Make sure the accelerator pump cam is properly adjusted as well. The screw with a spring is for this adjustability. I adjust mine so that there is basically zero clearance between the screw and cam, but with no pressure on the accelerator pump lever.

If that doesn't help, you may want to try a different cam for the accelerator pump. Try a richer cam and see if it helps or makes it worse.

 

yeah
every post i have read about this probklem says that it needs more fuel going in

i may pull the nozzle and try a bigger one
and then the cam

its a tiny thing that i should just probably just give to a proand be done with it

car runs to well for it to be something big
starts right up
idles fine
no smoking, missing, or knocking

so we will see

 

I remember this happening because I put a screw in the secondary slot to open all 4 at once. Then I put a gear drive on it and bigger Accelerator squirt and it went away.

 

ok maybe i found it
i was looking at my service manual
and noticed that the vacuum lines were wrong

it has that thermal vacuum thingy that screws into the intake
well anyway
the book says that the retard nipple gets manifold vacuum
the carb hooks to the thermal thing and then the thermal thing hooks to the vacuum advance

its hard to describe but if you look in your manual under 289/302 automatic it now looks like that

it instantly retarded the timing from 8 degrees BTDC to about 3 ATDC
but as soon as you push the gas it advances

havent had a chance to test it but it does start a little easier so hopefully tomorrow i can get it out for a full on test drive

oh and i have heard about putting the screw into the secondaries before but wasnt sure where to put it inside the slot

did you put the screw in so that the secondaries opened up immediatly or only made contact when the throttle was all the way open

 

well test drive went well

i did two tests
the first was with the vacuum lines hooked up the way the book says and the retard (dizzy not driver) hooked up

ran well hesitation was much better

test two was with the retard completely unhooked and the nipples capped off

ran even better and even has enough power to spin the tire at takeoff again

timing with retard hooked up at idle was atdc
timing with retard unhooked and advance (port vacuum) is 10btdc

hopefully this is the final fine tuning needed
i am going to start saving up for the gt40p and tri Y header swap

still curious about putting in the screw on the secondaries to make it mechanical
all the way up so the back 2 open with the front immediatly
or at the bottom so the secondaires open at wot
or somewhere in the middle

 

NO! NO! NO! NO! If you want the secondaries to open faster, put a lighter advance spring in the secondary canister. The stock holley secondary is set to open pretty late, if it will even open 100%. If you put a screw in the linkage to manually open the secondaries it will give you exactly what you have now- a major bog. A vac sec carb is meant to open the secondaries when the egine has a need for more air, so it will open as needed. When you try to force it to open, the engine may not need that much air yet and will give a nice big lean backfire, or at least a big sag in performance because the fuel cant start moving fast enough to match the sudden increase in airflow (which is the reason there is an accelerator pump on the primaries). If you want to open the secondaries manually, get a double pumper.

 

thats what i thought
i knew that mechanical secondaries have two pumps to give the extra fuel needed but a guy a few posts up said that he did this and it worked well
so i just wanted to make sure this was not a good idea
i have ran across so much conflicting info its hard to keep it all straight

 

Dont install gt40p heads until you check to see if the headers fit.The spark plug angle is different with the p heads.You may find the spark plug too close to the header.I had this problem with my 70 mustang 302.I didnt try the tri y headers but I would strongly caution you to test fit your combination.Also be aware that these heads were made for a roller cam and the springs are so strong they will eat your hydraulic cam and pushrods.$90.springs will remedy this.

 

No wonder my dads car bogs when i floor it. I need to take them screws out then.