My New HFI system!

[73k5blazer]

So I got sick of the weather changing constantly (Michigan) and me playing guessing games with my C10's Holley. I rebuilt the motor last summer, it runs great, but when the weather changes (humidity, temperature, atmospheric pressure, proximity to Saturn), I'm always spending half a saturday trying to make it run decent again. I guess not re-installing all the little thermal vacuum switches, air pump, and other related things, (usally refered to as "emissions" equipment, but a lot of it is there for drivability reasons too.), is the cause of my woes, but alot of it would have been very difficult to reinstall with the non-emissions intake, holley 4bbl (instead of tire old qjet 4bbl that was stock) and various other things I used when I built the motor.

Anyhow, so today I installed my new HFI system on it! Human Fuel Injection. I'll never attempt to tune another carb without this system! Human reads sensor/gauge, human makes adjustments to fuel system.
OK it's an electronic Air/Fuel Gauge (clicky) with a generic GM 80's o2 Sensor (clicky).
Now I can see EXACTLY what the heck was going on. Today, it was massive bogging (dieing is more like it) during acceleration. I would get these bogs, and I'd try different pump shooters or cams with seeminly no change, my trusty gauge told me it was a way way to lean bog, so I change shooter from 25 to 35, a huge change, one the books tell you never to make, and magic, gauge sticks right in the middle during acceleration now, and no more bog. Biggest shooter I had was 31 at the time, and I still had a bog, but the I noticed it didn't drop off to lean quite as fast with the 31 in there as it did with the 25 in there. Local parts store happen to have a 35, so I bought it and popped it in there. Sweet. But without gauge, there was no noticible difference in the bog and my head was telling me well, 31 is a huge jump, I should see a change, so I must have gone to far, and I go back and try a 28, still a bog.

Anyhow, I love this setup, $60, so fairly cheap too. Since the sensor is cheap, it doesn't work until the engine warms up a few seconds, if you bought the expensive $70 wide band sensor, it would work better. But for tuning purposes, the cheap one is just fine.

So if your scratching your head during carb tuning, this will help.

 

[dontoe]

Kool dude, I bought one just like that, but haven't hooked 'er up yet.
I prefer carbs myself.............firm believer in K.I.S.S.

A vacuum gauge is almost magic for carb tuneups too!

 

[73k5blazer]

I have a nice vaccum gauge. Wasn't tellin me squat. Of course, I may not know how to read it properly, and which of the 6 ports to hook it up to that do different things.
I haaaaate carbs. My K5 WILL NOT be equppied with a carb, I don't care how much it costs. I'll buy the $2000 accell DFI kit before I put a carb on it. Never, ever, never. Nothing but a tuning and drivability nightmare. Every time the damn humidity changes, my C10 runs differently. And, since it turned cold again, it was downright undrivebale. Ran ok last winter with minor adjusments, summer came, made some adjustments again, real summer came (90degress+), more adjustments, last weekend was 70, today we had an Inch of snow, more adjustments. Nothing but constant adjustments, thats why the OEM'sput all those thermal vacuum switches, various controlled vacuum stuff, etc, so the vehicle would remain drivable under most conditions.
I just never had the ear to tune them, it's always a struggle for me. It's an artform more than anything else. I have met a few people over the years that could do it, but these days it's downright rare. ANd here in MI, there's not even anyplace to take it anymore, they open the hood and see a carb, run the other way. 10 different cams with 3 screw holes each, and 2 screw holes on the throttle arm, and thats just one of 10 different adjustments to make, how the heck are you supposed to ever get it right.
Ok, enough rant, can you tell I hate carbs. Did I say that already? Mabey they work ok in constant climates, I've never had one, stock or aftermarket, that I would say worked good. Tolerable, but never perfect.
EFI...only way to go.......

This gauge helps alot though...

 

[dontoe]

So, what do ya think about carburetion in a modern gasoline fueled vehicle, my friend?

I love Quads and even better Edelbrock carbs!
Vacuum gauges work great for setting the idle mixture, simple and sweet!
I might reset the idle mixture twice a year.........

 

[73k5blazer]

So, what do ya think about carburetion in a modern gasoline fueled vehicle, my friend?

Is there anything that comes with a carb from the factory these days? Cars/Trucks that is. I know some bikes,sleds,atvs still have carbs.

I got the computer carbs on my Ski-Doo, I wish they would have EFI when I ordered it, I think they do now, but didn't back then. The computer carbs havn't given me a problem, aside from running a little rough at really cold temps. The carbs on my Honda NIghthawk have. Doesn't matter how I store it, stabil, complete drain, whatever, every spring it's a chore to get the bike to run properly again, always requires a carb sync, which is a nightmare with 4 carbs, fortunatly for me, there are still good people who know how to tune small engine carbs. I usally just take the thing to a local bike shop to have them sync the carbs for $100. THey had to be rebuilt entirly about 3 years ago. Bike is a '93 I bought new with 16k miles on it now. Carbs have been the only problem on that bike. Carbs on my old Polaris snomobile, nothing but a problem, rebuilt 3 times over it's 7000mi life with me, every morning was a worry how the sled was going to run today.
My next snomo is going to be an Artic Cat batteryless EFI. If Ski-Doo has EFI, I might go that way, I like the SKi-doo's better. I havn't looked recently, I usally buy a new sled every 4-5 years. My curent Ski-doo is a 2000 MXZ600, with 6800mi.
My buddy has an Artic Cat EFI, that engine never gives him any trouble, starts first pull every fall, runs great here or in the mountains, at 30degress or at -20 degrees. Of course there's other artic cat quality issues these days, like the steeering shaft bending, pull rope breaking, among other issues.
Carbs just can't hold a candle to what EFI can do, which is why all the OEM's moved to EFI by the end of the 80's. Can't beat the realiability, tunability, diagnostic ability, and drivablity under all conditions without the need to adjust anything.

 

[diesel4me]

Same dilema here...

I have similar problems with weather here too---often its damp and cool,and my carbed trucks run quite crappy for the first 15 minutes or so in those conditions..your Holley is probably suffering from the same thing..it may be running too "cool",not enough heat getting to the carb to vaporize the fuel correctly..

I had lots of "carb icing" in a few,that would cause them to stall the second you let off the gas pedal and try to let it idle..the Edelbrock carbs I had were the ones most affected,because I used an aluminum adapter to allow them to fit the stock GM Q-jet intake,and it blocks most of the heat the carb needed to prevent icing and properly atomize the fuel mixture..but I've had bone stock trucks do it too..

I got around this problem by hooking the "EFE" heat riser valve, to a manifold vacuum source,rather than its thermal vacuum switch..so the exhaust gasses would flow thru the intake's heat riser passages constantly..I figured it might restrict the exhaust flow some,and possibly reduce power or mileage,but I found quite the opposite to be true!.it ran WAY better that way,and it no longer stalled every time I'd let off the gas..it also felt peppier too!..got better mileage,because raw fuel was no longer being dumped in,and being wasted..

My concerns about the excessive exhaust restriction was unfounded--I soon realized when I opened the throttle far enough,the vacuum would fall,and the spring in the EFE valve opened the butterfly,and let ALL the exhaust out the y-pipe instead of under the intake--so I wasn't concerned with burning a valve,etc..

I fiddled with other jets,accelerator pump settings,etc,to no avail--every "adjustment" seemed to be useless when the weather changed again--when I gave the EFE valve constant vacuum,I learned the motor ran much differently!--I put the stock jets back in the "Performer",and set the accelerator pump back where it was,and the truck ran great ,never had to touch the carb again,right up until I sold it 3 weeks ago..

While "cool" fuel mixtures might give power increases to drag cars and those running in 90 degree temps,it can only HURT performance on street driven vehicles,especially those in cold climates with high humidity..