Repower update: Questions

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Well my 502 turned out to be a 454 Gen VI. Think it is a late 90's Mercrusier rebuilt....the Mercury Marine tag number 061047 and has less than 100 hours on it.

1) Can any one with a Mercury Marine book tell me what the details are on this ?

2) It has Vortec heads....is there an carb intake/setup that will fit this ? (Do not think there is one but I figured I'd ask...plenty for SB's...)

Thanks,

Rick

Will a Hardin manifold work ?

I used an Edelbrock oval port intake on mine, worked great

After doing some digging an Edelbrock RPM Air-Gap Manifold might do the trick....thanks

I run the Vortec heads (shaved and ported) with a gasket matched RPM Air Gap manifold and the 2" HVC super sucker spacer on my 468 BBC (Gen VI). I think they're great (so far...)

The heads have a good runner & combustion chamber design and so they seem to tolerate single plane manifolds well but I've found the dual plane RPM Air Gap to be the best so far.
I've tried / tested Dart, Merlin, Victor Jnr & Torker (incl 2.0) and so far, the RPM wins!

Just make sure you specify large oval ports and it's also best to gasket match the intake to the heads.

What's the block numbers on your BBC?

Good Luck!

The block is a "297" Gen VI roller. Heads are "279". Will be going through the engine shortly before I install it. I am guessing it a a standard 7.4 (not a Magnum: Will know when I pull the pan of and look at the crank....most likely cast)

It is a Mercury Marine rebuild (L061047 on the tag) and I picked it up from a boat mechanic that did a repower on a Fountain with twin 7.4's (The other engine was shot). It has about 90 hours on it.

What carb are you running ? I currently have the factory Weber.

Also what is your thoughts on fluild dampers ?

Thanks,

Rick

Some how got a duplicate reply in here...deleted.

For Carb I run a Holley 850 HP D/P. I'm trying to sort out the jetting / power valve situation at the moment!

Fluid Damper is a good quality item. I posted a thread on here a while back asking very similar questions! I wound up going with an ATI because I found one on sale locally. Do a search on dampers etc and you'll find a lot of very useful discussion from some top notch engine builders on what they use and why.

There's a lot of argument about which carb is best, Webber, Edelbrock, Holley Barry Grant etc. Personally, I needed bigger than 750 which is as big as Edelbrock make, I know nothing about Webber and I tried a BG Demon and couldn't get it sorted so now I'm trying the Holley and so far so good. It's up to you which way your preference goes but for my mind, there's a shed load of experience out there on tuning a Holley DP for your exact application and I'd prefer experience to what the book says or what YouTube tells you to do any day!

Let us know how you get on.