Spark Knock on an 87
Thread Starter
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Spark Knock on an 87
I am here in SoCal visiting bastet44, and her 87 is knocking like crazy!!!!
It's quite annoying, and, I am sure not good for the engine.
I have determined how to set the timing, removing the tan/black wire off the distributor and checking accordingly, but, what else could cause this?
Thanks!!!
:cheers:
It's quite annoying, and, I am sure not good for the engine.
I have determined how to set the timing, removing the tan/black wire off the distributor and checking accordingly, but, what else could cause this?
Thanks!!!
:cheers:
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Re: Spark Knock on an 87 (bogus)
When I wnt to Monterey in August of 2002, the highest octane gas I could find was 91 for my 92 LT1. It seemed to run OK, but didn't hear any knock even in the hills.
Sounds like bad/cheap gas. You could try some octane booster but long-term use may trash the cats if they are on the car. Dropping timing back a couple of degrees should help but you might feel a slight loss of power.
Sounds like bad/cheap gas. You could try some octane booster but long-term use may trash the cats if they are on the car. Dropping timing back a couple of degrees should help but you might feel a slight loss of power.
Thread Starter
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Re: Spark Knock on an 87 (scorp508)
Bad gas, bad plugs, etc. What did you set the timing to? 6* BTDC would be stock, go down if it keeps knocking.
I need to get a pin popper so I can remove said bypass wire... then I can check the base timing.
All gas in Cali is 91. That should be enough for a stock L98... Also, she uses good gas. This problem has been around for a while.
Wake was nice enough to loan me his timing light... mine is 2000 miles away... :thumbs: to Wake!!!!!
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Re: Spark Knock on an 87 (bogus)
I need to get a pin popper so I can remove said bypass wire...
Thread Starter
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Re: Spark Knock on an 87 (scorp508)
I need to get a pin popper so I can remove said bypass wire...
No you don't. Its got a clip on the connector. Just lift the clip and pull the connector apart. Its by the brake booster sometimes hidden in the wiring harness.
No you don't. Its got a clip on the connector. Just lift the clip and pull the connector apart. Its by the brake booster sometimes hidden in the wiring harness.
Thanks.
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Thread Starter
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Re: Spark Knock on an 87 (Pete K)
yea... found the wire... what a PITA... the wire was stuffed between the left head and the firewall. Add in a super short lead, it was nothing short of a bitch to remove.
But, I got it. I think base is now at 6*. It looked like it was 10*!!!!
As I understand it, if the computer is working ok, the adjusted timing would be 14*.....
Thanks, guys!!!! :cheers:
But, I got it. I think base is now at 6*. It looked like it was 10*!!!!
As I understand it, if the computer is working ok, the adjusted timing would be 14*.....
Thanks, guys!!!! :cheers:
Thread Starter
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Re: Spark Knock on an 87 (bogus)
oh, my. What an improvement!
No more spark knock! It starts RIGHT up, without that overly advanced hesitation.
The tranny is shifting better and all spark knock under load in OD is GONE!
Acceloration is much smoother and feels quicker.
I reiterate what I said earlier, I suspect the timing was at 10*, if I was reading it correctly. The indicator is a bit hard to see.
Which leads me to think the timing was set without the bypass removed, or, due to the cars questionable history, major work was done, and it was never set right then.
All in all - Fabulous! Massive improvement!
No more spark knock! It starts RIGHT up, without that overly advanced hesitation.
The tranny is shifting better and all spark knock under load in OD is GONE!
Acceloration is much smoother and feels quicker.
I reiterate what I said earlier, I suspect the timing was at 10*, if I was reading it correctly. The indicator is a bit hard to see.
Which leads me to think the timing was set without the bypass removed, or, due to the cars questionable history, major work was done, and it was never set right then.
All in all - Fabulous! Massive improvement!
Le Mans Master
Joined: Aug 2000
Posts: 5,192
Likes: 1
From: Airport Cruise-in 1 Veteran Airport Cruise-in 2 Veteran
Cruise-In II Veteran
Re: Spark Knock on an 87 (bogus)
Glad to hear the enigine is running good again. :cheers:
bogus, I know you found the EST wire but for others to use for future reference I took a picture of it. It's a big one so I'll leave the link instead of posting the photo.
http://temp.corvetteforum.net/c4/joh...cs/estwire.jpg
bogus, I know you found the EST wire but for others to use for future reference I took a picture of it. It's a big one so I'll leave the link instead of posting the photo.
http://temp.corvetteforum.net/c4/joh...cs/estwire.jpg
