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Merc 7.4 330 to 502 Ignition change

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Old 06-07-2006 | 02:05 PM
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Default Merc 7.4 330 to 502 Ignition change

Ok guys,

What is nessessary for me to change out as I swap out my old Merc with the new perfomance 502? I have heard that the factory ignition limiter is set to 4500RPM's? Please remember I am on a budget..

As always... thanks fellas.

Jared
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Old 06-07-2006 | 03:48 PM
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Default Re: Merc 7.4 330 to 502 Ignition change

Are you planning to keep certain parts from the old engine?
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Old 06-07-2006 | 04:00 PM
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Default Re: Merc 7.4 330 to 502 Ignition change

What year? TBolt IV?
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Old 06-07-2006 | 04:18 PM
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Default Re: Merc 7.4 330 to 502 Ignition change

Also, some hyd roller cams have steel gears and some cast iron gears. Steel gears require different dist gear. You need to find out what gear the cam has so you don't chew up your dist gear.

Hyd flat tappet cams all have cast iron gears.
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Old 06-07-2006 | 07:40 PM
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Default Re: Merc 7.4 330 to 502 Ignition change

The Merc 330 was out of my 96 22 Scarab... As for the Cam its the 502/502 crate cam
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Old 06-08-2006 | 12:35 PM
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Default Re: Merc 7.4 330 to 502 Ignition change

TBolt IV or TBolt V?
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Old 06-08-2006 | 12:59 PM
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Default Re: Merc 7.4 330 to 502 Ignition change

buy a MSD or DUI well worth the $
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Old 06-08-2006 | 02:30 PM
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Default Re: Merc 7.4 330 to 502 Ignition change

Rdo... I am not sure.. How can I find out?
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Old 06-08-2006 | 02:32 PM
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Default Re: Merc 7.4 330 to 502 Ignition change

I am trying to minimize cost as I am swamped as it is... so Yes I am trying to use as many parts from the old motor as possible. I also want to make sure that if I need better parts... I buy them. I am trying to be thrifty... not cheap.
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Old 06-08-2006 | 02:37 PM
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Default Re: Merc 7.4 330 to 502 Ignition change

The ignition module is probably on the side of the distributor. It may list TBolt IV vs V, and will definitely have a part number.
I think the V will have a knock sensor and rev limiter.
The IV will be a simpler swap.
As others pointed out, some of the roller cams may have problems with the distributor gear. You can call the cam manufacturer about that part.
Gary
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