Offshoreonly.com - 8.1 496 reliable build questions

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If you stick with the stock heads and cam do like the other guys have mentioned- get forged pistons. The stock rods can probably handle it if they are checked. Have the heads tested and call Raylar to get a set of their roller rockers and springs. The stock springs are very weak and likely the problem of the stuck valves. Between the roller rockers, new springs and Stainless exhaust you should have a reliable package good for close to 1000+ hours which is what most 496's run in commercial applications regularly.

Good call on the valve springs didn't even think of those. Thanks guys for the info. Now the question about cam sensors comes to mind and what timing chain set to use.

Quote:

Originally Posted by F-2 Speedy (Post 4568983)

never mind

Did I say something wrong here

100+ hours which is what most 496's run in commercial applications regularly.

What do you mean buy this.

no.....there might be a 0 missing on KA post

Edit: if your going to build an engine and expect it to last for many hours, it needs to be done by a reputable marine engine builder, all new everything.
oil pump, bearings, rings, lifters, check the block for square, line hone if need be, complete head rebuilds, and then the fuel system, clearances on bearings, lifter bores, and guides are not the same as a street application, good luck.

Quote:

Originally Posted by mouse4x4 (Post 4569034)

100+ hours which is what most 496's run in commercial applications regularly.

What do you mean buy this.

Fixed it 1000+

Quote:

Originally Posted by mouse4x4 (Post 4569031)

Good call on the valve springs didn't even think of those. Thanks guys for the info. Now the question about cam sensors comes to mind and what timing chain set to use.

Stock

Replace both.

Genuine Mercury & Mercruiser parts

Are you rebuilding or a shop?

I am having all the machine work done all new bearings and everything checked balanced so on. Just looking for ideas on what is needed to be beefed up to make it last. I will put the engine together myself but having a reputable shop do all the machine work. And as far as timing sets I know there were 3 variations of sensors and sprockets and I know for the latest set I need to change out the timing cover to have it work and I think there is a pigtail that is needed.

Just a quick question while I have everyone's ears, my engine being the hp1 version 375hp what is different between it and a regular truck engine. Hard part wise are the cranks and cam the same?

Quote:

Originally Posted by mouse4x4 (Post 4568949)

Now with pistons should I forge or shouldn't I. Also will they work with stock rods. Will the inconel valves resist corrosion also like stainless. Sorry for the questions I just don't want to trip over a dollar to pick up a penny. I just want a rugged build that will last. If you were in my shoes with this how would you do it.

Diamond and Wiseco make stock replacement 4032 forged pistons that are designed to use the stock rods. I would upgrade the pistons if rebuilding for peace of mind. ARP makes upgraded rod bolts for the stock rods. However, once you buy the rod bolts and resize the rods you've matched if not exceeded the cost of a set of Eagle/Scat H beams. Stock rods/bolts are fine at stock rpm levels.

Your machine shop should be able to source your valvetrain. Stock valvesprings are fine for stock cam/rpm levels. If you want to upgrade call Larry @ Raylar. Good guy with lots of knowledge on the 8.1.

Mercruiser 496's don't seem to have reversion issues. Maybe source a set of Merc manifolds/risers.

PT075H3 Wiseco

12705 Diamond