73 F engine tuneup, timing and compression. (2 Viewers)

[MadMace]

Looks like it. Can you rotate the dizzy clockwise to retard it without the engine dying?

I went out to try and rotate the dizzy. I loosened the dizzy clamp and it won't budge. Does the engine have to be running for the dizzy to rotate? I was trying to rotate it with the engine off to get a feel for how it would rotate and it won't rotate.

 

[Pighead]

Well, you're gonna have to make it budge. Engine does not have to be running. Is there something in the way of it turning? (vacuum diaphragm bumping into something?) will it budge one way and not the other? did you loosen the clamp that goes around the base of the dizzy?

 

[MadMace]

I was able to get the dizzy to rotate--man, was it stubborn. After letting some Kroil soak in, it is free rotating.

I started her up and as I rotated clockwise her RPMs slowed, engine seemed to run smoother. As I continued to rotate, the engine died. For reference, in the pictures I posted earlier, if the "1" was at the 11 o'clock position to start, when the "1" was rotated to the 11:30 position the engine slowed in RPMS and seemed smoother, at the 12 o'clock position engine died. What does that tell those of you with experience?

 

[MadMace]

I think I really need to get a timing light and a laser tachometer because I am not sure at what RPM she is running. My understanding is that she needs to be running at 650 rpm for the test. Anybody have any particular suggestions for a timing light and or tachometer. The selection on amazon is quite large.

 

[Pighead]

You're going to have to turn your carb idle speed up as you retard the timing. It's a little dance we do, turn the dizzy, adjust the carb idle speed screw. Laser tach? no, a cheap little tach/dwell gauge with alligator clips and a moving needle, not digital will do. your FLAPS will have one on the shelf. You do need a timing light though, nothing fancy, but sturdy.

 

[Dizzy]

Don't twist that distributor housing up. It's shaft needs to keep engagement with the oil pump below.

 

[thebigredrocker]

I’ve got an digital innova timing light. It will give a RPM readout & dwell. No complaints yet. Comes with nice storage case.

 

[MadMace]

Made some good progress tonight. After getting a couple of new toys (timing light and vacuum gauge), I got the dizzy locked in at 7º BTDC, RPM right at 600. Vacuum at approx 13mmHg.

The more I read, 10º BTDC seems to be where I need to set it so I'll likely get that changed tomorrow.

I have a lot to learn about vacuum. 13mmHg is the max I was able to get by adjusting the idle mixture adjusting screw with the timing and RPMs set at 7º BTDC and 600RPM.

Took her for a drive and she is definitely running cooler--and this was taking her up some pretty steep hills here in the hill country of Texas.

Thank you very much to all who shared their knowledge

 

[thebigredrocker]

Was your engine well warmed up when you took the vacuum reading? If so, that seems way low. Was the needle steady?

My 71 idles at 18.5hg once warmed up.

 

[MadMace]

Was your engine well warmed up when you took the vacuum reading? If so, that seems way low. Was the needle steady?

My 71 idles at 18.5hg once warmed up.

Yes, the engine was warmed up. The needle was very steady, not bouncing around at all. I was checking my pressure at the fitting located on the manifold where the hose to the dizzy attaches--is their another place to check it?

Marion has had all of her smog equipment disconnected. I already found one vacuum hose that was left dangling with a screw screwed into one end to cap it off--this hose originated at the same fitting the hose to the dizzy comes off of. Of course, I took that hose off and capped it off.

 

[thebigredrocker]

Yep manifold vac is where you want to hook up your gauge. Might pick up some “go no-go” feelers. Lisle make a set. They are handy for checking lash while your engine is running. Pin_head has mentioned their usefulness a few times.

If your dissy advance/retard is hooked into manifold vac, I’m certain that is incorrect. If your dissy is a stock 73, the points plate will rotate clockwise when suction is applied. If that’s what you have, FJ40Jim recommends capping the vac lines, set timing at 10°. Apparently the retard dissy’s run fine just using the mechanical advance created by the internal weights.

 

[MadMace]

Yep manifold vac is where you want to hook up your gauge. Might pick up some “go no-go” feelers. Lisle make a set. They are handy for checking lash while your engine is running. Pin_head has mentioned their usefulness a few times.

If your dissy advance/retard is hooked into manifold vac, I’m certain that is incorrect. If your dissy is a stock 73, the points plate will rotate clockwise when suction is applied. If that’s what you have, FJ40Jim recommends capping the vac lines, set timing at 10°. Apparently the retard dissy’s run fine just using the mechanical advance created by the internal weights.

The picture below shows what my dissy is connected to. What I'm going to do is cap the dissy and the manifold vac and set to 10º BTDC. I'll set my timing light to "3" to advance it to 10º. I've read enough to know that whatever you and FJ40Jim say should be closely paid attention to and done. Although mine is a '74, it is a late '73 with an "F" dissy.

 

[73FJ40]

The picture below shows what my dissy is connected to. What I'm going to do is cap the dissy and the manifold vac and set to 10º BTDC. I'll set my timing light to "3" to advance it to 10º. I've read enough to know that whatever you and FJ40Jim say should be closely paid attention to and done. Although mine is a '74, it is a late '73 with an "F" dissy.

View attachment 1719472

View attachment 1719475

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That distributor is vacuum advance. The vacuum source is supposed to be "ported vacuum", which on my non USA carb, is located just forward of the idle mixture screw, on the head side of the carb.

 

[MadMace]

That distributor is vacuum advance. The vacuum source is supposed to be "ported vacuum", which on my non USA carb, is located just forward of the idle mixture screw, on the head side of the carb.

The carb on Marion is not her original carb. The PO did have the original carb and I see exactly the ported vacuum port your speaking of, at least I think I do--I included a picture below of the original carb.

The carb that is installed does not have that ported vacuum nipple in that location. It has a diaphragm subassembly that I am pretty sure is not hooked up correctly--I also included a picture below.

I currently have Marion timed at 10º BTDC. I have capped of the manifold vacuum port and the port on the dissy. Should I just leave them capped?

This is Marion's original carb that needs to be rebuilt.

Current carb in Marion

 

[Adog]

That distributor is vacuum advance. The vacuum source is supposed to be "ported vacuum", which on my non USA carb, is located just forward of the idle mixture screw, on the head side of the carb.

I have a vacuum advance dizzy on 1977 2F with Holley carb. The dizzy vacuum line is hooked to the intake manifold. There is a plugged off port on the front of the Holley that does not get the vacuum that the intake manifold does, I have put the gauge on it before and it seemed not much vacuum at idle but has vacuum when engine turns higher Rpms. Is that the port you’re talking about? Maybe I will try that tomorrow.

 

[acoleFJ80]

THANKS MUD! This was helpful....

 

[73FJ40]

@Adog

I have a vacuum advance dizzy on 1977 2F with Holley carb. The dizzy vacuum line is hooked to the intake manifold. There is a plugged off port on the front of the Holley that does not get the vacuum that the intake manifold does, I have put the gauge on it before and it seemed not much vacuum at idle but has vacuum when engine turns higher Rpms. Is that the port you’re talking about? Maybe I will try that tomorrow.

I don't know Holley carbs. I was referring to my OEM carb, which has ported vacuum to connect to an OEM vacuum advance distributor.