Everytime i launch my car at the track when it doesnt spin and hooks it bogs then gets up and goes the carb is a unmodified 650 4150 electric choke vacuum secondary holley.

 

Sounds like a lack of fuel.

 

fuel pressure is steady at 6psi, the carb came with 3 secondary springs a medium, light, and heavy. The medium spring is in the carb.

 

what else could this be?

 

Try the stiffest sec spring.

 

I don't know much about vac secondary Holley carbs, but it sounds like its either too much, or not enough fuel, on the pump shot. Try a larger shot w/ more duration, see if things improve or get worse. Hows the car behave when its colder, does it have the bog, or does it get worse as it warms up? Might be a clue as to if its too lean, or too rich. You can try the same thing with a rod change, add some fuel, see if things get better...

 

id doesnt have rods like a quadrajet it has jets when its cold it will bog when i tap the gas once it warms up its fine but no matter if its hot or warm it will bog when flooring it from the line.

 

I would run some bigger jets and see what happens. Only try one change at a time, so you can pinpoint what works and what doesn't.

 

Try tuning it properly and see what happens.

Like sofa said, use a stiffer secondary spring. If you don't know what that looks like, go to Holley's website and look up their technical information. They have good explanations of how their carbs work there.

Bog happens when the main fuel circuit (in this case, the secondary main circuit) doesn't have sufficient flow yet as the throttle blades open. Note the use of the word "yet" - when closed, the fuel level in the secondary main circuit is down at the fuel bowl level. It takes time for the booster venturi to react to the flow of air through the secondary venturi when the secondary throttle blades are opened and draw fuel up through the main circuit into the air stream. The purpose of the vacuum actuation is to open the throttle blades slow enough to allow fuel to be drawn through the booster venturi before the overall mixture leans out too much causing the engine to bog.

Personally, I think the Quick Fuel secondary diaphragm is a very good investment if you must have a vacuum secondary Holley. With that system, opening is controlled by a needle valve in the vacuum circuit which makes it very adjustable - the spring then becomes the limit to how much the secondaries will eventually open (which is a function of engine size and RPMs), like it should be. Much, much better way of controlling secondary opening, and much, much easier to adjust. In fact, since the secondary housing has to be removed in order to change the spring (unless you have a quick-change housing, which is only stock on the SA series of Holleys), don't bother doing this until you have the Quick Fuel secondary housing in hand.

Or, go ahead and do it the hard way.

 

i have installed the quick change vacuum secondary spring cover when i first got the carb its a got a medium spring in it it came with a light medium and heavy.

 

what kind of stall do you have and what are some of the engine and chassis specs? sound like when it hooks it's out of your rpm range. more stall could help.

 

Maybe I'm missing it, but I don't see what cam is in the engine.

Try the heavy spring. If that doesn't help, you're barking up the wrong tree - like vacuum leak, grossly mis-matched parts, etc.

 

the engine is a stock l98 with the centerbolt iron heads with the stock 89 l98 cam 207 213 duration .415 .430 lift i think it is. The stall is a 2025 but it really only stalls to 1800.

 

When you put the quick change cover on the vacuum diaphragm housing, do you remember a check ball?

By the way, you said in your original post that the carb was unmodified. Putting the quick change cover on qualifies as a "modification".

 

I would invest in the holley spring kit that has all the springs for tunning...there is about 8 different springs that you could use what color of spring do you have in there now?
here is a link to help you out http://www.mortec.com/carbtip1.htm

later and

GB

rk