502 marine cam

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502 marine cam

Postby fastvette » Tue Sep 06, 2011 7:55 pm

I have here a 502 Magnum marine engine that was brought to me already apart. Some one else took it apart, and somewhere between there and here the cam and lifters came up missing. I need a cam just like the one that was in it. This is gong back in a boat that has two of theese engines. So it needs to be the same. Anyone have one,or know what I need, or what the specs are so I can get one ground?

thanks,
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Re: 502 marine cam

Postby Kenova » Tue Sep 06, 2011 8:38 pm

Do both engines rotate in the same direction, or are they counter rotating?

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Re: 502 marine cam

Postby Patriyacht » Wed Sep 07, 2011 7:44 am

There is an high perf. boat website called www.Offshoreonly.com where you might have some luck.
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Re: 502 marine cam

Postby Mmfh » Wed Sep 07, 2011 10:21 am

Boats like that I've done both engines turn the same way. Larger boats like fishing boats, I think will have the
starboard side turning counterclockwise.

If you call http://www.pacificpowerboats.net/home.html , the parts dept. should be able to tell you exactly
what you need.

Good Luck!

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Re: 502 marine cam

Postby jonsjunque » Wed Sep 07, 2011 12:44 pm

Any clues from the props/ drives as to rotation?

What kind of drives are they?

Is there a serial # anywhere on the Block? serial # search from oem may lead to specs.

Mercruisers should have a plate attached.....

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Re: 502 marine cam

Postby fastvette » Wed Sep 07, 2011 2:46 pm

It has a serial plate on the block but I was told that it is wrong. This boat originaly had small blocks in it. Here is the serial # F416015 on the block. The owner of the boat was trying to get a service manual for the engine and was told that # is for a small block.

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Re: 502 marine cam

Postby Patriyacht » Wed Sep 07, 2011 3:14 pm

If it's a Mercruiser Magnum, it's standard rotation. Counter rotating is taken care of in the outdrive or transmission if it's straight drive.
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Re: 502 marine cam

Postby fastvette » Wed Sep 07, 2011 5:41 pm

It is a Mercruiser Magnum with the fuel injection. I didn't get time to make any calls today.
I will see what I can find tomorrow.
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Re: 502 marine cam

Postby nascarfan7 » Wed Sep 07, 2011 6:29 pm

Roller or flat tappet? I believe the carb and MPI magnum variants of the 454/502 share the same cam

The 502 magnum flat specs 224/224 duration .510/.510 lift 115.5 LSA
The roller 502 Magnum specs 225/225 duration .483/.483 lift 115.5 LSA

Previous poster is correct that reverse rotation is taken care of by the drive or transmission. Are these both stock unmolested original 502's? Without knowing what the other engine has for a cam I'd make sure they both spec the same.
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Re: 502 marine cam

Postby rmbuilder » Wed Sep 07, 2011 6:42 pm

Specs for the 502 MPI cam
Chevrolet part # 12551622
Merc #431-850478
288*/288* seat
224*/224* @.050"
.483"/.483" valve
115.5* LSA
109* ICL
122* ECL

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Re: 502 marine cam

Postby Adger Smith » Wed Sep 07, 2011 6:50 pm

Saw Thus on E-bay a while back http://cgi.ebay.com/ebaymotors/_W0QQcmd ... MEWAXQ3aIT

New Billet Roller Hydraulic Cam BBC Big Block Chevy

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Price: US $30.00 Buy It NowBuy It NowBuy It Now

Returns: No Returns Accepted
Shipping: $16.00Standard ShippingSee more services See shipping discounts
See all shipping detailsEstimated delivery within 5-9 business days.

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Item number: 230237015096
Item location: Oshkosh, Wisconsin, United States
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Payments: PayPal, Bill Me Later, Personal check, Money order/Cashiers check See payment information
History: 137 sold

I had a coustomer that bought one nad put it in a street rod w/1.8 Rockers oval heads and 9-1 comp. It made gobs of torque and alittle over 500 HP. I think the specs were similar to what is listed in another post. I think the part number is listed in the ad. They are supposed to be takeouts.
Hope this helps.
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Re: 502 marine cam

Postby fastvette » Thu Sep 08, 2011 10:31 am

Thanks for all the info. I guess it uses a tie bar lifter? There is no provisions for the GM style lifter.

thanks,
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Re: 502 marine cam

Postby Adger Smith » Thu Sep 08, 2011 1:48 pm

Randy,
My customer got his tie bar Hyd lifters from Herbert cheaper than my cost on Comp. I was hesitant to use them thinking they might be China knockoffs. I'm not sure who makes them, but whoever did they worked well.There was no lobe for fuel pump so he had to run a electric pump. Since it was a Street Rod he put a modified GMC truck tank in it with the factory pump and modified it & regulated the pressure. I picked the right length pushrods to correct geometry. Seems to have worked out well for him. Good luck with your project.
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