Impco 425 backfire. I think this is the … IMPCO 425 Clean Air LPG Mixer.

Impco 425 backfire 5″ FLANGE. Buy It Now +C $35. The difference between an X1 and the IMPCO model E or L is the operating pressure in the Genuine Impco 425 Mixer Clean Air. from Impco Ct425m-2 Mixer With Holley 4 Barrel Bolt Pattern Ct425 425 Carburetor Lpg - IMPCO. Sign in. Backfire parts impco parts. Categories: 425 Series, Carburetors Tags: 425, ct425m-2, mixer. $72. Now from € 550,- for € 399,- Backfire parts ; petrol solenoid ; Inline adjuster ; Electric parts ; LPG hose ; Connectors ; We scored a complete Impco model 425 Propane Regulator and Mixer setup off of Facebook Marketplace to test on our mule. pdf), Text File (. The mixer operates by a pressure I've got an 81 dodge pickup, 318 w/ 360 heads, with an impco 425, model E, and VFF30. Learn more. The Does the Impco 425 provide significantly more fuel delivery and airflow in a blow through set up rather than in a draw through set up? 383NA 12 sec propane malibu. The power mixture adjustment is the big bolt in the mixer body. 78 Select options. i My 14x3 air cleaner I had doesn't seem to work with a single 425 mixer. IMPROPER INSTALLATION OR USE OF THE REFERENCED PRODUCTS MAY CAUSE SERIOUS INJURY, DEATH AND/ OR PROPERTY DAMAGE SERVICE i managed to adjust the power valve of the Impco 425, so that the engine runs around 15 on the scale of the gauge at full throttle. 36. Re: IMPCO 425: new base plate, binds when engine runs Post by kikkegek » Sun May 03, 2015 4:57 pm another thing. Google Impco's website - they have a comprehensive catalog. This is probably I have a twin impco 425 on a homemade adapterplate, and twin impco E vaporizer. A quick teardown of the unit could confirm this. shipping calculated at checkout. a 450 vs 600 holley Throttle body on Impco 425 - posted in Engine: Ive been running a 450 holley throttle body which has 38mm butterflies on my Impco 425 LPG carb for a long I'm getting tired of it and wonder if theres a proper way to set the mix. 5″ DUAL IMPCO 425 AIR CLEANER FILTER HEAVY DUTY ALUMINUM MOUNT HIGH FLOW HOLLEY LPG. did a Does the Impco 425 provide significantly more fuel delivery and airflow in a blow through set up rather than in a draw through set up? 383NA 12 sec propane malibu. 0 days. 3. Mar 5, 2007 2 AU. Sounded a a worn camshaft or jumped timing belt. Buy It Now +$55. The Gas Research units are a complex, adjustable APPLICATION:REPAIR KIT FOR AN IMPCO CT425M-2. 48 3. WARNING. Impco original CT425M-2 Propane mixer ; Silicone Diaphragm ; For propane up to 333HP ; Direct bolt on to Holley square bore throttle plate (600cfm). that I believe is the issue, check the intake manifold and when you find out which one is missing you ADAPTOR IMPCO 425 F100 TWIN PIPE. This is a IMPCO model 100 system and everything seems American Impco Air Valve using a “425” gas mixer. In Stock MIXER IMPCO 425 FEEDBACK. Sales, highest to lowest Relevance Name, A to Z Name, Z to A Price, low to high hi. This usually occurs Not saying sequential is the only answer just LPG has more of a tendency to backfire and could potentially do what he is describing all be it he is a bit The carb is an ADAPTOR IMPCO 425 TO FORD V8 EFI AIR CLEANER. The main mixture is the big bolt -set as Pro Gas has been supplying and developing LPG conversion systems for over 20 years. Impco 425 mixer can be used for cars with high power motor when the benzin system not will be used anymore. 70. CT425M2. gas hose connection for high capacities on LPG. This unit is available for LPG Vapor. For what its worth, the Impco 425 was more successful since the gas valve doesnt have the power piston to contend with. Your i'v did alot of searching and reading on the net about propane conversions. from Australia. Sep 23, IMPCO ADAPTER 425 MIXER TO ROCHESTER 4 BARREL QUADRAJET PROPANE LPG CARBURETOR. Forklift. Regular price $49. i'v already bought most of the parts i need to do the conversion but still have a few questions. anyone who needs info on making 425's work or on twin carb lowrise intake manifolds can contact me. 50 kg: Brand: Impco. 1 ounces. The one you get with the kits is pretty basic and there seems Up For sale Jack has this Impco Model Ep 425 CI-30 Propane Carburetor (F4L) LPG Gas (JSF6) Regulator Mixer - Weight: 10 lbs 10. Impco recommends using a CO analyser for proper The Impco 425 has a 5 1/8" diameter neck, so most Holley open air element assemblies will work. The cam is a Comp Cam 268h, 218/218 @ I have a 425 impco on a healthy 327ci and like most of us, I feel clearly the engine being limited @5000 rpm however the engine is capable of making strong power @ 6000 rpm. This propane carb is fitted with a s This IMPCO LPG Engine Conversion Kit is often used on American classical cars. It bolts straight to the 425 - see picture. This type of LPG Mixer is most suitable for American classics with extra high power from the brands About a 18 months ago IMPCO began supplying the 425 with Tamper resistant carb adjustments. 49 IMPCO LPG Parts - Reducers (Model E & Cobra) - Mixers (300A & 425) - Adapters - Filters and Accessories. (s): Installation Kit for ATB T2 Series to Impco 425. In Stock THROTTLE BODY IMPCO 425 2. bluelpg1 (11,417) 99. 16 shipping. Shipping calculated at checkout. Impco Master Catalog 2K9 2009 blowin through 425 impco for turbo. FSERVICE Senior Member. I had a cam sensor failure and backfired the performer and it can handle it, For 600 hp you will need 2 Help! I have a 1974 blazer k5 rock crawler on 40" tires with a Chevy 350 engine on a propane fuel system. LPG Parts. The reverse is also true. Power Valves. 00 hours. This kit uses the IMPCO gas mixer 425 that is positioned along side the carburettor using an extension arm Backfire Valves. Here we go again. IMPCO. Backfire parts ; petrol solenoid ; Inline adjuster ; Electric parts ; LPG hose ; Connectors ; Gas tanks ; Filler Hose ; Gas Filler ; Mini Filler ; Alias ; Adapter from Impco mixer 425 to Ey guys bout to put a impco 425 on me vh v8 to put it on straight gas since my carby needs rebuilding. trucks, cars, generators, tractors, boats, motorcycles, RVs etc. The Holley four barrel base plate bolts directly to the Impco 425 and the Offy intake. The fuel system consists of two fork lift tanks, a vff30 fuel lockoff Valve, than a ohg model x-1 pressure regulator/ IMPCO Mixer 425 Type CT425M incl. Impco's Model 425 mixer is used quite extensively on carbureted propane vehicles. Because of the size of the V8 and Does the Impco 425 provide significantly more fuel delivery and airflow in a blow through set up rather than in a draw through set up? 383NA 12 sec propane malibu. MIXER HOLDEN VN / VR COMMODORE V6. 25. 70 3. where is the power mix adj? It's an impco 425 mixer and an aussie b2 converter. Engine specs: Cadillac, 514 cui Cr 10. also twin 425's work perfectly fine on a street driven car even on a impco 425 for blow through 3. I think this is the IMPCO 425 Clean Air LPG Mixer. Backfire parts ; petrol solenoid ; Inline adjuster ; Electric parts ; LPG hose ; Adjusting Impco 425. About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features NFL Sunday Ticket Press Copyright About this item . Joined Dec 14, 2012 Messages 62 Reaction score 0. Buy It Now +$36. Q-Jet AA3-129 Adapter Assy, 3" Hose A2-47 Adapter, Air Cleaner Base 125 - 425M A2-54 Adapter, Air Holley 600 Base Plate for Impco 425 Post by 308RRC » Sun Sep 15, 2019 3:22 am I have been using a Rochester base on my Impco 425 but want to change over to a 600 brand/part no: impco ct425m-2 mixer (silicone), 5-1/8" air filter gasket, model eb regulator, 12v fuelock features: the 425 is designed to be a direct bolt on to the holley 650 4bbl throttle plate, Engine: Vortec V6 with Impco Regulator/Vaporizer; Impco Lockoff not used. The intake bolt pattern is 4 1/4 x 5 5/8. The AV1-16 is the standard valve that comes with the 425 mixer. Stock I have a Tennant ride on floor sweeper with a 1. I know of more than a few police type vehicles using a 200 on a 4. Valve TECHNICAL INFORMATION: LPG CARBURETOR ADJUSTMENT 1) Idle Mixture Adjustment Screw Turning the screw “IN” will make the fuel PROGASAUSTRALIAN LPG & CNG FUEL SYSTEMS PARTS SUPPLIER keeping business movingSHOP NOW Shop by Category Browse by automotive, forklift & carburettor parts and Im running a impco 425 with a turbo on 7psi with blow off valve venting to atmosphere. C $98. also found out the PCV valve was bad, causing a vacuum leak and thus higher idle. Joined Apr 2, The Model 425 carburetor is simply a Model 425 mixer mated to a 4bbl throttle body. I will answer your questions now: Did not originally adjust air/fuel mixture at carburetor; since I Impco: This system is more complex, but just as easy to set up. THROTTLE BODY IMPCO CA55. Weight: 0. Re: Pontiac 389 engine with a Impco 425 - The Impco CA-425 is a mass flow sensitive variable venturi. 280 posts · Buy Holley Holley 4 BBL Barrel Cfm Throttle Body Plate Fits 425 Propane New Lpg 600: Fuel Injection Thermo-Time - Amazon. The one you get with the kits is pretty basic and there seems IMPCO develops and manufactures solutions for the medium- and heavy-duty on-road and industrial markets. This is the larger Impco mixer and with the hood that we use it fits very well on the V8's throttly body. 50 5. hi INCLUDES: (2) IMPCO CT452M-2 MIXERS. IMPCO CT425M-2 Mixer $ 612. You don't need to install a balance line. C $283. Standard the port is blocked with a plug on the 425 and the converter has a brass mesh over it. You can see the 4 screws that are in the 425 base, these attach the two parts with a gasket. txt) or read book online for free. 2007-2009 LPG & Bi 2. mixers Fittingen__Bouten There are four gas valves available for the Impco 425 mixer. Brand New. 425 does not mean 425 CFM. 00 Impco #300A Mixer Algas Series 500 21277 10. Relief Valves. 07. Mounting Accessories. 36 shipping. The screws are The 253 and 308 (carby engines) are usually fitted with Impco 300A (both engines) or 425 (308 only, they are way to big for a street 253). 0L Service Manual HHI 2009 Emission Certified & Bi-Fuel Page 48 BACKFIRE Checks Action DEFINITION: I have a Waukesha 140-GKB engine attached to a US Light and Power 30 kW genset with an Impco 200 gas mixer. Language: en English. 46 shipping. therefore two will be around 900cfm. lowandslow Well-Known Member. . 2 Mild comp cam (270H) 1 setting my timing i have read Your intake will not survive a backfire if you run a mixer in front of it. A1-79. 37. 22 sold. IMPROPER INSTALLATION OR USE OF THE REFERENCED PRODUCTS MAY CAUSE SERIOUS INJURY, DEATH AND/ OR PROPERTY DAMAGE SERVICE Creative IMPCO 425 air cleaner set ups: Does anyone have any photos for air cleaner set ups for the Impco 425 LPG mixer/carb. L. add to cart more impco model e/lb/h420 Creative IMPCO 425 air cleaner set ups: Does anyone have any photos for air cleaner set ups for the Impco 425 LPG mixer/carb. Impco Repair Kit for the 425 Mixer. Sales, highest to lowest Relevance Name, A to Z Name, Z to A Price, low to high impco parts for the american car or for the heftruck, impco parts for the american car or for the heftruck, Backfire parts ; petrol solenoid ; Inline adjuster ; Electric parts ; LPG hose ; Yes this is correct. IMPCO AA3-80 ADAPTER. Post by dutchlincoln79 » Sat Jan 19, 2008 8:11 pm. Same with the vaporizer. The AV1-1637 valve supplies a rich mixture and Impco AD1-28-1 Idle Diaphragm and Gasket Assembly $ 15. Manufacturer Part Number. HOLLEY 4 BARREL 850 CFM THROTTLE PLATE. Brand. Accessories. S. Joined Dec 11, 2013 Messages 1,626 Reaction score it should stop flow after An Impco 200 or 225 works great at low to mid range speeds but falls flat at higher airflow. X1 regulators are used all the time with 425 mixers. Service Valves. 25 5. Post up some pics Hi I have recently completed a twin 425 gas conversion on my v8 Holden. The Backfire Valves. 99. However, given the close proximity of the mixer to the brake booster, IMPCO CT425M-2 Mixer quantity. pretty sure this is the idle mix adj. 60 The CA 225 (207 hp max) and CA300 (216 or 270 hp, 161 or 201 kW), and CA 425 Impco carbs (287 HP, 214 Kw) are better as stock replacement carbs on sixes and V8's, with a Does the Impco 425 provide significantly more fuel delivery and airflow in a blow through set up rather than in a draw through set up? 383NA 12 sec propane malibu. The difference between an X1 and the IMPCO model E or L is the operating pressure in the MIXER IMPCO 200 2-5/8" FEEDBACK SILICONE. scottal Discussion starter. Sale! Mixer Adapters, Mixers. Adapter Plate, Gaskets, and Bolts For Mounting a 425 Impco Mixer to any ATB T2 Series Throttle Body; All necessary brackets and hardware; Easy to install; Locate A Distributor. The one you get with the kits is pretty basic and there seems impco low clearance complete dual fuel propane & gas kit high hp 425 v8 454 lpg. Stock THROTTLE BODY IMPCO 425 2. They're running of a regular intake with a large holley throttle plate and the "Y" adapter to mount 2 425's on one The Impco 425 is designed to use a square bore Holley throttle plate. 25 8. 5 - 2 lbs of fuel pressure at teh 1/4" pipe plug on the regulator (impco cobra or jb2) more or less and its not gonna run right usually on of the diaphragms get Application: Adapts Impco Ct425m & Ca425m To 4" Air Filter Or Hose includes: All Gaskets, Mounting Hardware also: Fits On Holley 2 And 4 Barrel Carbs With 5 1/8" Air Horn Does the Impco 425 provide significantly more fuel delivery and airflow in a blow through set up rather than in a draw through set up? 383NA 12 sec propane malibu. The difference between an X1 and the IMPCO model E or L is the operating pressure in the The mixers (carbs) are impco 425's that have proform holley baseplates with a 4150/4160 bolt pattern of 5 1/8 x 5 5/8. We Find many great new & used options and get the best deals for IMPCO 425 Clean Air LPG Mixer at the best online prices at eBay! Free shipping for many products! the 425 mixer flows aprox 450cfm. Theres "Idle" "Balance" and a "big Try doing that with an Impco 425 and still be able to accurately meter the fuel at stoich (yes I have an o2 gauge on my dash) up to 80% throttle. The car goes good throughout all of the ranges while driving is spot on 15. it should get about 1. GASKETS AND SCREWS **WE MACHINE AN AIR FILTER THAT IS A DIRECT BOLT ON FOR THIS Impco 425 Mixer Genuine LPG Diaphragm suits both Clean Air and Feed Back. 1 x 425 Clean Air Mixer. 18 2. 6 GM engine. 6 V-8 engine and IMPCO® PROPANE FUEL SYSTEM 1998 GM Medium Duty Chassis Service Manual Supplement - Page 1 2/23/98 VEHICLE APPLICATION This IMPCO® propane system was Franz is on the money. you recommend a impco 225 E, but what about a impco 425? can it hold boost? the reason I say this is because the 225 I saw was a Impco 425 Mixer Genuine LPG Diaphragm suits both Clean Air and Feed Back. My current issue is that the engine is backfiring through X1 regulators are used all the time with 425 mixers. Stock A CA 300 has a backfire arrestor, which vents the gas to the atmosphere rather than trying to take the carby off! for instances I can gat used impco 425 mixers for about $25 AA3-80 Adapter, Dual 425 Mixer to Holley AA3-86 Adapter, 425 Mixer to Rochester. The Model 425 bolts up directly to a square-bore throttle body and can be bolted up to a Quadrajet IMPCO AFTERMARKET PARTS IMPCO has recently expanded its offering of regulators, mixers, and repair kits to provide a high quality IMPCO aftermarket option to customers operating Impco 425 Mixer OHG X450 Mixer 21071 8. The 425 will flow 476 CFM. There is 1 product. AFL Valves. it wont run more than a few seconds, then backfires. Cross reference part number/s: C1-28; IM992 Backfire Valves. This unit is available for Propane, Natural Gas, and Digester Gas applications. 69 shipping. storm Posts: 797 Joined: Thu Jan 11, 2007 4:10 am Location: NSW, Australia. 95 with . 5 afr on cruise and 14. Fill Valves. Theres quite abit of shit to tune it. INCLUDES:AV1-16-2 AIR GAS VALVE ASSEMBLY. Hi all, Just wondering if anyone knows how to adjust the mixture on a 425 (32coupe im sure you I still have my Camaro 68 with SBC 327 vortec L31 heads, that is fed with propane through a IMPCO 425 an model E converter. A1-80. 86. 60 Impco 425 mixer without hydrin diaphragm for ADP feedback system. Jump to Latest 2. English en; Nederlands nl; IMPCO LPG Mixers IMPCO I have a 1998 GMC 7. You may have had 800 CFM Impco 425 Mixer Genuine LPG Diaphragm suits both Clean Air and Feed Back. The vaporizer has a IMPCO Start assist connected. regular price $2,199. Words: 1,454; Pages: 6; Preview; Full text; SECTION 1: CARBURETORS & MIXERS 425 SERIES MODEL 425 STANDARD A nice 454 chevy which now has a twin Impco 425 setup. . 90. I think the carbs are Impco but im not completely positive. Level Arm Valves. Anyone who has ever seen a poor setup has probably seen what an lpg intake backfire can do to the inlet manifold/air box and it isnt pretty! A fan of Impco Does anybody have an impco 425 (good or bad) for sale cheap ? so blow through is the way to go then. $199. Air filter cover plate for IMPCO CA124 / CA425 mixer. 98 2. Additional information. It has started backfiring heavily under load , getting worse over a couple of weeks, to What happens is, if you get a backfire it blows one or more of the plugs out. Buy It Now +$37. This is roughly equivalent to a CD stromberg or SU carby. It has Anyone here running LPG with some form of forced induction? either supercharged or turbo? What setup are you using, lpg sequential injection or the good old fashioned venturi One good backfire can tear the mixer diaphragm on the impco units and they wont work any more. Add to cart. eBay Product ID (ePID) 703251029. I've got an 81 dodge pickup, 318 w/ 360 heads, with an impco 425, model E, and VFF30. Opens in a new window or tab. 14 shipping. Category: 425 Series Tag: ct425-2. Free Got a Suburban this weekend and it has a IMPCO300A on a Quadrajet and is connected to a IMPCO model-E vaporizer. One correction to the original comment. ADAPTOR IMPCO 300A TO 2-5/16″ AIR HORN. Impco makes a wide variety of mixers to suit just about any engine size imaginable. It has started backfiring heavily under load , getting worse over a couple of weeks, to Find many great new & used options and get the best deals for IMPCO Ct 425 Mixer Holley Bolt Pattern LPG Carburetor at the best online prices at eBay! Free shipping for many products! Impco 425 LPG Mixer Adapter Plate Kit to Suit Cart Thermo Quad Carby. Mar 5, 2007 #1 lcturblow Automotive. 350-S10 Discussion starter. Hello, I've installed a new edelbrock performer intake, with a holley throttleplate and a Impco 425 on impco 425 mixer (new style) Thread starter shawn213; Start date Sep 23, 2013; shawn213 Well-Known Member. There are 4 products. Mixer Adapters, Mixers. ADAPTOR IMPCO 425 TO FORD V8 EFI AIR CLEANER. Impco Master Catalog 2009 - Free ebook download as PDF File (. Multivalves. The one you get with the kits is pretty basic and there seems WARNING. Stock This forklift impco Diaphragm mixer 425 series is designed to meet the standards established by the OEM - providing superior performance during service or component wear. $70. Jump to Latest 11K views 39 replies 15 participants last post by dragrcr65 Jun 11, 2013. Stock Does the Impco 425 provide significantly more fuel delivery and airflow in a blow through set up rather than in a draw through set up? 383NA 12 sec propane malibu. 3 wot. 75 3. 18 Impco #300A Mixer Algas Series 500 21093 6. Gasket is used and shows compression marks IMPCO® PROPANE FUEL SYSTEM 1998 GM Medium Duty Chassis Service Manual Supplement - Page 1 2/23/98 VEHICLE APPLICATION This IMPCO® propane system was X1 regulators are used all the time with 425 mixers. Horses for courses ok. Now the manual is pretty clear on how to 3 Power Mixture Adj. 7K views 7 replies 4 participants last post by 350-S10 May 20, 2011. Top. Hurry up before the offer ends. A1-9. Description Additional information Description. 00 Download & View Impco 425 as PDF for free. BRAND/PART NO: IMPCO CT425M-2 FEATURES: HOLLEY 4 BARREL THROTTLE PLATE BOLT PATTERN TAMPER PROOF, ADJUSTABLE WITH 1/8" ALLEN WRENCH FREE Creative IMPCO 425 air cleaner set ups: Does anyone have any photos for air cleaner set ups for the Impco 425 LPG mixer/carb. About this product. 4l with Impco 425 that has a DualCurve 5924 with FCV2 solenoid Drove it today and it didn't die or backfire on me so hopefully I'm getting it tuned a impco 425 mixture adjustment. Purchase Online Request More Info View and Download Impco HHI service manual online. The difference between an X1 and the IMPCO model E or L is the operating pressure in the X1 regulators are used all the time with 425 mixers. Buy It Now. More details. In this case, I would favor the 425 over the 450. a 750base plate without the restriction of the holley venturis above it also flows just under 900cfm. Find many great new & used options and get the best deals for IMPCO 425 Mixer With Holley 4 Barrel Throttle Plate Propane Carburetor at the best online prices at eBay! Free shipping for many products! IMPCOÒ PROPANE FUEL SYSTEM 1999-2000 GM Medium Duty Chassis Service Manual Supplement - Page 6 Website 5/29/03 FUEL MIXER The IMPCO Model 425 fuel mixer is an i've searched but haven't figured out for sure where to adjust the idle mix and power mix on my impco 425. Impco 425 Mixer Genuine LPG Diaphragm suits both Clean Air and Feed Back. Pay in 2 interest-free installments of $24. Price: $649. The Model 425 carburetor is a single-diaphragm air valve carburetor/mixer. Our products are designed and manufactured to be durable, reliable, and Creative IMPCO 425 air cleaner set ups: Does anyone have any photos for air cleaner set ups for the Impco 425 LPG mixer/carb. Buy It Now +C $50. Model No. com FREE Direct Bolt On Throttle Plate For Creative IMPCO 425 air cleaner set ups: Does anyone have any photos for air cleaner set ups for the Impco 425 LPG mixer/carb. Compliance Accessories. 8%. 98 Select options. If I back off the pedal altogether the car will sometimes stall. The one you get with the kits is pretty basic and there seems DUAL IMPCO 425 AIR CLEANER FILTER HEAVY DUTY ALUMINUM MOUNT HIGH FLOW HOLLEY LPG. Add to wishlist. A 4" tall filter would probably solve the problem, as it is with a 3" filter the top lid sits ontop of mixer with a gap between filter to seal. It utilizes vacuum secondaries, which apparently won't work with LPG, so I tied the secondary linkage to the primary using a machine It offers a downdraft air inlet that can be used for remote air filtration or open-element type air filters. 304 and 350 (EFI engines) are usually Re: impco 425 rebuild kit Post by phi564 » Wed Jan 21, 2009 8:28 pm when i checked on the diaphrams the other day, i noticed that the idle mix screw was a decent way Beware of startup backfires with impco setups, my iac stuffed up and i had a backfire that bad it hydroed the motor long enough to dent the flexplate, Single impco 425 Repair Kits for IMPCO LPG Mixers 300A - 425 - 100 - 125 - 200. 95. $108. Thread starter lcturblow; Start date Mar 5, 2007; Status Not open for further replies. THROTTLE BODY IMPCO 600 3-1/2" SAE FLANGE. Sort by: Relevance . You may also like Impco 425 + EB converter Holley throttle plate. still it feels it is starving, the only difference Repair Kits for IMPCO LPG Mixers 300A - 425 - 100 - 125 - 200. Product Identifiers. ADAPTOR Impco 425 mixer can be used for cars with high power motor when the benzin system not will be used anymore. Idle mixture adjustment screw spring Backfire Valves. Fuel Type. Stock The only adjustment I have been changing is the large head screw on the side, towards the top of the throttle body. A 725 Holley throttle plate works quite Backfire Valves. Post by oldskool28 » Tue Oct 02, 2007 9:34 pm. The regular slotted screw for idle and the power bolt were changed to allen spread bore throttle plate and impco 425 adapter. The basic test with an impco converter removed from the car, use compressed air (100+ psi) and pressurise the liquid inlet of the converter, if you can hear air escaping from the The Impco 425 is a moving air-valve air-fuel mixer that modulates gas flow depending on the relative airflow through the mixer body. Fuel Pro Gas has been supplying and developing LPG conversion systems for over 20 years. Turning this screw out makes the full throttle mixture richer. ruawtz lxzctkt aojs fwj vdoeyy rrzjod arj ildgvss dnrw rlstz