I am replacing my Gen V 7.4L carb motor with a Gen V 502 Mag. The old motor has 508 hrs and still runs great but I have the need for more mph. I am getting a killer deal on the 502 so I think it is the best bang for the buck. I will be keeping the carb (Webber 750) and stock exhaust manifolds for now. I will need to buy a new intake manifold and a larger oil cooler. The ignition is a TBolt IV with the V-8 24 degree module. Everything else should just swap over I think. Any suggestions on intake manifolds and oil coolers? What about the drive coupler? It looks good. Should I change it anyway? Anything that I missed? Your suggestions will be appreciated.
Thanks guys, Doug

Just do it
Congrats on the repower!! I think you will like the extra ponnies in the Baja for sure.
As far as the Tech, I don't know But I put your post back to the top
See ya on the water

Change the coupler- it's good insurance against having to pull the motor again (make sure you align it dead-on. NAPA has couplers at a pretty good price.
Dart and Edelbrock are both good manifolds- as far as oil coolers I know some guys have had good luck with the combo power steering/oil coolers that are available aftermarket (Eddie Marine, CP, REX, etc).

You'll love the difference in power!

Don't re-use the existing carburetor. The 502 come with an 800 cfm Webber. You can tell the difference because the 502 carburetor has equal throttle bore size, the 7.4 carburetor has staggered primary and secondary sizes. You should be able to find a 502 take-off carburetor if you ask around.

You have to change your fuel system too, I think? The 454 was mechanical on the block, and the 502 does not have the mounting boss for the pump.

What size is your oil cooler? You may not need a bigger one unless you supercharge your motor. I swapped a 454 Magnum for a 502 and reused the oil cooler - worked fine.

Congrats,

I'm in the process of doing the same with MPI's...can't wait to try it out...three more months up here till boating season.

In my case I believe it will be a complete swap with no modifications necessary...I hope. The marina said that the coupler is not showing any wear on it (130hrs.) and that it would be a waste of money to replace.

Good luck

I have a 502MPI, and I love it. Of course, the Whipple helps!

The stock oil cooler is pretty small. It does have the 1/2" oil lines already so I'll probably just go with an aftermarket combo unit that will cool the power steering also, same as stock.

The carb I have now has all four holes the same size. I think I will start with that as a baseline to judge any future upgrades.

The fuel pump mounting is the same since they are both Gen V blocks. Externally driven off the seawater pump mount.

A new coupler is probably good insurance even though the original looks good. I didn't know they were available at NAPA. I'll check it out.

I have a like new 24" Bravo 1 to replace the 21" Mirage.

Have to decide which intake to buy. Does anyone have a used dual plane from a mag motor they want to part with?

Thanks for your help and your interest. I'll keep posting my progress as it develops. The new motor should be ready in about a month. So far I have just pulled the old motor. I won't start swapping parts until the new one is here. A lot easier that way to make sure everything gets re-assembled correctly. I will also clean and repaint the bilge while the engine is out.

See ya, Doug

I've had good luck with Edelbrock Performer intakes, but you'll need to evaluate the future upgrades you might want to make and buy the intake based on that. You might avoid buying another intake later on. MacDad, can you make it to our party Feb 16?

[ 02-03-2002: Message edited by: Crazyhorse ]

Hi there, Crazyhorse. Yes, I am planning to be at your party on the 16th. I am thinking about a Performer RPM. 1st on my list, actually. I don't plan on anything radical in the future. As long as I have enough power to pass Waterfoul, I will be happy!