Help a NOOB - A continuing saga

[68 P.O.S.]

Why do you still have the TCS connected, and does it actually work still?? If it works, and correctly, it's not allowing the vac advance to come in just yet as designed. I would disconnect it and remove the wiring; it was an early, crude emissions thing and it provides no benefit to your engine and only stops your vac advance from working correctly. The only people who really still use the TCS are those doing a factory correct restore, or they just don't understand the TCS. Plug your vac advance can directly to manifold vac and you should see the idle increase. If not, you have a bad vac can. Now you need to find out how many degrees of advance your vac can provides. You want it to be around 10 degrees, or you'll probably get pinging if it has more than that.

[ncpetersc]

Originally Posted by 68 P.O.S.

Why do you still have the TCS connected, and does it actually work still?? If it works, and correctly, it's not allowing the vac advance to come in just yet as designed. I would disconnect it and remove the wiring; it was an early, crude emissions thing and it provides no benefit to your engine and only stops your vac advance from working correctly. The only people who really still use the TCS are those doing a factory correct restore, or they just don't understand the TCS. Plug your vac advance can directly to manifold vac and you should see the idle increase. If not, you have a bad vac can. Now you need to find out how many degrees of advance your vac can provides. You want it to be around 10 degrees, or you'll probably get pinging if it has more than that.

Okay, thanks again for the info. I have read abut the TCS, and thought I might remove eventually. But I have been trying to move forward while changing as little as possible. That being said, it seems like now would be the time to remove it so I can check the vac advance. I've got a drive shaft issue to deal with, but I will get back on this soon.

[68 P.O.S.]

Glad I could provide a little insight Yes, definitely a good time to remove it Let us know how it goes and good luck with the drive shaft

[Steeveedee]

The TCS system was used to limit vacuum advance until the vehicle was warmed up and in high gear. This served to cause faster warm up and to limit hydrocarbon emissions. It is pretty much only a California emissions system, and can be bypassed if you want. Simply take the vacuum to the thermostatic switch (if still so equipped) and connect it directly to the vacuum advance chamber. You can also remove all the wires, if you want, as they won't serve any more purpose once the vacuum side is dealt with. You might want to keep the parts in case someone wants to put their system back to stock.

[ncpetersc]

Looking for advice with the driveshaft. Thought I could remove straps on rear yoke and carrier mount then push forward, drop back of it then pull out entire thing from rear. I can’t push it forward enough to disengage trunion. Would jackingh up rear frame to extend suspension help? I don’t know that I can disassemble a different joint under there.

[ncpetersc]

Originally Posted by 68 P.O.S.

Why do you still have the TCS connected, and does it actually work still?? If it works, and correctly, it's not allowing the vac advance to come in just yet as designed. I would disconnect it and remove the wiring; it was an early, crude emissions thing and it provides no benefit to your engine and only stops your vac advance from working correctly. The only people who really still use the TCS are those doing a factory correct restore, or they just don't understand the TCS. Plug your vac advance can directly to manifold vac and you should see the idle increase. If not, you have a bad vac can. Now you need to find out how many degrees of advance your vac can provides. You want it to be around 10 degrees, or you'll probably get pinging if it has more than that.

After staring at the motor for a while and considered my options, I decided I wasn't going to be able to manually turn the thing without taking too much apart. So instead I decided to see what I could figure out just using the starter.

I pulled the coil wire from the distributor and pulled the #1 plug. It didn't take a whole lot of tries to get it to hit +4 and 0 degrees on the marking tab. Both of these positions the piston seemed to be TDC to me, could touch it with a screwdriver just inside the plug whole. Since the ring on the balancer slipping seemed a little less likely (though possible I am sure) I decided to go ahead and assume my balancer mark is fine, and has not slipped.

Call me lazy, I'll agree with you, and I'll just hope it's a safe assumption for now.

So, then I was going to try to take the TCS business out of the picture. But before I did I set the "initial" back down to 10deg or so, expecting the 22deg could be too much with vacuum advance about to be added. I initially just bypassed the solenoid but observed no additional vacuum. It turns out that I was set up with a "ported" vacuum port and the TCS solenoid.

I switched to using a manifold vac port, as suggested. My vac advance gives about 20 degrees it turns out. My dist must have moved a bit (it wasn't tightened yet) but I had 9 BTDC with the vacuum disconnected and 29 with it connected. Does this sound alright? I know 10 deg vac advance was mentioned, but I have certainly heard from others that they have around 20deg.

So I am currently thinking that it is very likely that I never had any vacuum advance before, and the TCS solenoid didn't function.

I rev'd up the engine and observed a total of about 52 degrees timing. I hope this is all in but I really hate rev'ing it that high under the hood for some reason, so I might have chickened out a little. I probably observed it about 3000rpm at least.

So now that I am on full manifold vacuum, I'm trying to figure out proper next steps. It seems like you can get varying opinions on this subject, and that's fine, just looking for ideas.

Personally, I have been convinced by some things I read that using a vacuum gauge to time and to tune the idle circuit is a good way. But I am not knowledgeable, maybe just gullible.

What's that definitive way to time and adjust idle to perfection?

[68 P.O.S.]

I would use a piston stop and do it right to be 100% sure. My luck, I would go with my assumption and end up grenading the engine �� But if you're comfortable with it, cool.

Yeah, it sounds like you probably never had any vacuum advance going on. Good job putting it on manifold vacuum. No, 20 degrees vacuum advance is way too much. Yes, other people run 20 degrees, likely on ported vacuum, because they probably don't understand it. Distributors in the 70's/80's had high vaccum advance to make up for the late timing they ran for emissions. You want 8-12 degrees vacuum advance..

The next step now that you're on manifold vacuum is to get an HEI. Haha.

Tuning with a vac gauge is a good idea, but timing with a vac gauge isn't. I suppose you could adjust initial timing for best vacuum and then use a timing light to fine tune the total advance.

On a carbed engine, there is no definitive way to adjust timing and idle to perfection, besides adding fuel injection. Too many environmental factors that change everyday. You can get a wideband and a carb calibration kit and get damn close.