Holley 600 dp jet help

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Torkmnstr

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Hey all, I dropped a 600 dp on my 273. I think the secondaries are a tad to big for it. Runs great off the primary which are 66's. But rolling into the throttle it seems to big and I get a raw fuel smell after. The secondaries are 72's and the carb is all tuned out with a vacuum gauge so I know I'm good there. What jets should I throw in the back? Thanks all.

Tork
 
Is this on an auto or stick car?
Check the secondary linkage and see if it is progressive.
 
It's an automatic car. When get it to kickdown it will suck it down, but when I just roll into it it seems to big some, I will check for that linkage.
 
Figure out whether you are lean or rich, then go up or down 2 jet sizes at a time until it smooths out...
 
I would disconnect the secondary linkage and tune the primary first. Get the engine throttle response nice and crisp on the primary first, then tune the secondary. My guess is you are too rich on the primary also. Start with a 64 up front and see how it runs. Check pump shot also. As soon as you add throttle the primary shot should occur. Secondary shot as soon as the rear butterflies move. I assume you have the idle mixture, float level and timing curve correct already.
 
Its a DP
Maybe too much secondary pump-shot?
Or maybe the powervalve is coming in too early.
If it was mine, I would defeat the secondaries and block them shut;then fine tune the primary side first. That's what I would do. Many times the PV can be delayed, or the Pmain leaned out some. After the primary is cleaned up, then I would go back to the secondary side. That's what I would do.
Also, make sure the timing is close to correct.

Missed it by 4 minutes......
 
It is all tuned out with a vacuum gauge so I am in optimum range for mixture. So when adjusting the secondaries are you referring to the spring and screw on the accelerator arm or cams? It has the stock 6.5 power valve. I need to put the gauge on it again but I think I had around 20" when it was all tuned out you think I could benifit from a 9.5 pv? I think the primaries are ok at 66 there is no hesitation at all.
 
Spring and screw on the accelerator arm adjusts the pump shot. Stock cams are usually pink and use #1 hole.
If it runs good with a 65 PV leave it as is for now. A 95 PV will add more fuel sooner.

If this is a used carb a previous owner could have changed the secondary linkage rod to open the secondaries faster. The primary should be open around 1/2 way before the secondary starts to open.
 
A vacuum gauge can/may be used to help tune the low speed circuit, and specifically the idle circuit,but nothing more.
Your carb has several more circuits.
Try not to be overly concerned with a specific vacuum number, because, by itself, it reveals very little to nothing about mixtures.Ignition timing has a much bigger effect on the specific vacuum number than fooling with the mixture screws.
If your carb is not factory original, you may have to tune several other circuits and things.
If your carb is factory original, it will be pretty close, but may still require tweaking.
I think I read a very good article on the Holley website.
 
When I'm trying a different carb I always return it to out of the box specs, that way I'm not working around what ever someone else did to it. Stock jets, stock PV, stock squirters etc. A 600 in stock form should be fine for that motor.
 
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