Holley 4160 question

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Badart

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I have another question about my 4160 600cfm. My problem is more annoying than anything. While cruising in 3rd gear and I roll into about half throttle my engine cuts up a little, like it's running lean. Idles perfect and when I put it to the floor it runs like a raped ape.

Background on the combo is 318 with only about 800 miles on it, flat top pistons 9:1, XE256 flat tappet cam, 1.6 roller rockers, magnum heads, accel dist, chrome box, headers, 3k stall convertor, 3.89 gear.

For jetting I am running 66 primaries and 72 on the secondaries (I installed a secondary metering plate because of it being lean on the top end). 6.5 power valve and I am pulling 12" of vacuum at idle. Timing is set at 16 initial, 34 total and with vacuum at 3k I am all in at 52 degrees of timing. Spark plugs look good after a hard run.

It almost seems like the secondaries can't decide if they want to open or not. Should I try a stiffer/lighter spring in the secondaries? Or do you think it is a dist spring issue? The dist advance seems to working just above 2k rpm. I am running champion plugs. After reading a recent thread I am wondering if it could be my plugs. Thanks for the help.
 
i have the same exzact problem on my slant with a 390 holley. like it is going lean in the transition circuit. i noticed it got better when i went with bigger primaries, but then i started getting a strong gas smell. i havent found a solution. but i havent messed with it much as im going to be switching to an edelbrock 500. sorry i cant help. good luck tuning.
 
Come on guys. Someone knows this. I don't want to just throw more parts at it. Plugs do look a little lean. What do you think?

Spark plug.jpg
 
I think that I will just fatten up the primary side a little judging by the plugs. I never thought a 318 would need 67/72 jets. We had the warmest day of the year so far, in the 60's and it ran fine (smoked some douche bag in his mom's BMW SUV on my way to work). I know, I know, but he was taunting me a little. So I know that it only does it only when it's cold and I am running an air gap intake. It definalty does it when the temp is in the 30's-40's at night.
 
the only think i can think is maybe the accelerator pump or squirters being a little clogged, pf course playing with the jets can could be the solution. I'd watch the accelerator pump in action at idle and see fuel us flowing out of the squirters is un-obstructed.
 
streetdak said:
the only think i can think is maybe the accelerator pump or squirters being a little clogged, pf course playing with the jets can could be the solution. I'd watch the accelerator pump in action at idle and see fuel us flowing out of the squirters is un-obstructed.
Click to expand...

I agree...

If the accel pump is not obstructed, you may want a bit bigger "shot"...if that's the case you may want to invest in these Acceleartor Pump Cams, swapping them out till you find the one that works for you.

hly-20-12_cp.jpg


"Get maximum accelerator pump performance!

These Holley accelerator pump cams will allow you to "tailor" accelerator pump performance to the engine's actual requirements. They include cams that have a different shape or profile to give different results. Cam "lift" directly affects the accelerator pump stroke, and, therefore, pump capacity. Ramp profile or shape controls the "timing" of the shot. A steeply-rising ramp shape will give a fast, heavy fuel shot right off idle. Conversely, a gently sloping ramp will spread the pump action over a longer period of time."

http://www.summitracing.com/parts/HLY-20-12/?rtype=10


Good luck to you..
 
The squirter is working fine and is adjusted properly. I have already stepped up to a 35 squirter. Maybe I need a 37?
 
Does it get worse when you change the jets? What altitude are you at? (unfortunately, "northern Utah" isn't found on google maps so I couldnt tell how high up you are). Are the floats at the proper level at idle? Are you getting enough fuel from your pump? my 3310 came with 73's stock. Might be runnin a little lean on the primaries. Vacuum secondaries or is this a double-pumper? It wouldnt be the accelerator pump at cruise since the linkage is well past the pump cam at cruise. Pump cams affect off-idle performance and thats about it.
 
Cooter said:
Does it get worse when you change the jets? What altitude are you at? (unfortunately, "northern Utah" isn't found on google maps so I couldnt tell how high up you are). Are the floats at the proper level at idle? Are you getting enough fuel from your pump? my 3310 came with 73's stock. Might be runnin a little lean on the primaries. Vacuum secondaries or is this a double-pumper? It wouldnt be the accelerator pump at cruise since the linkage is well past the pump cam at cruise. Pump cams affect off-idle performance and thats about it.
Click to expand...

Thanks for the advice. It actually has gotten a little better everytime that I have stepped up jets on the primaries and scondaries. Altitude is about 5,000 ft. Floats are at the proper level at idle. Fuel pump is a holley blue with the regulator set at 6 psi. Carb is a 4160 with vacuum secondaries and I have installed a secondary metering plate.

I think I will step up on the primaries to a 67-68 and see how it runs. The problem isn't bad and only does it when it's cold outside, but it annoys me and changing jets is easy.
 
Cooter said:
It wouldnt be the accelerator pump at cruise since the linkage is well past the pump cam at cruise. Pump cams affect off-idle performance and thats about it.
Click to expand...

My bad.

I missed that "at cruise" part in the original post...
 
What is the vacuum reading at cruise. You may need to step up the PV, higher number, to get the circuit fattened up a bit on roll in. Might need to open up the PV channel restrictors (PVCR) as well.
 
crackedback said:
What is the vacuum reading at cruise. You may need to step up the PV, higher number, to get the circuit fattened up a bit on roll in. Might need to open up the PV channel restrictors (PVCR) as well.
Click to expand...


Good to know Crackedback. I will look into it.
 
yeah really.. I would have like a 7.5-8.5 PV with 12inch at idle in gear.

the pump cam profile might need a lil attention-just a side note.

what color pump cam? what stall convertor?
 
1wild&crazyguy said:
yeah really.. I would have like a 7.5-8.5 PV with 12inch at idle in gear.

the pump cam profile might need a lil attention-just a side note.

what color pump cam? what stall convertor?
Click to expand...


I ordered a 7.5 PV and 67 jets for the primaries last night. I will let you guys know after I install them.
 
crackedback said:
What is the vacuum reading at cruise. You may need to step up the PV, higher number, to get the circuit fattened up a bit on roll in. Might need to open up the PV channel restrictors (PVCR) as well.
Click to expand...


X2 I'm with him on the power valve, check with a vacuum gauge.
 
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