I know this is ever so slightly out of place but I dont feel like registering for every forum on the internet but agree I may have to find one that is more on topic. Thought I would try for any intel on here first though.

I just bought a boat with a siezed motor. It is a 1974 Mercruiser 302 which means its a 1974 Ford 302 with marine peripherals; it has Ford stamped all over the place.

Anyone with a boat knows marine crap is super expensive so I thought I would look into finding a decent long block from a car or truck at pick n pull. Can anyone tell me up to what year would be viable for this? If numbers or anything are needed let me know. Thanks!

 

The 302 never changed in basic design and dimension so any year motor will do, and a late model roller motor would be ideal here with a '96 Explorer motor being the closest to a marine in every way except for the cam.. though even the stock cam isn't too bad. The next best candidate would be an '87-95 Mustang 5.0HO, and then a '94+ truck 5.0, and then earlier truck motors. The worst thing to use would be the lopo 5.0 from a Crown Vic or Towncar.

 

Will the fuel injection cam work with a carb? Also what about the crank weight? If i bolt the original flywheel to it will balance be an issue? The late exploders are what I was considering.

 

One thing you'll need to make sure of before going further is make sure the marine motor isn't a reverse rotation engine. As for the Explorer cam working with a carb, a carb actually works better with the wider LSA's that EFI cams have. Another choice as for long blocks go is the 94-97 5.0 from a pickup or a van. These run the same cam as the Explorer/Mountaineer but with the same heads that the Mustang motors came with. The flywheel is going to be a 50 oz/in vs your earlier 302's 28 oz/in, so you'll need to get a matching flywheel to do this.

 

The explorer/mountaineers ran gt40p heads that use diffrent plug angles, make sure your manifolds will clear plugs and wires. The heads they ran are a better set up than the e7te(truck, stang) head better flow. I bought a set for my 351w but have put them off to the side due to not wanting to deal with headers.

Curtis

 

The marine manifolds offer plenty of room for plugs...

What about getting the flywheel to work? I will know more once I pull the short block all the way out so maybe the 50oz will be the same dimensions?

The other thing is the mechanical fuel pump. Do the newer motors have the port to bolt this up?

 

If it is a diffrent set up get a marine 50oz. balance flywheel for it, no big deal there they ran the 50oz. stuff in boats too.
fuel pump, swap your timing cover and other required parts and your in business.

Curtis

 

Cool. Dizzys the same? Firing order... Sorry for all the questions. Just want all the ducks in a row.

 

Here's a dumb question.... Did the newer engines switch to metric threads on the bolts? I was already planning on replacing a bunch of the hardware; it would probably be a good idea to get the right thread type

 

The Explorers run a different timing cover, no provision for a fuel pump. Ditto for the 87-93 Mustang, 94-95 Stang, 87-97 pickup and vans. To use the 74 timing cover, you'll need to remove the cover locating dowels and install the balancer before tightening the cover bolts to align the cover with the front seal. Or you can use a timing cover from an 80-up Crown Vic, this cover uses the locating dowels and has the provision for the fuel pump (although you may need to punch out the pump hole) You'll also need to swap your fuel pump eccentric and cam dowel to the newer motor. Then there's the distributor: you'll need to run a steel geared distributor to match the roller cam. You can swap the gear on the 74 distributor to accomplish this, There are several vendors for the gear, Ford Racing is one. The gear swap isn't hard, you just have to pay close attention to the instructions in doing the swap. The only bolt threads that were changed were the ones for the pressure plate on manual transmission flywheels, all others are std thread. You'll likely also need to swap the oilpan from your motor to the new one as well as the rest of the parts. I know this sounds like a lot of swapping, but the roller engine performance and reliability is well worth it. More compression, more power, smoother running vs a 74 motor.

 

I really appreciate this feedback. Gonna keep the thread going until I am done with pics...

Another question. The current engine has a brand new (rebuilt) holley marine 2bbl on it. Is this enough of a carb for the newer engine?

Also... Wondering in an electric fuel pump wouldnt be easier/cheaper than sticking with the mechanical.

 

'96 to 97.5 Explorer motor got regular GT40 heads.

 

What CFM? If it's upwards of 500cfm you'll be fine.

 

Its a holley h2-2300. Any advise on picking the best donor?

 

I mean in terms of what to check. Obviously turnIng its a good idea as well as a compression test. Anything else...