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Re: 340 6 bbl metering plates ?2 [Re: Cab_Burge] #2760209
04/04/20 11:16 PM
04/04/20 11:16 PM
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Posts: 1,979
s. e. pa.
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calrobb2000 Offline OP
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calrobb2000  Offline OP
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holley , chicago corvette no got !

where else ?

Re: 340 6 bbl metering plates ?2 [Re: calrobb2000] #2760223
04/05/20 01:59 AM
04/05/20 01:59 AM
Joined: Jan 2003
Posts: 1,908
Nebraska
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4406bbl Offline
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Nebraska
Originally Posted by calrobb2000

holley , chicago corvette no got !

where else ?


I would drill and tap for the mains for 6-32 setscrews and drill what you need. If the idle is drilled solder them up and redrill. What size are they now? You could buy the quick fuel plates also.

Re: 340 6 bbl metering plates ?2 [Re: 4406bbl] #2760398
04/05/20 02:37 PM
04/05/20 02:37 PM
Joined: Jul 2007
Posts: 291
St. Louis
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Imrare Offline
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St. Louis
The Power Valve Channel Restrictions (PVCR) on the new Holley metering plates were measured as follows: Drivers side, .086; Passenger side, .073. The prior plates that the Holley plates replaced measured .084 Drivers side, and .072 Passenger side. These plates were probably okay but these plates probably replaced the "drilled" plates by the last rebuilder to handled the carburetors. I went ahead and installed the new Holley plates I had purchased since they met the specs exactly (see attachment) that I had on the 340 2300 series end carburetors.

Not sure what you meant in your response by "qft". However, if you remove the old needles and inspect them, you should be able to tell if they are "true" or not (for the minor cost, I would just replace with new). Also, closely inspect the end carb "seats" on the base plates and clean the seat that the needles screw into. Make sure no debris gets between the needle and seat. The new needles are a little longer than the OE needles from 1970 (and easier to adjust) and you will not be able to reinstall the small "caps" that fit on the base plate and go over the needles heads to prevent further adjustment. I believe when you buy the new needles you will also get new "cork" seals that go around the needles to prevent inadvertent movement of the needle once set. Tip: install the seal in the needle channel first and then screw in the needle.

Scan0002.jpg
Re: 340 6 bbl metering plates ?2 [Re: Imrare] #2760436
04/05/20 04:47 PM
04/05/20 04:47 PM
Joined: Jan 2003
Posts: 9,436
Blair County,PA
62maxwgn Offline
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Originally Posted by Imrare
The Power Valve Channel Restrictions (PVCR) on the new Holley metering plates were measured as follows: Drivers side, .086; Passenger side, .073. The prior plates that the Holley plates replaced measured .084 Drivers side, and .072 Passenger side. These plates were probably okay but these plates probably replaced the "drilled" plates by the last rebuilder to handled the carburetors. I went ahead and installed the new Holley plates I had purchased since they met the specs exactly (see attachment) that I had on the 340 2300 series end carburetors.

Not sure what you meant in your response by "qft". However, if you remove the old needles and inspect them, you should be able to tell if they are "true" or not (for the minor cost, I would just replace with new). Also, closely inspect the end carb "seats" on the base plates and clean the seat that the needles screw into. Make sure no debris gets between the needle and seat. The new needles are a little longer than the OE needles from 1970 (and easier to adjust) and you will not be able to reinstall the small "caps" that fit on the base plate and go over the needles heads to prevent further adjustment. I believe when you buy the new needles you will also get new "cork" seals that go around the needles to prevent inadvertent movement of the needle once set. Tip: install the seal in the needle channel first and then screw in the needle.




I'm a little confused with the PVCR for the end carbs as there is only the secondary metering plate with idle feed restrictions and main metering restrictions,PVCR is in the metering block unless you are referring to the mechanical set where each has a metering block.Also, you will find the longer screw you are referring to does not have the correct taper as the original..

Re: 340 6 bbl metering plates ?2 [Re: Imrare] #2760507
04/05/20 07:46 PM
04/05/20 07:46 PM
Joined: Jan 2003
Posts: 1,908
Nebraska
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4406bbl Offline
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Imrare, just pointing out the taper is wrong where the needle seats, I doubt the holley tech guy knew that, anyway just trying to establish a baseline of design specs for both the 340-440 setups, so guys don't keep buying parts that they do not need.

Re: 340 6 bbl metering plates ?2 [Re: Imrare] #2760525
04/05/20 08:46 PM
04/05/20 08:46 PM
Joined: Jan 2003
Posts: 4,707
Moved to N.E. Tennessee
GomangoCuda Offline
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That 6 bbl tips page has been messed up for many years. For the front and rear carbs it should say Main Fuel Restriction or Main Jet instead of PVCR. The sizes are ok but they are not pvcrs. And that Venturi nozzle is probably unobtanium. I think it just has a distribution tab on it.

Last edited by GomangoCuda; 04/05/20 08:51 PM.

In theory, there is no difference between theory and practice. In practice, there is.
Re: 340 6 bbl metering plates ?2 [Re: 4406bbl] #2760553
04/05/20 09:48 PM
04/05/20 09:48 PM
Joined: Jan 2003
Posts: 9,436
Blair County,PA
62maxwgn Offline
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Blair County,PA
Originally Posted by 4406bbl
Imrare, just pointing out the taper is wrong where the needle seats, I doubt the holley tech guy knew that, anyway just trying to establish a baseline of design specs for both the 340-440 setups, so guys don't keep buying parts that they do not need.


iagree

I have talked Holley techs over the years and some didn't have a clue what I was talking about.On the needles,incorrect on left,main metering block screw used primarily on 71 and later plus current production,middle correct end base screw,no variation since initial production,right
main metering block screw that has been tapered,you can make your own if you have a drill press.

P4051026.JPG
Re: 340 6 bbl metering plates ?2 [Re: 62maxwgn] #2760742
04/06/20 12:54 PM
04/06/20 12:54 PM
Joined: Jan 2003
Posts: 1,908
Nebraska
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4406bbl Offline
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Nebraska
Originally Posted by 62maxwgn
Originally Posted by 4406bbl
Imrare, just pointing out the taper is wrong where the needle seats, I doubt the holley tech guy knew that, anyway just trying to establish a baseline of design specs for both the 340-440 setups, so guys don't keep buying parts that they do not need.


iagree

I have talked Holley techs over the years and some didn't have a clue what I was talking about.On the needles,incorrect on left,main metering block screw used primarily on 71 and later plus current production,middle correct end base screw,no variation since initial production,right
main metering block screw that has been tapered,you can make your own if you have a drill press.


Thanks for the needle pic, saved me digging thru my junk. Holley techs did not know the different styles in the the 80s, they would not, or could not give me any measurments, just sell the new parts.

Re: 340 6 bbl metering plates ?2 [Re: 4406bbl] #2761065
04/07/20 11:11 AM
04/07/20 11:11 AM
Joined: Jan 2003
Posts: 9,436
Blair County,PA
62maxwgn Offline
master
62maxwgn  Offline
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Joined: Jan 2003
Posts: 9,436
Blair County,PA
Originally Posted by 4406bbl
Originally Posted by 62maxwgn
Originally Posted by 4406bbl
Imrare, just pointing out the taper is wrong where the needle seats, I doubt the holley tech guy knew that, anyway just trying to establish a baseline of design specs for both the 340-440 setups, so guys don't keep buying parts that they do not need.


iagree

I have talked Holley techs over the years and some didn't have a clue what I was talking about.On the needles,incorrect on left,main metering block screw used primarily on 71 and later plus current production,middle correct end base screw,no variation since initial production,right
main metering block screw that has been tapered,you can make your own if you have a drill press.


Thanks for the needle pic, saved me digging thru my junk. Holley techs did not know the different styles in the the 80s, they would not, or could not give me any measurments, just sell the new parts.


Also,here are the jetable plates you can get without paying the price for billet plates that you are not going to see.

P4071027.JPG
Re: 340 6 bbl metering plates ?2 [Re: 62maxwgn] #2761213
04/07/20 06:08 PM
04/07/20 06:08 PM
Joined: May 2004
Posts: 851
Brisbane Australia
5
572B1 Online content
super stock
572B1  Online Content
super stock
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Joined: May 2004
Posts: 851
Brisbane Australia
Originally Posted by 62maxwgn
Originally Posted by 4406bbl
Originally Posted by 62maxwgn
Originally Posted by 4406bbl
Imrare, just pointing out the taper is wrong where the needle seats, I doubt the holley tech guy knew that, anyway just trying to establish a baseline of design specs for both the 340-440 setups, so guys don't keep buying parts that they do not need.


iagree

I have talked Holley techs over the years and some didn't have a clue what I was talking about.On the needles,incorrect on left,main metering block screw used primarily on 71 and later plus current production,middle correct end base screw,no variation since initial production,right
main metering block screw that has been tapered,you can make your own if you have a drill press.


Thanks for the needle pic, saved me digging thru my junk. Holley techs did not know the different styles in the the 80s, they would not, or could not give me any measurments, just sell the new parts.


Also,here are the jetable plates you can get without paying the price for billet plates that you are not going to see.


That's great info 62maxwg. would you have brand and part number on hand. thanks in advance.

Re: 340 6 bbl metering plates ?2 [Re: 572B1] #2761482
04/08/20 12:56 PM
04/08/20 12:56 PM
Joined: Jan 2003
Posts: 1,042
Slidell, La.
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doctor_mopar Offline
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Slidell, La.
I have previously installed the Pro Max metering plates in my 340 outboard carbs . So from what I am reading here , I beleive I was correct , to meet stock requirements in putting .086 jets drivers side , and .073 jets passenger side . Is this the correct conclusion ? Thank You


------------------------ It doesn't matter what you do.........As long as you look good doing it !
Re: 340 6 bbl metering plates ?2 [Re: doctor_mopar] #2761769
04/09/20 12:15 AM
04/09/20 12:15 AM
Joined: Jan 2003
Posts: 1,908
Nebraska
4
4406bbl Offline
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Nebraska
Originally Posted by doctor_mopar
I have previously installed the Pro Max metering plates in my 340 outboard carbs . So from what I am reading here , I beleive I was correct , to meet stock requirements in putting .086 jets drivers side , and .073 jets passenger side . Is this the correct conclusion ? Thank You



Yes, and .037 idle feeds from what others are measuring.

Re: 340 6 bbl metering plates ?2 [Re: 4406bbl] #3209629
01/31/24 07:29 PM
01/31/24 07:29 PM
Joined: Nov 2008
Posts: 660
San Diego
formula S Offline
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Joined: Nov 2008
Posts: 660
San Diego
I know this is an Old Post, I did a Google Search and found it so I decided to read it. I've used the Promax metering plates, there is an engineering problem with those plates. They do not seal to the body of the carburetor with the large cavity behind it, the guy at Promax says not to use the little thin plates, well they don't cover the Promax metering plate anyway, the last six pack I built I use AED jettable metering plates and they seal up fine, I saw on this thread someone posted about jettable non-billit metering plates, are those available, I've never seen them before?

Re: 340 6 bbl metering plates ?2 [Re: formula S] #3209809
02/01/24 03:39 PM
02/01/24 03:39 PM
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Slidell, La.
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doctor_mopar Offline
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Slidell, La.
Formula S . Now you have me wondering . I ran with the Promax plates jetted like i said in my post . What would the symptoms be if they are not covering properly like you said . i did not use the thin plates under them. I am in the process of changing engines now to a 340 stroked to 418 . I planned to go to a 3310 750 holley on an LD340 manifold. I have felt like the 6 pack would be hard to tune with the big motor, and have intended to sell it . I may consider running it though, and some insight on what I should be doing with the jetting.


------------------------ It doesn't matter what you do.........As long as you look good doing it !
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