C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Distributor rotor install help

 
Old 04-11-2019, 05:22 AM
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Tempest302
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Default Distributor rotor install help

Hey guys,

I found a c4 I am looking to purchase tomorrow but he has the distributor cap and rotor out and didn't mark anything. Been googling around and I have found wire diagrams for generic SBC/BBC distributors but not a c4 l98 specific one. Is it the same order? If not, anyone have a diagram?

Also, how to make sure the rotor goes on in the right location? I.e. Not backwards?

thanks
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Old 04-11-2019, 07:16 AM
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confab
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If the wires are still attached to the cap you can just install the rotor, cap, and go.. It is indexed and should only properly install in one orientation.

If not:

Replace the rotor on the engine.

Rotate the engine till the #1 (Front, Driver's) cylinder is up on compression stroke. You will know this because the piston will be at the max height of its travel, verifiable with the balancer or by testing through the spark plug hole with a small tool, like a screwdriver or a 1/4 extension. Both valves to this cylinder will be closed.

From the front of the engine to the back, the driver's cylinders are 1-3-5-7. The passenger's cylinders are 2-4-6-8.

Then following the rotation of the distributor, the firing order is the same as the rest of the small blocks - 1-8-4-3-6-5-7-2. Replace the wires in that order around the cap.

Then, set timing.


Last edited by confab; 04-11-2019 at 07:18 AM.
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Old 04-11-2019, 11:04 AM
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Joe K
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Rotor has a slot, distributor a tab so it is hard to install incorrectly. Cap has some type of index also. Firing order is 18436572 going clockwise on the distributor. While looking at the cap #1 is usually the 2nd wire to the left of the electrical connectors. HTH.

Joe K

Last edited by Joe K; 04-11-2019 at 11:57 AM. Reason: Cap has index too.
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Old 04-11-2019, 11:59 AM
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Joe K
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Just looked at my cap #1 is 2nd wire. YMMV. Sorry for any confusion.
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Old 04-11-2019, 12:53 PM
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ctmccloskey
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Don't say it can't be done.... I drove my VW to a dealer with my distributor 180* off. I somehow put it in backwards and the car still ran.... And the VW mechanics told me "it was not possible to run an engine with the distributor in 180 off". That was a distributor and not just the rotor or cap.

Like mentioned above the rotor and distributor cap are both indexed so you can't/Shouldn't be able put them in backwards.

On my L98 the #1 wire is at approximately 5:30 looking from above the distributor.

Best Regards
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Old 04-12-2019, 07:28 AM
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Tempest302
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cool thanks, pick up the car today and uh... lets just say the reports on what was removed were less then accurate. Talked him down another 500 but they also took apart the drive shaft and exhaust system. Good news? New clutch and slave cylinder.
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Old 04-12-2019, 08:14 AM
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He's taking the driveline apart and just replaced the clutch master and slave? Could be trans problems.


Not a deal breaker, but something to keep in mind if you can't drive it.
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Old 04-15-2019, 11:53 AM
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ctmccloskey
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Sometimes it helps to have an experienced hand with Corvettes with you when you are looking to buy one. I have a cousin who is into Corvettes so he helped me on my first purchase of my 1968 C3 L71 convertible with four speed. I have learned so much since then, this forum is a quick way to learn and there are so many people with practical experience who can help you solve your Corvette's Issues.

There are so many expensive components that you can't test by driving the car. It is possible the cap and rotor were removed to "keep you" from seeing or hearing something else, or even driving the car.

If you are buying this car you should have a mechanic look at it to avoid expensive repairs. When I bought my 1988 C4 I was at Carlisle Corvette show and there were a lot of C4's in all conditions available. I spent hours looking over the cars before deciding and I still missed important items that could have helped the price in my direction. A couple years later the brake lines started developing leaks which indicates lack of maintenance and lack of usage. I flushed everything out and still had a fuel line plug up internally causing even more expenses that I had not planned on.


I hope that this will be a positive experience for you!
Chris
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