302 bogging issues.

Well guys, I still haven't found the solution to the issue of my 302 bogging down when trying to kick in the 4bbl. I've had mechanics work on it and still not fixed. I have a new Edelbrock 600 on it. Before that it had a new Holley 600 and was doing the same thing. Fuel pressure good, timings right. Everything's new. Even swapped out the carb for a "known" good Holley carb and still bogging. Runs good at idle and revs good while in park. Drives great at normal throttle. But kick in the 4bbl and all hell breaks loose. Any suggestions?

Thanks

 

When you say the fuel pressure is good, is it being monitored throughout the RPM range? Fuel lines on these cars can be crushed just behind the drivers side front fender due to misplacing a floor jack. It might run OK until you put it under a load, at which point the engine is not getting sufficient fuel flow. A clogged filter or any restriction in the fuel system feeding the carb can have the same effect.

It becomes a process of elimination.

 

Is it bogging only when the secondaries are opening? Or does it bog immediately when the pedal is mashed to the floor? If other carbs did the same thing, I would suspect ignition timing or major vacuum leak introduced when the throttle is wide open.

 

That's a thought. Something I hadn't thought of nor had anyone else that's looked at it. All lines are new with the exception of the main steel line running the length of the body. I could bypass that steel line with a rubber fuel line at least on a temporary basis to see if that's the culprit. I do remember after installing my new carb that it got trash in it from the steel line. That line could be restricted with old trash and rust. I haven't monitored the fuel pressure through the RPM range. Thanks for the input.

 

The timing is set and there are no vacuum leaks. It runs fine until the secondaries are applied. Then it is as if it is running out of gas.

 

What is the timing curve at? What springs are in the distributor? Does it have the original balancer?

 

Not sure on the timing. That was set at the last shop it was in. The distributor is new as is everything on the motor. The 302 is a reman from RockAuto and the balancer was included.

 

Agreed...

WOT is a giant vacuum leak that's supposed to be pulling fuel along with the incoming air... No fuel you just have the vacuum leak, so it falls on it's face... At that point any leak (if there was one) on the base plate, intake lines, PCV, etc is insignificant...

 

Is the fuel filter new?

 

In drive, does it bog immediately upon opening or rev momentarily then bog?

If it bogs after a couple seconds, maybe it is fuel supply. Did you check the filter at the sending unit?

Micah

 

These guys ask good questions about EXACTLY when the bog comes into play. Just relying with "when the secondaries open up" is far too vague as it's tough to know exactly when they are activating unless you have a go-pro mounted in the engine bay to actually see them opening. If in fact it is occurring when they open it would be easy to verify by not allowing them to open. Bog disappears?.. you know where the problem lies. If not?.. start looking elsewhere. Takes one hell of a lot of sudden secondary opening to bog a motor excessively as you describe and they usually just fall flat on power but still eventually rev to full rpm just fine.

They are also eluding to the fact that your balancer pointer may be incorrectly set up for the application and spark timing is not actually set where you/they think it is. Ford was notorius for changing things just for the sake of changing things. At least 3 different possibilities and Tom probably remembers the when and wherefores of all that nonsensical hubbub. lol

And Micah makes another good point but I doubt that unless your fuel bowl settings are WAY off(which unloads the emulsion holes and reduces bowl fuel reserves) your little motor is consuming all that fuel bowl reserve in as little as 1 or 2 seconds. 500 or 600 horsepower big block?.. maybe. Given the fact that it did the same thing with 2 different carbs.. I think you are barking up the wrong tree in another entirely different forest altogether.

If you want serious help tuning it I will be off work for a few days and could help you dial it in but we need MUCH more specific and detailed tuning information. A video of the occurrence would be the best to eliminate much time texting and loss of interpretation.

 

It does not bog until I try to kick in the 4bbl. Normal acceleration it runs fine. Gets up and goes.

 

I'm going to check off a thing or two to start with. (Look for a crushed fuel line)(blow out the original steel fuel line and check for trash or obstruction) then go from there. When it bogs down, it does not get over it and then go on like it should. It continues bogging until I let off the gas. It's like it doesn't know what it's supposed to do when it's floored. It's totally confused at that point.

 

As others have mentioned it really should not bog immediately on WOT, there should be enough fuel in the carb bowl to at least start to accelerate... Also unless you're seeing the carb secondaries open you don't really know when/if they are opening at all... Sounds more like it bogs down at ½-¾ throttle(which assuming carb hasn't been monkeyed with is still on primaries) then can't recover till throttle is closed...

 

That's exactly how it does.