HoLun - if you have a handfull of the Holley secondary springs to sort, grab the black painted one. It has about 7 active coils and is .035 diameter wire. I usually just put the stiffest one in there for starters and this is it. With a caliper you can sort them down from this one by wire size.

The accelerator pump linkage at front left needs to have some play - a slight clearance between the spring wrapped adjustment screw and the pump lever at idle - like .010/.015. The pump cam on the throttle linkage has a couple of positions usually marked one and two. If you don't like what "one" does try the other. 

It think the idle transfer slot / blade position will be like your Autolites.

 
 Steve Metzger       Tucson, Arizona

I'll try some more tomorrow.





I think I know whats making my car does that weird 2500rpm power surge, when I use my timing light to check mechcanical advance, the timing suddenly jumps to max while I up the RPM, i think one of the weights is sticking or something, gonna pull the dist apart tomorrow.



I also swapped out the power valve with the 8.5, the one came with the carb is 2.5" Hg, made a difference there. but the vacuum drop to like 11 when fully warmed up, so I am going to use the 7.5 instead.

The accelerator pump is adjusted with the primary throttle in the wide open position.  The arm should be within 0.010"-0.015" from being bottomed out.  What you're doing at this point is insuring that you're not bottoming out the accelerator pump diaphagm.  If you set the accelerator pump with free play in the idle position, then you'll likely have a flat spot or stumble.

Lorena, Texas (South of Waco)

So I got my carb set up pretty good, I think I need to fine tune the accelerator pump.



do you think the 30cc pump is big enugh for my application?

when should I use a 50cc pump?



I want to know because when I accelerate from a stop somewhat hard, from about 1500rpm i can spin the wheel for like half a second then it catch and slowly accelerate.



it have the orange cam on it now, do you think more fuel earlire will make the trie spin more/ accelerate harder? or 50cc pump will help on this?



also when I pedal to the metal from a stop at regular get going rpm, like about 1500, the acceleration feels like it pulls then not as hard then keeps pulling.



I dont have different cams on hand, and will need to order some, if a 50cc pump wont be too much then I'll order that instead.

My experience with 50cc pumps is that they are typically too much fuel for most Y's.  I'd suggest trying larger sized shooters before playing with the pump cams.  If your pump shooter is a '25' (0.025"), then going to a '31' (0.031") would be the next logical progression in shooter sizes.  Experimenting with larger shooter sizes will give you an idea if additional pump shot through a cam is worth playing with.

Primary fuel jetting could also still be on the lean side contributing to your 'flatness' in performance when the tires quit spinning.

As an FYI, my roadster engine likes as little pump shot as possible and this is with a single plane intake manifold.  Using larger shooters and cams slowed down the 60' times.  And the engine also likes the black secondary spring which opens the secondaries as late as possible.  Lighter springs slowed down the overall et.

Hope this helps.

Lorena, Texas (South of Waco)

the carb came with a .035 shooter, should I try .040 one?

Shooter sizes are the just about the easiest thing to change up on the Holley carbs so it's definitely in your best interest to experiment in that area first.  I'd suggest trying both larger and smaller shooter sizes just in case you haven't yet optimized the carb jetting.  Lean jetting would need a larger shooter size while rich jetting would prefer a smaller shooter size.  You might also look at the phasing of the pump cam to see if it's in the optimal position.  You'll notice on the side the throttle lever where the cam can be installed in one of two positions so that the actual timing or phasing on the pump cam can be altered.

Lorena, Texas (South of Waco)

so I ordered some nozzles, and a set of assorted cams. will tune more when they get here.



on the pump cam settings, If I want #1 and the cam have 2 holes, I just line up the top hole to #1 correct?



not the bottom hole to #1?



I am asking because theres only very slight difference of position just by looking at it, like both of the holes are almost lined up on the cam and on the throttle bracket.

The pump cam positions are adjustable to compensate basically for the throttle opening or an increased idle speed to insure a full range of movement to the accelerator pump diaphragm.  The larger the camshaft and in turn the required increase in idle air through the primary throttle blades, then the more important this tuning feature becomes.

Here's the text from the Holley website giving their explanation on the pump cam and adjustments.

"Once a pump nozzle size selection has been made the accelerator pump system can be further tailored with the pump cam. Holley offers an assortment of different pump cams, each with uniquely different lift and duration profiles, that are available under Holley P/N 20-12. Switching cams will directly affect the movement of the accelerator pump lever and, subsequently, the amount of fuel available at the pump nozzle. Lay out the pump cams side by side and note the profile differences. This little exercise may help to better explain the differences between the cams and their effect on pump action. Installing a pump cam is straightforward. It’s a simple matter of loosening one screw, placing the new pump cam next to the throttle lever and tightening it up. There are two and sometimes three holes in each pump cam, numbered 1, 2 and 3. Placing the screw in position #1 activates the accelerator pump a little early, allowing full use of the pump’s capacity. Generally, vehicles which normally run at lower idle speeds (600 or 700 RPM) find this position more useful because they can have a good pump shot available coming right off this relatively low idle. Positions #2 and #3 delay the pump action, relatively speaking. These two cam positions are good for engines that idle around 1000 RPM and above. Repositioning the cam in this way makes allowance for the extra throttle rotation required to maintain the relatively higher idle setting. Pump arm adjustment and clearance should be checked and verified each and every time the pump cam and/or pump cam position is changed."

Lorena, Texas (South of Waco)

Hmm I don't know if its the problem, I run a 195*F thermostat in the car right now, is it possible that it is too hot for the Y block? I am using the 200 on 180 off fan switch, I notice just before it completely warms up, it seem to run better, I might switch out to the 180 thermostat tomorrow and the 185on 170 off switch, and see if its the problem.



and today, after I finished some test pulls. 5000rpm + and heading back to the house, after a stop sign the oil light came on, but my aftermarket sunpro electric gauge is showing normal pressure. the pressure switch I have on is auzone's "duralast" brand, I am pretty sure its the switch, as the wiring seems fine and the switch is Teeed off the pressure sender for the gauge., haha I am not going to buy duralast stuff again.