Re: Holley 750 vs 850 vs 950
[Re: skrews]
#2530949
08/03/18 01:30 PM
08/03/18 01:30 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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Probably just going to run the 1.45 carb as I probably won't get a lot of hits, and I'm trying to iron out its unstable fuel curve. Modified a set of scrap metering blocks thinking it might actually want more emulsion not less. We shall see LOL. I'm interested in hearing how you've set up the carb, and what you're seeing w/ the fuel curve issues you mentioned. I made a few shake down runs at the local 1/8 mile track and the wide band skipped around by 3/4 of a point or so. My 1.375/1.68 carb was very steady,and the 1.375/1.75 carb was pretty behaved too. All these carbs have 3310 primary blocks with 2 .027 e holes and 26 to 28 HSAB. Despite the 1.45 carb's erratic fuel curve, it still managed to tie the best ET and generate the best MPH at the local 1/8 track in worse air. I added a third .027 e hole to a set of scrap 3310 blocks, and will also try bumping up to the supplied .032 HSAB and see what happens at the 1/4 mile track Friday. I love this stuff and you SHOULD see it dip rich down low a tad then trend lean up top with the .032 hi bleeds............I say SHOULD......... Lookin forward to your results.........
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: Holley 750 vs 850 vs 950
[Re: skrews]
#2530969
08/03/18 02:03 PM
08/03/18 02:03 PM
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Joined: Jan 2003
Posts: 2,094 central texas
krautrock
top fuel
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top fuel
Joined: Jan 2003
Posts: 2,094
central texas
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Probably just going to run the 1.45 carb as I probably won't get a lot of hits, and I'm trying to iron out its unstable fuel curve. Modified a set of scrap metering blocks thinking it might actually want more emulsion not less. We shall see LOL. I'm interested in hearing how you've set up the carb, and what you're seeing w/ the fuel curve issues you mentioned. I made a few shake down runs at the local 1/8 mile track and the wide band skipped around by 3/4 of a point or so. My 1.375/1.68 carb was very steady,and the 1.375/1.75 carb was pretty behaved too. All these carbs have 3310 primary blocks with 2 .027 e holes and 26 to 28 HSAB. Despite the 1.45 carb's erratic fuel curve, it still managed to tie the best ET and generate the best MPH at the local 1/8 track in worse air. I added a third .027 e hole to a set of scrap 3310 blocks, and will also try bumping up to the supplied .032 HSAB and see what happens at the 1/4 mile track Friday. what jetting were you running the 1.45 carb?
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Re: Holley 750 vs 850 vs 950
[Re: skrews]
#2531100
08/03/18 06:13 PM
08/03/18 06:13 PM
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Joined: Jan 2003
Posts: 14,539 So. Burlington, Vt.
fast68plymouth
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 14,539
So. Burlington, Vt.
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My HP950 that I built from scratch over 15 years ago uses a genuine Holley HP950 body, 1.375x1.750 configuration. I installed Braswell stepped boosters with .160 feed holes and lightly blended the Venturi. When I first put it together I used some billet metering blocks from BLP. We discussed what size the main wells and angle channels would be, but I don’t recall what those dimensions are. I tested it on a few motors on the dyno and it was really rich everywhere unless unusually small jets were used along with big hsab’s. The problem with that was, the throttle response was on the poor side. I swapped to some stock 3 emulsion HP metering blocks which helped some(smaller main well and angle channel), but had to keep going up with the hsab to try and reduce its tendency to richen up at the top end of the curve, while allowing for big enough main jets to help with the response.
It still doesn’t have “awesome” response, and still tends to slightly richen up in the upper rpms, but all in all it runs well enough to be used as a decent dyno carb. Jets are 74pv/83, hsab is .040.
What it really needs is a booster change to something with a smaller feed hole, which would allow for bigger jets and smaller hsab. I have the boosters....... and someday I’ll probably get around to swapping them out.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Holley 750 vs 850 vs 950
[Re: Thumperdart]
#2531387
08/04/18 07:07 AM
08/04/18 07:07 AM
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Joined: Jul 2012
Posts: 432 Washington
skrews
OP
mopar
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OP
mopar
Joined: Jul 2012
Posts: 432
Washington
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Probably just going to run the 1.45 carb as I probably won't get a lot of hits, and I'm trying to iron out its unstable fuel curve. Modified a set of scrap metering blocks thinking it might actually want more emulsion not less. We shall see LOL. I'm interested in hearing how you've set up the carb, and what you're seeing w/ the fuel curve issues you mentioned. I made a few shake down runs at the local 1/8 mile track and the wide band skipped around by 3/4 of a point or so. My 1.375/1.68 carb was very steady,and the 1.375/1.75 carb was pretty behaved too. All these carbs have 3310 primary blocks with 2 .027 e holes and 26 to 28 HSAB. Despite the 1.45 carb's erratic fuel curve, it still managed to tie the best ET and generate the best MPH at the local 1/8 track in worse air. I added a third .027 e hole to a set of scrap 3310 blocks, and will also try bumping up to the supplied .032 HSAB and see what happens at the 1/4 mile track Friday. I love this stuff and you SHOULD see it dip rich down low a tad then trend lean up top with the .032 hi bleeds............I say SHOULD......... Lookin forward to your results......... Made to the track. Wind was blowing pretty good so the powers that be decided to run 1/8 mile. LAME. Anyway I tried the 1.45 carb with the .032 HSAB for the first few runs, then swithed out for .027 on my last pass. The AFR was rock solid stable with the .032 and varied about half a point with the .027. MPH fell off a few hundredths with the .027. This was with the untouched 3310 metering blocks. Main jets are 78/86, AFR was 12.9-13.0. Didn't seem to run rich at the bottom of the gears with the .032 HSAB. All in all I'd say if the car picked up anything it wasn't enough to notice, but a fun tuning/learning experience none the less. More flogging is necessary
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Re: Holley 750 vs 850 vs 950
[Re: skrews]
#2531428
08/04/18 11:55 AM
08/04/18 11:55 AM
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Joined: Oct 2007
Posts: 4,219 New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,219
New York
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Watch the facial expression of a carb tuner when some 2-stroke person says "why would you want the A:F ratio to remain constant throughout the RPM range, and in every gear?"
Boffin Emeritus
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Re: Holley 750 vs 850 vs 950
[Re: skrews]
#2531481
08/04/18 01:43 PM
08/04/18 01:43 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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Flow tested a few carbs the other day, thought I'd share my findings. The Ultra HP carbs are the older design from around 2005 they are no longer sold.
Holley Ultra HP 750 part#80675 1.375 venturi / 1.687 base plate 819 cfm
Holley Ultra HP 950 part#80676 1.375 venturi / 1.75 base plate 825 cfm
Holley 850 "old style main body" part# 9380 Choke horn milled off, slabbed throttle shafts, annular boosters 1.58 venturi / 1.75 base plate 945 cfm
I'll be replacing the 1.375 main body of the 950 with a 1.45 main body and retesting in the coming weeks.
This test backed my suspicions about the true flow of the 950, as it was only able to make about 5 more HP than the 750 on an upper 500 HP 360 motor. 950 my ass lol, I know Holley took a lot of [censored] over that carb and the new XP950 has a 1.6 venturi because of it. Be aware that that new 950 with the 1.60 venturi is a poor choice. The entrance shape causes turbulence. I've had 3 on my flow bench, put every booster available in it. Flow and booster signal are down because of it, and I can get a 1.45 venturi Quick fuel to flow the same and have a much better booster signal. And you can hear the turbulence on the bench. Quick Fuel/Proform bodies are a much better choice, the entrance to the venturi is shaped better, as well as the new billet bodies from BLP and APD. I've heard that about the 950 XP. That's why I'm working with the 1.45 QFT main body. Should be a good match to my engine. If I missed it, what motor are you testing these on.........
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: Holley 750 vs 850 vs 950
[Re: skrews]
#2531500
08/04/18 02:41 PM
08/04/18 02:41 PM
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Joined: Jul 2012
Posts: 432 Washington
skrews
OP
mopar
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OP
mopar
Joined: Jul 2012
Posts: 432
Washington
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[/quote] If I missed it, what motor are you testing these on......... [/quote] 360 11.75 comp 596 heads 2.02/1.6 flow 265/180 worked over M1 single plane 2" tapered spacer 1.75 Super Comp headers .528/.528 252°/252° @.050 108+5 SFT Duster 3350#, 904 5800ish converter, 4.56, 28x10.5 Here is the intake about half way done
Last edited by skrews; 08/04/18 02:42 PM.
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Re: Holley 750 vs 850 vs 950
[Re: skrews]
#2531648
08/04/18 10:03 PM
08/04/18 10:03 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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[/quote] If I missed it, what motor are you testing these on......... 360 11.75 comp 596 heads 2.02/1.6 flow 265/180 worked over M1 single plane 2" tapered spacer 1.75 Super Comp headers .528/.528 252°/252° @.050 108+5 SFT Duster 3350#, 904 5800ish converter, 4.56, 28x10.5 Here is the intake about half way done [/quote] Good combo, and fwiw, 18+ years ago, I ran an 850 speed demon which flowed 920 cfm on my daily driver stock stroke 360 w/stock heads, a solid Isky cam and a Pettis valve job at about 11.5 iirc and went a best of 11.88 @114 mph at LACR's altitude track. I mixed race gas but the point is that motor like most responded to more cfm and went from mid 12's to my 11.88 so I like to over carb apparently but it seems to work MOST of the time but not always...........
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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