[malibu man]

This winter I plan to pull the intake for a Performer RPM QJET and to fix the leaks, and pull the heads for CC'ing and checking the valve seals/guides. I also plan on putting in some lower gears. I'm in a last effort to see what is going on in this engine before jumping into tearing everything apart.

I get a crackling noise out of the exhaust and a rev limiter effect only in gear with a load acclerating when the engine gets up to 3K plus rpms. I get a missing or a roughness when holding rpms above idle in neutral, and it gets progressively worse as the rpms increase. Idles fine (except for inconsistant idle and vacuum), flat revs fine to wherever, and generally accelerates fine until I get up around 3K rpms.

I shorted out the plugs with the engine idling and couldn't find any missing cylinders at idle. Can this rule out ignition problems?

Then I reset the preload on the valves to roughly 1/4 past zero. Went for a test drove and the valve adjust didn't help any. One thing that I did notice while adjusting the valves is that a couple of the pushrods didn't turn as fast as the rest. But, all the valves seemed to open the same. The springs all looked to be in good shape. Can a bad valvetrain be ruled out?

I think I have a problem with my valve seals or guides on the one head, as previously determined here. Would the increase in rpms have enough effect to cause the engine to miss when the rpms are up?

Another thing that I thought of is a vacuum leak causing a lean condition which causes missing or popping. Possibility?

What kind of condition am I actually seeing with this driveability problem?

Just want to know what i'm dealing with for when I pull the top end down. No sense throwing an intake on and having the heads checked, then having the same issues again when put back together.

383
292H
225 psi cranking comp
GM HEI-Accel Coil in Cap-8mm Wires-R43T's
Quadrajet

 

[BB68]

It sounds like ign, have you tried new plugs, also could be the dist module or the coil. definitly rule out those before disassemble becuase I have been there before also

 

[malibu man]

Plugs are fairly new. They're fouling up on the left side with oil from the head problem I believe. Maybe it is as simple as that??? Any recommendations for plugs? May pick some up tomorrow. Thought about trying out some NGK's. They're working well in my 4 cyl tractors.

Is their a way of checking the coil, module, pickup, etc? The distributor was checked over in the fall of '02, but that probably doesn't say much anymore.

 

[Schurkey]

EDIT: Dead link--trying to find another

 

[malibu man]

There was an error on that link.

 

[malibu man]

I've got another question. Does anyone know how much cranking compression I would drop if I went from 110/106 to 110/110 on the cam? Is their any way of calculating, or guessing?

 

[malibu man]

Plugs were gray on the porcelain, electrode, and ground strap. Not full of metal flakes, but just a grayish tint instead of tan or black. Never seen gray, what does that mean? I cleaned them all up and stuck them back in. Next I pulled the coil out of the cap and pulled the wires out of the cap. Pulled the cap off and guess what I saw. The rotor screws weren't tight. The rotor was totally loose! After showing someone that it was indeed loose, I tightened it back up and put the cap back on.

Then I decided to check the plug wires for an ohms reading, as many of you say is a good test. I'm using parts store brand (carbon core?) wires, currently, that haven't been on long enough to go bad. Here are the results (in K Ohms:

1)7.3 - 32"
2)7.2 - 32"
3)9.0 - 40"
4)6.1 - 26"
5)4.7 - 22"
6)5.8 - 26"
7)4.7 - 22"
8)4.6 - 22"

Just for comparison I did a test on an old pair of Moroso Blue Max 8mm pre-crimped wires that I thought were shot.

1)1.8 - 32"
2)1.8 - 32"
3)1.8 - 32"
4)1.5 - 26"
5)1.3 - 22"
6)1.8 - 32"
7)1.3 - 22"
8)1.3 - 22"

Is this a good test? Does it distinguish that one is shot and the other is ok?

I put the parts store wires back on and put the coil back on so I could get home. Fired it up, ran it hard a bit, and shut it off right away. Pulled a plug and it was oily right away. So the valve seal condition can't be helping much.

Looks like tightening the rotor down didn't fix it though. I can pinpoint the rpm at 3400 rpm where the exhaust starts making a different sound. The engine feels rough like it's missing and vibrating up until exactly 3400 (all the time) on the tach, where the exhaust makes a rougher tone and the engine starts getting that rev limiter effect. I did this in neutral with no load as well and it also feels rough up until 3400 where the exhaust starts to make a different tone and it gets that rev limiter effect. I can free rev it until wherever, but I first noticed this driving and accelerating.

 

[malibu man]

According to what Moroso's claims are, these old Moroso wires tested out very good.

What's everyone's general consensus on the KOhms of the other wires, and the gray plugs? I'm not sure what gray plugs mean. Vacuum leak? Lean?

 

[malibu man]

Anyone have any more troubleshooting ideas, or suggestions, or opinions, or anything at all, for me?

Do you think those Moroso wires would work, or should I purchase a new set?

Or anything else........?

 

[quikss]

I would put the Moroso wires back on first. They are much better than the others you tested. You want the lower resistance.

I see you have an HEI distributor, are the advance weights moving freely. Try spraying them with a penetrating oil to lube them a bit.

Also have your coil tested. The ground strap for the coil is in place right? Is the coil connected correctly? Have you ignition module tested?

Do these things before going further, it will eliminate things.

Jeff

 

[malibu man]

Are the Moroso's a good wire to use? Or is their a better set? I'm going to purchase a new set anyways, as the Moroso's that I have now are stained badly and have tiny punctures in them up by the cap from shorting the boot connections out. I'd like to have the order in so I can get them before the weekend.

The ground strap is in place underneath the coil, and all the wiring is intact.

The distributor has been gone through by Von in the fall of '02.

I'm going to grab the wires, clean them up a bit, then pull the cap/coil/rotor off and check the weights out. Any tests that I can do to the coil, cap, and module while i'm in there?

Thanks for the suggestions!

 

[malibu man]

Tried getting a hold of Moroso today too, but the phone line was busy until the top of the hour. Thought that I would see what they thought on the resistance of the wires.

 

[malibu man]

I checked the Moroso wires again tonight and I couldn't get a reading at all on them through both boot holes, unless I pierced into the boot. Strange huh? I'm just going to stay with my decision that I stated on the above post and get a new set. Any recommendations?

I disconnected and pulled the coil off, pulled all the ignition wires off, pulled the cap off, pulled the rotor off, and got down to the distributor base. The advance weights couldn't be any free'er. Everything was intact underneath the rotor base. I did find the rotor loose though, the other day when inspecting. The screws were loose. Just a caution to people to maybe put some loctite on them, or get them snug. ??? I tested the resistance between the coil harness ends and they seemed to be solid. I tested the continuity between the two wires on the coil and I got 0.6 Ohms. I tested the continuity between the center contact and the outer contact on the roter and got 0.4 Ohms. I tested the continuity between the outer terminals and inner contacts on the cap and got 0.4 Ohms. That should rule out a continuity problem on any of those components. I couldn't get a solid test on the coil and module as I don't know how to test them. Does anyone know how to test them?

 

[malibu man]

I've done some tests and came to the conclusion that the pickup coil may be bad. One of the tests that I did on it points to it being bad. But how the engine can run with it being bad, makes me wonder. The one thing that I couldn't test is the ignition module. How are those tested?

I just put an order in for a new set of Moroso spiral cores and a low-resistance HEI secondary button from Summit. I called the local parts store and they have a pickup coil on hand as well as a set of Autolite 145's, and I ordered a set of Autolite 26 copper cores to try out as well. Parts from Summit should be here by Friday, parts from the parts store will be all in by tomorrow.

I'm now either going to get the ignition system all fixed and working, or else i've got the option of pulling the top end down right away and checking for an intake leak or possible valvetrain problem. They both sound fun. I can't check for fuel pressure now with the ignition system apart. I've got some time to kill until I get the parts, but then if I pull the top end down then I won't be able to use the parts right away anyways.

What's your opinion on what to do?

 

[malibu man]

Got the new pickup coil in, put the old 990 module in it, and put everything together. I tested the pickup coil and it seems to show the ohms to be at 700. Used new Autolite 145's and tried the old Moroso wires. After getting it to keep running, I got it timed to 16* at about 900 rpm. Starts amazingly great, better than it did before. Throttle response is excellent. Just seems to even idle smoother all the time. Definately made the engine sound better. But..........but.........I can still see the engine shake sometimes at idle. After just a little bit of revving when initially adjusting the timing, I pulled a plug on the left side and it was oily already. Also I took it out on the road for a quick mile spin. She drives a bit better, smoother at lower rpms. That could be the change to the better wires. Still isn't 'sewing machine smooth' when slowly increasing rpm above idle or when holding the rpm above idle. I can't wait until I get the new wires put on hopefully Saturday, should make an improvement. I got on the engine mildly accelerating and I did notice a change. Instead of the exhaust starting to pop at 3400 rpm, it started popping at 3800-4000 rpm. Also, I didn't feel a rev limiter feel kicking in from the engine. Even though it was 'sputtering' or 'popping' out of the exhaust, I ran it right up to 5500 rpm. I didn't feel good about doing it, but I just wanted to see what it acted like. Then I got it back in the yard, and I must of ran it out of fuel. I ran it up in rpms again just to see when the exhaust noise came in, and all of a sudden the engine started slowing down, then speeding up, and back and forth until it finally killed. The gauge wasn't quite on 'E' yet, but was probably close enough. I managed to find a hose to extend the gas nozzle to the tank, as I wasn't quite close enough to the fuel tank. After a bit of cranking and pumping, the engine fired right back up, and I parked the car in the shed. I haven't taken a vacuum test yet, and I haven't done any adjusting with the mixture screws. I'll see if I can do that tomorrow. I also still have the vacuum advance disconnected. I tested that while the distributor was off and it starts at 6*.

I'll have to see what it's like when I get the new wires on it. So what can I figure the new pickup coil helped, and could the fuel system still be an issue even if i'm not getting the rev limiter effect anymore?

 

[malibu man]

Just checked the idling fuel psi until the float bowl ran out and it's a steady 6psi.

 

[northern 396]

Trevor,

It sounds like it is running better than before, so maybe you now know what you wanted to know.

If you want to experiment further, you might try switching distributors and coils, if you can find others to try without necessarily buying them.

Regarding plug wires, I would recommend looking for a new set of Taylor wires. They have an excellent reputation.

David

 

[malibu man]

Didn't really seem to fix anything, besides get rid of the rev limiter effect, raise the rpm where the exhaust starts rapping and stuttering, and cleaned up the idle a bit. The pickup coil was shot though, just don't know how it ran before since it tested bad.

 

[malibu man]

Checked the vacuum and it's more erratic than it ever was. I tried adjusting the mixture screws and couldn't notice a change in the engine at all, but I did when I first put the carb on. When idling around 1000 rpm it's around 12" manifold in neutral and idling around 600-800 it's around 6" manifold in neutral. It doesn't smooth out until around 2500 when it's at 14" manifold. I ran it up to around 4000 and the vacuum is as smooth as can be. Maybe the exhaust is just choking the engine. Maybe that's all that i'm hearing? It's not a detonation/pinging sound, it sounds like when people rap their straight pipe. Maybe i'm just too worried.

I saw a suggestion to spray some penetrating oil into the carb to see if the engine would smooth up. I tried it, and it actually didn't change the way the engine ran at all.

I pretty much feel that I have to get the valve seal (or intake seal) issue fixed. I think it's a simple missfire. Man the engine runs hard, and then that exhaust noise worries me, then the transmission shifts and the engine is very strong. I feel it's stronger after each shift. I checked a few plugs after I just ran the vacuum test. They were oil soaked, and I was blowing a bit of haze out each exhaust. Went out and ran it hard, came back and shut the car off right away. Pulled a couple plugs, and they were dry and showed a perfect heat range.

 

[malibu man]

Put the new wires and coil button on. I think it may have cleaned the idle up some. Especially when the engine was cold. After idling and revving, the plugs are oil coated. After running moderately hard down the road and shutting her down, the plugs are dry and black. On both sides.

I did a little looking and I saw moisture on the inside of the PCV hose (and on the outlet). I also pulled the modulator line/hose and thought I saw moisture inside the fitting on the intake, but am not 100% sure.

Any other tests that I can do to check vacuum-pulled oil from the intake area?