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I dont have the original equipment but it looks like that might be the vaccum secondary actuator. Is it fuel leaking from the linkage at the bottom or is it a vacuum leak from the diaphram at the top? Either way I cant see it causing the issue you describe other than a fire hazard if its leaking fuel. If the linkage is sticking it might be causing the secondaries to stick open which would cause starting/running issues.
Last edited by panteraturbo
...If looks as if The 'Choke' System has been completely removed!? If this is so; ONE of those 5-6 holes that are left at the carb body, will be the 'Vacuum Source' for the heat stove to the chokes' coil. If you do not realize and plug this hole(put sealer on an appropriate size screw and screw it in), it will be a great vacuum leak!! The picture IS of the vacuum secondary canister, if you hear air leaking here, you must have a blown diaphram. It will be leaking More air as the revs go up and the primaries develope more vacuum to this canister. That is why I think you are hearing the Vacuum leak at the unplugged choke vac. source. I see a few pictures of these Holleys with the chokes removed, but the vacuum orifice is never plugged! Check it out again...
Judging from the photo I would say that your hard start problem could simply be a low fuel pressure situauation combined with no thermal protection to the carburetor.

First. The Pantera fuel supply system is not good. I wanna say that it suck but sometimes it won't.

The pickup tube and a single mechanical pump do not pressurize the carb enough when the engine is hot and is shut off.

What I mean is that the heat rises out of the warm engine and boils the fuel out of the carb. If not all at least to the point where the level is too low to flow into the idle circuit.

There isn't enough residual fuel under pressure to keep the bowls full enough.

At this point even if you suspected this and looked at the operation of the carb, you would get some fuel squirting out of the pump jets.
You would surmise that the carb was ok.
Actually if you opened the bowl level screw at this point (when it's hard to start) the bowls would be low or empty.

This perculating situation (actually like a coffee pot sometimes) will cause a momentary vapor lock in the fuel supply line.

I'll bet you a nickel too that if you checked fuel pressure it would be low too. Probably 2-1/2 or 3 psi. The vapor lock for a stock pump like that is hard to overcome immediately. You have to crank the engine quite a bit sometimes.

The way the stock Pantera pickup and fuel line is routed the pump has a long tube to draw on to start the fuel flow.

Fix? Use a phenolitic carb gasket or assembly.
Next replace the stock fuel pump with a decent mechanical pump like a Holley with a 7.5psi output.

Check your fuel level in the bowls HOT. Please don't set yourself on fire either.

If the problem persisits you may need to install an additional booster pump like a Holley electrical fuel pump.

Be advised that these things don't like to draw uphill either and they like to be located down towards the bottom of the tank.

Ideally they should draw from the bottom of the tank like the drain plug location. Probably even the stock mechanical pump would work better drawing from there also.

What you have isn't a defect per se. It is just a figment of the '70s engine operation. It was not unusual at all to have to crank the engine a bunch to start it hot back then.

A lot of this stuff never was "corrected" on US cars until FI was introduced here.

The idea of using the electric fuel pump on the pickup isn't bad either but make sure you limit the fuel pressure at the carb to 7-1/2psi max.
As PantertaTurbo said thats the vacuum secondary actuator valve and if its leaking vacuum it will only affect when the secondaries (your second set of 2 barrels)open at speed. Whats "leaking" from this? There shouldn't be any liquid as it deals with air only no fuel. If its leaking vacuum with the car off thats not what is leaking (as Marlin said).

I think Panteradoug is right on with the vapor lock solution. When this happens again do like Panteradoug suggests and crack (just CRACK) the foat bowl level screw. In your picture it is just off to the left of the vacuum valve in the middle (you can just make out the round circle of the screw in the pic). There are two; one one each end of the carb on the side of the float bowls on the throttle cable side of the carbs. Have plenty of rags around just in case. Open this screw slowly. If fuel spews out the float levels are too high and your carb is flooding the engine (not likely). If no fuel flows out at all you might have the vapor lock situation (likely) but your floats could also be too low (not so likely). Vapor lock can be time consuming but usually just amounts to keeping the fuel as cool as possible when the engine is shut down. Panteradoug pretty much covered all that well.

Last edited by fahrenheit351
Thanks guys. It seems some liquid is coming from that bottom screw area of the vacuum secondary (that is where it is wet anyway, not on the post up to the vacuum secondary). If it comes out again, I will photo it. Randy (my Group 4 bud) came by and checked the float level just after starting up and it was ok with just a slight amount coming out (but then the engine was not real hot). This slight liquid (I suppose gas) might be unrelated to my starting problem, but I just happened to notice it the same time.

Walk me through how to test the fuel bowl level when the engine is hot and hard to restart. Would I slightly unscrew the bowl level screw with or without the engine running?

Also, I took another photo below, and it has a fuel pressure guage. After shutting the engine down getting prepared to start it again, should there be any pressure read on that guage while not running? Then if the car starts what should that guage read?

This is just all so odd...I never had restarting problems before, but all of a sudden, there you go.



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Last edited by does200
I think it is poss that it could be coming from there although that would have to be unusual I would think.

When it won't start just open one of those level screws (righty tighty lefty loosey). Car should not be running (that can get real messy). Put a rag under it so you don't get fuel all over. Crack it open until fuel comes out. Check the flow out. If the floats for that bowl are set properly once the screw is all the way out and removed only a very little amount of fuel will come out. Too much equals wrong float level. None coming out could be your vapor lock. Since you said that the float level is set correctly when the car is cold it would stand to reason that if this changes when it is hot you have fuel boiling or purcolating in the carb. On this carb the level screws are right next to each of the fuel inlets that you can see in the pic. How long have you had the car? Reason I ask is the weather in So Cal has been warm lately. If this is your first time driving it in the summer this may be an issue the car has always had but is only now showing itself to you due to the heat.

As for fuel pressure you're not talking much. Your guage reads a max of 15 lbs and bet if you're half that you're high but don't know exact numbers. There should be no pressure at this gauge until you have turned on your electric fuel pump or started your car and gotten the mechanical pump going.

PM me and I'll give you my cell phone number if you want. It might be easier to walk you through it although it isn't difficult.

Just consider that when the engine won't start it is one of only two things 1)no spark 2)no fuel.

If you have a vacuum leak somewhere, it is not keeping the engine from starting...idle up yes, but not a starting problem.

Don't forget what was said about the solid state ignitions. One minute it won't start, then it cools down and then it will start. This is true.

Also, if you leave the ignition key on the coil gets hot enough to boil out the oil in the coil.
Don't intentionally leave it on without the car running.

If you need to have it on to work on the car, pull the coil horseshoe off.
Thanks for the tips. I think it may be flooding for some reason after shutdown. I don't think it is the vapor lock thing, because even after only 5 minutes or so of slight warm up, if I shut down and then try to restart, it will not start again. However, if I put it to the floor it turns over no problem, which makes me think flooding. I checked the floats and they seem level. It was interesting doing the floats though because it seems that it is the "nut" itself that does the adjustment, and screwing in the top "bolt" just secures the new nut setting. I originally thought the nut going in and out adjusted the float, but apparently not (see link below). So, whatever the issue is I will leave it alone and just floor the pedal to start it. Drove it around the hood, but then noticed gum shoe riding around and then turning in the middle of the street to come my way, so I headed for the garage with quick open and shut bat mobile style.
That's backwards.

The "nut" is a lock nut that keeps the screw from moving. If you do not tighten the lock nut (technically a "jamb" nut) the the float screw is free to move. Its the screw that adjusts the floats....

As for flooring it before starting that opens the butterflies (metal doors in the carb) allowing more air flow. This is why it works on a flooded carb because it leans out the air/fuel ratio.

But hey if it works it works
According to my Haynes Holley Carb Manual, the nut adjusts the float level while the screw does the locking. I know it is opposite of anything I have ever seen but my personal experience has shown this to be strange, but true. Photos 7A.7 and 7B.11 both describe the lock screw and adjustment nut.


Originally posted by Fahrenheit351:
That's backwards.

The "nut" is a lock nut that keeps the screw from moving. If you do not tighten the lock nut (technically a "jamb" nut) the the float screw is free to move. Its the screw that adjusts the floats....

As for flooring it before starting that opens the butterflies (metal doors in the carb) allowing more air flow. This is why it works on a flooded carb because it leans out the air/fuel ratio.

But hey if it works it works
Actually both of you guys are right depending on which carb you are speaking of.

On the original factory Ford 427 with 2-4v carbs it had a different float ajusting screw/nut arrangement then is currently produced.

On those carbs the nut is a lock nut and the screw is the adjustment device.

The current Holley carb set up (since the center floats came in around 1968) the nut is the adjuster and the screw locks the ajustment in place.

They are different Holley needle seat assemblies, different part numbers.

The 427 style is actually kind of rare.
I agree, at least with my Holley I believe it is the nut that adjusts the float and the screw that locks it. Operationally it is kind of hard to imagine how it is constructed with the nut (not me Smiler) doing the adjusting, as it seems logical that the nut would only have a tightening function as we are used to a nut doing. But it is true, because I can loosen that screw slightly which then enables the nut free to spin on its own for several rotations with no grabbing functions onto the nut what so ever. I learn something new almost daily playing on these cars, and in this instance was glad I didn't blow myself up playing with gas.
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