Hey guys i drive a 1986 305 5sp z28. I just swapped from quad to a holley 4160, and put in a vac advance distributor. I can get the car to start and idle fine but when try to give it gas i dont go anywhere(no power or acceleration). The reason for switching from the quad was because it and the electrical were FUBAR and i was losing power around 3500rpms, the engine would get louder but the tach and the car wouldn't pick up. I've checked the vacuum and everything is fine, i still need to play around with the timing though because its pretty messed up. What concerns me is the still lack of accleration/ not being able to rev above about 3500 and after the swap and a loud rattling/ping/knock???. Maybe i'm missing something, any input would be greatly appreciated

 

When you step on the gas, do you get full throttle cable travel? For a while I could not get my car to get any power, then I realized that when the pedal hit the floor, the carb was only opening half way. After some adjustment to the bracket and pedal, I got it to open 100%.

 

yea its def opening, i think i've finally nailed down the timing but my battery died, i'll have to wait until tommorrow to find out...

 

When you step on the gas does the engine see to shut off or does it still rev up just not to what you think it should. If it just kind of sits there making noises then its probably your pump shot. You may need to go up in your shot. If your already at speed and you hit the gas to accelerate then you probably need to tune your vac. sec. to open later. A little more detailed info and we could help better. Whats your base timing/ total timing? Engine set up?

 

i've got the car running pretty well, i've finally nailed down the timing and it's set at 8 degrees, as for the total advance im not exactly sure... As for reving it's alot more responsive than it was but its still alittle off. The problem i'm having is 1) when i open the throttle fully from a dead stop it doesnt take off 2) when im gear, say 3rd for example and then step on it it doesnt really pull at all, just gets louder and accels slowly. Everything is fine if i don't hit the throttle hard. I'm going to look into getting the secondary spring kit... do i need to go stiffer? a bigger pump shot would probabaly help too right...

I've got a stock 305 5sp, and cat-back exhuast with hi-flow cats, i just put in the holley 4160 with vac secondaries and vac-advance distributor.

 

from what your describing, and without me being there it sounds like your secondaries are opening to soon when you punch it in gear. Explains the louder noise and not accel. fast enough. You will need to put in a stiffer spring for that. As for the deads stop to WOT probleme it sounds like you need a larger shooter to get the gas going sooner. Check your acc. pump arm and make sure its adjusted right. Look at your carb w/ the engine off and move the throttle; as soon as the touch the throttle gas should be squirting out of your squirter. If not your pump arm needs adjusted. Good luck.

 

How do you have the advance curve on the distributor set up?

 

ok guys i need some help, i'm having some major trouble. it starts up and idles fine... but when i try and rev it wont go above 3000 and if i give it gas quick it stumbles. its only drivable if i keep under 1/4 throttle. I put in the hei coil in cap vac advance distributor and its set at 8 degrees back, and i know you can advance the timing curve using the 3/32 allan key. how can i tell if exactly what im setting the advance curve at? I just need to know where to start so i can get this thing running like a champ again, i want to make sure everythings perfect with the timing before i start adjusting the holley

* my engines also been running pretty hot, it was at 240 before, and the little performance i had got even worse, any ideas?

-mike

 

Are you setting the timing with the vacuum to the distributor disconnected? If not, you need to.

It should be set to 8-12 degrees before top dead center, not "back". That means as you're facing the engine from the front, the mark should be to the left of the "zero" on the timing tab.

"Total" advance is the mechanical part of the advance, checked again with the vacuum disconnected and the engine RPMs up to the point where the timing isn't advancing anymore. If that takes 4000 RPMs, that's a "slow" advance curve. Typical performance curve have it all in by 2500-3000 RPMs. Regardless, your timing tab doesn't go far enough, as typical SBC mechanical is in the 34-36 BTDC range, and the tab only goes to about 16-18 degrees.

The 3/32" adjustment you referred to is the vacuum advance adjustment. It only adjusts how much vacuum advance is applied for a give vacuum level. Basically, after the mechanical adjustments are where there should be, you adjust the vacuum advance so you don't get pinging at partial throttle light load cruise conditions (going up a gentle hill in high gear, for instance).

FWIW, the vacuum secondary isn't the right type of carb to be using with a T5. If the secondaries are open during aggressive driving, when you back off the throttle between gears, the secondaries won't close right away, causing RPMs to flash. Not a good situation, especially with a T5.

 

Yes the timing is set correctly, that would mean that i have to make an adjustment on the carb correct? when i rev it with the throttle it hits a point around 3000 rpms where it tops outs, visually it starts spitting gas back up like a backfire but without the pop, any ideas...

And yes i should have gone with mech secondaries