 vac.