Holle7 600 on a 302

[likesoldjunk]

Guy's,
I posted this on the MII forum but didn't have much luck, I
thought their might be some Carb Guru's here....

This summer I installed a holley 600 and manifold off an ~83
into my 77, which has an otherwize stock 302. (It's OK, my
other car is a '72! ) it's all running fine (even the automatic
choke !) except for one little thing.

If I'm cruising at about 60, and then just touch the gas, it
will balk then go. It's almost enough to give you whiplash. The
same thing happens if you are constantly gently accellerating, it
will do it right about 2000RPM.

If you accellerate aggressively, there is no problem... she's
outa there.

I tried tightening up the tollerance on the accellerator pump
to no avail, and that really wouldn't explain the hesitation
through constant accelleration anyway...

Any thoughts ?

 

['69Stang]

What do you mean by "tightened up the tolerances" on the accelerator pump?
The 60 MPH hesitation sounds like you need to step up the accelerator pump a size or 2. What's happening is that the butterfly opens up and there isn't enough fuel to smoothly transition the atomization of gas into the venturis and it "gulps" too much air, and then recovers. That is my gut feeling on that.
This could explain the 2000 RPM "hiccup" also. But it makes me wonder if you have checked your plugs. What do they look like? Are you running very lean? I would imagine that you are. Have you adjusted the secondary vacuum setting? What springs are you using and what color carb cam do you have?

You may want to jet up your primaries one number but you really need to check your spark plugs before you do anything. Check back in with us after checking your plugs. Make sure you don't have any vacuum leaks either. Sorry a couple more questions, what ignition do you have and what is your base timing set at? There are a lot of good carb peple on this board that will be able to help you out.

 

[likesoldjunk]

Well... Lots of homework for the weekend !

- As for the Accellerater pump tollerance, the Holley manual
gives a proceedure to adjust the screw that actuates the pump
lever. I was refering to the clearance between that screw head
& the lever.

- Plugs - I'll check on the weekend
- Timing - If memory serves, it's 14 initial. It's std steup anyway.
- Carb Cam - No idea. I'll check
- vacum leaks- I think I'm good. Nothing major anyway.
- Vacum Secondaries - I bought a spring kit, started with the
one recommended in tha package, then did the test drive thing
changing springs until I got a bog on WOT accelleration, then backed
off one. I don't remember the color I wound up with but I'll check.

Someone else suggested this, but to be honest I'm confused. If the
secondaries were opening too soon, wouldn't it REALLY bog when
you floor it ? As I mentioned there is no issue with aggressive
accelleration....

 

[Max Power]

Yes it would.

many additives in the newer fuels eat up the rubber flapper that is your accelerator pump check valve, if you have that style. That might be a problem, as well as the power valve.

I would just rebuild the whole thing and go from there.