Carb advice
#2270487
03/16/17 12:36 PM
03/16/17 12:36 PM
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Joined: Aug 2009
Posts: 1,324
Ohio
jlatessa
OP
pro stock
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OP
pro stock
Joined: Aug 2009
Posts: 1,324
Ohio
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Getting close to dynoing a new 512 build, have a used ProForm 950 w/1.750" throttle bores with the following specs:
30cc pump pri. white cam, #1 hole
50cc pump sec. brown cam, #1 hole
#76 jets pri.
#85 jets sec.
IABs, #32 inboard, #71 outboard pri. & sec.
.110" holes in each butterfly
#40 squirters, pri.
#35 squirters, sec.
downleg boosters
Engine specs:
512 RB
10.7 CR
Victor heads, MW
Bullet cam; 290/295 @ .20 Part #503000
.651 gross lift
separation 110*
timing events @ .50;
Intake, 22.5-54.5
Exhaust, 66-18
106* centerline
1.5 rockers
Indy dual plane MW
4 speed, 3.54 gear, 3900# car
Need to know if the carb is going to be close to what's needed
or if I should make some preliminary changes to be closer and maybe save some dyno time.
This is for a mainly street application,
Thanks to the experts in advance,
Joe
P.S. I am using a 1" blended spacer for acc. pump clearance
Last edited by jlatessa; 03/16/17 12:38 PM.
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Re: Carb advice
[Re: jlatessa]
#2270530
03/16/17 01:57 PM
03/16/17 01:57 PM
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Joined: Jul 2004
Posts: 19,318
State of confusion
Thumperdart
I Live Here
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I Live Here
Joined: Jul 2004
Posts: 19,318
State of confusion
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Getting close to dynoing a new 512 build, have a used ProForm 950 w/1.750" throttle bores with the following specs:
30cc pump pri. white cam, #1 hole
50cc pump sec. brown cam, #1 hole
#76 jets pri.
#85 jets sec.
IABs, #32 inboard, #71 outboard pri. & sec.
.110" holes in each butterfly
#40 squirters, pri.
#35 squirters, sec.
downleg boosters
Engine specs:
512 RB
10.7 CR
Victor heads, MW
Bullet cam; 290/295 @ .20 Part #503000
.651 gross lift
separation 110*
timing events @ .50;
Intake, 22.5-54.5
Exhaust, 66-18
106* centerline
1.5 rockers
Indy dual plane MW
4 speed, 3.54 gear, 3900# car
Need to know if the carb is going to be close to what's needed
or if I should make some preliminary changes to be closer and maybe save some dyno time.
This is for a mainly street application,
Thanks to the experts in advance,
Joe
P.S. I am using a 1" blended spacer for acc. pump clearance What emulsion package as in how many and what sizes........
72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
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Re: Carb advice
[Re: jlatessa]
#2270752
03/16/17 08:11 PM
03/16/17 08:11 PM
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Joined: Jul 2004
Posts: 19,318
State of confusion
Thumperdart
I Live Here
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I Live Here
Joined: Jul 2004
Posts: 19,318
State of confusion
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Are the gaskets brown(real old) or the blues...........they can be a bear and a razor knife in the gaskets, some fluid and gentle prying should get em apart......
72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
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Re: Carb advice
[Re: PorkyPig]
#2271069
03/17/17 11:33 AM
03/17/17 11:33 AM
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Joined: Aug 2009
Posts: 1,324
Ohio
jlatessa
OP
pro stock
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OP
pro stock
Joined: Aug 2009
Posts: 1,324
Ohio
|
Porky: I bought it from a member here who had it on similar set-up and thought it would perform well as-is. Have not run it though.
Thumper: Was able to coax the metering blocks off this AM, here's what I found;
Primary:
6.5 Power valve
#33 orifices at top of idle feed channels
Inboard channels w/4 threaded openings have a plug second from bottom.
Scondary:
Same as primary with exception of P.V., of course
The metering blocks are purple anodized Al. with no I.D.
I could see.
Thanks, Joe
Last edited by jlatessa; 03/17/17 11:35 AM.
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Re: Carb advice
[Re: jlatessa]
#2271070
03/17/17 11:39 AM
03/17/17 11:39 AM
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Joined: Feb 2010
Posts: 1,645
Phila. Pa.
Mattax
top fuel
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top fuel
Joined: Feb 2010
Posts: 1,645
Phila. Pa.
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Good job! I'll remove most of the now irrelevent suggestions I posted and add the following instead. It will be easier to tune in after changing the IFR location. This recent thread covers it well starting about 2/3 down the first page https://board.moparts.org/ubbthreads/ubbt...tml#Post2260468The threaded holes in the vertical channel are for air bleeds into the main well. Almost everyone calls them emulsion bleeds (e-bleeds). Very likely will want to plug another one. It's helpful to take a pencil or marker across from the fuel level site window to note on the block the normal hight of fuel relative to those holes. Holley Carb Passage & Restriction Location & Identification A little WD40 is OK for killing the sticky on the gaskets before assembly.
Last edited by Mattax; 03/17/17 12:02 PM.
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Re: Carb advice
[Re: jlatessa]
#2271103
03/17/17 12:33 PM
03/17/17 12:33 PM
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Joined: Aug 2009
Posts: 1,324
Ohio
jlatessa
OP
pro stock
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OP
pro stock
Joined: Aug 2009
Posts: 1,324
Ohio
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Good reading! I guess the low position for IFR is now the consensus.
Is this an easy mod or should I have Thumper do mine?
Or are they available for my application cheaper?
I can measure my intended fuel level (slightly above hole?) and see where it falls on the metering block, but what am I accomplishing by blocking another orifice?
Bear with me, I've had my nose in engines longer than some of you have been alive, but a lot of this is new to me.
Joe
Last edited by jlatessa; 03/17/17 12:34 PM.
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Re: Carb advice
[Re: jlatessa]
#2271225
03/17/17 03:59 PM
03/17/17 03:59 PM
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Joined: Feb 2010
Posts: 1,645
Phila. Pa.
Mattax
top fuel
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top fuel
Joined: Feb 2010
Posts: 1,645
Phila. Pa.
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I guess the low position for IFR is now the consensus. I prefer to think of it as physics.   Fluid dynamics are complicated enough to begin with. IMO there needs to be a darn good reason to make it more complicated. Most of the time, there isn't. I can measure my intended fuel level (slightly above hole?) and see where it falls on the metering block, but what am I accomplishing by blocking another orifice? Usually the new style bowls have a big clear window, and they use the center of the window as the fuel level. Classic Holley's use a threaded plug clear or brass. Those always use the bottom of the hole as the normal fuel level. Second part - short answer is that when there is too much air bled into the main channel the tiny bubbles have a tendency to join together into big ones. When that happens fuel doesn't flow consistantly. Many of the new carbs have a combination of too many or too large bleeds resulting in inconsistant most of the time. Long Explanation at RFS: Emulsion Tuning Short Example: http://racingfuelsystems.myfunforum.org/viewtopic.php?f=25&t=578
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