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

Re: Merc 7.4 330 to 502 Ignition change
 

Are you planning to keep certain parts from the old engine?

Re: Merc 7.4 330 to 502 Ignition change
 

What year? TBolt IV?

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.

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

Re: Merc 7.4 330 to 502 Ignition change
 

TBolt IV or TBolt V?

Re: Merc 7.4 330 to 502 Ignition change
 

buy a MSD or DUI well worth the $

Re: Merc 7.4 330 to 502 Ignition change
 

Rdo... I am not sure.. How can I find out?

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.

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