my 76 ray

You also didn't say when the plug wires were changed. I've seen that problem caused by wires routed to the wrong cylinder.

78pacer

Thanks for the reply, my76ray,
As I posted earlier, the plugs and wires were both changed. I did this after noticing #3 and #5 were wet with fuel. Both wire caps at the plugs were arching. I will yank the valve covers and see if all rocker lift is the same. Then a pushrod adjustment will be done. Where's the best place to get those oiler clips to keep the mess to a minimum?
Mike

austinseanchris

Ok, so I know I'm opening an old thread here, but I've got my fingers crossed someone stumbles across it with some miracle answers...

I am trying to find some answers myself and came across your post from a few years back. Im hoping since that time you were able to diagnose the problem you were having. Your initial post sounded almost EXACTLY like the situation Im currently having on my 78. As with you, all emissions equipment has been removed and Im running the hooker side pipes(so no cats and no mufflers). As you have probably noticed, anytime you post a "technical issue" on the forum, you get about 100 different replies with what the problem is, lol. Thats not necessarily a bad thing either, b/c all it does it give you more ideas of things to check! The sad part for me is, I've tried about all 100 and yet I'm still in the dark on this one.

I hate to take up all your time by blabbering on but I'd be interested in knowing what the final verdict was on yours?

I know in my particular situation, car ran like a top. I had an edelbrock performer intake on her with a holley 600cfm. She ran good but you could tell she wanted more fuel. So I decided, it was time to buy a better carb for my application and thought "Hmmm, my polished intake is looking pretty rough...why not go ahead and buy a new one." So I did and while I was at it, I decided to go ahead and buy a new MSD HEI distributor. Now I had the stock distrib in it, but had the MSD coil, rotor, chip and cap on it. I also decided at this time to do the side pipes and took out the true dual exhaust that I had that had exhaust cut-outs on it.

So dummy me did everything at once. I put new intake on, put new distributor in, side pipes on and new carb. I originally bought a 750 SpeedDemon and on lower RPM's, car ran fine. But as soon as youd open her up, shed stall out. After taking the car to several "carb guru's", the final verdict was "The carb is bad"...even though it was brand new. Soooo...I bought a Holley 650cfm double pumper. Again, wouldnt run right...actually ran worse. I even tried a Holley 750 with vacuum secondaries that I knew worked and still ran like crap! So I took it to another carb guru with the 650 double pumper on it. Actually took it to the guy who does all the carbs for Doug Herbert's drag cars here near Charlotte Motor Speedway. This guy seemed to know his stuff and should since he's been doing it for over 50 years! First thing he changed was the springs inside the distributor. That instanly made the car run a lot better. He adjusted timing, etc. It still wasnt right and am now experiencing problems like you stated. So, I was told to change plugs and check wires. I changed to new plugs and all wires checked fine. I have bought the spark plug tool to check wires and all wires are getting fire to the plug.

I decided to take a infrared thermometer(with the laser) and hit all the header tubes right near the head to see how hot it was running. All tubes are running between 700-900 except cylinder #8 which is running around 200 degrees! First thought was it wasnt getting fire. Checked all that and it is. At idle, I get an occaisonal pop out of the right side tube. So I did a compression check of that cylinder. First check was 160, then 150. All other cylinders were in the same range. Timing is spot on and wiring is right. Im totally confused and have tried about everything. I even just for shi*s and giggles, decided to take the plug outta cylinder #6 and swap with cylinder #8 and swap the plug wires too. Temp was still around 200 on #8 cylinder but now all the sudden the header tube coming off cylinder #6 was glowing read and was running over 1000 degrees? I've got plugs gapped at .045 which is recommended by AFR.

What all I've checked:
-New plugs with correct gap
-New MSD wires
-No vacuum leaks
-Changed jets in carb with no difference
-Compression checked ok at 150
-Getting fire from distrib to plug
-Plug is not burnt nor is it gummed up or wet from fuel
-Timing is set at 11*


Pertinent info that may be useful:
-180cc AFR Eliminator Heads(3 years old with maybe 2000 miles on them)
-Edelbrock Air Gap intake
-Hooker sidemount headers and side pipes
-comp cams cam 270 lift, 470 duration
-comp cams 1.6 roller rockers
-holley 650cfm double pumper w/ 67 front jets/73 rear jets
-MSD HEI distrib
-MSD Wires
-Champion plugs(originally had Delco rapidfires)

Like I said earlier, Im very interested to know what your problem was. Ive got people stating things like "Sounds like a lobe is worn off the cam shaft." and "Sounds like you've got a bent pushrod.". But, I havent went as far as yanking the head off b/c to me, it just seems like its an ignition problem...Im no mechanic guru or anything either, but it just seems that the head is ok(no leaking anti freeze or anything either). Would compression stay up with a bent pushrod or worn out cam lobe? I would think it would drop drastically as far as compression testing. Nonetheless, thank you guys for your time if you sat here and read all of this.

my 76 ray

Compression can stay up with a wiped cam lobe because when a lobe is wiped, the valve doesn't open.

Thinking things through.

All other cylinders are firing so coil, distrib, etc are good. Carb is working. That means either no gas getting to number 8 or it isn't firing on the compession stroke. I would first make sure I have a spark at number 8. Take out the plug and clamp it to a ground. Have someone crank the engine while you look at the plug for spark. If you don't have spark there may be a problem with the distributor cap. It sounds like the wire and plug are good because you switched them with number 6. If you have spark then double check the firing order. If you have spark and the firing order is correct then possibly one of your valves isn't opening. If the exhaust valve isn't opening and the intake is, then you likely will have a backfire through the carburator. If the intake isn't opening then you won't have any combustion taking place.

If the valves aren't opening it could be as simple as your rocker arms being way too loose. From there it gets worse. Bent or worn pushrods or valves or rocker arms, or a collapsed lifter. If a lifter is collapsed or a lobe is wiped, you should be able to see that the rocker isn't opening the valve as much as the other cylinders.

I hope this helps.

austinseanchris

Well, i popped off the valve cover last night just to take a look. The rocker arm is tight and the spring is tight as well. Next step for me is turning the engine over and seeing if it goes up and down like the other 3 cylinders on that side. I hope it does bc if not, I think thatll answer all my questions. U would have done that last night too but its hard to turn the engine over while standing outside the vehicle watching thr valves lol.

Aflac

if you're that set on it beng a wiped lobe, pull off one valve cover at a time, start the car and watch the rocker arms. all should look to be moving the same amout.

i agree that it's likey not a lobe as much as it is a timing issue

mrvette

I have a '89 truck SBC, L98 heads, and when new back in '97 the engine had a ZZ9 cam in it one of them TPIS pieces of junk they refused to do a thing about....

well the engine ran very smooth and nice for about a year, maybe 5k miles, then the idle started to be very erratic and ragged, engine shaking, and me wondering WTF was going on, went through ALL of it, injectors, spark wires, had a problem with spark plug boots arcing to headers, 8 jacobs ceramic boot ends solved THAT crap in a hurry....

But engine still had that raggedy assed idle even at the programed 850 rpm, it would smooth out and pull good, but the idle just flat went to hell and it stayed like that for years....

here several months ago I finally tired of the high ragged idle and poor fuel economy, so pulled cam to change to stock L98 cam....got new chip for 650 idle speed....engine smooth as silk now, same injectors fuel pressure, cam and chip only changes.....

SO, looking at the ZZ9 cam there are the cam lobes, 6 of them had the hardened surface worn off them, cracking on all the lobe surfaces, and looked like pitted also, the lifters were fine, mag glass smooth as could be, bearings also....back into service.....

so the cam lasted since sometime in '98 and maybe 50k miles with it coming apart like that, thankfully I change oil/filter often, and not had any oil pressure issues,

I expect crappy cam hardening....is your problem.....

austinseanchris

Well after a day of dreding and debating when to trying to decide when I wanted to see the bad news, I finally turned the engine over tonight to see if potentially a cam lobe was worn off. To my surprise, it appears that it may be ok? I watched those springs along with all the others and they looked just like the others as far and going up and down. I was under the impression if a lobe was worn out, it'd barely move or it'd be pretty obvious as those springs wouldnt move as much. Assuming this is correct, I guess I pop the intake off and check the rods next??? I'm assuming those will probably check out fine too and I'll be back at square one...STUMPED!

my 76 ray

Did you verify that you are getting spark to that cylinder? If the valves are opening and closing then I doubt you'll find anything wrong with the pushrods. Assuming the valve opening and closing at the right time is not the problem based on your observation then there should be only three possible issues that could cause that cylinder to misfire.

1. No spark- I highly recommend that you verify that the plug is actually getting enough current to fire.
2. No gas - I suppose there could be a blockage in the runner in the manifold but I would think it highly unlikely.
3. Spark and gas not there at the right time. - either the firing order is incorrect or the way the wires are run is causing the current to jump to another wire or ground and not get to the cylinder that isn't firing.

austinseanchris

Well, I've went all the way back to square one myself and sat down and said "Let's start with the basics here, you gotta have 3 things to make it work, right? Air, fuel, and spark!" 76 ray, I've done everything humanly imaginable, lol. I did a spark check. First, I checked all wires for resistance. All checked out ok. From that point, I went to Harbor Freight and bought one of the cheap spark plug tools. One end looks like a spark plug, it has a light in the center and a boot on the other end. You plug the spark plug end into your wire, plug the boot end into your plug in the engine while its running. If its lighting up, youve got spark. Sooo, needless to say, she's got spark. I even went as far and taking plug and wire off cylinder #6 and swapping plug and wire with #8 cylinder...same results

Tonight, I did a compression test on every cylinder with all the plugs out of the car before starting. Needless to say, out of 8 cylinders, the lowest reading I got was 162 and the highest being 187. Sooo, for me, that eliminates several issues with the head. Last night, I popped off the valve cover to check the rocker arms and springs. They are all in tact, tight and not cracked, etc. While watching the springs, I had my g/f turn the ignition over(of course having distrib unplugged) for about a minute while watching the springs go up and down. I just knew it was a worn out lobe. Nope, they look identical to cylinders #2, #4 and #6. They are rising and falling just as the others do with no noticeable difference .

A buddy of mine with a lot more mechanical know-how than me says "I still think its something stupid." And ya know, I hope it is but in the same sense...I'm to the point where I dont give a F*#@ what it is, just come out, slap me in the face and lets get this crap straightened out, GRRRR! I pulled the carb off tonight and ran a metal coathanger down through the intake just to make sure there wasnt a peice of debris(like packaging styrofoam) in there...CLEAN! As far as vacuum goes, no vacuum leaks at all. Any unused ports are plugged off and I'm getting great vacuum pressure.

I mean as far as timing goes...I feel sure the car could probably use a little tweaking to get it "optimized" to peak performance. BUT, I dont think that "not being tweaked" is going to cause a cylinder to just completely not fire or be dead. Right now I'm sitting at 11* and 34* total timing. Even if the timing was royally screwed up, I dont see where it'd cause a cylinder to not fire at all. It still leads me down a path telling me there's a problem somewhere in that cylinder itself...Again, I'm no genius when it comes to cars. I know the basics, but beyond that...I'm still learning.

I'm about to just throw the towel in...

austinseanchris

Oh yea, let me throw a curveball in there. This is an HEI distributor setup pictured below and is how mine should be wired.

Now, based on that diagram, my wiring is not the same. HOWEVER, every wire is located 1 spot to the left(or counter-clockwise). So for example, where #1 is located, mine is #8. Where #8 is at, mine is #4. Where #4 is suppose to be, mine is #3 and so on and so on, etc. I thought, hmmm, well this aint right. Let me change that to the way its suppose to be. Ummm, the car starting shooting flames out the side pipes and sounded horrible...it wouldnt even crank. Put the wires back to how I had them before(all one spot counterclockwise from where they're suppose to be). Bang, fired up first time! So, not sure WTF is going on with that...? Anyone with any ideas or solutions, please chime in...Again, would this cause cylinder #8 to not fire???

larrywalk

If you change the plug wire sequence, you also need to re-clock the distributor gear mesh with the cam gear, and then, re-time the engine. Although the wire arrangement looks better if done as in that diagram, it will still function if the firing order is right and the engine is timed properly.

As I read your post, my first thought was to check for proper ignition firing sequence (make to follow the wires ALL the way), however, I'd still redo the wiring posts to match the recommendations, and then re-clock the dist.

The next thing would be to replace the #8 spark plug as it could be shorted internally.

Good luck!

austinseanchris

Yea, I talked to a few guys today who said the exact same thing as you. But, I know the plug isnt bad b/c Ive swapped over to cylinders that I know had working plugs and vice versa. I think its time to yank the distrib, wires and all out and start over. If that fails, Im sure Ill be shouting obsceneties so loud that you can hear me.

my 76 ray

I know you used the Harbor Freight spark tester, but I would think it will light with a lot less current than it takes for the spark to jump the gap on the plug. Try checking for spark the way I have in bold print.

If you take the plug out after running the engine is the plug wet?

austinseanchris

Alrighty, Ill give that method a shot as well. I suppose you may be right as far as if any current going through may allow it to light up. Any tools that you know of to measure how much power is going through each wire? Id rather not stick a ohmeter in the end of the plug and kill myself lol.

'75

Do you know what cam is in there? Seems like there was a cam available that would change the firing order, maybe someone slipped one of those in there.

austinseanchris

Yea, its a comp cam w/ a 270 duration and .470 lift. I know it wasnt one of those cams b/c I put that cam in there right at 10 years ago and its been fine.