Proper direction for timing tape on HB

[Screaming Metal]

Only things attached to vacuum are PCV and I also added a power brake Master which is attached to the front carb vacuum port since no port on manifold exists (all new hose and fittings, tight)

Just because they're tight doesn't mean they're not leaking. All manifolds have places to screw nipples in and get vaccum....A vaccum tree is as close as your nearest parts house....

 

[TriodeLuvr]

Vacuum line was NOT plugged into vacuum advance for the 1st test. 2nd test it was plugged in. Same readings though throughout.

Do you mean the amount of advance at idle doesn't change when you connect the vacuum hose? If that's true, you're probably plugged into the timed vacuum port, not the port that provides constant manifold vacuum.

I'm thrown by the fact that it idles and accelerates better with 4° advance than with 12°. Can you measure advance again with the idle RPM reduced? I know it's cam-dependent, but my 350/TH400 idles at 750-800 in Park, about 600 in Drive. 1200 RPM might be bringing in the mechanical advance, although that doesn't explain why it wants a reduced advance setting.

Do the idle mixture screws adjust properly after the engine is fully warm? IMO, that will tell you more than a vacuum gauge.

Jack

 

[Screaming Metal]

OK, lets have a recap here. A T of unknown quality. Motor has timing set a 4 Degrees BTDC. We don't know if the HB is spun or not, if the timing is accurate. Has a piston stop been used to establish TDC????
Its a dual quad motor. Said it was smooth at 4. At 12 it idled up, which its laboring less. It it doesn't idle smooth at 12, back it down to between 8 and 10. If it still isn't idling smooth, I bet it has a mild cam in it. Can't tell that unless you pull the timing cover and get the #'s off the end of the cam.
One question....You DO know how to set the idle on a dual quad setup, right?
We know very little about this....he's added headers and a power brake booster. Vac. adv. works when he sucks on the hose, but not when its hooked up.
....I gotta go fix a motor....

 

[cptn60]

If it has an HEI check for sticking or stuck mechanical advance weights. Used to be fairly common.

 

[Robert]

Sitting on the fence here drinking a cup of coffee, polluting the air with my stogie....yes, somethings fishy here. Are you plugging in to ported vaccum? Is your PCV plugged into the base of your carb, or a big manifold fitting?

Heres a couple of more questions that need to be answered. Idling, does the motor idle smoothly, or is it choppy and/or loping? You suck on the vaccum line going to the distr. can on the distributor, it moves, correct? Suck on the line, make it move, then plug it off with your finger to see if it holds. Does it?
I think he needs to grab a can of carb cleaner and go on a vaccum hunt....I'm with Keeper, it should've idled up enough to have to reset the Idle Speed Screw.
And Yes, A vaccum gauge is in order....

There are zero vacuum outlets on my manifold, all vaccum derived from carb ports.

When I changed timing from 4 BTDC to 12 BTDC it did idle up a bit.

Idle is now choppy and loping at 12 BTDC, whereas at 4 BTDC it was smoother.

Used mouth suck technique then apply tongue to hose end on new hose to distributor vacuum - - yes, it moved internal 'strib plate and held vacuum well.

Then removed old vacuum hose from carb to 'strib and held wet finger over one end and sucked on other then applied tongue, it held vacuum well.

Photos attached here of my PCV routing, one ~4 foot long braided aircraft hose tees off and goes under firewall to demodulator? on THM400 tranny.

Will make another separate post on my brake and tranny cooler.

 

[Robert]

If it has an HEI check for sticking or stuck mechanical advance weights. Used to be fairly common.

Yes, already checked it with top off (top cap over weights) and weights seem to be moving smoothly.

 

[Robert]

OK, lets have a recap here. A T of unknown quality. Motor has timing set a 4 Degrees BTDC. We don't know if the HB is spun or not, if the timing is accurate. Has a piston stop been used to establish TDC????
Its a dual quad motor. Said it was smooth at 4. At 12 it idled up, which its laboring less. It it doesn't idle smooth at 12, back it down to between 8 and 10. If it still isn't idling smooth, I bet it has a mild cam in it. Can't tell that unless you pull the timing cover and get the #'s off the end of the cam.
One question....You DO know how to set the idle on a dual quad setup, right?
We know very little about this....he's added headers and a power brake booster. Vac. adv. works when he sucks on the hose, but not when its hooked up.
....I gotta go fix a motor....

One question....You DO know how to set the idle on a dual quad setup, right?

It's a back and forth thingy - - you adjust one carb - - then you go back and adjust the other to get highest RPM's at idle. Cannot be heavy handed, it's a delicate operation.

 

[Screaming Metal]

If it has an HEI check for sticking or stuck mechanical advance weights. Used to be fairly common.

I love the Hell outta that avatar! Hahaha.....

 

[Screaming Metal]

Well, I guess since we're moving on here, that the overheating problem was cured....or the original gauge was off.

 

[Keeper]

Can you try something.

Let the car idle, then spray your vacuum connections with carb cleaner. (or an un lit propane torch) and see if the idle rises. That will eliminate those locations from having a vacuum leak.