Need Holley Vac Tuning Tips

[PLUM_72]

Anyone have any good tips on tuning a Holley 600 vacuum secondary carb? Its the 0-1850 list model with Eddy performer manifold on a 318. The problem Im having is when I really stand on the throttle there is not much bottom end, its okay but could be better (could be timing) but, when the engine develops RPM, the car kind of surges a little and then goes again. Any ideas?

[6 packin]

So is it a bog problem, or more of a flat spot, or not pulling on top end? Give us a better idea o whats going on, like every thing about your cars setup, things like timing, car info,gear,converter,compression. It may not be opening up for the secondaries, the bog maybe from to light of a spring in the pod. To check your carb 2nds are opening, which will not open winging the engine wile parked! Simply put a paper clip, or bobby pin, on the rod going down from the vacum pod to the butterfly shaft on the pass side of the carb. Push it up against the pod take it for a spin, roll the car and carb to WOT in high gear. If opening the rod being pulled up and opening the 2nds, should have slid the paper clip down the shaft, telling you just how muxh its opening. Also surging is a sign of a lean condition or vacum leak! If the carb bogs from a dead stop idle to WOT switch to one step heavy spring, if it still does, go one more!

[GODofTHUNDER]

I have the same setup on my 72 Challenger, and had the same problems that you are talking about. What I did was bump the timing up a tad, and leaned the carb out a tiny little bit. The result was pretty impressive, but there is still a tiny bit of hesitation when you first take off. Just make SMALL adjustments to the timing and then go for a short ride. I'm sure you will find the right setting. Also, I installed a set of headman hedders, and that improves things quite a bit ! Converted to the MOPAR electronic ignition, (Orange Box) and that pretty much solved the problems. Hope this helps you out.

[PLUM_72]

The basics to the engine are 318, 9:1 compression, 302 heads with 1.88 intakes, 1.60 exhausts, Comp XE262 cam degreed at 106. 727 trans with a 2400-2800 stall convertor, 3.90 gear. Currently I have the car timed at 11* initial. I have to buy or find someone with a dial back timing light to do further timing mods. Those damn timing tapes dont stick long enough to tune the car. The car runs strong if you ease into the throttle. No noticable bog. If you jump on it, thats where you start to notice things.

[6 packin]

if you have a stock distributor, you should run maybe 14deg intial

[PLUM_72]

More info...still have bottom end issues. Timing set to 34 degrees at 2600 (this is the MP electronic distributor and orange box). The initial is where ever it fell to after it was timed at 34. The car has about 11-12in Hg at idle with is about 850. The long yellow spring in the vacuum pot on the carb helped things a little. Still looking for more. Next change will be a 8.5 power valve in place of the standard 6.5. Im still not convinced with the distributor timing. If I bump the initial timing up, the rpm speeds up and it idles better, but total advance goes way up to like 40 degrees, maybe more depending where I have the initial. How much timing can I run without hurting things?

[cuda66273]

If I bump the initial timing up, the rpm speeds up and it idles better, but total advance goes way up to like 40 degrees, maybe more depending where I have the initial.

Right....so you need the distributor curved and phased...as said earlier you need 14-16 initial and 34 total with it all in at about 2600.

Timing first them carb.

http://www.4secondsflat.com/Carb_and...rder_form.html