Cool Old School Small Block Chevy With 8 Stack Injection For A Fiat Drag Car

[@stevemorrisracing]

Use code STEVEMORRIS50 to get 50% OFF your first Factor box plus 20% off your next month of orders at bit.ly/4807sCL!

[@VitoF111]

You need to start by centering all the butterflies. Warm the motor. Back off all the idle stops and disconnect the linkage to each side. Then loosen the Allen screws on each throttle blade. Lightly tap each butterfly so it is completely closed. Then carefully tighten each butterfly. Go back and check your work. Now carefully connect linkage side to side setting the butterfly air gap (.004" using a feeler gauge!). Now you have a place to start setting the idle setting. Next you need to flow the barrel valve. Using a leakdown tester set it around 28-32. Now you can carefully connect the barrel valve linkage to the butterflies. After that you need to flow your idle and main bypass valves. Actually, after watching this video you should send the entire injection unit to Kinsler and have them do it for you. Hope this helps.

[@markdiehl8050]

I assembled hundreds of those units when i worked for Kinsler in the 80s. What I see missing on that unit is Spring screw linkage that we used. That would allow adjustment between pairs of butterflies for better sync.

[@fstjack6525]

@@markdiehl8050 Butterflies might have to be reclocked on shafts to get correct bore orientation. After running and cycling and reinstall a lot of parts seem to move around.

[@steve-jl4jy]

I fought enough Lucas McKay and Kinsler constant flows in my past on old GTP and CanAm cars > one sloppy heim joint was all it took to mess with you > Still have 2 paper copys of the Kinsler Handbook > A Must for ayone dealing with these systems

[@dazaspc]

Indeed, I remember way back in the 70's as a kid helping/hindering someone setting up a Formula 5000. It was on a Holden V8 and it used 4 paired intake throttles. Each pair was independently adjustable. He used a paper to start and then set via a airflow meter you drop in the top of the trumpet and fine tuned the vacuum for each pair. Years later I borrowed his airflow meter to tune the idle after replacing some linkages on a 6 pack Aussie Chargers Webber carbs. I dont exactly remember what brand of injection it was Maybe Aunger? The one thing I do remember was that engine had throttle response like a light switch.

[@WPAPi3.14]

Is Chuck related to you?

[@WPAPi3.14]

You need to balance the injection vacuum downstream of the throttle plates Steve!!!

[@mtechcbs]

Your throttle body butterflys and the linkage between the sides need to be re-rranged such that when opening they mirror side to side. Currently they appear to be both opening clockwise when looking from the front of the motor, which means your lefthand bank injectors are on the upward opening side of the butterly and your righthand bank are opening on the downward opening side of the butterfly. This leads to part throttle power and idle problems as the airflow through the intake port and across the injecters has completley different charactristics on the left bank compared to the right bank. Also if you run the motor like this the only time both banks will get the same air/fuel loads will be at wide open throttle, at every other part throttle position the left and right bank cylinders will be different in power output and therefore part throttle driveability, very common with mechanical ITB systems if run like this.

[@homesteadjackass4979]

So this guy knows his ishh

[@patrickshaw8595]

Humph. Nimrods.

[@zetagynz]

I like your theory and I know nothing about this stuff but can't seem to imagine how the linkage between the two sides could work when they will be either expanding or decreasing the gap when operating opposite/symmetrically? 🤷‍♂️ it's probably really simple and I'm overthinking it but none the less very interested in your theory

[@marylandsteve5441]

@@zetagynz 1 side points up the other down to reverse the direction the blades open on the few of these ive seen

[@raykaufman7156]

That is a real pain in the ass to get right (I did ALL of mine counter rotating). SUPER important for street use or part throttle in a race car. Probably not as big a deal in this drag application...

[@ko9446]

Set up a ton of these on Sprint Cars. Cleaning after every race was a must, alcohol is corrosive if you let it sit there for even a week. We pickled them down at the end of race night and cleaned all nozzles and filters on Tuesdays. Tested barrel valve adjustment weekly and changed high and low side pills as weather/tracks needed.

[@Hydrazine1000]

Alcohol itself isn't corrosive. But the fact that it draws moisture from the air (pure alcohol is "hygroscopic") means it becomes a water-alcohol mixture and _that's_ corrosive.

[@rexschimmer7394]

Having worked , back in the day, on a large number of sprint car, midget, Indy car motors and now the little one liter motor that my son and I run at Bonneville all with constant flow injection. These systems control fuel flow by controlling the fuel pressure and that is done by the barrel valve at low RPM and the return jet at higher RPM. Although the pump outlet flow is theoretically linear the pressure set by the main return jet is not, it can be calculated which you should do but I will not get into "how to" right now. The basic progression is to set the idle which is best done with an air flow meter on each inlet (most of the engines will have the ability to set each butterfly, the engine you have you can only adjust each bank) . Set the barrel valve for good tip in and throttle response but the barrel valve typically only controls fuel pressure to about 1/2 throttle, at full throttle the main return jet sets the pressure the size of the main return should be found as the jet that gives the best torque as that is the RPM that requires the most fuel but after the max torque RPM is reached the fuel flow going to the engine will increase faster than the horse power increases therefore at max RPM the engine is rich which means the high speed lean out return needs to be set to lower the fuel pressure so that less fuel is going to the engine and the fuel curve better matches the horse power curve which provides max HPs. Crude but it works. Constant flow fuel injection is used almost exclusively for engines that run at close to max HP and RPMs and things like idle and smooth operation at low speeds is not important. They don't work well on street driven engines, especially with methanol. Lot's of good info from Kinsler if you want to have a good source. BTW our little 1 liter (61 cu.in.) Bonneville engine makes 210 hp at 12,000 (3.44 hp/cu.in.) NA. Rex

[@redchemicalsltd2324]

Thanks for sharing your excellent knowledge on this type of fuel injection set-up...👍🇬🇧.

[@DSRE535]

Holy Sh!te 1.0 L 210hp ls insane!!

[@HPRaceDevelopment]

What is the 1 liter engine you run

[@74jojo]

Really interesting to hear about your setup.

[@2HacksGarage]

There is so much to learn when it comes to mechanical injection. The “old timer” I work with has been doing them since the early 70s. Off camera, we are rebuilding quite a few old hilborn setups. My advice, use a modern style waterman pump, the old pumps are prone to failure. That being said, good luck! Oh, one more thing, having the ear of Don Enriquez helps. There are a few rare books from back in the day specifically for mechanical injection, I have read them many many times.

[@michellepettas363]

That pump in the video is as good as it gets these days. It is a Kinsler Tough Pump. Waterman went out of business and/or was bought out by Aeromotive and aren’t what they once were….

[@mrmongo6722]

There’s no school like old school! I also have a friends in North Carolina one of which lives in Asheville but was lucky and went a long time without running water and power. My other friend and his family fared well but was prepared to live without power and water. We need to continue for everyone affected and pray for Florida!

[@loud88gt]

When setting the throttle blades, just get it to idle and then use a Weber Redline Carburetor Synchronizer to adjust each to an equal number. Much easier than measuring with paper and more accurate as you are measuring the air flow.

[@rhnstjegilrhkscvn1djhrj969]

right answer

[@picklesontheroad]

Flow meter and vacuum gauges is how I set multiples like that my whole life. Worked every time. It's tricky, but like one guy said, close all the butterfly valves. Lock those rods and then all you gotta do is fine tune.

[@hunnybunnysheavymetalmusic6542]

I've always loved velocity stack race motor builds!!! Whether they work or are just for looks, I love them!

[@rocknrolljesus3197]

Looks like you could use "carb sticks" (think motorcycle) to set equal vacuum per cylinder at idle

[@KRCDEC]

Yes I set my cb750f with mercury gauge set set 3rd carb 1 2 4 adjusted for cfm

[@jeffphillips3796]

Hi Steve I have adjusted many multi butterfly systems and your ear is very good at hearing the difference's in the blade opening. Use a stethoscope or even a piece of tube to listen to each one you can really hear which needs to be adjusted.

[@clintonsmith9931]

Use to remove linkages. Set throttle blades then attach linkage.

[@schmuckie6791]

“America is built on speed, Hot, nasty, badass speed.” Eleanor Roosevelt 🇺🇸

[@dan7764]

She lived her life a quarter mile at a time

[@cptbuiltk7944]

2nd Throatus behind Nancy Reagan, the THROATUS GOAT🎉

[@Lobo-tommy10]

😅

[@kermitahnenerbe3722]

By speed i don't think she meant all people were motorhead...

[@loganmerryman202]

"No replacement for displacement" -Davey Crocket

[@dondotterer24]

My Dad ran a 55 gasser back in the 60s. 327 hilborn injection. 550 Isky Lagara gear drive cam with a Vertex Magnito. Hard to.tune. they even un bolted the headers to look at the flame coming out.

[@planesofpaper]

Chucks face said it all. I enjoyed a old school learning. Thanks from Rex

[@mccanlessdesign]

Love 8-stack - dream is to build a Can-Am ZL-1 (on gasoline) for a hand-built McLaren M8-B replica - my retirement project soon (almost 62). Can't freakin' BELIEVE how much I'll get from this video - thanks a mil!

[@vtfast1]

Spark plug indexing is also to align the electrode with the intake valve to help insure proper flame propagation. I have to admit that I have not heard of using it for clearance but, makes sense.

[@drewmclean1]

Steve, there are multi carb synchronizers that you can buy cheap! $20 range. Essentially an adjustable vacuum gauge so you can sync all of them evenly. I’d add a link to one I found but it won’t let me

[@phogandivephogandive3885]

You can also torque-tune by varying the length of the intake trumpets. Shorter moves it to higher rpm. longer boosts low end torque.

[@TailSpin46]

We used to use a dollar bill to set the butterflies. Loosen them all from the shaft, tap them all down to be snug in the bores, tighten them all up, adjust until you are just able to drag a dollar bill past the gap.

[@adamaxe1]

reminds me of sinc'ing the Mikuni rack on the KZ1000 seems insignificant but really crisps it up. The constant flow is crazy

[@hoofarted8709]

It would be cool if you had an o2 and egt sensor attached to each exhaust header:)...maybe you dont have to but when i was at SAMTEC in efi school they had it set up that way and could tune each cylinder perfectly...but reading spark plugs after each pull is good enough...i just thought it was cool that they had so much data to look at is all:)

[@markpeterson9546]

I was laughing watching you go thru setting up that manifold, I have an old Hilborn for SBC that I converted to EFI with a Speeduino ECM, been thru a good number of trials and tribulations with it and learned a ton. I'm happy you got it figured out, love the channel keep up the good work I learn something just about every episode.

[@bluegizmo1983]

2:20 I've got a rev limiter chip in my 363ci '71 Maverick 😁 love these old school MSD 6AL boxes!

[@atheplummer]

Seems like synchronizing procedure on those throttle bodies would be similar to synchronizing Johnson/Evinrude Looper V6 & V8 carbs. The way I do it, is to take all idle stops off, and let all the blades close all the way, then lock down all the connection points. Then when you set your idle blade distance, all you have to do is adjust the first idle stop open till it idles where you want it. The paper idea is actually a better 'feeler gauge than a metal one, since it will conform to the shape of the throttle blade. Instead of being stiff like a metal feeler.

[@kx454]

My old man's workbench still says "Loopers beware, Crossflow Country" across the top shelf...probably been there 35 years.

[@patrickshaw8595]

I have four identical clamp-on dial indicators. They tell me when the butterflies move and by how much.

[@ldnwholesale8552]

I know a lot of sprintcar owners/ tuners/ drivers. In the last 25 years they have managed to make them far more fuel efficient and responsive. To the point of using a litre a lap less! Even the oil stays clear instead of the inevitable milk tinge.

[@patrickshaw8595]

100% that is all due to better pumps, higher pressure, finer nozzles, better distribution & and better atomization!

[@vegasparke]

With hillborn systems that I used to use in the past I would first set the butterflies all shut and make sure that they all opened up in sync and then simply use the idle settings screw to set the idle. And then once you get a steady idle use a unisink to micro adjust each throttle body.

[@vegasparke]

He'll also want to confirm that the barrel valve is in the correct position as based on where the barrel is set will determine how rich or lean it is at idle and throughout the rest acceleration curve

[@patrickshaw8595]

How I always did it. The throttles shut and there is your reference point for all other throttle openings. PS - the barrel valve should just crack open at the exact same "time" the throttles do on the way to WFO.

[@Eric-s5f4z]

I learned something today,awesome video always wondered how mechanical fuel injection worked and you talked about it in a way that I could totally understand, that return line jet and the fuel barrel totally get it now 👍

[@mongreluc1588]

The barrel valve is pretty much your idle mixture. It shuts most of the fuel off to the injectors. As it opens it allows more fuel to flow to the injectors. The other valve in the system is normally a high speed lean out.

[@davidgough1161]

The barrel will progress with throttle input, all done!

[@EASTSIDERIDER707]

A masterclass in troubleshooting and problem solving. I appreciate your effort and sharing.

[@krusher74]

Not using a $50 syncronometer To quickly even there throttle plates is not a "masterclass" when you are being charged by the hour.

[@geepeerces]

hah, back in the early 70s, when I was still a punk kid, i spent a year on my aunts farm in rural NH, and their friends were running a sprint car, oval track racing. it was a bored/stroked old school SBC with mechanical fuel injection, 8 pack, burning methanol, straight pipe exhaust, magneto ignition, in the Super Modified class. they were the 2nd slowest car in the class, but they were having fun. no transmission, no clutch, just an in-out box, and adjust the gears in the rear axle (not a differential) ... I played jr gopher on their pit crew that year. This was at Star Speedway in Epping NH.

[@cjm5002]

I love the sound of stacks on anything! Can barely hear them in your dyno room but experienced ears can hear that thrum. I had a V6 that sounded like a trumpet when the RPM went past 7k... who needs a shift-light when you got that kind of alarm!?

[@walteranderson1245]

I started on modifies when I was only like 12 years old that’s like 1972. Dad’s car oldest brother driver. Good old hilborn back in the day. So cool to see.

[@CS_247]

Now THAT is something i DO know a great deal about, except we run a Lucas metering unit instead of the Kinsler barrel vslve. We run these in 5.0 liter small block form in Lola T70s.Love them... ❤

[@8180634]

You need a vacuum synchronizer so you can adjust each throttle body individually while it's running to get the same vacuum on each one.

[@macknorris4005]

Great video! Brought back some memories! As was said in the comments, I disconnected the left and right bank linkage. Then used a synchrometer at idle to adjust each of the banks throttle stop. To fine tune I had to adjust the butterflies for each cylinder. I was lucky though to have had EFI! lol. Thank you for the great video!

[@MMBRM]

Scotch tape is about 0.002" so if you need to add an exact amount of thickness to something to check clearance it works well. You can keep stacking it.

[@mooneyes109]

Finally 🙏an answer to my prayers! Between an injected SBC and a Screw Blown Hemi, two of the greatest things ever created!!!

[@Thecleananunseenteam]

I still have a few msd that takes a chip with the 2 step with a chip an a box of chips 💯🇺🇲🦅🏁 let's kick it old school 🏫😂

[@gregmyers1514]

Leak the barrel valve down to 24% and that’s a real good starting point.

[@jasongariss5858]

Love this finally something close to our sprint car engines that I can relate to gotta love have nothing but 8 wires does it have a low speed an stumble valve and my thoughts and prayers go out to all those struggling with the hurricanes

[@RobertFothergill-u1z]

I can't believe those initial numbers, that thing is spicy.......no wonder those sprint cars fly 😮

[@biggunbob2673]

My son builds dirt engines that run methanol at Buege Racing Engines in Burnett, WI and sets that style injection systems up by fuel ratios and air density and they are fast

[@Wreckedekcoupe]

Whats up Wisconsin friend. My dad had a 427 fe side oiler built at buege for our 67 fastback in waupun!

[@biggunbob2673]

@Wreckedekcoupe Burnett, Wisconsin my son has been there a long time

[@NiklasJohansson70]

airflow clock or vacuum clock is used to sync carburators on multicarb setup on motorcycles. It does a heck of a different to have them proper synced!

[@VernLeRoy1962]

Steve, they make a tool for motorcycle's that might work on that injection style, it messures the VAC flow. you would need Two of these Fuel Vacuum Carburetor Synchronizer Carb Tools sync 4 Gauge Kits with Hose Tool , Just need to drill & tap the intake. give them to the owner to keep with his engine. This works great on my 1971 CB75-Four Honda, no guessing

[@mikemyers3515]

Before you tube and the Internet,, I learned about pistons closing the spark plug gap the hard way. Not knowing any better, I pulled the heads and enlarged the notch in the piston.

[@jhh8688]

it takes about 80 cfm with a 2 bbl carb to idle so i would say around 10 to 15 cfm per cyl is needed to work

[@taverncustoms]

air also bypasses the blades via the injector nozzle, thats wat that little hole if for just above the throttle plate.

[@robertherold9658]

Start at .0025 and don't move it for anything other then sise to side balance. Barrel valve start 18-20%. Add or remove fuel to set final idle speed

[@AuthenticAustinRon]

@Steve Morris - I remember there being ‘idle’ screws😊 on carburetors to control fuel at low rpms.

[@frankensteincreations4740]

My B&U also had two of the three butterflies loose between the shaft half’s, that kept giving me a hanging idle. However every time I measured them they were same. So I backed everything off including the thumb screws, loosened all 9 blade screws, forced everything closed, to center the blades in the bore, tightened all 9 screws back up, and set the thumb screws for a base idle. Boom. Started up and was so low it almost shuts off… lol

[@jayventransportllc]

On webbers, we used a vaccum gauge…it attaches to the velocity stack and the engine “sucks” on it while at iddle…the goal was to make about tue same vaccum at each “ITB” once set, the we would focus on tunning fuel and timming

[@fstjack6525]

First set up throttle bodies, make sure all throttle bodies are synced to open the butterflies at the same time. Call kinzler and ask him what to flow the barrel valve at. Flow the barrel valve, use with a 2 gauge leak down tester. If you don't start their you're really going to be fighting it forever!

[@drcolster]

Took Me 32 comments done to find someone who knows the right way.. Using a leak down tester to set the barrel valve... I would of thought Stavros knows that one...

[@fstjack6525]

@@drcolster Thank you

[@roostingthe6520]

Yup! Never did one without using a leak tester on barrel valve first, and fuel flow meter and vaccum guage on throttle bodies.

[@firestorm755]

On a bike to sync the buttery there will be an adjustment screw with a spring to hold it. Even a 1/16 turn will make a difference to idle.

[@arrowkart4j]

We use Hilborn mechanical fuel injection on our sprint cars. Spend many hours adjusting and cleaning after every race. Love them . Currently looking for old big Block mechanical injectors for my vintage sprint car project.

[@raykaufman7156]

Call Enders. That's who ended up with my 3" Crower. He's a long time supermod engine builder, so I'm sure he has a few more lying around...😂

[@gregmckinney6977]

Transition pill for that dip. You can also rotate the barrel valve slightly to lean the whole mixture curve. That's if it's rich all the way.

[@MadsWorld34]

now you working on something i know a little about and i use to use a DOLLAR bill as a filler gauge.

[@tiredofit1235]

I've synchronized multi carb setups by using the idle vacuum port. And attach a hose filled with a light oil like trans fluid. Then attach hose to 2 of the carbs and make a loop on hose so that the oil is sitting on the bottom of the loop. Start engine and adjust throttle plate so that the oil in hose as at the same level. Then adjust all carbs/throttle bodies based on one carb/throttle body.

[@vehdynam]

Great video . I love mechanical fuel injection with alcohol , especially when on top of a blower. Good comments below about linkage. The tool is a Uni-Sync. Thanks.

[@agresa]

I have a stack injection setup I bought for my car, but I'm in the planning process of fitting Injectors to it to convert it to EFI. Ideal distance and angle to the inlet valve seems controversial in an ideal situation, let alone the space restrictions I'm dealing with. Some words of educated experience would be welcome if anyone has been down this road before. The engine is an old combo, methanol 383 SBC, Brodix track 1, 23 degree heads, 13.5 :1 comp, around 620bhp.

[@anamerican1054]

Oh man. I had three, two barrel Webers DCOE's on my old Z. Having good linkage is very important. Going through it all is the hardest part. Once it's in the car you need to make sure the bump stop is set for wide open throttle. You don't want the 300 pound gorilla bending the linkage. Yeah to set the idle you need a way to measure how much air per cyl. Many years ago the tool was 45$.

[@bigbearvenom6145]

The have a device called a uni-syn !!!!! You kept almost saying the word I was wanting to call you. Its a synchronization tool that reads air flow at each butterfly at the throat with a sealed base which reads as a vacuum through a tube with a floating ball in a clear tube that has gradient marks giving a reading of inches of mercury as air flows pass ball in tube. But this enables to match each other better than a feeler gauge, feeler gauge is only good for initial butterfly setting but not as accurate. But the uni- syn is more accurate because it is based off entire perimeter of butterfly and what air is flowing through the uni-syn flow meter. Once each adjusted is adjusted and tuned then their is one link that you adjust that keeps them all together from that point and keeps them synchronized. But like the way you went around for the initial adjustment on butterflies. Butterflies are actually tighter at shafts verses out at the sealing surface perpendicular to the center line of throttleshaft. The plates are actually kind of oblong. Awesome video Steve a love the way you work through things... Good mind

[@scottgoodson6046]

Individual o2 then if you know fuel at idle you can adjust each blade to be exact.

[@LibertyLabs776]

Used to run this setup on my sprint car. Start with .003 blade gap and 2psi fp!

[@Jcarney87]

A carb synch tool like for bike carbs would probably help get those throttle bodies synched up and flowing evenly.

[@rexschimmer7394]

I was asked what our 1 liter engine is. It is a 2000 Kawasaki 4 cylinder 1000 cc , built by Engine Dynamics, Petaluma, CA. Stock cams, JE pistons, 15:1 compression, Carrillo rods, custom headers , Kinsler constant flow injectors, 2 inch dia butterflies, MSD "Midget" ignition, runs on methnol.

[@mpiemanb]

Assembling an aircraft valve butterfly, I am required to use a gauge pin and have to center it on the butterfly. Other than a volumetric measurement, That's all I do.

[@brracing7861]

Isky Cams used to sell the Stack Injection IR Synchronizing tool. Its in the 1969 Iskenderien Master Cam Catalog I have. I have a Kinsler IR Mechanical injection with 2-1/2 " inch Butterflies a friend dropped off for his pump gas 454 Dart Little M Tall deck raised cam Tunnel engine. I am going to pay you a visit soon for his engine machine work and my own Pontiac V8 engine.

[@briantoga2626]

You can use a plate with a hole in it, use a second plate to fill the hole. Then use a valve spring to connect the 2 plates together. You will have a visual indication on the vacuum. You have a nice metal shop, it could be fast and dirty to build.

[@bds598]

You would also need to know the manifold vacuum at idle to calculate the airflow flow rate.

[@rogerminter3599]

I have only used mechanical injection on early water cooled VW's. 1.7l. Maybe less or more litres. I wish I had this video earlier. I understand what you're doing.

[@richardpauza2075]

Every Mech Fuel System I Ever Worked On Started With A Barrel Valve Leak Down Check for Idle Set up...

[@bjornljung9375]

My friend (a perfectionist) drive his blueprinted Ford 302 nascar engine with four Weber carburators, and got fhose numbers. Put in his DeThomaso Phantera.

[@davidgough1161]

It is obvious you already know about this stuff! I should have known! I love to learn from you, it is always a journey! You need to go play with vintage road race cars, they can be a challenge. That is where I learned about mechanical injection stuff, it is cool!

[@ls1jeeper]

People don't know how good they have it lol .. I remember having to look thru the ol MSD chip box every time you wanted to change leave, shift or limit rpm.

[@xtremeaerialvision9413]

You need to set the butterfly’s once the intake is heat soaked. Or the left bank will open once it heats up

[@FadeToBlackRacing]

While we’re on this old school stuff, the head of the bolt on the float bowls of a carburetor is the perfect height to set the float height with! Now you know! No extra tools needed

[@racerd9669]

It is called a Un,ison. you sit it on the top of each T B and read the Vacuum. Edelbrock sells them.

[@unleavenedkaraiteplus3412]

With a clearance of 0.003 inches around a 2-inch throttle blade, the available flow area is approximately 0.01885 square inches. To convert this to CFM, we need to know the pressure differential and the discharge coefficient, which are critical to calculating the actual flow.

[@jerrygustin2276]

we used to fold a note paper that was a 1/2" wide to make it a 1/4" wide re. .004 thou thick to set the butterflies equal.

[@acurarl9929]

After throttle is set you run all the stops up so the idle is not dependent on that link arm and will for ever be set an forget the idle where if no stops in play means as that link arm wears the idle would change. Set barrel valve at WOT so your getting max valve at WOT witch would have helped out your lean condition. As far as setting throttle blades you use a multi vacuum gauge sync 50$ amazon

[@timnorth8130]

Great job mate. Single throttle per cyl will always show that funny little hump in the torque curve, like two peaks as such. And when you change the main you must change the high speed pressure setting. I’m not sure if you had a pill in the HS or just flat out. The IRL kinsler valve is a bit more tune able but the diaphragm HS are great value for money. :-)

[@richardphelan8414]

Hillborn fuel injection ,Lake Forest California ,they have been doing mechanical fuel injection since the early 50s .

[@yorkenworthy]

You need what’s called a unison for checking flow from individual carburetors or throttle bodies designed for the original SU and Webber’s

[@sjones1557]

that mid range dip was audible. the sweep slowed down at 5500 too.

[@karans14]

Post throttle balance tube needed with an electronic valve or mechanical bleed valve

[@ralandhill7037]

you set the barrel valve with a leak down gauge

[@gothicpagan.666]

Thought you might disconnect all the linkages, adjust air flow with the motor running using the throttle stops, use an old carb syncroniser to measure air flow, Spend the next hour getting the linkage adjusted spot on, then dial in the fuel reference linkage. Those old constante flow injection systems are brilliant when right, just a pain in the posterior to get there

[@generalsixty2133]

Beautiful piece. I love simple mechanical old school.

[@kenmcguigan6805]

Always thought that setup is super slick

[@allendammann8677]

That's why on a outboard application they have a specific sized hole drilled in each throttle blade for idle air

[@finalcallracing]

Leak down barrel valve a little under 30%. Your bv and throttle linkage need to be close to parallel. Its cheater way, but I drill a little hole in butterfly to even cylinders heat at idle, start very small and work up in size, it doesnt take much.

[@WPAPi3.14]

Different length induction tubes will spread out the power band! That was like the BIG BLOCK CHEBBI WE TUNED FOR CAN-AM! Got a good

[@edzinator8499]

we use flow meters and balance meters to set throttle plates, the paper idea will get ya close, look for an adjustment between the two stes of each bank

[@piercer4882]

If you provide the pressure at the butterfly valves, then the CFM can be calculated. I was guessing at 15" Hg, but that only gives a flow of 0.00045 cfm per cylinder, which seems to low (0.0003" gap with 2" circumference with delta p of 7.365 psi)

[@briantoga2626]

Look up vw dual carb sync, vacuum gauge sitting on top of

[@emoshawn77]

Just for idle... First thing I would check for is vacuum leaks. I would start the engine without any throttle valve linkage on it. At operating temps I would synchronize air flow with each throttle body until the desired rpm was achieved. Then adjust the fuel at each cylinder and and set timing. I would double check the air flow with a synchronizer. After I was happy with idle rpm, timing, and AF ratio/EGT. I would start putting back the linkage's. I would synchronize it again to make sure my air flow values are still, "Balanced." But, there many ways to skin a cat. This is just how I would do it. Like setting up an old Weber. Thanks for sharing Steve. EFI has made me forget how old mechanical stuff worked.

[@mikeskidmore6754]

Rochester Fuel Injection actually worked very well if you knew how to tune it for the weather ect. GM Manuals were very comprehensive. I don't know anything about Hilborn mechanical Fuell Injection other than Sprint cars and Indy Cars ran them with Methanal. E.J. Potter ran his 327 Chevy block with no water in it and ran Fuel Injection with Methanol .. He was the three time record holder for the 1/4 mile on a Motorcycle. He added some Nitro Menthane for his record time runs.