Questions about hilborn settings to run on street

I am putting a hilborn unit on a sbc.....I am following Hilborns directions as far as running the lines etc. They have given me the pop off pressure for the primary setting and my question which they do not cover is the pop off pressure for the secondary by p***.....they explain what it does and how but no starting pressUre for the secondary.."......any suggestions?

 

There has been considerable discussion about these on this forum......you might try to find the various threads.

If you plan on using Hilborn for technical ***istance to run the mechanical stack injection on the street........don't hold your breath. Their official line is these units are not for street use.

That being said.....out of the box, Hilborn is correct......it will not be suitable for street use. But......with some smart design changes, and some smart component mods, and some fabrication of new parts, it can be made into a street-friendly injection.

 

but it can be done ... as hotrodart says its all here on /in the search

 

You said a mouthful without really saying anything. Unless it's electronic fuel injection system, it will not work on the street. Having said that, I had one. We made a lot of changes. If you're not knowledgeable, and able to do some machine work, forget about it.

I did get mine working on the street, but as I've stated in other threads, I could not overcome the 2 to 3 miles per gallon for in-town driving. It was also a problem with different al***udes.

 

Only if you are an engineer and make several pages of calculations will it work. There's only one person alive smart enough, and you ain't him.

 

Do you mean THE smartest guy in the world? (didn't know he was into cars)

 

Wow. Deja Vu... Actually most of those threads never got into the details Grinch is looking for. If it was a BBC on methanol, I might be able to help ya....

 

kinda confused when you say" primary and secondary" on the byp***es.you should have 3 byp***es,idle[primary?] main[secondary?] and hi speed.Idle comes off time spool valve in the center of the manifold-should be set by pressure.the main usually comes off the pump and is set by the size of the restriction{pill}this does NOT have a pressure setting,the spring is there to act as a 1 way valve and to hold the pill in place.the hi speed is run parallel to the main and IS set by pressure-it opens at WOT and keeps the fuel pressure from getting too high.now for the fun part-any change on any setting affects the others.

 

Here we go again!

 

The spring rate on your secondary byp*** will be a function of a number of things........engine displacement, volumetric efficiency, cam specs, head flow rates, ****erfly diameter, nozzle size, fuel pump specs, fuel line sizes, main byp*** pill size, and a few others. The quick way is to start with what you have in it, then increase or decrease the spring rate depending on the results.

 

Not that simple, that won't work. Once you start running it, and get a load pulling, everything goes to **** very quick.

 

oh yea-when they say "it wont work on the street" you just have to define"work" and "street" after all a dragstrip is just a real short street with all the traffic going the same way!!

 

correct

 

you forgot barometric pressure,air temp and humidity-all affects it also

 

You are correct. The secondary byp*** keeps the engine from loading up when getting off the throttle quickly, but also helps part throttle response.

 

and ger ---altatude -n- fuel specific gravity--

 

Well...I appreciate the replys and admit there is a ocean of headaches ahead. I am following the hilborn diagram with the exception of the high speed byp*** part. Hilborn says for the main byp*** it should have a 70 to 80 pill and the poppet should have a 1 to 3 lb setting. This I have. Hilborn says the secondary byp*** should have no pill and they don't say anything about having a pressure rate to hold the poppet closed. This unit is not going to actually run on the street as it is going on a 1960 ish restored race car...I just hope to get it to half decent.....appreciate the comments.....Jim

 

when setting a constant flow injection always remember the theory behind it-8 blind guys urinating fuel into your intake ports,and a couple of them may have prostate issues

 

I notice nobody gave you a number for secondary byp*** pressure. I run a blown sbc with Hilborn 4 port so that's a whole other bag of tarantulas, but my secondary byp*** is set at 38 lbs. A bit high but it works and I will tell you how I reached that number. After I would "blip" the throttle the rpms would kinda "float" down instead of snapping back down. It was explained to me that my lower secondary byp*** pressure ( about 30 lbs at the time) was allowing more fuel to byp*** and so the engine was a bit lean and the rpms would come down as the engine began to gradually load up. By adding shims to the secondary byp*** poppet spring I raised the pressure thereby keeping more fuel available to the engine
and the rpms now snap back down as they should. I know that's still doesn't answer your specific question, but maybe it will help. PM Yo Baby on here and I guarantee he will help you with this. I'm guessing your are going to be in the high 20's but that honestly only a guess. Ask Yo Baby.

So far as running mechanical fuel injection on the street...I wouldn't do it without converting it to EFI. Yeah I know.....BUT...it just ain't gonna happen otherwise. I will give you one quick reason why it will be nearly impossible. I know some guys try to run that dial-a-gadget that allows you to change pills on the fly to adjust to ever changing weather conditions. Problem with that is...when you change pills you need to adjust your barrel valve and when you adjust your barrel valve you need to adjust your idle. That's just one idea presented from a relative simpleton on the subject. I thought about doing it too, but abandoned it. If your dead set on it EFI is your friend. Oh and that's $$$$ but what aint when it comes to speed?!

p.s. I currently don't run a high speed cut out. That **** can be a bit dodgy with blowers.

 

Mechanical injection is designed for WOT and not much else. When driving on the street you rarely see WOT. More often than not your are feathering the peddle and injectors don't really know how to respond to that *****footing around....they like it fast and rough

 

Put me down for EFI too....



.

 

Big, big difference between a car with a trans that has to start,idle and run and a restored circle track car that will make exhibition laps.if its the great looking car in your photo I would not run the idle or high speed byp***es and only run the main.put the pill in hilborn says,make sure the barrel valve is leaked down to where hilborn suggests,push start it and more than likely it will run great without a bit of problems.its not going to matter if it idles at 900 rpm instead of 400,its not going to matter if your down 30hp because its to rich at full throttle.many thousand of races were won with only a main by p*** in the car.drive it and enjoy[if you have the choice I,d run on methanol,way less sensitive on ballpark settings,but tell hilborn for the baseline]

 

It's gonna be a pig on the street. JMO. And you are right, it will be half-decent. Lippy

 

I'll actually answer your question:

Lots of variables, but ~12-16lbs on the secondary should get you close.

Another suggestion would be to get the biggest baddest ignition you can afford. Makes it much more forgiving on the street.

Let me know if you need any more help, I have done it and you won't need 5 pages of calculations.

Lippy is right, you can make it half decent- it will be somewhat compromised as far as efficiency and will be a pig at times. (and a grizzly bear sometimes too!)

I have done it, in fact drove mine last Lonestar Round Up from the fairgrounds to the Emb***y on Congress, through the hour long stop and go crawl all the way up Congress ave. You will need a big gas tank, and lots of spark plugs while you are dialing it in.

Dve

 

Here is a buddys "street car"...



Like the NOS plumbed in for giggles? Gets 2 miles a gallon on methanol so that should net ya about 4 mpg on gas. How's that for somewhat compromised efficiency??! Hehehe.....9 second street car though. Guess it's just whatever your willing to sacrifice in the name of fun.

 

Thanks to everyone that answered...I'm close to firing it up and my initial start will be just to hear it idle. Going to cap off the secondary completely,see if I have a idle. Will keep you all posted ,this Otta be fun. By the way my main jet is a .75

 

Well here's a so far report...it runs. Tried a 75 pill first, started but was too rich went to. a 125 pill and it ran and idled on its own.....as I shut the fuel off I noticed that it idled faster and ran better....so I believe it's till too rich at idle...will try a few different settings this week and see what happens.....thanks for your suggestions

 

You set idle with your barrel valve and then your idle speed adjustment.

 

you are going to want a secondary. when you close the throttle it dumps the pressure spike at the barrel valve. with out it will load up and stumble back to idle. An afternoon with an air fuel sensor and a ch***is dyno will be worth your time. Get WOT right with pump size, nozzels, main and high speed. Then tune part throttle with barrel valve and secondary.

It can be done