I got my 69 360 with holley 2300 500 cfm running perfect except it seemed to be running a bit rich. It smelled rich and was going through gas more than I thought it should. It had size 74 holley jets in it and I replaced them with 64 (I knew it would be too small I was going to bore them until I found the approximate jet size that would work)

It seems to run fine with 64 jets if I'm light on the throttle but it will stutter if I mash it down. I was wondering if maybe I could advance or retard the timing to maybe stop the stutter and just keep the 64s I read on another forum a guy had 64s in his and it worked perfect.

Thanks guys!

 

I would not keep the 64's. Unless you want to drive low RPM all the time. 500CFM Holleys have a 1 11/16" bore. 64's are already a little lean for a FE if it had a 600CFM with it's smaller 1 9/16" front bores. 64's will work low RPM but as you crack open the throttle they won't keep up with all the added air flow. Leaning out a FE can ruin your day,If ya know what I mean. I'd try 70-71 range.

 

Did you make sure your accelerator pump linkage has no play when it's at the idle position. If any play at the this adjustment and it may cough and not get the pump shot of gas needed when you step on the gas pedal.

Any time you remove the float blow you must recheck the acc pump linkage for being out of adjustment..

Changing to a different pump cam can also correct this flat spot. And pump shoot squirter can also help correct those types of conditions.

That 500 cfm are not great for gas mileage more on the performance 2 barrel carb. But it needs larger jets to mix with all the air cfm your opening those butterfly's up as you put your foot into it..

Jets are flow tested and matched in pairs and by drilling them will screw up the flow patterns. But should replace then with a flow matched ones once you figure out the best size.

Ford carb jets are matched to drill bit sizes where as the,
Holley's start out the same as drill sizes and then drift off to odd ball sizes about in the mid 50's sizes if I remember right.
So if you use a drill bit that is 0.67 it won't match up to a #.67 holley jet.
You'll have to find the cross ref. chart to figure out the jet size needed.

I do have it but not sure where its at right now.
It's should be in a Holley Catalog tho.
Orich
Holley jet #'s

D/S= drill size


D/S H/J

49= .048
50= .049
51= .050
52= .052
53= .052
54= .053
55= .054
56= .055
57= .056
58= .057
59= .058
60= .060

61 = .060
62 = .061
63 = .062
64 = .064
65 = .065
66 = .066
67 = .068
68 = .069
69 = .070
70 = .073
71 = .076
72 = .079
73 = .079
74 = .081
75 = .082
76 = .084
77 = .086
78 = .089
79 = .091
80 = .093
81 = .093
82 = .093)
83 = .094
84 = .099
85 = .100
86 = .101
87 = .103
88 = .104
89 = .104
90 = .104
91 = .105

Hope this helped, it came straight out of a Holley Book so it should be accurate on the jet sizes.

 

I'm thinking about goin with a 69 and calling it good. All linkage is tight and working properly it just bogs down once it burns the initial squirt from acc pump.

I was driving it with the choke pulled a little and it runs great. Doesn't ping or anything and accelerates nicely. Definitely smells leaner than before. Could I leave it like this until the 69s arrive without ill effects?

 

My 360 runs almost to lean with 71’s in it. I think I’m running 73’s and it is about right. I would look at needle and seat, float and power valve as well.

 

If you have a bad power valve you can close the idle air/fuel screw jets and the engine will keep running and not stall out.

Having to run with the choke pulled little an it runs better does sound like it's on the lean side for sure..

But it is a lot of cfm opening up all at once. I don't think you'll like the mileage from that carb over a smaller Motorcraft 2100 carb you can run about 52-57 jets in.. just my 2cents
Orich

 

Drive it soft on the pedal untill the 69's arrive.