What Jets for my Proform 850 race serirs carb (408w street/strip) - Ford Mustang Forums : Corral.net Mustang Forum
 
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post #1 of 9 Old 05-30-2018, 01:26 PM Thread Starter
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Suggestions please! What Jets for my Proform 850 race series carb (408w street/strip)

I am completing a N/A 408w street/strip motor for my '61 Falcon (2600 lbs) and am using a Proform 850 race series carb. I was hoping to get some help or recommendations on selecting the right jets for this carb. My motor has 11:1 comp, AFR 185 heads, Edelbrock RPM Air Gap intake, comp cam XR288RF-HR w/ 288/294 duration, 236/240 lift @ .050, 110 LSA. Thanks in advance.
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post #2 of 9 Old 06-22-2018, 07:21 AM
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Mines at 72 front and 78 rear at the moment. Still rich at WOT, and Ive got a few other little issues but its around 12-13 air/fuel currently cruising. I need to jet the back side of the carb down a tad more....

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post #3 of 9 Old 06-22-2018, 12:30 PM
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Quote:
Originally Posted by Cajones View Post
I am completing a N/A 408w street/strip motor for my '61 Falcon (2600 lbs) and am using a Proform 850 race series carb. I was hoping to get some help or recommendations on selecting the right jets for this carb. My motor has 11:1 comp, AFR 185 heads, Edelbrock RPM Air Gap intake, comp cam XR288RF-HR w/ 288/294 duration, 236/240 lift @ .050, 110 LSA. Thanks in advance.
Regards,
Casey Jones
I highly recommend you tune it on a chassis dyno to start with, then tweak it on the street. Last two builds ive picked up 30 & 40 hp by tuning on chassis dyno. Good luck

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post #4 of 9 Old 06-24-2018, 08:41 AM
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With jetting every single setup is different, so asking this question will get you potentially thousands of different answers; and a lot of them vastly different and others just "close".

Close ain't any good.

IMO, take it to the track. Start jetting DOWN until MPH starts falling off. Read your plugs too. When doing this, don't make any other changes-JUST jetting. When it begins to fall off, you're too lean. Go back up 2 numbers and call it good. Keep in mind you're probably going to have to adjust for weather conditions especially if you're racing in a temperate climate. Don't go by the ET. MPH is the indicator of horsepower and you'll see max HP when the carb is very slightly lean, where most folks say you're way too lean. If you're bracket racing, I like it a little on the lean side for consistency in the weather swings that we have here. AND...I also like less timing than most (typically around 30 to 32 deg on typical aluminum head SBF)-and the reasoning behind that is it lets the bottom end (and block on the stock block 8.2 stuff) last a little longer.

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post #5 of 9 Old 08-04-2018, 05:39 PM
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Originally Posted by tbirdz12 View Post
I highly recommend you tune it on a chassis dyno to start with, then tweak it on the street. Last two builds ive picked up 30 & 40 hp by tuning on chassis dyno. Good luck
Where are you dynoing? Just curious.

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post #6 of 9 Old 08-04-2018, 08:55 PM
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I tune mine with a wideband. No guess work.


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post #7 of 9 Old 08-14-2018, 05:57 PM
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Turbotodd is correct. Do you have powervalve or running a block off. That makes a difference too.

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post #8 of 9 Old 08-29-2018, 12:43 AM
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There are 4 circuits to tune in a carb. Idle, tip in, cruise and wot. tune for each. Pick the fuel you will be using and tune accordingly. Stoich for idle and cruise for the fuel you use. Tip in is the least amount of fuel you need to not to be lean and pop. This is tricky as you can be a little richer and pull harder to top end. At top end or close to your afr will need to be where you run the fastest mph per the above statement.
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post #9 of 9 Old 11-13-2018, 09:15 PM
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you also want the primaries and the secondaries to feed equally What I mean is the WOT reading with the primaries only to be set at 11.5 on the wideband O2 sensor then using all 4 barrels adjust only the secondary jets up or down until you achieve 11.5 or whatever you have set the primaries to. I know this is more work but do you want it OK or right? The last post refers to the driving part with the idle and part throttle settings,that is a whole different thing and should be done before any WOT work.
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