LOW VACUUM

[Albert P.]

Re: LOW VACUUM

I didn't degree the cam when I put it back in, reused my original cam; just aligned the dots on the crank and cam when I installed it. I just reinstalled a manifold gasket, waiting for RTV to set, set timing at 12* btdc, and put new carb gasket on; waitng for RTV to set before starting. Thanks.

[William C.]

Re: LOW VACUUM

Was the carb rebuilt when you had the engine down?

[Albert P.]

Re: LOW VACUUM

No, but what I did today was rebuild it as it was laying around for a few months.

[Albert P.]

Re: LOW VACUUM

I got car started today and it ran for longer than 2 minutes; static timing was set at 12* btdc; vacuum varies though between 6-10" hg and I cant't get revs up past about 600 RPM; I did notice that the vacuum advance has no effect on the timing; any ideas?

[Albert P.]

Re: LOW VACUUM

Finally got car to idle at about 600 rpm with vacuum at 10-12" hg; I adjusted static timing to 14*btdc;Readjusted valves using Hinckley/Williams procedure; what happens is after running a while vacuum drops off to zero then stalls; I also noticed some black liquid droppings on floor from bottom of muffler; could this be a possible blocked muffler causing this?

[Albert P.]

Re: LOW VACUUM

It's not a blocked muffler; still have same problem; runs erratically for a few minutes with 10-12" hg; then, vacuum starts lowering, then stalls. It seems to start right up when I suck on the vacuum advance and block it off at full advance but then does the same as described above.

[Michael H.]

Re: LOW VACUUM

Garth,

It's beginning to sound like you have a very weak set of cent advance springs in the distributor and the actual timing is still well below specs because the weights are coming out way before they should. Your timing setting of 12* may actually only be 0* because the difference is the fact that the cantrifugal advance is not at reas, or zero, when you set the timing. I had a feeling there was some problem with this in my first response to you several days ago when I recommended pulling the timing up higher than it was actually supposed to be. Give that dist another yank and set it to about 20 deg and see what happens.

One way to insure that you are setting the timing with the cent adv completely relaxed is if you use a rubber band to hold the weights in the zero, or "in" position. Eventually, you will have to check the adv springs to see if they are indeed original or some aftermarket soft springs. It sounds like they are allowing the cant advance to come in way too early. Let us know how it runs set at around 20*, just for a test.

The black drops coming out of the mufflers would probablt be condensation mixed with the black residue in the muffler. Once the engine gets up to temp, this should stop.

[Albert P.]

Re: LOW VACUUM

Thanks, I'll try that tonight when I get home; I did notice while I was in the distributor one of the springs on the cent advance was extremely light while the other was stiffer.

[Albert P.]

Re: LOW VACUUM

Michael: note that I've been setting the timing statically by aligning the tdc mark on the damper with the degree marks on the engine then rotating the distributor till the points just open.

[Michael H.]

Re: LOW VACUUM

Ok, that's the way to get it close for initial fire. Should have you withi a few deg.

One thing that just occured to me is, do you know for sure that you have a matched set for the balancer and the timing chain cover? If one or the other happens to be from a 69 or later, the mark or timing deg plate may be off by 10 degrees which could possibly be part of the problem. You may be setting the timing at 10* but it may actually be at 0. (or possibly the other way around, depending on which piece is incorrect) When you first assembled the short block, did you happen to check and see if the timing marks lined up properly when #1 piston was at TDC?

I remember that after I suggested that you bump the timing up several deg, you said the engine seemed to run a little better. That's why I keep thinkng there's some problem with the cent adv unit or the initial timing setting. There are a number of things that cause the problem that you have but these are the easiest to check first.

[Albert P.]

Re: LOW VACUUM

Balancer and timing cover are matched;timing marks line up when #1 at tdc. thanks.

[Albert P.]

Re: LOW VACUUM

Now that you mention the centrifugal advance, I did drop the distributor and shattered the rotor at one point; the plate looked a bit bent but the weights seemed that they were free to move.

[Albert P.]

Re: LOW VACUUM

Michael: I think you are on to something; I statically set timing to 18-20* btdc; car started and ran around 100rpm, a bit erratic , but ran for a while, a few minutes, before stalling out; what do you think I should look for next? thanks.

[Michael H.]

Re: LOW VACUUM

I'm running out of ideas here but it sound encouraging that it is making some progress. (did you mean 1000 RPM, not 100?) Can you tell if it died rich or lean? Any black smoke out the exhaust? Does it have fuel in the carburetor after it dies? Sounds like it won't restart after it dies?

If you didn't already tell us that you are certain the cam was indexed properly, I would have wondered about cam timing but....

So difficult to diagnose over the internet. Wish I could be of more help.

[Albert P.]

Re: LOW VACUUM

Yes, it was 1000 rpm; it does have fuel when it dies, squirters squirt; after it dies I can restart right away. thanks.