PontiacBonnevilleClub.com

Oh ya that engine sounds strong!

You should be well into the 12's now.

Usually the engine rotating assembly is balanced using the flywheel, balancer, crank, pistons and rings.

If you have to replace any one of those items, most don't rebalance the entire assembly every time.....but if you want to balance a dime on top of the SC. (probably never get this engine that smooth)

radomirthegreat wrote:Judging from the belt routing, L67.

What does the Flywheel have to do with belt routing?

Jr's3800 wrote:

radomirthegreat wrote:Judging from the belt routing, L67.

What does the Flywheel have to do with belt routing?

X2

Crap, I read it as "harmonic balancer." Sorry.

Okay lets see if I get everyone's questions in here.

I can't use the L36 HB because it doesn't have the second set of ribs for the supercharger . The fly wheel was changed over from the L67. I was pretty careful to get it back to the same position, but I would almost bet it may be off a little bit. I have a single timing chain and am still using the balance shaft, but the vibration is almost identical to if I was using a double roller without the balance shaft. It really isn't that big of deal, but it has some decent vibration under load and accelerating, but nothing major. Like I said, just like if I was using the balance shaft. And yes, everything is put back in to spec and torqued correctly.

My car is a crappy 2 door 94 toyota tercel. Girls car, but hey, it gets 40 MPG and has 182K on it and still goes like it did when I bought it 5 years ago.

I wonder how much different the L36 Flywheel is weighted than the L67 flywheel...

At this point the Flywheel is the only thing I can think of that may be throwing it off kilter a little...

SuperSLE wrote:My car is a crappy 2 door 94 toyota tercel. Girls car, but hey, it gets 40 MPG and has 182K on it and still goes like it did when I bought it 5 years ago.

I assume the wife gets the SLE due to the two extra doors and kids?

00Beast wrote:

SuperSLE wrote:My car is a crappy 2 door 94 toyota tercel. Girls car, but hey, it gets 40 MPG and has 182K on it and still goes like it did when I bought it 5 years ago.

I assume the wife gets the SLE due to the two extra doors and kids?

Yep, you got it. Plus my little car is a four speed manual, dinky little 13" tires, no traction control, it just snowed two feet last night, and no AC for the summer.


I think that it is the flywheel being off just enough to cause it to do this. Not really that big of deal, but it is a little annoying to the wife. Oh well.

How do you know the flywheel is off a little?

I believe that the L67 and L36 Flywheels are weighted differently are they not? The L67 internals are heavier than the L36 internals..

That's correct.

So I switched over to the L67 fly wheel, so maybe it has more or a little less rotating mass on it then the L36 one did and is now causing a little vibration?

Another dumb question.
Why would the L67 rotating assembly be different?
If the L36 has higher compression, wouldn't the pistons be flatter, less dished, and therefore heavier.

L67 rods are heftier, so the whole internals are heavier. L36 and L67 flexplates are weighted differently, as was pointed out.

If you decide you can't live with the shakes, you need an L36 flexplate from a 258mm TC-equipped n/a car, or an L26 flexplate (which is already drilled for either 245 or 258mm TC's).

Correct. The L36 flexplate is built and balanced to match the rotating assembly (lighter) in an L36. You have an L67 flexplate on an L36, so I'm not surprised you have some vibration.

It really isn't all that bad. Just a little annoying. I guess if I get ambitious I will change it out, but right now I don't really care enough to do it. But that makes sense. Guess I know what my next project is when I get bored .

I'm guessing the weather in Idaho is pretty mild right now or you have a heated garage. I can't motivate myself to go out in the garage to fix an exhaust leak this time of year, much less swap a flexplate.

Well it is -10*F and we have two to three feet of snow on the ground. Not heated in the garage, but not too bad with a sweatshirt and insulated overalls. I just had the whole motor out so it isn't really that big of deal.

So we have been discussing that the L36 internals are slightly lighter than the L67 with this vibration issues. So I therefore deducted that since they are a bit lighter that the HB is probably a little lighter also as well as the flex plate. Since I put on the L67 flex plate and am now using the L67 HB for the supercharger belt I figure I was just a bit heavier with all of that rotating mass than a typical L67. So the consensus was to change out the flex plate since the L36 plate is basically a bit lighter and the counter balances where causing the vibration issue with acceleration. So the problem was to either pull the whole engine apart from the tranny again to change the flex plate over to the L36 plate to decrease the rotational mass. So I started thinking, what If I just decrease the rotating mass of the L67 plate? Each flex plate has a section of counter balance weight on it. So I took two chunks of counter balance weight off the flex plate that is still installed in the engine with a metal saw and a lot of patience. :bonk: I figured that the worst case senario if it didn't work was that I was still going to have to pull it all apart to change the flex plate. Well guess what, my theory actaully worked. Simple physics. Decrease the rotational mass in one direction and equal it out right?

So I took it out for a llittle test drive and perfecto! No more vibration. How about them apples.

I also recorded a new video since I got all the bugs worked out. Took her out scanning and I have 0 KR and 18* on a 3.3 pulley at WOT. Time to get busy :burnout: .

Wow, that sounds insane! Must be way better in person! Fantastic! I wasn't at all expecting the whine and exhaust to be that prominent. Very awesome!