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 Post subject: Jet chart
 Post Posted: Sat Sep 22, 2012 4:02 pm 
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Posts: 49
This is a jet chart from Larry Meaux's Maxracesoftware website , I have pinned most of the jet sizes on here and it is very accurate. Also it shows area when using a PV , the chart that Max jet gives you is way off because it follows holley numbers , which are not accurate.

Image


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 Post subject: Re: Jet chart
 Post Posted: Sun Sep 23, 2012 10:51 am 
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Joined: Tue Apr 18, 2006 6:38 am
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Since I don't own a pin gage set I went and looked up those MSC sets they got on that sheet. Man, they're proud of them things aren't they? And they're not much cheaper on fleabay either.

Me, I just use the small drill bits I get off fleabay for "cheap" to gage holes instead. ;-) After all, if you're gonna use one of them to MAKE the hole then why not use one to check them?


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 Post subject: Re: Jet chart
 Post Posted: Mon Sep 24, 2012 9:07 am 
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I don't think the area for jet #92 is right. I come up with .00976. The listed area for 92 is more than the area for 93. But the point of checking them is well taken though. I've heard guys say that one 92 doesn't always measure the same as another 92.


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 Post subject: Re: Jet chart
 Post Posted: Mon Sep 24, 2012 11:01 am 
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Location: Auburndale, Florida
Ken, I bought some plug gauges off fleabay. .013 to .250 I've probably got less than $50 in both sets. I use them for everything. If I drill it, it gets gauged.

I forgot, the best area chart I have came from page 150 of Doug Roe's book on Rochester Carburetors.


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 Post subject: Re: Jet chart
 Post Posted: Mon Sep 24, 2012 12:11 pm 
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the #93 I get .01002 , not .01012 .... I guess Larry Meaux's point is Holley lists #91 , #91 , and #93 all at .105 , pinning clears that up. I got .00967 @ .111 and .00984 @ .112 , sheesh and I hated math in school!!


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 Post subject: Re: Jet chart
 Post Posted: Mon Sep 24, 2012 4:01 pm 
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FYI, in case you didn't already know, there's several Holley jet sizes that have the same ID hole. What IS different on them though is the LENGTH of that hole as the longer ones will offer more resistance to flow than the shorter one, hence the different jet number.


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 Post subject: Re: Jet chart
 Post Posted: Mon Sep 24, 2012 5:29 pm 
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Ive read that many times , and it may be true , but when you pin them , they are not the same diameter. I try and always use Max jet , they only go by orifice size , and when I pin them , they are right one.


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 Post subject: Re: Jet chart
 Post Posted: Mon Sep 24, 2012 8:16 pm 
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Milan.. wrote:
Ive read that many times , and it may be true , but when you pin them , they are not the same diameter. I try and always use Max jet , they only go by orifice size , and when I pin them , they are right one.


It's why I had switched to the max jets and now the BLP jets. FWIW, the Holley air correctors are all over hell's half acre from what they are stamped. I either use set screws or I just buy the .023 Holley ones from Summit, file off the numbers and drill the holes to what I want.


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 Post subject: Re: Jet chart
 Post Posted: Tue Sep 25, 2012 4:53 am 
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nomad wrote:
Milan.. wrote:
Ive read that many times , and it may be true , but when you pin them , they are not the same diameter. I try and always use Max jet , they only go by orifice size , and when I pin them , they are right one.


It's why I had switched to the max jets and now the BLP jets. FWIW, the Holley air correctors are all over hell's half acre from what they are stamped. I either use set screws or I just buy the .023 Holley ones from Summit, file off the numbers and drill the holes to what I want.


I pinned all the emulsion jets in my 950 aluminum Ultra all marked .029 , four of them pinned .031 , guess you do need to pin everything!


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 Post subject: Re: Jet chart
 Post Posted: Tue Sep 25, 2012 7:40 am 
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Location: Auburndale, Florida
webermaniac wrote:
Don't know if it helps but I flow jets with 1 meter of water pressure for a whole number of minutes then measure how much water they pass and look up the ID in a table. I found out this to be a rather precise way - up to a couple of hundreths of mm, especially if flowed for over a minute and repeated several times (>=3).


This could really be helpful when trying different brands of jets. I think Holley measures CCs per minute and BLP pounds per hour.


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 Post subject: Re: Jet chart
 Post Posted: Tue Sep 25, 2012 7:41 am 
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Location: Auburndale, Florida
Milan.. wrote:
nomad wrote:
Milan.. wrote:
Ive read that many times , and it may be true , but when you pin them , they are not the same diameter. I try and always use Max jet , they only go by orifice size , and when I pin them , they are right one.


It's why I had switched to the max jets and now the BLP jets. FWIW, the Holley air correctors are all over hell's half acre from what they are stamped. I either use set screws or I just buy the .023 Holley ones from Summit, file off the numbers and drill the holes to what I want.


I pinned all the emulsion jets in my 950 aluminum Ultra all marked .029 , four of them pinned .031 , guess you do need to pin everything!


It's that or drill blanks.


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