1988 HEI Pro's HELP...
Thread Starter
Racer
Joined: Apr 2001
Posts: 452
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From: Tulsa Ok, Racing the wind
1988 HEI Pro's HELP...
I have a question about my 1988 HEI. While changing the cap, rotor and plug wires I noticed that the rotor had some play in it, like a 1/4 inch turn without any resistance. I have changed many caps and rotors and don't remember such an amount of play.
Is this normal, or do I have a problem with the HEI. I have been searching for reasons for a stumble in exceleration for about a year now. Could this excessive play in the rotor be causing lag in my timing???
Any pro's with advise (Yea or Nay) would help me out a great deal. :confused:
Is this normal, or do I have a problem with the HEI. I have been searching for reasons for a stumble in exceleration for about a year now. Could this excessive play in the rotor be causing lag in my timing???
Any pro's with advise (Yea or Nay) would help me out a great deal. :confused:
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
Re: 1988 HEI Pro's HELP... (BigTodd)
My HyperTech HEI has a similar play so don't think it is your problem.
To deal with that stumble I suggest you:
-clean the TB plates & bore with TB cleaner
-set the base idle (450RPM) TPS voltage at .65 Vdc and tweak max WOT voltage
-bump base timing from 6 deg BTDC to 8 deg BTDC.
-check the dist cap for carbom tracking, the wires for breakdown and plugs condition
To deal with that stumble I suggest you:
-clean the TB plates & bore with TB cleaner
-set the base idle (450RPM) TPS voltage at .65 Vdc and tweak max WOT voltage
-bump base timing from 6 deg BTDC to 8 deg BTDC.
-check the dist cap for carbom tracking, the wires for breakdown and plugs condition
Melting Slicks
Joined: Apr 2002
Posts: 2,118
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From: St. Charles, MO Route 66 Corvette Club
Re: 1988 HEI Pro's HELP... (BigTodd)
My 89 Vette (41,000 miles) also has about the same radial play in the rotor. You have to note that this slack will be eliminated (in the clockwise direction) as the cam is driving the rotor and oil pump. I think you condition is "normal" due to tolerances between the cam and rotor gear.
Thread Starter
Racer
Joined: Apr 2001
Posts: 452
Likes: 0
From: Tulsa Ok, Racing the wind
Re: 1988 HEI Pro's HELP... (Sam Lam)
Thanks, the play just seemed to be a little strange, I will try the suggested timing and TPS settings to see if the stumble will reduce. It's been a real pain trying to figure out what the problem is.
This is the first time I have changed out the spark plug wires, they also may be contributing to the problem, Also going with the NGK FR4 Vpower plugs. Running the AC delco Platnums currently. The NGK's really helped out my 93 LT1 when I put them in. Autocross season is just around the corner and I don't want to miss out on the fun..
:yesnod:
This is the first time I have changed out the spark plug wires, they also may be contributing to the problem, Also going with the NGK FR4 Vpower plugs. Running the AC delco Platnums currently. The NGK's really helped out my 93 LT1 when I put them in. Autocross season is just around the corner and I don't want to miss out on the fun..
:yesnod:
Melting Slicks
Joined: Apr 2002
Posts: 2,118
Likes: 0
From: St. Charles, MO Route 66 Corvette Club
Re: 1988 HEI Pro's HELP... (BigTodd)
In addition to the suggestions from 65Z01, I would also do the following:
1. If the O2 sensor has 30,000+ miles, change her out
2. Replace the fuel filter
3. Check fuel pressure
4. Check resistance on each injector and "listen" to the action of the injector. You can do this by placing a long screwdriver on the injector and placing the other end to your ear. You will be able to hear the metalic "cling". All injectors should have the same sound and resistance.
Good luck!
[Modified by Sam Lam, 6:59 PM 2/12/2004]
1. If the O2 sensor has 30,000+ miles, change her out
2. Replace the fuel filter
3. Check fuel pressure
4. Check resistance on each injector and "listen" to the action of the injector. You can do this by placing a long screwdriver on the injector and placing the other end to your ear. You will be able to hear the metalic "cling". All injectors should have the same sound and resistance.
Good luck!
[Modified by Sam Lam, 6:59 PM 2/12/2004]
