Holley Carb questions and answers

[Big-Foot]

Mike - I'm sorry to hear of your trouble.

I presume that the floats are not sticking and that when you double-check the levels, they are where you set them (no fuel spilling from the sight-holes).

What fuel pressure are you running? If higher than 6psi, turn it down. I set most cars - even our race cars to 4.5 to 5 PSI. After setting the pressure check the float levels again as they will change with the different pressure.

Ignition system - where is your advance at? Do you have a good strong spark? If you have it (and I recommend it) do you have a vacuum advance distributor? Is it connected to ported or manifold vacuum?

Synchronizing carbs is an art and not typically done correctly the first time by a newbie. If you have a good "ear", you can set the carbs by the sound of the "suck" by using a piece of windshield washer tubing, down the primary throat of one carb (listen) and then down the throat of the other carb (listen again) - adjust so both carbs have the identicle "hiss"...

Remember one thing - you only have 427 cubes you are working with here. That engine would be just as happy as a clam at anything under 50% of it's power band on just one of those 600 Holleys. Right now you are feeding it a lot more fuel than it would normally get if you have the idle speed screws out of synch and the fuel transfer slots are TOO exposed.

[Michael C Henry]

These are the carbs that came with the car .I can only emagine that I have closed off a whole bunch of vacume leaks.I don't remeber having this problem two years ago before I took the car apart. This time, before the plugs fouled , it seemed like a barn burner . I thought I could feel the secondaries open.
I have taken the carbs appart and checked the jets.Primaries are #68 s and secondaries are #74. I beleive I'm over my head here and I could spend all next summer trying this and that. I need someone that is more in the know and equiped.I'm guessing at this point. I had #68 all the way around before the rebuild of the carbs. yeh ,it was fouling plugs then also.It is carring 9-10 inches of vacume at idle and could acctually accelerate at 9 .It has 4.5 power valves now. The floats were where I had set them. The venturies aren't fumeing when engine is stopped and no fuel drueling or wetness as before. The plugs were all sutted up as times before the carb reuild. the idles are just 1/4 turn off the bottms primaries and secondaries and idle is around 700 when warm.I drove around the neibor hood a few times .I came back and picked up my billfold and cellhone.I started for I 5 . As I was getting close, I noticed that it was missing so I didn't enter the freeway. Never got on the freeway just city streets wit posted limits of around 35mph .Idle wasn't too bad but any thing above was bad .

[Ron61]

Michael,

Did the car run ok before you worked on it? If so, does it just do this under load or after warm up what happens if you rev it up while not moving? You could be getting a lot of unburned fuel because of not enough spark to ignite it under load conditions. Randy is giving you good advice. If that doesn't help, try finding a good Holly person in your area to look at yur set up.

Ron

[Michael C Henry]

Yes it did run great before I worked on it two years ago. At that time it had two mushroomed lifters and flatened lobes on the cam shaft.I've installed a new fuel system,ignition box, and many other things. same Mallory distrib and coil wires..Just added a new HyFireVI box and a filter. Noow you think ignition is suspect.Other things that worked just fine with the old adminastration have gave up shortly after the reinstallation.
I have what I would have considered an improvement in the fuel system .A Berry Grant adjustable fuel log with pressure set at 4.5 psi.
It started fouling plugs when restarted after the engine rebuild .It ideled great during warm ups, cam breakin but when I would actually take it ot for a drive it would foul the plugs.It was fouling plugs before I had the carbs redone by Quick Fuel Technology.Before it had #68 jets all the way around but drueled gas and fumed when the engine was off. I blamed the carbs .They looked old and burnt. Now they have #68 jets primaries nd #74 jets in the secondaries, and 4.5 power valves. No fumeing or gas drueling now .Carbs are dry now. I'm starting to suspect the ignition now. I don't want to start throwing money at that and time is getting to be presscious.

[Michael C Henry]

Well it fouled the plugs again .lots of dry black soot. I'v visited and called around and have been told to look at the ignition system .I will try to check one other thing.Maybe the ignition is failing at driving conditions .So now I'm checking the power supply. I have a balast resister controling the system .it maybe dropping too much .maybe some componets should bypass the balast resister.It's all mallory stuff.

[Big-Foot]

Mike - I think you're on the right track. Check the input and output voltage of the ballast. Make sure that the output of the ballast is going to the + side of the coil. You should have a nice fat blue spark when you crank it over.

[Michael C Henry]

I almost ran the printer out of ink amassassing all pertinent ,and some not ,inofrmation about Mallory 38 series distrib ,Mallory 29440 coil,Mallory HyFire VI 685 cd ignition box ,Mallory 700 balast resisterand mallory active power filter #29351. I may have made a wiring mistake .I'm prepairing the garage for a upcoming investigation ,doesn't that sound impressive?.Comfort with les distractions so it isn't a hurried afair.

[Michael C Henry]

I found that I had energized the yelow wire that powers the coil from two sources the box and the balast. I disconnected the one yellow lead from the balast resister . That may have made a difference but not enough.I drove the car around beyond the previous limits. It seemed to be running correctly . I was beyound where it previously would've start to miss . So I headed for I5 to test it at a greater speed limit than 35mph. I had enough confidance that I actualy got on I5 at S 56th heading South. It was starting to miss by S74th so I got off at 512 exit. back North on S Tacoma Way to S74th. It got bad. Then I got held up at the left turn light on S74 and again at the rail road tracks. I idled just about normal but under a load it stumbled and shuttered big time . I did manage to get the car home under its own power .
I have an cheap old Radio Schack multimeter and it pegs on the rx1 OHM scale. I'm looking for .75 to 1.5 Ohms. I can't read Ohms that low. Time for a new meter.
Thereis a blurb under the distrib instruction sheet .when they show the wireing with componets like mine they mention that "Note: an ignition balast resister is not required for this ignition to function properly. However ,installing one allows you to easily switch back to standard ignition , if necessary."

[Big-Foot]

Mike - I would remove the ballast or jumper around it for a test and see how it goes. A lot of high performance ignitions do not work well with them at all. I think you are on the right track in checking through the ignition.

Make sure, too, that you have a good solid ground from the chassis to the engine block.
I've seen cars that started and idled fine - run well under light loading, but when they were warmed up and driving down the street, they ran poorly. Cause in some cases was a bad ground from the block to the frame.
It's odd because you would think that the engine would not crank over to even start if there was not a ground strap. Not so - the bloody thing will ground itsef through the transmission, gears, needle bearings in the u-joints, driveshaft differential gears through the differential to the springs to the chassis! I've also seen them ground themselves through the throttle linkage and cable - one car almost caught fire when the throttle cable lit-up like a toaster element!

[Michael C Henry]

I really thought I had made an advancement.I had it running around longer than any time since getting it back together and then it crapped out . Rest assured it is grounded seven ways to sunday.But the directions said that it isn't affected by the presence of a ballast resister.If that not using a ballast resister does it, then you can't beleive everything you read.Who would have thought that just changing an ignition box would have all these wrinkles ?I was just trying to follow the directions.I used their parts .Now my system is just what they showed in their diagram , and still it is fouling plugs .Actually the same plug as before just cleaned , same distributor,same coil ,same carbs but now I have no doubts about . If I was putting some dieying guy's car tgether and all this stuff happened ,no one would beleive me , like I wasn't making all this up. Next attempt tomorrow will be new plugs and no ballast resister. Well at least the carbs are really good looking now, they don't fume and druel. You can't point to a part on this car that I don't have a story about all the struugles I had to go through. and I bought a running and liescenced car. If I told anyone thinking about one of these cars all the crap you'd start seeing a lot more middle aged guys buying new mustang instead . It does reach a saturation point. So my carb thread turns into a ignition thread. Sorry to derail my own thread. I at least hope others have been reading this thread and 1 think I'm a dolt, and 2 no dual fours for me. Dual fours would never be my choice again. but that is the boat I'm in now.Do you Think the Monster Garage ,or Tunner Overhaul ,etc could get it together in one season let allone one episode ?

[Big-Foot]

Hang in there Mike...

I use pretty much all MSD ignition components these days so I can't speak about the HyFire box . The Ballast resistor you have may be causing too much resistance (along with the resistance of the coil) for the HyFire box to handle.
Sometimes there are multple causes to problems like this as well. I had a dial adjustable rev limiter (MSD) so bad once and it would change the rev limit RPM all over the chart all by itself when it got warm. It took a while to find that one too. We were sure we had an ignition coil that was breaking down.

You'll find it - just be patient and methodical in your search.

[Michael C Henry]

I'm up and about at 7:30 am on a Sunday. Planning on removing the old spark plugs and installing fresh new NGK plugs. I'll check all the programed modes on the box , change power source from after balast to before, and look into a heat sheild for coil. The coil is mounted exactually where is has been since before I bought the car.Sofar I've been running with the hood off and outside temps are a whopping 47°. But I did read in the coil directions not to mount the coil to the engine. Guess where it's located and asfar as I know ,allways has been located?
I've been using the ARP lube on the sparh plug threads . Could that be a problem ? I've been careful to keep it off any part other than the threads.I't 's imbarrassing to have this great looking car with all this engine stuff showing and be limping home with the engine . doing the huck-a-buck. You should have seen it a couple of months ago when I had flames allternately comming out the carbs and exhaust sidepipes .

[Big-Foot]

Hi Mike, No- there is no problem with using a lube on your plug threads. I've not had any trouble in mounting the coil to the cylinder head either since it is getting a relatively cool stream of air from the front of the car.
47 degrees there? Wow - I just checked - it's 12:35 in the afternoon and it's warmed all the way up to =o= ZERO here! It was -7 when I got up with the dog about 6:30... (((chattering teeth)))

Another thing to check is to make sure you have a large enough wire carrying the current to that HyFire box. I know MSD's are REAL picky about that...

[Michael C Henry]

I came from DesMoines Iowa,Moved away in 75.The wires I supplied are larger than the wire that came on the componets. It turns out that the yellow wire I thought was wrong was a resister bypass wire from the starter relay.So next thing to try is to bypass the resister.I have questions about the little power filter to the distributor.it is mounted off the front of the intake and abovethe coilbetween the coil and distributor.The Hy Fire Vi box wiring diagram shows a wire in the pair of wires that I figure are the memory power and ground. Do you think the actual HyFire VI cd box its self needs to be grounded?

[Big-Foot]

Hi Mike,

It would not hurt to ground the chassis of the HyFire box. The filter is actually a filter and voltage regulator to keep voltage spikes from hitting the Uni-lite or Magnetic trigger amplifier. Uni-Lites are nice, but very fragile when it comes to the current..

The funny part about running a ballast resistor prior to the ignition coil is that most CD and MSD type ignition systems gain their advantage by stepping up the primary voltage that is fed to the coil. The Ballast Resistor just knocks it back down..

[Michael C Henry]

I have bypassed the resister. I have run another wire to ground the box its self.I have changed the plugs and removed a little material around #6 plug hole ,It was holding my socket when I installed that plug.Just another aggravation ended. I redid the wiring to that power filter so that little harness would be long enough to bypass the filter.The filter is a little 1.5x2.5 box with two short three wire leads with one lead haveing a male three pin connecter and the other lead having a female connecter.I removed the vacume gauge from the rear carb ,I'm done with that part of this project. and capped the nipple.Next is to go through the programing of the CD box to make sure I havent set something wrong.

I set the normal rpm limit at =5700
selectable lower rpm= 2500
start retard =8°
number of cylinders =8C

If it happens again I want to get the car to a service center with test equipment and a dyno roller to find if the fouled plugs caused the missing or if the missing caused the fouled plugs.

[Big-Foot]

I'm curious about the "selectable lower rpm= 2500" part - Are we sure that this rev limiter is not being invoked?

Keep us posted.

[Jerry Cowing]

Mike,

Sorry about all your problems, it can really be frustrating running down electrical problems. Those invisible electrons make it hard to see if something is broken. :-) It's much easier to find a leaky radiator hose.

When I start having problems like this, I like to step back and start with the basics again rather than keep changing things.

You stated the car was worked on and then was backfiring through the carb, etc. That tells me that the timing is off. What could cause this? One is the electronic ignition which is what you seem to be concentrating on. The other is that the distributor could have been installed wrong. It could be one gear or more off. Your electronic ignition can compensate for a misaligned distributor a little, but not at all RPMs.

After you pull the distributor and make sure it is aligned correctly, then disconnect all your electronic ignition wires and one by one make sure they are connected per the ignition instructions.

A third timing problem could be the cam was indexed wrong when they re-built your engine. There might be a way to check your cam index without pulling the cam cover, but I don't know that procedure.

Finally, it could be your valves are adjusted too tight and that's why it's backfiring through your carb. If you have hydraulic lifters, this is probably not the problem, but if you have solid lifters ...

I'd definitely go back to these basics and check your valve adjustments, distributor, etc. before you redesign your electronic ignition system and burn something up.

Good Luck,

[Michael C Henry]

If you havent guessed I'm on vacation . I'm burning up use or loose annual leave. my goal is to get this running and fouling cured . When it actually was back firing through the carbs I had ruff timed it usung a method that worked for me thirty years ago With a point distrib. I could turn the crank over bringing #1 up on compresion and set the timing marks at 8°bftdc .I would have a grounded plig in #1 wire and turn the distrib untill that plug sparked. and it would end up at 4°bftdc. It didn't work with the Mallory Unilite distib.I ended up at 12 after tdc . I had to pick up the distributor and move it one tooth. That makes a 48° change.With the mechanical tach drive I can't have move the distributer that farr by just turning it.
Every time this happened I took the plugs out and cleaned them
( glass beed blasting) before trying anything again. I blamed the carbs.They were drueling gasoline at one time ,and after all , too much gas causes carbon fouling. I didn't suspect my new ignition system. I relpaced an old Mallory HyFire IV cd box with a new Mallory HyFire VI 685 cd ignition box and the same Mallory Unilite 38 series distrib and Mallory Pro Master 29440 coil that worked before I took the car apart . The rev limits are different ,normal is set at 5700 rpm and when I flip a switch on the dash sending 12volts to the box by a particular wire it goes to the other rpm limit that is set at 2500 rpm . There was no balast resister in the old system .but Mallory has a shorting plug that elinates the box and a resister is needed when that is used. the directions said that the presence of a resister would not affect the operation of the system ( them telling me that it didn't take much power to operate).There is a small message saying that some racing application may operate without the balast resister.I'm gettin tired of swapping plugs , cleaning etc. I need to determine If the fouled plugs are causing the missing==to much gasoline. Or is the missing causeing the fouled plugs== Ignition system failing.None of this was obvious when ideling or reving in neutral like during cam breakin which lasted for periods of twenty minutes three times, in close sucsession in the alley with a rented fan stuffed in the nose after warm up. It only happened when in gear under way.

[Jerry Cowing]

Mike,

I'm in the use-or-lose situation also and am home replacing my water pump. The pump housing cracked on the lower bolt housing on the passenger side. I've never heard of that happening before. Engine got up to 240 before I noticed it. Heard this weird sound like a wire dragging on the ground or a rubber tire rubbing on the fender and thought something was amiss in my rearend. Came to a stop light, the noise stopped, started driving again and the noise came back, pulled off the side of the road and discovered the water pump leaking.

If wasn't running rich before and it's running too rich now, it's probably your Holley power valves leaking. These things are a pain in the you know what. I have a dual carb setup and have replaced mine in both carbs three times. If your car has ever backfired, even once, they probably blew the power valves and so extra gas is running into your intake manifold. Mine has the quote power valve protection valves unquote and they don't work. Also one set of power valves was leaking new from the factory.