No power under Load-Sparkplugs???
Thread Starter
Intermediate
Joined: Jul 2008
Posts: 30
Likes: 0
From: St. Charles MO
No power under Load-Sparkplugs???
Hi, this is my first post.
Quick run down I baught an 86 iron headed 4+3 with 83,000 miles. The car had sat for almost 10 years. I started reading and using the search function here for about 2 months. My issue is I have adjusted the valves, full tune-up w/ fluids, new 02 sensor and a few other repairs. I have finally been able to get the check engine light to stay off but I have no power above idle under power. It free revs fine. When I replaced the sparkplugs I removed the short threaded plugs and installed the longer threaded plugs. Auto Zone swears I have the right plugs but I am questioning this. So to end a really long post, For an Iron Headed L98 is the thread barrel on the plug long or short??? I installed AC 41-629 is this my problem????
Quick run down I baught an 86 iron headed 4+3 with 83,000 miles. The car had sat for almost 10 years. I started reading and using the search function here for about 2 months. My issue is I have adjusted the valves, full tune-up w/ fluids, new 02 sensor and a few other repairs. I have finally been able to get the check engine light to stay off but I have no power above idle under power. It free revs fine. When I replaced the sparkplugs I removed the short threaded plugs and installed the longer threaded plugs. Auto Zone swears I have the right plugs but I am questioning this. So to end a really long post, For an Iron Headed L98 is the thread barrel on the plug long or short??? I installed AC 41-629 is this my problem????
Melting Slicks
Joined: May 2007
Posts: 2,171
Likes: 1
From: Warwick RI
If it is running and revving plugs are probably not your issue. I would put a fuel pressure guage on the schrader and see what it is doing when you put it in gear. Go for as much of a ride as you can and see what you FP does. I am no expert but it sound like the FP regulator is not doing it's job when vacuum drops out.
Just a guess though as I am not one of those ASE cert guys but that will rule out FP so you can move on. You don't want to throw parts at it for sure
Just a guess though as I am not one of those ASE cert guys but that will rule out FP so you can move on. You don't want to throw parts at it for sure
Melting Slicks
Joined: May 2007
Posts: 2,171
Likes: 1
From: Warwick RI
Thread Starter
Intermediate
Joined: Jul 2008
Posts: 30
Likes: 0
From: St. Charles MO
I did the timing at 6btc, and the "brown wire" is fine.
I do not have a way of checking the fuel pressure. But that would make sense with how long it sat that the diaghram could be bad on the regulator.
So that is the correct plugs for an iron headed L98???
Long or Short threaded plugs??
How many degrees shopuld the timing advance under load???
I do not have a way of checking the fuel pressure. But that would make sense with how long it sat that the diaghram could be bad on the regulator.
So that is the correct plugs for an iron headed L98???
Long or Short threaded plugs??
How many degrees shopuld the timing advance under load???
Drifting
Joined: Feb 2003
Posts: 1,614
Likes: 163
From: Davis CA
I think that you got a plug for the aluminum heads. The partsamerica site shows that plug fitting an 87. Why just 87, I don't know. That said, I would be surprised that the wrong plugs would make that much difference.
I also have an ironhead 86 and I sometimes tell the counter that I have an 85 Corvette when all ironheads to get the right part. If it were me, I would look up the right part from NGK and ask for those plugs.
Additional information. I went to the Autozone website and said my Corvette was an 85. The recommended AC Delco was R43TS
When I said 86, it was the plug they gave you. The also list the 410629 for an 87. Clearly, they gave you the plug for an aluminum head.
I also have an ironhead 86 and I sometimes tell the counter that I have an 85 Corvette when all ironheads to get the right part. If it were me, I would look up the right part from NGK and ask for those plugs.
Additional information. I went to the Autozone website and said my Corvette was an 85. The recommended AC Delco was R43TS
When I said 86, it was the plug they gave you. The also list the 410629 for an 87. Clearly, they gave you the plug for an aluminum head.
Last edited by Chatman; Aug 31, 2008 at 03:26 PM.
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Melting Slicks
Joined: Feb 2008
Posts: 3,286
Likes: 6
From: Palm Beach
I think that you got a plug for the aluminum heads. The partsamerica site shows that plug fitting an 87. Why just 87, I don't know. That said, I would be surprised that the wrong plugs would make that much difference.
I also have an ironhead 86 and I sometimes tell the counter that I have an 85 Corvette when all ironheads to get the right part. If it were me, I would look up the right part from NGK and ask for those plugs.
Additional information. I went to the Autozone website and said my Corvette was an 85. The recommended AC Delco was R43TS
When I said 86, it was the plug they gave you. The also list the 410629 for an 87. Clearly, they gave you the plug for an aluminum head.
I also have an ironhead 86 and I sometimes tell the counter that I have an 85 Corvette when all ironheads to get the right part. If it were me, I would look up the right part from NGK and ask for those plugs.
Additional information. I went to the Autozone website and said my Corvette was an 85. The recommended AC Delco was R43TS
When I said 86, it was the plug they gave you. The also list the 410629 for an 87. Clearly, they gave you the plug for an aluminum head.
Thread Starter
Intermediate
Joined: Jul 2008
Posts: 30
Likes: 0
From: St. Charles MO
I am not sure if I disconnected the fuel line I would be able to tell the difference between some pressure and being the correct pressure. I guess if it is just trickling instead of shooting.
I will go get a fuel filter (not sure why I have not changed it yet) when I get some different plugs.
So to get rid of any confusion on plugs, that makes sense to ask for 1985 plugs.
Thread Starter
Intermediate
Joined: Jul 2008
Posts: 30
Likes: 0
From: St. Charles MO
First off, Thank You to those that replied.
I recieved the right plugs from Autozone and installed them and a new fuel filter. I then proceeded to test drive my Corvette on the way back to Autozone to get my refund for the other plugs. It was running ok better than it ever has but still way down on power and sputtering if I did not feather the accelerator pedal. I pulled into there parking lot and it died and could not get it re-started. I purchased a fuel pressure gauge and proceeded to test the pressure fuel sprayed out some while screwing it on but then I had no reading on the gauge. I took it back inside and asked if they had another I could exchange since it was defective, they refunded my money. I went back out side to trouble shoot my car. After disconnecting the MAF, checked for spark, then I pushed the schrader valve and there was ZERO pressure. WOW was I a Dumb AZ, I went into Autozone let them no there pressure gauge was not defective. My fricking Fuel Pump is what has caused all the issues. Swapped it out in the parking lot. Easiest electric fuel pump I ever changed. Long story short, car runs great, now I can actually start to enjoy driving it.
I recieved the right plugs from Autozone and installed them and a new fuel filter. I then proceeded to test drive my Corvette on the way back to Autozone to get my refund for the other plugs. It was running ok better than it ever has but still way down on power and sputtering if I did not feather the accelerator pedal. I pulled into there parking lot and it died and could not get it re-started. I purchased a fuel pressure gauge and proceeded to test the pressure fuel sprayed out some while screwing it on but then I had no reading on the gauge. I took it back inside and asked if they had another I could exchange since it was defective, they refunded my money. I went back out side to trouble shoot my car. After disconnecting the MAF, checked for spark, then I pushed the schrader valve and there was ZERO pressure. WOW was I a Dumb AZ, I went into Autozone let them no there pressure gauge was not defective. My fricking Fuel Pump is what has caused all the issues. Swapped it out in the parking lot. Easiest electric fuel pump I ever changed. Long story short, car runs great, now I can actually start to enjoy driving it.
Burning Brakes
Joined: Jun 2005
Posts: 1,191
Likes: 15
From: Wallingford Vermont
Call me " a day late & dollar short"
I had the same thing happen to my vette years ago. I was rolling north from NJ to Mass, and it started missing. 'A little at first, then progressively got worse. 'Come-on, baby, just a few more miles...
It acted like I was loosing ignition power; if you ever drove an old car on just the battery (with no alternator) you know what I mean. I kept checking the voltmeter: steady as a rock @ 13.7v.
Well I made as far as the Mass turnpike. As I pulled away from the toll boothe, they old gal gasped and died. A flatbed ride home was only an hour away.
The next days had me scratching my head looking at the distributor, finally on desperation I hooked up my FP guage: I think I had 10psi
I had the same thing happen to my vette years ago. I was rolling north from NJ to Mass, and it started missing. 'A little at first, then progressively got worse. 'Come-on, baby, just a few more miles...
It acted like I was loosing ignition power; if you ever drove an old car on just the battery (with no alternator) you know what I mean. I kept checking the voltmeter: steady as a rock @ 13.7v.
Well I made as far as the Mass turnpike. As I pulled away from the toll boothe, they old gal gasped and died. A flatbed ride home was only an hour away.
The next days had me scratching my head looking at the distributor, finally on desperation I hooked up my FP guage: I think I had 10psi
