Slop in original timing chain on 78k 430

My 430 runs like that too, a piece of vacuum hose used as a bushing. No power timing, initial 2 BTDC, Manifold Vacuum to VA. Runs great.

 

Also check that the outer ring on the balancer has not slipped. Had that happen on 2 stock 455 balancers over the years. If it did then the timing will not be accurate.

 

Is your ported vacuum source plugged so that there's no--or reduced--vacuum?

Ported and manifold vacuum should be identical above idle.

 

Yes I plugged the ported. Took it to the local show yesterday and I'm still flabbergasted by the improvement! Hasn't run this well in over 30 years! Of course I've heard that they run fantastic just before they fly apart jk

 

The point I was trying to make is that the car shouldn't RUN any different connected to ported, or connected to manifold vacuum. It will IDLE different, but above idle the two vacuum sources should be the same.

Therefore, if switching from ported to manifold makes the car run better (not just idle differently)...my best guess is that the carburetor passages for the ported vacuum nipple are damaged/plugged, or leaking vacuum. I've seen folks use the wrong carb gasket during a rebuild, that blocks a vacuum passage or perhaps allows an air leak into the vacuum passage. I've seen hardened filth plug the vacuum passages. You need to inspect/clean out the carb passage(s) so that you have a proper vacuum signal through the ported nipple.

 

Thanks That is definitely a possibility. I checked both ports with vacuum gauge and they seemed strong just no vacuum at idle on ported. I probably should have bought the adjustable va. Carburetor rebuild kit from Cliff is about half way down my to do list. I'm sure accelerator pump is due. I'm just happy it is so fun to drive right now A slight brake torque burn out does not work with ported advance. But sure lights em up with manifold!

 

Yes. Initial is set below 0* so it doesn't ping. Probably lots of carbon buildup after 50+ years.

 

Pure speculation but I wonder if the cam is flat and you have excessive cylinder pressure as a result. Likely that motor is no where near the advertised 10.25:1, it should happily run on pump gas.

 

Possibly but it sure does run smooth now...... I was thinking maybe this motor just happened to have more compression and horse power than most built that year.

 

Apparently you never met Tom, or went for a ride with him.

 

O Ya, WOT dude, my kind of guy.

 

Usually they will idle and run smooth but fall apart at high rpm with a flat xam

 

Seems to stay strong at high rpm but seems to shift early. I should add a tach and other gauges. I also suspect she runs a bit warmer than 180*. Lots on the should do list.

 

How timely this post is for me. I've had all my questions and concerns answered here today.
One simple change to make tonight and hopefully my Buick will be running the way I want it to be.
If it isn't running as expected it looks like I'll be changing over to the manifold vacuum. I've found some vacuum leaks,
addressed and fixed. But was still left scratching my head and wondering about this and that, until I read this post.
Too may issues to list in here, I've ironed a few out this week but still wondering over others. You guys have helped
tremendously! I will have a few more things to check in the spring when I get the Buick out of storage, but for this fall
I'm happy where it's at or at least going to be.
Thanks guys
Dvae

 

So I switched from ported vacuum to manifold vacuum tonight. Engine warmed up, I checked my timing, it's now sitting at 12* advanced idling at 550.
Is this to much advance??? Once warmed up it's running great in my opinion. It takes a bit to warm up without the choke working at 12 *C weather here in southwestern Canada. But once the engine was hot it seemed to run pretty good to me. This is a freshly rebuilt engine and the shop had the vacuum advance ported, I ran it that way all summer but it felt sluggish to me. It feels more responsive on the manifold. I'm just curious about the amount of advance.

Thanks

 

I think a lot of these engines came with a spec of 10 degrees BTDC for initial timing. If you are saying you are 12 degrees before TDC at 550 RPM, that's close.

Drivability and lack of pre-ignition are the ultimate tests. Also make sure the Temperature in the engine stays where it should be (when it's hotter out, LOL).

 

Hey Larry,
I did set the initial timing at 0*(TDC) with the vacuum advance disconnected and plugged. The vacuum advance is working and the idle was dialed back once connected. I failed to mention that.
I have read and printed out your post about adding the 30* mark (1.75"), I plan on adding the mark on the balancer in the spring once I get the Buick out of storage and then checking the total vacuum advance. Who knows maybe I'll get it done before I put the car into storage. Once the 30* timing mark is added it won't take long to check the total advance. By the way, loads of info on that post, loved it.
I do know the vacuum advance was changed years ago by a good friend who pasted away a few years back. Before my friend helped me with the distributor (about four years ago) I use to get pinging but since we worked on the distributor, no more pre-ignition.
I don't know what my vacuum is, you mention 16", I don't think I have a way to check it.
With the vacuum advance ported for the the summer the engine did run a few degrees hotter this year than it has in the past, I figured it was due to the fresh rebuild. I use to have a 180* thermostat in it, this year a found a 190* thermostat. It never use to go over 195* no matter how hot it was here, this year it was pretty steady at 198* and one hot day it got up to 201* but cooled back down to 195* once I got to town and was cruising around at 1500 RPM. After reading some of the posts on here I thought it may have been running warmer this summer because the vacuum advance was ported and going back to 0* at idle. I don't know, I may be stressing over nothing.
So what I'm getting from you Larry is that the timing at idle isn't to far advanced but maybe a little shy. I was only at 4* before I eliminated a vacuum leak when hooked up to the manifold and I noticed a difference in performance with that over ported.