The toughest kid to diagnose...a new everything engine
03-09-2016, 11:52 PM
#1
Melting Slicks
Thread Starter
The toughest kind to diagnose...a new "everything" engine
Problem:
Intermittent miss...like a plug wire breaking down occasionally. .
Finally ran it enough miles to get plugs to read... 45/50 miles or so to the muffler shop...and a few test drives to adjust the TV cable on the 200-4R.
#2 and #6 were smoked like a rich carb, or weak oil ring...also #1 and & #7 on the opposite bank to a lesser degree. Definitely have an issue on #6 and probably # 2..maybe all 4 mentioned above. Can't isolate the miss with sparkplug wire removal...too eratic.
The engine was a bought new from a Florida GM dealer (crate ZZ4)...BUT it sat in the crate in my climate controlled shop since 2008 (manufactured in 2006).
It is a carbureted engine. Carburetor is a new SMI Quadrajet prepared especially for a ZZ4 by Sean Murphy....it also sat in the shop for a few years.
Distributor(s) are brand new GM HEI that came standard with the new GMPP ZZ4 .
Compression is 190 psi across the board ...give or take 5 lbs on a couple cylinders.
Engine runs very cool 165-185 cycling the Spal fan on those intervals...with a 180 degree thermostat.
Considerable work has been done in the following areas.
Two near perfect carburetors have been tried....(just in case the SMI had a glich). Both carbs adjust perfectly..and evenly from left to right side ( One required about 2-1/8 turns out on both sides and one required about 1-3/4 turns out on both sides...give or take 1/8 turn on either side). Both will stay running at 650 easily...but needs a little more (about 725 in neutral idle) to be happy when shifted into Drive.
Vacuum when carbs adjusted is steady 17 inches.
Valves were adjusted just to see if they were off from the factory. All were on the money. I/2 turn out to clatter and tighten 1/2 turn after zero lash.
Two different (new) ZZ4 distributors were installed while hunting the intermittent miss before the plugs were readable...and 3 dfferent vac cans. Many timing combinations.
Started with crate sparkplugs...then installed one new set with custom plug wires and looms soon after. Then installed two more new sets of spark plugs after the first set (sometimes they get handled roughly at the parts houses..and can crack the porcelain ). Also installed a second set of plug wires with factory boots yesterday..(not a custom built assembly like the first set).
Exhaust sounds like it's fluttering a little at the tip on right bank "sometimes"...? Like a a slightly tight valve on a solid lifter engine back in the day.
BUT...All the rockers visually appear to be traveling the "full" distance up and down...and seem to adjust perfectly.
What am I missing..??
I can't think of anything else ... (... rings or something after sitting so long?) But the engine wasn't stuck...and cranked over easily in the beginning with a high torque mini starter, and fired quickly with a primed carb.
I'm NOT looking forward to a teardown on a new engine...at all...
Any ideas gentlemen..?
Thanks...Stan
Intermittent miss...like a plug wire breaking down occasionally. .
Finally ran it enough miles to get plugs to read... 45/50 miles or so to the muffler shop...and a few test drives to adjust the TV cable on the 200-4R.
#2 and #6 were smoked like a rich carb, or weak oil ring...also #1 and & #7 on the opposite bank to a lesser degree. Definitely have an issue on #6 and probably # 2..maybe all 4 mentioned above. Can't isolate the miss with sparkplug wire removal...too eratic.
The engine was a bought new from a Florida GM dealer (crate ZZ4)...BUT it sat in the crate in my climate controlled shop since 2008 (manufactured in 2006).
It is a carbureted engine. Carburetor is a new SMI Quadrajet prepared especially for a ZZ4 by Sean Murphy....it also sat in the shop for a few years.
Distributor(s) are brand new GM HEI that came standard with the new GMPP ZZ4 .
Compression is 190 psi across the board ...give or take 5 lbs on a couple cylinders.
Engine runs very cool 165-185 cycling the Spal fan on those intervals...with a 180 degree thermostat.
Considerable work has been done in the following areas.
Two near perfect carburetors have been tried....(just in case the SMI had a glich). Both carbs adjust perfectly..and evenly from left to right side ( One required about 2-1/8 turns out on both sides and one required about 1-3/4 turns out on both sides...give or take 1/8 turn on either side). Both will stay running at 650 easily...but needs a little more (about 725 in neutral idle) to be happy when shifted into Drive.
Vacuum when carbs adjusted is steady 17 inches.
Valves were adjusted just to see if they were off from the factory. All were on the money. I/2 turn out to clatter and tighten 1/2 turn after zero lash.
Two different (new) ZZ4 distributors were installed while hunting the intermittent miss before the plugs were readable...and 3 dfferent vac cans. Many timing combinations.
Started with crate sparkplugs...then installed one new set with custom plug wires and looms soon after. Then installed two more new sets of spark plugs after the first set (sometimes they get handled roughly at the parts houses..and can crack the porcelain ). Also installed a second set of plug wires with factory boots yesterday..(not a custom built assembly like the first set).
Exhaust sounds like it's fluttering a little at the tip on right bank "sometimes"...? Like a a slightly tight valve on a solid lifter engine back in the day.
BUT...All the rockers visually appear to be traveling the "full" distance up and down...and seem to adjust perfectly.
What am I missing..??
I can't think of anything else ... (... rings or something after sitting so long?) But the engine wasn't stuck...and cranked over easily in the beginning with a high torque mini starter, and fired quickly with a primed carb.
I'm NOT looking forward to a teardown on a new engine...at all...
Any ideas gentlemen..?
Thanks...Stan
Last edited by Stan's Customs; 03-10-2016 at 03:47 AM.
03-10-2016, 12:21 AM
#3
Melting Slicks
Thread Starter
03-10-2016, 12:40 AM
#4
Team Owner
When its running squirt some starter fluid around or wd40 around intake...see if that makes a difference in the running...
03-10-2016, 01:00 AM
#5
Melting Slicks
Thread Starter
I've always used carb cleaner spray for checking for worn carb throttle shafts and carb base gaskets for leaking....it speeds up the engine a little....but is eats paint too.
Thanks...Stan
Last edited by Stan's Customs; 03-10-2016 at 01:03 AM.
03-10-2016, 02:37 AM
#7
Melting Slicks
Thread Starter
36 degrees mechanical all in at 2800 rpm, with 18 degrees initial ...no vacuum advance.
Tried three vac pots to get 10 or 12 vacuum advance degrees...still working on that, but best pot so far only added 8 degrees vac advance to the 18 initial.
Also tried ...10 degrees initial...no vac advance as GMPP recommends.. I forget what the the all in #'s were were with 10 degrees initial they recommend...but wasn't impressed with that setting ...
The stock pot is supposed to be left disconnected. It pulls 20 degrees ...although I still want to try 10 degrees initial with the stock pot connected. According to Lars...30 ish is good at idle (initial plus vac advance)with full manifold vacuum.. if the all in isn't over 46 degrees at 2800-3000.
Seems to like the 1st one is the best so far ...but none of the above and several other experiments seemed to cure the intermittent miss at idle.
That's when I found the sooted up plugs ...and realized I had yet another problem.
Tried three vac pots to get 10 or 12 vacuum advance degrees...still working on that, but best pot so far only added 8 degrees vac advance to the 18 initial.
Also tried ...10 degrees initial...no vac advance as GMPP recommends.. I forget what the the all in #'s were were with 10 degrees initial they recommend...but wasn't impressed with that setting ...
The stock pot is supposed to be left disconnected. It pulls 20 degrees ...although I still want to try 10 degrees initial with the stock pot connected. According to Lars...30 ish is good at idle (initial plus vac advance)with full manifold vacuum.. if the all in isn't over 46 degrees at 2800-3000.
Seems to like the 1st one is the best so far ...but none of the above and several other experiments seemed to cure the intermittent miss at idle.
That's when I found the sooted up plugs ...and realized I had yet another problem.
Last edited by Stan's Customs; 03-10-2016 at 02:38 AM.
03-10-2016, 03:02 AM
#8
Team Owner
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St. Jude Donor '05
Unless it were a vacuum leak Id be miffed sounds like youve been over it wtih a find tooth comb;sounds ignition related
Leakdown rther than compression test MAY reveal (doubtful) something but storing the motor or carb shouldnt hurt a thing. Would not tear it apart
Stored one for almost 10 yrs was mint
Does this only happen when its good and warm or cold also?
Know not every plug esp with a dual plane may look exactly the same sure you do though.
Can you spot a timing "band" on the backside of the plug strap?
Sometimes a goofy plug can do this also.
Leakdown rther than compression test MAY reveal (doubtful) something but storing the motor or carb shouldnt hurt a thing. Would not tear it apart
Stored one for almost 10 yrs was mint
Does this only happen when its good and warm or cold also?
Know not every plug esp with a dual plane may look exactly the same sure you do though.
Can you spot a timing "band" on the backside of the plug strap?
Sometimes a goofy plug can do this also.
Last edited by cv67; 03-10-2016 at 03:23 AM.
03-10-2016, 03:34 AM
#9
Melting Slicks
Thread Starter
Unless it were a vacuum leak Id be miffed sounds like youve been over it wtih a find tooth comb;sounds ignition related
Leakdown rther than compression test MAY reveal something but storing th emotor or carb shouldnt hurt a thing. Would not tear it apart
Stored one for almost 10 yrs was mint
Does this only happen when its good and warm or cold also?
Know not every plug esp with a dual plane may look exactly the same sure you do though.
Can you spot a timing "band" on the backside of the plug strap?
Sometimes a goofy plug can do this also.
Leakdown rther than compression test MAY reveal something but storing th emotor or carb shouldnt hurt a thing. Would not tear it apart
Stored one for almost 10 yrs was mint
Does this only happen when its good and warm or cold also?
Know not every plug esp with a dual plane may look exactly the same sure you do though.
Can you spot a timing "band" on the backside of the plug strap?
Sometimes a goofy plug can do this also.
Happens all the time...but less noticeable when on fast idle choke warm up.
I'm stumped...
It may be ignition related , but I can't find it if it is.
Maybe I should try a MSD distributor or something ...other than one of these GM stockers..
Vacuum leak... I guess a deep one maybe? But unusual on a brand new engine, .. the intake as has been suggested. Plugs looks like some kind of dry soot fouling...I guess a vac leak could do that, but not sure...I haven't run across a vac leak doing that yet. Which means nothing, there s a first time for everything. Can a intake vac leak cause plug sooting...?
I could pull the intake...even if the spray test doesn't net anything.
I would be overjoyed for sure, if an intake gasket fixed it ! I'm really disappointed with this engine...along with a lot of past issues on this car. The whole project has been a real biotch from day one.
Yep I know about the plugs looking different...but a couple of these are waay smoked up...as if they weren't firing at all, but they have to be because it runs ok... just misses intermittently (sorta).
I don't know what a " timing "band" on the backside of the plug strap" is..? I'll look for it if you can describe what it is..
Thanks...Stan
03-10-2016, 03:35 AM
#10
Pro
If you have access to an old osilascope it may guide you, intermittent s are tough but if you're pulling steady vacuum and your fuel is on a constant supply you're ignition is most likely the prob possible coil .,what ignition are you running remember an internal combustion engine is nothing more than a pump.
03-10-2016, 03:44 AM
#11
Melting Slicks
Thread Starter
If you have access to an old osilascope it may guide you, intermittent s are tough but if you're pulling steady vacuum and your fuel is on a constant supply you're ignition is most likely the prob possible coil .,what ignition are you running remember an internal combustion engine is nothing more than a pump.
No scope available to me...used to use a Sun scope back in the 70's. Didn't use that thing for anything but locating bad plug wires,lol...wish I had it for a half hour now, it might actually help.
Last edited by Stan's Customs; 03-10-2016 at 03:44 AM.
03-10-2016, 04:01 AM
#13
Melting Slicks
Thread Starter
03-10-2016, 06:22 AM
#14
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Location: Greenville, Indiana
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Are you using the right heat range plug?
03-10-2016, 06:34 AM
#15
Melting Slicks
Any VAC accessories like PB? Plug them all to see if they have a small leak.
03-10-2016, 06:51 AM
#16
Team Owner
A vacuum leak would make you run lean, not foul or soot up your plugs....simple enough to run an unlit propane torch around likely leak spots with engine running. If there is a leak the engine will speed up. It won't "eat paint". I hate HEI distributors, it'd be interesting to borrow a regular distributor and ignition coil and see if your problem disappeared.
You might try running the engine in the dark and look for any spark flash over but that's an unlikely culprit and I assume you've checked firing order at least 3 times. Does the engine have a PCV valve ?
I can tell you that a friend and I worked on one crate motor where there were two defective hydraulic lifters and although the car would run; the lifters wouldn't keep an adjustment and caused the motor to missed erratically.
You might try running the engine in the dark and look for any spark flash over but that's an unlikely culprit and I assume you've checked firing order at least 3 times. Does the engine have a PCV valve ?
I can tell you that a friend and I worked on one crate motor where there were two defective hydraulic lifters and although the car would run; the lifters wouldn't keep an adjustment and caused the motor to missed erratically.
Last edited by Frankie the Fink; 03-10-2016 at 07:40 AM.
03-10-2016, 08:30 AM
#17
Team Owner
A vacuum leak would make you run lean, not foul or soot up your plugs....simple enough to run an unlit propane torch around likely leak spots with engine running. If there is a leak the engine will speed up. It won't "eat paint". I hate HEI distributors, it'd be interesting to borrow a regular distributor and ignition coil and see if your problem disappeared.
You might try running the engine in the dark and look for any spark flash over but that's an unlikely culprit and I assume you've checked firing order at least 3 times. Does the engine have a PCV valve ?
I can tell you that a friend and I worked on one crate motor where there were two defective hydraulic lifters and although the car would run; the lifters wouldn't keep an adjustment and caused the motor to missed erratically.
You might try running the engine in the dark and look for any spark flash over but that's an unlikely culprit and I assume you've checked firing order at least 3 times. Does the engine have a PCV valve ?
I can tell you that a friend and I worked on one crate motor where there were two defective hydraulic lifters and although the car would run; the lifters wouldn't keep an adjustment and caused the motor to missed erratically.
I like that idea...saves the paint and doesn't leave a mess....
I've always 'in the past' used starter fluid or wd40 to check for leakage...time to change my ways...
03-10-2016, 08:38 AM
#18
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Non-chlorinated brake cleaner will do the same thing and won't leave a residue like WD. It also works well as starting fluid that isn't as rough on your rings as either. Excellent parts cleaner too.
03-10-2016, 10:22 AM
#20
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The miss sounds more ignition related.
Did you swap coils and cap when you swapped the HEI?
When a coil breaks down and starts to fail it loses enough spark at low rpm to cleanly light an imperfect mixture under compression, before becoming more noticeable at all rpm ranges as coil damage increases. The coil connections may have also oxidized in storage.
Is the ballast resistor needed with the HEI?
A new engine tends to soot plugs until breaking in seats the rings. Some cylinders see only mild soot, others more. Unless all are sooted up I would not focus on fuel (unless it is bad across the eight).
Did you swap coils and cap when you swapped the HEI?
When a coil breaks down and starts to fail it loses enough spark at low rpm to cleanly light an imperfect mixture under compression, before becoming more noticeable at all rpm ranges as coil damage increases. The coil connections may have also oxidized in storage.
Is the ballast resistor needed with the HEI?
A new engine tends to soot plugs until breaking in seats the rings. Some cylinders see only mild soot, others more. Unless all are sooted up I would not focus on fuel (unless it is bad across the eight).
