spuddering --

i have had alot of troubles since buying a zz4 crate and having someone put it in my 86 z28 for me.

anyways one problem i have now is my car seems to spudder. sometimes it runs fine...and others it runs like ****. i step on the gas and it just chugs and almost backfires. the idle even seems a little rough. its starting to **** me off. could this just be a loose plug wire?

i recently fixed the timing...it was way off at idle. the vaccum advance is till a little off but would this cause my car to spudder just driving it around town? besides its only like 10 degrees off at 4000 rpms.

any ideas??

[76 Mustang II]

Sounds like fuel/air mix to me... pull out a spark plug and see what color it is... if it's black from carbon buildup... it's too rich. also, if you're running platinum plugs.... could be the platinum has burned off, since they're not really for "hotter" engines. It could be timing, but I'd check the plugs for fouling/damage first.


But to be on the safe side.... if you really want it to run good.... pull out the bowtie junk and put in a FORD...LOL Just kidding, but watch how many people jump on me...LOL

[danny]

jump on you? no way, you ford guys have enough problems aleady-j/k-- what size/type carb do you have on the zz4? how old is the distributor?

the distributor came with the crate motor, it has about 2000 miles on it. i have a 670 cfm carb that was recently put on. however i used to have a 600 cfm carb and i was having the same problems which is why im starting to think its an electrical problem.

could this be a fuel pressure problem? im starting to think my tank is filled with concrete or something haha.

do u guys have any reading on how to properly adjust fuel/air mixture? when do u know its good?

and the other is how do u adjust the vaccum advance timing on a distributor?

[danny]

if your problem is intermittent then i would suspect the fuel supply/delivery system. i once had an oldsmobile that had a pin hole in the fuel pump diaphram, it would run well at low speeds but would cut out at higher speeds. just a thought. remember that just because a part is new it doesn't mean that it is good(dist), all parts are prone to failure. the vaccuum advance might be adjustable through the vaccuum tube with an allen wrench. also make sure that the vaccuum is connected to the correct port on the carb as most distributors don't use vaccuum at idle.

k&n sells an air fuel ratio monitor so you would hook up the oxoygen sensor in to the exhaust and it will send a signal to a control box mounted on the dash.with lights telling if it"s lean or rich this will allow you to set all the stages of the carb by setting the jettings,metering rods and accelerator pump to get the proper air/fuel ratio for all the circuits.


if you are claiming intermitant problems and you claim the advance is off 10 deg yes this would cause the car to sputter.was the distributor in an auto or manual before this could be the problem both are blueprinted differently.to set the distributor advance or blueprinting is done on a bench rotator and the mechanical and adjustable vacum canister are tailored to the requirement of the engine and vehicle.

with the vacum hose plugged and advancable light ready bring the rpm up to 2000-2600 rpm and verify the mechanical is fully advanced a shot of wd-40 on the weights will keep them operating smoothly and should be done periodicaly. then at 2600 rpm plug in the vacum and it should advance several degrees.you will be needing 38-44 deg. total advance.adjusting the vacum advance through the canister tip were the hose plugs into will adjust the sensitivity not the amount.so your total mechanical and vacum generally should be in buy 2600 rpm for an automatic 4000 and off buy 10 ?????????but setting up the advance circuits is usally best left to qualified personell.unless you have patientce,gas money and a stop watch.your car may need a little more or less hear and their.

and i guess test the pressure on the fuel line about 7-8 pounds there and check the volume displaced in a certain time limit.i forgot all the facts on this but looking myself i got them some place.and if you run some gas into a glass jar and let it settle you can see the amount of water content.could be filters or bad bypass.

are there any ways of telling if i have a bad distributor??

before i go that route im going to check my fuel pressure and mess around with the fuel/air mixture and floats on the carb. i will do this tomorrow night and reply to see if i fixed the problem.

if you cannot get things rung out and get the floats or air fuel ratio on the holley setup and the fuel supply in order and need some distributor advice then just ask.

finding a bad distributor is a process of elimination there is many test that you can do you would need advanceable light,ac/dc/ohm metre,rpm and vacum gauge,hei testing plug or grounding device(screw driver) felt pen,a dial indicator but yours is new so i would not think there is much play in it and a 9/16 box end wrench.but having it tested on an oscilloscope is the prefered method.but if you would like we could give some procedures to follow for general testing.


sorry i miss read your post thought i read your distributor had as in when you got it instead of has 2000 miles.if it came with the crate then maybe the vacum was not set up at all.

hey i used to have an old z28 with the sam problem and wat i did is i sent to the junkyard and got a ford!!

[danny]

ahhh, the splendors of walking. lol

[76 Mustang II]

He said he was tired of walking.... he recycled the chev the in one of the acceptable methods... one...junk it (preferred...LOL) two... find an idiot to buy it....LOL Just kidding

[danny]

ahhh, the splendors of walking. lol. i once owned a ford, the neighbors made me get rid of my lawn ornament-something about a waste of sheet metal or an ugly art masterpiece or something. go figure. lol

hey i was wondering...could a lack of back pressure cuz this by any chance??

say because my exhaust is too big ? or cat banged out?