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Discussion Starter #1
I've written 2 emails to Barry Grant's tech support team and also called them once but couldn't wait as long as I needed to to talk with someone so I left a voice mail and my phone number. This started a month ago and no one has ever responded to any of my attempts.

Has BG dropped tech support? What's going on? I LOVE the 625 vac. sec. carb I got from them but I have a question about rejetting recommendations after getting an A/F reading on a dyno. I also wanted to get a recommendation on a carb for my next engine build.

Thanks,
Steve
 

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Discussion Starter #6
I'll make a post about the issue. I built a 331 stroker with a conservative cam, X305 GT-40 heads, a 625 VS Road Demon, and Doug's Tri-Y headers. I got the car dyno'd and the A/F chart shows the carb real rich at WOT only. I need jetting recommendations and to know if the chart indicates any need for change in the powervalve because of the momentary lean condition when the pedal is floored, then goes rich. Throttle response is amazing so I am pretty sure the accelerator pump is just fine.

Here's the dyno sheet. I built the engine for street driving in my wife's '66 Mustang. I am real happy with the torque curve, and this is N/A.

Dyno Sheet

Steve
 

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Discussion Starter #8
I'll be putting it on a dyno again next year after jetting changes are made, so the "outcome" will be a little ways off, but at least you can get the circumstances and recommended changes.

Steve
 

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Don't hold your breath cuz, I'm an Aussie - don't even own a Falcon and I've been waiting 3 months for ARP's tech centre to respond to my enquiry.
BTW, if you're into Broadmeadows assembled Fords what are you doing with windsors?
You should be running Geelong cast Clevelands to keep 'em origonal.
G'day from Victoria, Ian.
 

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For all practical purposes your wide open A/F ratios are not that far off. Trying to interpret the scale you are maybe around 12.3:1 or so on average. Just a couple of jet sizes smaller on the secondary side should put you somewhere in the typical ideal range of 12.6:1 to 12.8:1. Only doing back to back pulls on the dyno will tell you exactly what the engine likes. Might like it rich as is might like it 13:1. Overall the jetting is pretty darn close if that's out of the box.

On the lean area I suspect it could use more accel pump. Even though it appears the A/F lags the hit of the throttle I'd verify that for sure. I'm going to guess there is a lag between readings and the lean spot is coincident with the hit of the throttle. Just a guess based on the fact that at the hit of the throttle the PV circuit should open up right away. Lowering the PV vacuum rating I don't think will do anything to bring that circuit in any sooner.

That is certainly a very nice smooth torque curve and should be a very nice running engine.
 

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Technical Support Barry Grant
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Aussie XAXB and I have being sending messages back and forth through P/M to get his situation taken care. As Rick WI he's close enough right now with out of the box jetting that he'll have to actually try the different jets on the dyno to see what his specific combination likes the best.
 

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Discussion Starter #12
IanRiordan said:
Don't hold your breath cuz, I'm an Aussie - don't even own a Falcon and I've been waiting 3 months for ARP's tech centre to respond to my enquiry.
BTW, if you're into Broadmeadows assembled Fords what are you doing with windsors?
You should be running Geelong cast Clevelands to keep 'em origonal.
G'day from Victoria, Ian.

Ian, [email protected] has been quick to respond with information on my situation. I am going to try the recommended 2 jets smaller and see what happens next year on the dyno.

As for the engine being a Windsor, this one is in my wife's 1966 Mustang. The engine in my XB Falcon clone (is originally an XA) is a genuine Aussie 351C with 302C 2V closed chambered heads. There is also Aussie extractors on it, though I am not sure what brand. Believe me, I wanted the Aussie engine in my car!

BTW, my wife works at the Cleveland Ford plant, birthplace of the beloved 351 Cleveland. :D

Rick WI, I was just wondering if it is preferred for the mixture to be richer at WOT after what I saw in a tech article in a magazine. So at WOT is it usually best to be rich? I certainly wouldn't think that 12.2 (average) would be good. But then again there may be some physics things I am not aware of. THanks for your input.


[email protected], Thanks for all your help!

Steve
 

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Discussion Starter #13
Rick WI said:
That is certainly a very nice smooth torque curve and should be a very nice running engine.

I was impressed with the curve too. It IS what I was trying to achieve and is why I agonized over specifications of each component. My wife wanted something that idled smooth and was well mannered, but would plant you in the seat when "required", so I only built the engine for low-mid torque, and wanted to make as wide a powerband as possible. Usually I have only seen this flat of a curve on something like a supercharged 4.6L .

The heads, intake, and carb were all put on right out of the box. I did deburr sharp edges first though. In a couple years, after I get done with some chassis modifications, I will yank the heads and do some pocket porting and see what that does for it. I might also have a back cut put on the valves.

Yes, the engine runs and drives like a dream. When it's time for "spirited driving" it is a ball!!
 

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Sounds like a great driver. 12.2 is pretty rich and I have never seen that A/F ratio make best power, at least on my dyno. Anywhere from 12.6 to 13.1 is generally the sweet spot. This is the range we tune around with N/A motors.
 

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Discussion Starter #15
Thanks Rick. Do you know any reason why the richer mixture (more than stoichiometric) is required at at WOT?

Steve
 

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Simple answer, it takes fuel to make power and keep the engine from eating itself up.
 

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Aussie XAXB,

Stoich is a good overall number, but best economy is always going to be leaner, and best power is going to be richer. Depending on the equipment used to measure the A/F usually mid 12's at Peak power is what you're going to want to see.
 

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"Simple answer, it takes fuel to make power and keep the engine from eating itself up."

I just installed a Holley Fuel Pump gives 110 gph @ 6.5 - 8 psi.
It´s made a world of difference.
 

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Discussion Starter #19
Thanks for all the info everyone. As long as I have been into cars I never knew about WOT A/F needs being different.


Steve
 
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