Modified Holley Ultra H/XP "850" 1.58" v 4150 Carb

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Joined: Wed Apr 03, 2013 11:34 am

Modified Holley Ultra H/XP "850" 1.58" v 4150 Carb

Post by BradH » Tue Jul 31, 2018 4:34 pm

I own too many carburetors and have decided to sell a couple. This one is a modified Holley Ultra H/XP "850" 4150 built from all new parts, EXCEPT the base plate came from a low-use / dyno-time only Holley Ultra H/XP "950":

=> Suggested application: A 4150 street/strip or strip-only carb for a serious 450-500+" big-block in the 650 - 750+ HP range
- The large 1.58" venturi size will be better suited to a 500+" engine with 4K+ stall and turning 6500-7000 RPM or 450+" engine with 5K+ stall and turning 7000+ RPM
- May sacrifice some street manners for the higher flow capability using a traditional 4150 configuration

=> Holley XP venturi "850" main body with venturi blended from 1.56" to 1.58" to eliminate the casting lip and improve flow
- Braswell downleg boosters installed to improve booster signal and fuel atomization with a large venturi 4150
- Stainless-steel accel. pump check needles & high-flow squirter screws w/ .037" nozzles
- Includes the Ultra H/XP adjustable bypass air valve & tension spring; NOTE: this feature is functional ONLY on a base plate with a hole drilled in the center of the base plate like the Ultra H/XP plates have
- Drilled & tapped for interchangeable Transition Slot Restrictions (TSRs) using 8-32 x 1/8" brass set-screws (has .081 w/ current tune)
- The metering block mounting surfaces have been resurfaced after the boosters installation and an anti-corrosion coating applied using a Bonderite (formerly Alodine) Touch-N-Prep pen

=> Holley Ultra H/XP 5-emulsion gas billet metering blocks w/ .140+" angle channels
- Drilled & tapped lowered Idle Feed Restrictions (IFRs) that use 6-32 x 1/8" brass set-screws
- Plugged secondary power valve and tube-style (encapsulates the jet) extensions
- Stainless-steel large-head mixture adjusting screws replaced standard Holley screws

=> Holley Ultra "950" HP billet base plate; dyno-time only and in excellent condition
- Has "Ultra 950" high-flow slabbed throttle shafts; the Ultra H/XP "850" comes with the more restrictive half-round shafts
- Assembled with stainless-steel no-hole butterflies and Braswell low-profile screws

=> Holley Ultra HP aluminum fuel bowls with sight windows
- Holley standard primary & notched secondary floats
- BLP .128" Needle & Seat assemblies
- #6-AN fuel fittings
- GFLT alcohol-resistant accel. pump diaphragms

*** This carb is an upgrade over a standard Holley H/XP "850" 80804 due to the blended venturi, better boosters and high-flow throttle shafts. It is also more tuneable than an "out of the box" Holley H/XP "850" due to the the addition of replaceable TSRs & lowered IFRs. ***

It will come w/ a detailed build sheet that covers all the components and as-delivered baseline tune settings, so you'll know EXACTLY what you have.

$800, including ground shipping & insurance in the lower 48 United States.
- Sorry, NO international shipments and NO PayPal
- I accept only cash and U.S.P.S. Money Orders as payment, unless other arrangements are made in advance (e.g., cashier's or certified check)

For an additional $30 (i.e., $830 total), I'll include the following tuning parts:
- .028, .032 MABs (has .030 w/ current tune)
- .073, .076 IABs (has .070 w/ current tune)
- extra drill-your-own 6-32 x 1/8" IFR blanks (has .035" w/ current tune)
- extra Holley .029 e-jets that can also be enlarged for PVCRs (has .028/plug/plug/.028/plug emulsion & .059 PVCRs w/ current tune)
- spare set of BLP/Reinze metering block & fuel bowl gaskets
- Holley 82/92 + 86/96 jet sets (has 84/94 now)

PM me here, or text me at 7zero3.threeOne7.7nine8seven. I'm in Virginia outside of Washington, D.C., so please keep in mind I'm on Eastern Standard Time.

1. This carburetor is sold "as is" and is not returnable. Once it leaves my possession, I have no control over the skills or capabilities of the person who installs and adjusts it.
2. I do my best to provide a usable baseline, but the purchaser should NOT expect to simply "Bolt on an go!"
3. As with ANY performance carburetor, additional tuning (jets, air bleeds, etc.) will likely be required for YOUR engine & car combination!
CRB 1.58.jpg

Posts: 577
Joined: Wed Apr 03, 2013 11:34 am

Re: Modified Holley Ultra H/XP "850" 1.58" v 4150 Carb

Post by BradH » Thu Aug 02, 2018 12:57 pm

8.2.2018 - Update: No longer willing to consider cashier's or certified check as payment, since they seem to be the latest "bait of choice" with the online scammers who have been texting me.

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