Dad and I are prepping his 57 Chevy for the Meltdown Drags next month and are having trouble telling if all cylinders are firing or not. We are running a 1962 hilborn stack injection unit on a 327 sbc with a vortex mag. After running the car we pulled the plugs (AC R45 plugs) and most of them were wet, but a few looked just dark and carbon covered. We suspected the 1 and 3 cylinders to be not firing, because the fenderwell header was cold enough to hold onto. But we tested the spark and there's enough to shock you. So we changed the plugs, started it for only about a minute and checked the headers with a heat gun. They read only 200 to 240 degrees where only some of the others read 100 degrees hotter. This makes us wonder if the temperature is an accurate way to tell if cylinders aren't running or theyre too lean or rich. Any help would be greatly appreciated.
If the plugs are wet, it is either way rich or not firing. Did you have the injectors flowed and set up for your engine or just put it on without having it checked? Sent from my Moto G Play using The H.A.M.B. mobile app
I had this exact problem before. I thought it was ignition related for the longest time. It turned out to be bad fuel hoses. They deteriorate on the inside causing a blockage. I could start the engine and at idle disconnect a hose. The hose had no fuel coming out. If i revved up the engine building pump pressure fuel came out but just barely. If it were my engine i would replace all the rubber fuel lines if they are more than a few years old. I would also have the pump checked by gene adams. The nozzles should be pulled to verify they are not plugged with dirt. Another thing that will kill a cylinder is if the ****erfly is too tight. This will not allow any air into that cylinder. I fold a dollar bill in half. I open the blades and stick it in. I then close the blades on the bill. The bill should slide out with a little drag. I check all eight this way. They should all be even.If the bill gets pinched and wont pull out then the blade could be bent or the blades need to be readjusted or the idle screw is not adjusted right. The idle screws should be backed out so the blades close fully. The screws holding the blades on the shaft should be loosened. The shaft then gets slapped shut to center the blades. Holding tension on the shaft tighten the screws. Then set the idle screw with the dollar bill. Do each side seperately. Use the lightest return spring possible. Using too strong of a spring will cause the ****erflies to flex and disrupt everything. I put my spring in the middle of the shaft not on the end for the same reasons.I set my linkage arms with a angle gauge to make sure they are even side to side. About 30 degrees. The arms cannot be set to go over center or the throttle can get stuck wide open. If you have trouble pm me.
Had the hoses off after I posted the thread, I blew air through them by mouth and then by compressor. Air seemed to flow through them fine. The ****erflies seem like a logical explanation because the plugs are really wet but look like they're maybe hitting half the time. That could be because no air at idle like you mentioned. The other half of the time the throttle was being cracked on and off. We set the ****erflies last year following the Hilborn instructions, same as you just described. We have the light springs as well with it set in the middle. I'm starting to think it might be hitting on all cylinders, but maybe not. I just don't understand why I'm getting really different header temp readings still. These temps are rough averages 1- 230 3- 220 5- 350 7- 320 2- 265 4- 400 6- 380 8- 300 Keep in mind this is just at idle
No expert but it would only be fuel or electrical. What about the Vertex, are the leads and connections OK?
I think 600 is more what you should have at idle so something is wrong but how long at idle till you measure? less temp would be fuel fouled (as indicated by wet plugs) is this petrol or methanol?
Have your mag checked in the mean time do you have a dist you can drop in to fire it. Those temps are way too cold. Which usually relates to too much fuel.
We need to have more info. What fuel are you running? What nozzles do you have? The number is stamped on it. What number is stamped on the barrel valve ramp? This would be above the screw driver slot? What percentage of leak is the barrel valve at? What is the idle byp*** set at? These settings all control fuel flow at idle. You are a little far away from me or i would say bring it over. If you have a good sprint car racer in your area you may want to reach out to them. They do this all the time. A sprint car racer taught me.
Can you swap problem cylinder hose with another of the same length? See if the problem moves, you san do same with plug wire too. Swap injectors around
One thing I can tell you about Hilborns. They weren't made to idle. Maybe install EGT gauges or just make a full WOT p*** and read the plugs. Start with new plugs. It would be nice to know what nozzles you have.
I agree with richfox on the need for a pyrometer or air fuel gauge. You need to verify you have the correct parts first. Thats why i asked all of those questions. Once thats correct we can move on to tuning. If you dont have a leak down gauge already you need to get one. The morosso large single gauge works best. The double small tavia brand unit is harder to work with. You also need a gauge to set the byp*** valves. I made my own with pieces off a old air compressor. You need to be able to connect the valve to air pressure. The pressure going into the valve needs to be adjustable. Starting at zero increase the pressure until you hear air coming out of the valve. Record this number. The pressure can be adjusted with shims. If you dont have any br*** shims get a ***ortment from hilborn. The idle pressure should be around 50lbs. These units work great once they are sorted out.
Running on gas and with 6A nozzles. The barrel valve has no stampings or screwdriver slots. We set the leak down to hilborns spec after talking with them on the phone. Dont remember the exact number but dad will know, I'll ask him when he's home from work. Last night we leaned out the barrel valve but haven't ran the car since because it was already 11pm or so. We don't really think it's the mag because it's got good fire on those cylinders.
Is this a new or used unit. Its good that you have a reference point on the leak down. I have always found on a drag car that the leak needs to be set a little higher than factory specs. Its probable around 18. I have gone as high as 30. Each flat on the bar is about 1.5 percent. Injection doesnt have a accelerator pump. Sometimes a little extra fuel at idle makes the car leave harder.
hi mike here, with the early stack fi units each bank run off the same ****er fly shaft. whats happening with your set up is the cly that are running cold that ****erfly is not open as much as the hotter cyl. in order to get the temp equal on all eight cylinders. you need to use a holborn air flow gauge. this gauge sits in each stack and you read the air flow going across each ****erfly. to get them all the same you need to tweak each ****erfly until all cal are reading the same. before doing this there is a procedure you need to follow setting up hilborn fi. your problem is in the adjustment not in your mag. or hoses etc. you may not be using the correct barrel valve or nozzles but if you are then you need to adjust each cyl. through the injector stack. the newer fi units each ****erfly can be adjusted independently on the same shaft. I probably confused the **** out of you but go on the how to adjust holborn fi site they have a video on how to do it. its not hard just need a lot of patience . good luck ps this procedure is for idle your car is probably running fine at wot. is this car a race only or street and strip..
QUOTE="RichFox, post: 12107460, member: 23545"]One thing I can tell you about Hilborns. They weren't made to idle. Maybe install EGT gauges or just make a full WOT p*** and read the plugs. Start with new plugs. It would be nice to know what nozzles you have.[/QUOTE] Exactly, and with gasoline you have a need to be spot on with your main by p*** pill or jet or you will run rich or lean. Alcohol is much more tolerant and running rich to a point is OK. My experience is you need to start with WOT runs (or preferably on a ch***is dyno) to get the WOT fuel/air ratio correct (main by p***) and then work on your barrel valve, high speed by p***(if in your system) and secondary by p*** (if in your system) to get the acceleration and idle as best possible in that order. The answer to the question posed by the ***le of the thread in my opinion is it's a trouble shooting indicator after you have gotten the set-up correct initially.
I've had to step away for a few days for work, but I think I'll look at the ****erflies first off. It seems to make the most sense to me. Had the car out this past weekend on the street and it seemed like it wanted to load up at launch. Wondering if a 140 pill is too rich still. This is in a 327 Chevy, also we are only running a single return line to the surge tank.
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