car stals out

[mag2555]

I would do three things that take a total of 30 minutes.

1) confirm that once the motor is revved up and the throttle is let off that the voltage at the battery is not below 13.5 volts .
I have seen regulators go bad where they will drop down to 9 volts and then rise back up slowly, but by then it's too late.

2) confirm with a timing light that when the throttle is released that the base timing is still there and had not gone below the base setting.

3) yank out all the plugs and remove the cap and spin the Crank back & forth to check for slop in the timing chain.

If all of these check out good then I would conclude that a Intake gasket is bad.

[chevy art]

hey mag 2555 i believe your assessment of thi problem is exactly the way i was looking at this problem. checking the timing as the car stall out is a great idea and your final conclusion is one of the things my buddy brought up at the very beginning about bad intake gasket . any suggestions on how to check for a bad intake gasket short of taking the intake manifold off. thanks Art in NY

[mag2555]

Also I have had power brake boosters that where starting to go bad do that exact same thing when coming to a stop now that I think back!

Unhook and cap its vacuum source and see if things change.

[chevy art]

hey mag 2555 i dont understand the part of disconnecting the brake thing. he has some hi tech hydra boost brakes on car and i think they run off belts (is that possible) thanks art in ny

[mag2555]

With hydro boost forget what I posted.

[V12MECH]

So the p/b booster is out, so carefully spray some carb cleaner around intake manifold where it bolts to heads , some like to use propane torch, unlit of course , while you work throttle to keep running, and see if it will idle, this is assuming the leak is on topside of casting.

[chevy art]

my buddies carb has the small vacuum port for dist. vacuum advance coming out of metering block and he says this is where the vacuum advance goes, my carb has that small vacuum port on the base plate of the holley carb. what is the difference of these two vacuum pots and are they both OK to use for vacuum advance for distributor thanks Art

[HQM383]

my buddies carb has the small vacuum port for dist. vacuum advance coming out of metering block and he says this is where the vacuum advance goes, my carb has that small vacuum port on the base plate of the holley carb. what is the difference of these two vacuum pots and are they both OK to use for vacuum advance for distributor thanks Art

Side of metering block definitely ported. Starts pulling vacuum only after a predetermined amount of throttle is opened. You will see the extra hole in one of the primary throttle bores other than transfer slots and idle fuel holes. On yours, you will have to put a pic up or at least model number so someone might know if it’s ported or direct manifold vacuum.

Which one to use? Trial and error for modified engines/vehicles is the best way to determine. While writing this though I’m picturing the all in fight scene in Anchorman. Something similar may ensue.

Pic below
Larger hole on right in throttle bore is idle feed. Vertical slot is of course transition slot. Small hole just below blade is ported vacuum feed. Throttle has to be a little less open than this to start drawing vac. Black horizontal sharpie line is where blade is fully closed pre idle speed set (should end up a little higher set correctly). Two channels bottom right on baseplate lead to baseplate fittings - top is exposed to full engine vacuum all the time. Bottom has a hole drilled to intersect with ported hole below throttle blade. Yours could be configured either way.

[skinny z]

my buddies carb has the small vacuum port for dist. vacuum advance coming out of metering block and he says this is where the vacuum advance goes, my carb has that small vacuum port on the base plate of the holley carb. what is the difference of these two vacuum pots and are they both OK to use for vacuum advance for distributor thanks Art

The fitting on the metering block is ported which is OK to use for vacuum advance.
The fitting on the base plate (a small one similar to the metering block fitting size) is full manifold vacuum. This is also OK to use for vacuum advance.

Two things worth mentioning here: One is that with so many variations of Holley carbs out there, it's always best to use a vacuum gauge to determine exactly which vacuum source it is.
The other is that the tuning procedure between the two sources are different. The easiest to work with is ported vacuum. It doesn't come into play at idle so the idle timing is whatever the set initial advance is.

Full manifold vacuum can be problematic depending on the engine's characteristics. I prefer full manifold vacuum for my combination however it's taken an adjustable vacuum can (which should be part of the plan regardless of the vacuum source) as well as a limiting plate in the distributor.

Art, if it were me tuning, I'd start with ported vacuum. That should connected to where your buddy has indicated but do your a favour and test the port.

[chevy art]

thanks HQM and skinny for your replies today. ive been around Holley carbs since the early 1960s and really never understood vacuum advance, never even used vacuum advance distributors(always centrifigal advance).always knew what the ported vacuum was and what manifold vacuum was but i never really understood it. now i do know due to you guys explanation. also thanks to all other members who helped with this problem, still not solved yet, but i will chime in as to what the problem was when we find and fix it. Art in NY

[Geoff2]

GM used MVA in production until emissions forced the useless PVA.

More on MVA:

www.hotrodders.com/forum/vacuum-advance ... 47495.html

Scroll down to post #6.

[Ks Fats]

The statement "ran fine till he took the motor apart" opens up a lot of scenarios, incorrect intake gaskets, valve adjustment, cam timing etc. all come to mind. Rather than chasing an unknown work with what you do know; check the compression and do a leakdown before you start throwing parts at it.

[skinny z]

The statement "ran fine till he took the motor apart" opens up a lot of scenarios, incorrect intake gaskets, valve adjustment, cam timing etc. all come to mind. Rather than chasing an unknown work with what you do know; check the compression and do a leakdown before you start throwing parts at it.

Seeing as the engine has been apart, it could be any number of things.

I'm with you on that one.