hotrod85z

iTrader: (1)

I just had my heads ported on my 85 z28, it ran fine before
now it runs REAL rich even with the fuel regualtor turned down to 40psi the car has a serious backfire problem, the engine has no power! COULD THIS BE my MSD 6al??? Im running an accel incap coil, and 8mm wires and accell u-groove plugs, Ive never seen a TPI run this bad!!!!!! any help would be appreciated~!!

iroc-si

Are all cylinders running rich? Have you checked that you get a decent spark by removing one and holding it against a good ground?

Si.

Rob Wade

Timing OK?

Mkos1980

iTrader: (8)

Valves adjusted right?

Rob Wade

My experiences with a bad msd box is they just don't start. Period. I don't think thats it. Mkos1980 makes a good point. If you have a valve to tight it may be staying open add causing your backfire or the timing is off. How is the idle? You might have a bad plug. Need more info. Bad idle, bad under load but cruises ok etc.

hotrod85z

iTrader: (1)

i just reset the timing again just to be sure! I set it at 4 degrees advance at the timing tab, but the timing light says its at -10 at idle with the orange wire unplugged, the car idles good for a zz4 cammed tpi with stock ecm! but Its fouling plugs!
I put a new set of accel 576s header plugs in before i had the headwork, but it wasnt fouling the plugs before.

So lets get up to speed:

Ive pulled the distributor and set base timing!
Ive set the valves three times now! I got it up to 180 degrees temperature and then killed it, pulled the valve covers one at a time and loosened them off and tightened them until the quit rattling!


The only change that has been done is the heads were ported at a 61% increase in flow. I am trying to get the stuff together to datalog whats going on!!

i cleaned the plugs and put them back in, Im gonna put my hooker 2046's on tonite, after cleaning the plugs it should run a lil smoother!!!

Rob Wade

You don't have any headers or manifolds on it? You can't run an engine like that. The headers/manifolds create a vacuum or scavenging effect to help empty the cylinders of the burnt exhaust gasses. This could be part of the problem. Timing should be at +8* not 4.

hotrod85z

iTrader: (1)

im sorry, the engine has the factory tpi exh manifolds on it right now, i droped the distibutor in at +4 on the timing tab, it seems this engine likes alot of advance!!! it always has, I advanced the distributor quite a bit,b/c at 4* advance, it wouldnt start, so its more like 12-16 now. it runs but rich and feels like its still retarded, but I cant advance it anymore the plenum is in the way!!! is a chip gonna be my only answer, if i leave the ecm unplugged from the dist, it will run, rough,but it'll go in gear and run, if i plug it back in, the car idles up high around 1500rpms, but stumbles and dies when u put it in gear!

BTW, wouldnt the msd6al put out enough spark to burn any excess fuel, i am running a stock fuel pump and the 24#svo injectors, my afpr is set at 40psi

Rob Wade

Go back to the basics first. Its a bit of work but this is what I would do. Pull the diz. Put #1 at TDC (pull #1 plug to make sure your on comp stroke) Install diz w/ rotor pointed at #1. Start and set (w wire unplugged ) at +8*. Reset your IAC. You may have the diz installed 1 tooth out and thus you've run out of adjustment. If you don't have enough adjustment your firing late and the a/f isn't being burned properly. The motor ran before you had the heads done right. How much are they ported? They didn't go through a wall somewhere did they. Are you sure you have no vacuum leaks? I would also throw in a new set of plugs and make sure your firing order is correct. Just fishin' now!

hotrod85z

iTrader: (1)

thanx, i'll try anything at this point, I did readjust the iac and the tps after setting the distributor,it made for a choppy,but decent idle quality.
BTW, can I set the distributor in where its turned back toward the firewall? as long as the rotor is pointed at #1 terminal right? that would give me more room to advance it!!!

before i reset the distributor, I think i had it set at TDC on #6, BC if I barely bumped the timing up or down it would either make the starter noisy, or wouldnt even fire!!

Ive heard that 6 and 1 are both all the way up at one point, put that its not on the correct stroke, this is what the dampener mark is for correct?

call me crazy, I'm damn near to being a ASE certified tech, guess I need to get back to my books soon!!

Rob Wade

Again, keep it simple s----d (kiss method). You know the balancer is set for #1 tdc so use #1 and eliminate any possabilities of an error there. If the heads are the only thing you changed BEFORE it ran like crap then you need to focus on that. How much are the heads ported. You may have a port alignment issue either with the intake gasket or the the intake to head connection. Check there closely for leaks.

hotrod85z

iTrader: (1)

the heads are 186 casting camelhumps 1.94/1.50
.600 lift dual springs, with a port job where the machinist, adger smith, made about 6 cuts inside the head to clear up the flowing
he showed me the book and which cuts made how much difference, it equalled out to a 61% increase in flow!!!

i am running a zz4 cam, I showed adger the specs and he said,he said thats about the best cam especially a dual pattern for my engine!

LIke I said the engine ran 13's flat without any tuning and that was spinning!! with the headwork and lower gears(3:42's), I
expect to run maybe a 12.8 if I can get it right and get it to hook!

I am going to reset the distributor in the morning and at 0 tdc!

and I am going to put the terminal end of the distributoralmost touching the firewall, so that I can advance it enough to get it drivable,until i can burn a chip! btw, do u happen to know where I can get a good used aldl ~serial port cable,??

I've GOT to find out whats going on in my ecm!!!!

hotrod85z

iTrader: (1)

I found my book on valve timing. I set the valves with the engine stopped and set them by the book! my timings set at 6* advance, and the car runs excellent, i have also changed over to a set of hooker 2460 headers,

also changed my fuel pressure back to 40#, it idles fairly smooth, and does not run rich at cold start!

I believe the biggest problem was the valves were not set correctly, many people set them by ear, or by ft pounds on the nut, these are ALL INCORRECT!

its scarey!, i had a friend of mine, saying my valves were ticking and too loose. so i told him knock him self out, he reset them with the engine running, after that, my starter grinded , and screeched! i pulled the valve covers off, and had them race worked, he had over tightened my valves, bent 2 pushrods, and broke 2 springs!, the last time i let someone else work on my engine!

joshnryandad1

you live and you learn brother!! i had a friend help me put a new set of heads on my truck once he set the valves and got them too tight to the point that it made my new cam flat!!

Shagwell

- also, set your timing via the light, not the tab. Unless you use an adjustable pointer and dial it in while the heads are off, the tab isn't accurate. - Otherwise, sounds like you've found most your issue. Improper valve adjustments will get you everytime.
My motor used-to start stumbuling/popping everytime a lifter started going bad. Ran good at WOT, but crappy at part throttle. - My springs are duals and they're pretty high psi @ valve lift, but to turn the rpm's I do, I need it. I fixed it by finally putting a set of aftermarket lifters in....

civicsmasher

is this car fule injected? if so clean the injectors this mite work.
civic smasher