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Old 06-08-2013, 11:07 PM
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Need some guidance tuning in my Holley.

Alright ill cut right to the chase. Holley 4160, 6619-1.

Always had a small bog with my setup. With my old Th350, It had a very weak launch, decent 2nd but just fell on its face in 3rd. Before I could start doing a Fuel pressure check on 3rd gear to check the bog, the th350 gave out.

Fast foward to now, I went to a 6.5 Power valve, via idle of the car in park while not moving. I have read that its better to go with a Power valve that is a hair under the reading while cruising not at idle. Would this be correct?

As far as Jets, currently it has 68 on the primarys, which I steppd up from 66 that it had and the motor seemed to like it. Rear it does not have a primary block so no jets there.

As far as the secondary's go, It had a black spring in it, which did not make the secondary's open at all that much. Swapped to a purple spring and secondary open up at around 3000rpm when flooring it. Meaning it will slowly accelerate then kick in, it has a slight kick to it but nothing too harsh, should I go with a step lighter spring?

Pretty much my main problems right now are that from a cruising speed, punching it will give me a slow climbing acceleration, then at around 4000rpm it will kick in and accelerate like normal. Like i said changing springs helped this a bit.

Another question is the idle transfer slots. Before my setup had about .30 opened, from my reading it seems that the right way is to have it bearly seeing the opening, I did this and opened the secondarys the same amount I closed the primarys. Any feedback on this? With this change my car seems to like the idle mixture screws almost bottomed out, they are currently at 1/2 a turn from the bottomed out point.

As far the accelerator pump goes, I fixed alot of the play in the linkage that it had, and swapped to the 2nd screw point on the white cam it had. I might pickup holleys cam set and play around with that next.

Any feedback or advice would be nice. Honestly my next move is probably investing in a wideband.

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Old 06-09-2013, 12:28 PM
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post all the tune up specs you are currently using:
spark plug gap/type
ignition timing/type/spark plug curve and coil
carb float level/jetting
engine specs/cubes/cam timing
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Old 06-09-2013, 09:36 PM
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-Autolite Plats AP26 which are @ .45
-Base/Initial timing is 12 and 34 total in before 2800rpm, Hei ignition
-Wires are Advance Auto Parts brand, 8mm.
-Floats are currently set to dribble when rocking the car for primarys and slowly dribble by itself for secondarys.
-Jets are 68 for Primarys, this 4160 uses a plate for secondarys.
-Engine block is unknown, Came with the Car, 3970010. Heads are 487X. 350.
-Exhaust is Hooker 2055s 1 5/8, to 3' Flowmaster Catback

So I pulled two spark plugs today and found this.

These plugs were installed when the new 700r4 trans was installed so pretty much less than 250 miles. There is black spots if you can see them on em. Any ideas?

I might just replace the mech fuel pump since its a cheap replacement and see if that does anything.
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Old 06-14-2013, 12:28 AM
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Raise your plug gap to.055 if you've got a good aftermarket coil, and i suggest starting from scratch with the carb. check manifold vacuum at idle in gear with an auto trans. whatever that reading is cut that in half and thats the size powervalve you want to put in front metering plate. 68 main jet is probably close on the main jet. Start with your afr screws on side of meter plate about 1and1/4 turns out. after you get all that take it out on an open road bout 55 mile an hour and mash the throttle if it screams and goes nowhere fast you probably need a weaker spring in the secondary diaphragm let me know how she works then!
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Old 06-20-2013, 07:06 PM
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I have done this again, and now im experiencing some problems.

I really think its a fp problem. I have everything adjusted just like the book says. One of the recent things I did was adjust the idle transfer slots properly and have it showing the right ammount like it says it should.

Now with everything right, I can bottom out the idle mixture screws and the car likes it that way and gets the highest vacuum reading, remember that my 6619 is a backwards carb and turning it in, richens the mixture.

So basically the car has no huevos at all, from a 35+, it just feels like its crusing at wot.. Launches the car spins the tires for maybe a second before just bogging out. Im really leaning towards a fp issue. The mech fuel pump looks decent and has no leaks, but might replace it this weekend to rule it out.
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