Advanced or Retarded Timing - Which can cause overheating?
Thread Starter
Burning Brakes
Joined: May 2002
Posts: 751
Likes: 8
From: Escondido CA
Advanced or Retarded Timing - Which can cause overheating?
Hello Corvette Nation,
Quick question...1986 Corvette L98 engine, early version with cast iron heads.
Which would cause the engine to run hotter - if the timing is too far advanced or too far retarded?
6 BTDC is the base timing spec, correct?
Thanks in advance for your assistance!
Quick question...1986 Corvette L98 engine, early version with cast iron heads.
Which would cause the engine to run hotter - if the timing is too far advanced or too far retarded?
6 BTDC is the base timing spec, correct?
Thanks in advance for your assistance!
Last edited by kbuhagiar; Aug 12, 2018 at 08:07 PM.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
I've heard people claim that too advanced will too....but I've never seen it. Engine will ping...and if pushed into more advance, "kick" and "buck" and be hard to start before any evidence of overheating.
Safety Car
Joined: Aug 2009
Posts: 3,752
Likes: 276
From: Melbourne, Victoria, Australia
And give real crap gas mileage
, too far advanced will knock and ecm will retard the timing dramatically.Don't forget always confirm TDC before adjusting advance, the balancer outer ring can slip.....
Last edited by gerardvg; Aug 13, 2018 at 10:54 PM.
Thread Starter
Burning Brakes
Joined: May 2002
Posts: 751
Likes: 8
From: Escondido CA
TDC: #1 Piston at the top of its stroke, both valves closed, correct?
Last edited by kbuhagiar; Aug 13, 2018 at 11:55 PM.
Thread Starter
Burning Brakes
Joined: May 2002
Posts: 751
Likes: 8
From: Escondido CA
**UPDATE**
This morning I replaced the knock sensor (I was having a problem with intermittent pinging under load). That seems to have fixed the pinging problem.
Afterwards I checked the timing (after verifying TDC), it was right on 6 BTDC.
Went out for a 10-mile test drive, combination of freeway and stop-and-go. Ambient outside temperature at the time of the drive was 92 - 95 degrees.
Temp gauge stayed around 185-195 on the freeway. Stop-and go bumped it to around 200. Last half mile of the run is all uphill to my house, it topped up at 220, then idled in front of the house for about 20 minutes, and never got above 230. Based on how hot these engine run when installed in a Corvette (mine is in my 47 Plymouth with a Turbo 350, with a single electric pusher fan), I think this is normal...Yes? No?
PS Temp sender is located in the factory (hottest) location, driver's side cylinder head.
Thanks in advance.
This morning I replaced the knock sensor (I was having a problem with intermittent pinging under load). That seems to have fixed the pinging problem.
Afterwards I checked the timing (after verifying TDC), it was right on 6 BTDC.
Went out for a 10-mile test drive, combination of freeway and stop-and-go. Ambient outside temperature at the time of the drive was 92 - 95 degrees.
Temp gauge stayed around 185-195 on the freeway. Stop-and go bumped it to around 200. Last half mile of the run is all uphill to my house, it topped up at 220, then idled in front of the house for about 20 minutes, and never got above 230. Based on how hot these engine run when installed in a Corvette (mine is in my 47 Plymouth with a Turbo 350, with a single electric pusher fan), I think this is normal...Yes? No?
PS Temp sender is located in the factory (hottest) location, driver's side cylinder head.
Thanks in advance.
Last edited by kbuhagiar; Aug 14, 2018 at 05:51 PM.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
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Intermediate
Joined: Jun 2018
Posts: 39
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From: West Seneca NY
You are probably not looking for stories/advice, but if you suspect the timing is weird and possible inconsistent then I would replace the balancer. Part of the issues with my car led to a wild goose chase because it was slipping as mentioned by a previous reply.
Thread Starter
Burning Brakes
Joined: May 2002
Posts: 751
Likes: 8
From: Escondido CA
I am aware of the balancer issue, and based on my rudimentary check of TDC yesterday, I think it's still good. Fingers crossed.
Le Mans Master
Joined: Aug 2017
Posts: 6,944
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From: New Jersey
You happen to use a light to check the timing? And if so did you have the brown advance wire disconnected so you didn't have the computer adding timing? Just checking. on mine, after the fan runs for 30 seconds my temp comes down to 215 then climbs back up to 230 where the fan comes on. The only time I almost exceeded the fans ability to cool was the 30 minutes of sustained 2k+ in my drive way when it 100 out breaking in the new cam. Turning on the heater solved that. The stock cooling system is a lot better than most give it credit for. I may have also had my timing pretty retarded because I didn't know if you were supposed to adjust it before revving up the engine...
Thread Starter
Burning Brakes
Joined: May 2002
Posts: 751
Likes: 8
From: Escondido CA
Just checking. on mine, after the fan runs for 30 seconds my temp comes down to 215 then climbs back up to 230 where the fan comes on. The only time I almost exceeded the fans ability to cool was the 30 minutes of sustained 2k+ in my drive way when it 100 out breaking in the new cam. Turning on the heater solved that. The stock cooling system is a lot better than most give it credit for. I may have also had my timing pretty retarded because I didn't know if you were supposed to adjust it before revving up the engine...
Le Mans Master
Joined: Aug 2017
Posts: 6,944
Likes: 1,490
From: New Jersey
Light - check. Brown wire disconnected - check.
Thanks for that. I am familiar with the efficiency of the C4 cooling systems (I also have a 92 Corvette). The issue at hand is with an 86 L98 engine installed in a 47 Plymouth, so we are dealing with a non-Corvette cooling system.
Thanks for that. I am familiar with the efficiency of the C4 cooling systems (I also have a 92 Corvette). The issue at hand is with an 86 L98 engine installed in a 47 Plymouth, so we are dealing with a non-Corvette cooling system.