Lost horsepower
Thread Starter
Intermediate
Joined: Sep 2010
Posts: 42
Likes: 0
Lost horsepower
I had a new opti-spark distributor installed in my 1996 Collector Edition. Upon picking it up from the repair shop I immediately noticed: the crank was slower and it turned more than it did before (it usually turned once and fired right up). Once started the idle was weaker, an upon take-off I noticed I had less power. I took the car back and the mechanic said everything was operating properly. I went to several other vette shops anf hi-performance shops and they said the same thing. All codes were set correctly. Does anyone out there have any ideal what could have gone wrong for my vette to lose power?
Last edited by cbullitts; Sep 25, 2010 at 11:21 PM. Reason: Misspelled word
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Plug wires interchanged. Plug wire/s open circuit, check them all with an ohmeter. Optispark installed incorrectly and timing is off. You cannot measure timing on an optispark. If timing is off I would expect idle speed to also be off. Bring a grounded wire very close to the metal clip inside the boot of an unplugged spark plug wire while someone cranks the engine and during cranking or if the engine runs, open the distance with the grounded wire, the spark should be snappy and be at least 1/2" long. Weak spark can cause your symptoms. During this test try not to open the gap so far that no spark occurs. Check that all the spark plug wires are full seated in the optispark and also fully seated onto the spark plugs.
Thread Starter
Intermediate
Joined: Sep 2010
Posts: 42
Likes: 0
Lost horsepower
Hi jfb-
Thanks for the great tips. One thing I keep hearing is that optispark distributors can't be installed incorrectly. I've heard different as well. What is your input on that?
cbullitts
Thanks for the great tips. One thing I keep hearing is that optispark distributors can't be installed incorrectly. I've heard different as well. What is your input on that?
cbullitts
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
From my memory we have had two posters that installed their optisparks incorrectly. If you take good care to get the optispark key to line up with the depression in the cam gear it runs off of, then all is ok, BUT, it is possible to not have it aligned and force the opti onto the block by cranking down on its mounting bolts.
Safety Car
Joined: Aug 2008
Posts: 4,344
Likes: 48
From: San Marcos CA
I'd certainly check firing order as that is much more likely than the opti having been forced over the notch on the drive wrong.
You might also be able to tell from a quick sniff of a smog machine if the firing order is ok.
You might also be able to tell from a quick sniff of a smog machine if the firing order is ok.
Thread Starter
Intermediate
Joined: Sep 2010
Posts: 42
Likes: 0
One thing i forgot to mention. After having the distributor installed, on occasions the car backfires upon crank. I spoke with a Corvette specialist and he told me that the car may have been progrmmed, and when they installed the disttibutor, the programming was lost. What's your thought on that?
Last edited by cbullitts; Sep 27, 2010 at 01:26 AM. Reason: FORGOT INFO.
Race Director
Joined: Jan 2002
Posts: 12,263
Likes: 86
From: O'Fallon Missouri
You need to find a new "Corvette Specialist"!! Programming and installing a distributor/opti have NOTHING in common.
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Joined: Oct 2006
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From: Waukesha Wisconsin
Some of the aftermarket units, including ours can be installed 180 degrees off. I'm trying to figure out what makes ours different so that it can be redesigned. Anyone more mechanically inclined that can help would be appreciated.
