Does 1990 MCM 350 mag Tbolt IV already have melonized distributor gear? Replacing engine, have some questions..

[500dollar744ti]

I read somewhere that all the thunderbolt IV and V distributors use a melonized gear regardless of flat tappet or roller cam, is that a fact?

The original MCM 350 (1990 year) Mag in my boat is mixing water in the oil, always winterized in my 9 years of ownership. Noticed issue last year with slight misfire at WOT, thought was ignition related but wasn't. This year the misfire has become worse and water is getting in the oil, and cylinders. Maybe head gasket, or head crack, I don't know.

I have a 383 engine in my garage I had been putting together for this boat. It has the XM270HR roller cam, forged pistons, and vortec heads.

I want to make sure my distributor gear matches up for a roller cam.

Should I use one of the composite fuel pump pushrods or a brass tipped one?

Also was planning on using the same quadrajet carb from the 350 mag (270hp), I don't expect the new motor to be more than 320hp, it's just some more displacement, vortec heads and a cam. Should I see how it runs and maybe rejet at a later time if lean?

I had been putting off swapping this engine because the original motor was running fine, but now it's not, so..

Thanks in advance.

 

[Bondo]

Ayuh,..... I've swapped Merc distributors between motors, roller cam, 'n flat tappet, without issues, so I guess, Yes, go for it,....
As for the pump push rod, whatever the cam builder says,....

 

[achris]

..I have a 383 engine in my garage I had been putting together for this boat. It has the XM270HR roller cam, forged pistons, and vortec heads.

.. I don't expect the new motor to be more than 320hp, it's just some more displacement, vortec heads and a cam.

If you're running an Alpha drive, be gentle with your right hand! I've run the numbers, and I think you're being too conservative on the power output of that 383!

Chris....

 

[Paintman1960]

If you're running an Alpha drive, be gentle with your right hand! I've run the numbers, and I think you're being too conservative on the power output of that 383!

Chris....

I agree, a 383 engine should be making more power than that, I know mine does !
I have one in my Camaro as well ,

 

[Scott Danforth]

If you are worried, get a brass dizzy gear. However I wouldnt bother

Use what ever pump pushrod you want

You will need to rejet, and to do so, you have to read plugs and actually tune the carb ( no such thing as a canned calibration/tune)

Run a rev limiter. If you prop looses bite ( coming off a wave), the alpha wont survive the return to loading

Watch your holeshot