hei distributor and carb questions

[chuck]

well i got my quadra-jet in peices on my garage bench for a rebuild and when i get finished with that i want to change the distributor.really hope i can get the carb put back together lol man it was filthy.so i want to put in a hei distributor,and what i want to know is how difficult the job is,and how much will the parts cost?any recommendations?i don't need anything hi -performance i just want to resurrect this thing back into a daily driver.if you buy new does it come with instructions on how to change it over? from the old style to the new style,how much wiring will be involved? i am looking for something thats relatively inexpensive but don't want to go cheap if you know what i mean.....

i have the carb torn down and in carb cleaner and the kit i bought did not come with a float set so i will be ordering that today.the instructions are kinda vague it looks like this kit is used for several different carbs it does come with a float guage for setting the float but it does not have any other specific instructions for setting anything up or any pre adjustments

is there anything i need to do other than setting the float and idle? could be i bit off more than i can chew.

when disassembling it i notice that at least 1 jet tube was clogged solid and most of the parts that were internal had a heavy yellowish varnish on them. very nasty stuff.

should i also replace the accellerator pump at this time too? how doe you know if that is bad?i manually activated the diaphragm a few times and though i can hear air moving it doesn't appear to suck or blow out of the nipple.

Well i am a little nervous about the whole carb reassembly thing,i really hope that it work or i may have to buy a carb...does anyone have any expirience with drop in replacement carbs wher all you do is set the idle?that may be more my speed lol.

btw i am working on a '69 cst/10 with a 350 4 bbl,the carb is a quadra-jet mv4 i think but the model #is 7029202 and on the ignition stuff it doesn't look like it has ever been changed except i did the dist cap ,rotor and wires but the coil looks old as hell,the points look ok not pitted so maybe they have been changed.

i am planning on a crate motor in a few months and i would like to get all the other stuff up to snuff before i do that and at least get it drivable ,it was running before but missing pretty bad at times and backfiring a bit as well,my friend tells me its the carb but i am leaning toward ignition but if i do both it will solve the problem i think or at least i hope

[rubberchicken]

Chuck, I've been to this same point before and I can tell you from my own experience that you would be better off to go down to your local parts store and purchase these items already rebuilt. I say this because as far as the carb, if you don't replace the throttle shaft bushing as well the thing will suck air and not run right. The hei can also be had at your local parts store or salvage yard and the hei that I have purshased either way, I've had no problems. The hei switch is simple and the crate engine will appreciate it as well.

[Fred T]

Q-jet is one of the easiest carbs to throw a kit in. The only adjustment you really have to worry about is the float. Biggest problem, already mentioned is body wear. Throttle shaft leakage is real common, and the reason most of them get rebuilt by someone who doesn't know what to do. After the kits in, the carb still sucks air and is trashed. What I would consider doing is finding a local shop that will rebuild the carb or bush the shaft for you. Either way, you will probably end up with a better carb than what you can buy as an off-the-shelf rebuild. The one's Ive seen weren't all that great.

[Piecesparts]

Is the Q-jet a Carter or a Rochester? The old Carter Q-jets are made WITHOUT bushings around the jet tubes and the Rochester had a brass insert. The lack of bushings allows for the body of the carb to errode and then the transition from primaries to secondaries is really lousey. The statement above obout the throttleshft bushings is true, but I would check the slop before I got too excited. If this carb is a Carter, toss the body and look elsewhere. BEEN THERE AND FOUGHT THAT BATTLE BEFORE! Remember what is rebuilt on the shelf was done by some guy that is NOT going to use the carb, he just gets paid $7.95 an hour plus breaks. He could give a doodley about your day.

[speedracer]

the great thing about hei is its self contained. first off its a bolt right in no problems there. and for the wiring the ignition wire running to your points can be attached to your hei system. only difference is points systems run on 6 volts thats why they resistors on the ingnition wire. the hei's use 12 volts so throw away the resistor and plug it in.

[chuck]

ok thanks for the info guys,the carb is a rochester and so far as i can tell by checking the shafts that i can find,i don't notice any slop,anyway i should get it back together maybe this week end.

thanks for the info on the hei sounds like the way to go but first thingd first let me get busy with that carb...i'll post my pass or fail results upon completion...thanks again

[rambler]

I would like to hear your results as well, I'll be going this exact same path soon.. (As soon as I replace the grill, radiator, support, fender,and bumper from the deer incident....

[Fred T]

I realized no one addressed a couple of things. Accelerator pump - replace it while the carb is apart. It used to be in the kit as a part to be replaced with every rebuild.

I would assume there are both ignition and carb problems. You probably need a new set of wires. One way I check is to run the engine in total darkness and watch for sparks. Have a flashlight ready, and where you see sparks turn on the light and see where the problem is. Then you can check that plug and wire to locate the problem. Electricity will find the easiest path to ground.

[chuck]

thanks Fred,yes the kit did come with the pump, and i replaced the cap,rotor, wires,and sparkplugs already....i left the points,and coil alone though.the problem never showed up at idle ...it would only show up under a load,i.e. driving,and was intermittent.
btw almost got the carb back together i can't find 1 peice though but i am looking for it today and i am having a problem assembling the choke,fast idle,vacuum assemblt linkage but i will get there.i sure am glad my bike is fuel injected lol

[Fred T]

Here's a link to a diagram. http://www.carbs.net/diags/4mv.jpg
They also have a lot of replacement parts, hopefully you won't need any.

On the ignition, if you aren't careful, it is easy to crack the insulator on a plug when installing. I've been guilty of that myself in years past. :hammer:

[chuck]

well i got it all put back together and installed and it fired up but it was leaking fuel from the throttle shaft where it comes thru the carb on the passenger side. so i took it off and disected it but everything was according to the diagram so i ended up buying an el cheapo supreme carb for 160. it runs fine but i still have the ocasional miss at mid range on the road i think my next move will be the hei distibutor

[trucknut]

Double check the spark plugs now that the carb is back to normal. Don't let a partially fouled plug (fuel or oil) cause you more headaches. Yes, hei will definatly make a difference if your still using points.

The carb you replaced sounds tired. It's more common to see throttle shafts worn out on the left side (drivers side) usually because of a "door slammer" return spring which wears out the housing. There is a kit you might be able to still find that allows you to install new bushings in the throttle plate but they are getting harder and harder to find. Also a high float level causing too much fuel to pass through the carb will show up as a leak in the throttle shafts.

Glad you got it running again, lookin forward to hearing the performance change with the HEI :)

[chuck]

so i am riding along on my way to work...i figure i can deal with the occasional misfire,,,,,wrong,it backfire about 3 times and died,wouldn't start,had to get towed to town,anyway turns out that the wire from coil to battery was burned up so that was replaced and it starts now but runs rough and misses more frequently.i am hoping the conversion to hei will solve this but if it doesn't what else is there to check?
ia m going to pull the plugs tonight after work because it just occured to me that the miss used to be intermittent but last night was fairley steady.

i am using the accell stock replacement plugs as of now and my first thought when i pulled them out of the box was **** these look like garbage,in my bike i run the ngk irridiums and if you look at the build quality betwwen the 2 types its pretty unbeleiveable also when i put the irridiums in my bike i noticed a slight increase in mileage,i am wondering if i shouldn't try to put in a better quality plug because as i said the accels were almost comical looking

any recommendations?also i have another question....do i need to change the plug wires when i change over to the hei ignition?

[trucknut]

honestly, I wouldn't worry about your misfire. Once you get the HEI, Wires and Plugs installed... all should be good again.

[Fred T]

Also, when you install the HEI, replace the wire to the coil with a 12 ga. running from unfused ignition on the fuse block to the coil. No ballast resistor. I also put in a 20 Amp fuse in the line.

[chuck]

well out of the frying pan and into the fire,the engine is totally missing now and will barely run at all when you put a load on it.starting to wonder if i have some electrical problems i noticed that when it has one of its seizures the ampmeter totally pegs to the positive side like its over charging,i wonder if that was realted to the coil wire burning up.seems to idle ok but as soon as you try to drive it it acts up and especially when the engine reaches normal operating temperature, i can't seem to wrap my brain around the idea that it is 2 seperate problems,and i got a quote for doing the hei distributor but i am now afraid it won't make it to the shop and even if it does that may not be what is causing the problem.....i tend to beleive it is something loose somewhere because occasionally it will run correctly almost as if something has vibrated back to the correct location.
if anyone has any other ideas i am open to suggestions

[chuck]

well i dug into the ignition system again yesterday and found burned points,so i switched them out and replaced the coil,i am still gonna do the hei dist but its going to be awhile for me to save up the money.i think i may still have an overcharging problem though.

[modelkitbasher]

I guess nobody told ya man that when you convert over to hei you will need to gap your plugs from .35 to .45 so It will run right.

[Old Dave]

You can check your charging system if you have a voltmeter (digital or analog). Fire it up and check the voltage across your battery. It should be 13.5-14.5 Volts if your alternator and voltage regulator are working correctly. Voltage should rise to no more than 14.8 volts at 2000 RPM. If the voltage is above or below then you have a problem either with the alternator or regulator. ;)

[68sittinlow]

I say, get rid of the points and get a new ignition system without points. I did that and haven't had anymore problems, except for my motor was a 2 bolt, and now its not anything at all lol. OOOPS. Got a 4bolt going together now. 2 Bolts and 383 just don't hold up that long. Hope your ignition problems work out,

[WingnutNC]

Hey y'all. I am new to this site, but could use a little help diagnosing an ignition problem. I have a 71 c10 LWB w/350 and th350 trans. I was experiencing a lot of missing, hesitation, and generally poor ignition symptoms. I had decided to install an HEI (new, accel), wires (new accel), and plugs (new bosch). Which I did. The distributor came new with a coil etc. After installing the distributor, I have eliminated most every problem, save one. I have an intermittent miss all the time. I was checking the initial timing when I noticed the strobe from the timing light showed the miss. It was irregular/random, but frequent. I decided to check other cylinders and found this condition on every cylinder. With a new distributor, coil, wires, plugs, and power to the distributor/coil, I am running out of possibilities. I have not connected the timing light to another vehicle or another light to my truck yet, but will. Has anyone else experienced this problem? I realize I could have a bad coil or distributor, but want to eliminate other possibilities as well. The engine has two grounding straps to the body and the negative battery cable to the right bank head. There are a couple old wires of the harness running down the back of the engine (starter and such). I was wondering if a bare/frayed hot wire bumping/shorting to the block could cause such syptoms?

[Fred T]

Wingnut, the loose wires shouldn't be causing this problem. I assume they are the old wires that ran to the previous coil. I would either remove or secure and tape them, however.

Just to be sure, is your HEI powered by a wire from the unfused ignition terminal on the fuse block? It should be at least 12 gauge.

Aside from that, I will default to others who know more, such as Piston.

Also, you will probably get better results by posting this question as a new thread. Add-ons to a long thread will sometimes get lost in the shuffle.

[GMCJim]

A comment on HEI distributor units..... For optimum performance and fuel economy; have the HEI unit re-curved by a shop that has a distributor machine. Most all the distriburors availalble from the wrecking yards are from vehicles manufactuted in the '80's. HEI's during that time period were calibrated for low emissions and are not the best for fuel economy and overall engine performance. The GM Service manuals will list the centrifugal and vacuum advance spec's for the various engines used in the respective model years.