Hi Guys,

Have pulled 351w out of my boat. I started breaking down the block, prepping for a very mild rebuild. I found that I have aluminum ( or at least non magnetic) pistons. The tops don't look like any Ford pistons that I have seen while rebuilding any of my pick ups in the 70's or 80's.
They are flat tops with a rounded rectangular recess, deep into the piston top for valve clearance. There is also a .040 stamped on top ( I can only guess they've been bored).
I am not the original owner, and I have no way to research what work has been done.

Has anyone seen pistons that sound similar to these? Is this just a way to get killer compression? Is this a marine use thing that is common? Could this be a piston that has to be used because maybe it has been stroked too? I hope to start popping out pistons tommorrow, after work. When a 351w is stroked, the crank is changed, but are the rods stock size or are they changed?

Any ideas on what to look for?

Thanks,
Kenny

 

sound like a .040 overbore w/ forged aluminum piston, I think that the rods are stock, but don't quote me on that.

 

They're stock .040 replacements. You can raise the compression by substituting flat tops with no dish., that is of course, if you can bore it another .020 (to .060 over if it needs to be bored)

 

Alot of boat engines have dished pistons to clear the valves. Normally they have more lift than an auto engine. Marine engines use a higher lift cam to help them breathe better while they run at 3500 all day long.

 

All the post 70's 351's used the same (huge rectangular dish) piston. The cam had nothing to do with it. Same Marine cam was used in the 82-84 5.0 HO in the Mustangs with flat topped pistons with valve reliefs. The lift specs on the marine cam aren't even close to being maxed out with stock pistons.

 

Thanks guys,


Just got home and will start pulling pistons.

Kenny

 

What do you mean by very mild rebuild? I wouldn't want to be out 20 miles offshore and have the bottom end give out!! On a boat that is kept at a fairly high rpm for extended periods you need a rock solid bottom end. If you took the time to take it out and open it up might as well take your time and rebuild the whole motor top to bottom!! I would run a gear drive timing set up for even more reliability!! Everything you do to this motor should be for reliability. If the boat is a displacement hull building in more hp isn't going to make it go any faster than the design speed. Don't waste money on high performance parts that don't contribute to the reliability of it!! Make sure all your tolerances are spot on when you build!!

 

I agree w/ blue beast, I'd have machine shop go over it w/ a fine tooth comb.... line bore the journal's, hone out the cylinders, and deck the block

 

That is what I meant by 'Mild Rebuild", meaning not going for high performance, high rpm, racing stuff. Just got back from dropping the block off to be done, and the crank to be checked. Ordered complete marine rebuild kit including:

Perfect Circle cast steel piston rings
Clevite rod, main, and cam bearings
Victor-Reinz marine gasket set (exhaust gasket, thermostat housing, and exhaust manifold cooling gaskets sold separately)
Cloyes 3-piece double row timing set
Melling oil pump
Sealed Power piston set
Pioneer BRASS freeze/expansion plug kit
Melling marine camshaft
Topline Hylift Lifters
Plus a few other goodies on the side.

No. No way am I cruising 60 + miles to my usuall hunting grounds, in the Atlantic, without knowing damn well I'm getting back. The 10 horse kicker is an insurance policy that I don't want to depend on.

Thanks guys.

 

I'd see if they will swap that chain drive for a gear drive or just buy one outright!! The kicker motor is alright until you get to the inlet, if it's anything but slack tide you are in for a ride!! Your having the block magnafluxed? I got the 12 pack of buzzweiser when you get it finished!!

 

Sure, anyone who helps me is more than welcome to go chasin' stripers, makos, tuna, whatever, with me. Especially if your packin' more beer.

Couple more questions:

You had suggested painting the block up in cold galv. If I do that, I would still want to paint Ford Blue over it. I can't help my taste of color. Out in my shop, my '74 chopper is wearing a coat of Ford Blue on all tins. I'm thinking about painting up my '42 flathead too.

Question is: will the galv paint stand up to engine heat? I seem to think it would start to flake off and take the over paint with it, but I don't know that, never tried it. I do fully intend to put about 93 coats of gal paint on the oil pan, and just leave the pan shiny. It might even help to see things down there later, with a light color.

I was thinking about using rustoleum rust reformer, as a preventative measure, prior to painting.

Also, I have never had to change points & stuff to electronic ignition. I kinda' just got used to setting points and dwell and such. Is changing over to electronic worth it? Is it a big major production?

Kenny

 

PS....



I found a stamped, not cast, set of numbers on the block.

On the rear of the block, below the port head and above the bell housing.

CA43947, stamped out twice in a row.

I am trying to research if that is a Ford number (which I strongly doubt because it is stamped), an OMC number (maybe) or What I fear, it's just a number that a shop (maybe who bored it out) put on for ID?

Oh well, hello... google?

Ken

 

I got plenty of overspray on my block when I painted my oil pan, but I think if you check marine paint suppliers they got block specific high zinc paint. If you can fit a extra capacity oil pan in there I would go for that, If you don't have the depth you could weld some "cans" on the sides of the pan, Basically have a good welder fab up some quart size cans and weld them to the sides of the oil pan, That extra oil could be a life saver!! Both systems have their plus and minus to them, I say go with whatever you are more comfortable with, Of course murphys law rules the sea so bring extras and you won't have to use them!! What ever you choose, bring extra of the most failure prone parts and Running double fuel water seperators wouldn't hurt either. That is why I don't like sailboats, It is kind of hard to carry an extra mast and fix it while 20 miles off shore!! Yes I have been offshore in the Atlantic with a broken mast on a hobie cat, Not a good feeling and not something you can fix with duct tape!! lol Of course no radio and no lights and no flares!! I know what you are thinking knucklehead or deathwish, but we were kids and didn't think that far ahead!!

 

I know a good welder. Me. I am a Local 638 Steamfitter. I weld all day long. I build steel tube boilers. Industrial sizes. In schools, hospitals, powerhouses, etc. I weld pipe all day. Lots of low pressure steam, some high. Even 700 psi amonia systems that power icehouses.

I once got busted, with a bunch of my friends, by the coast guard. The harbor had frozen over, then thawed partial. Instead of walking all the way around the harbor in the dead of winter, we jumped on a thick ice sheet, and with a few "borrowed" oars, we paddled across. We almost made it when the cutter showed up. My dad beat the living crap out of me.

 

Well that saves a trip right there!! I got that idea for the cans on the side of the oil pan from my dirtbike, They have a kit to increase the fuel capacity of the bowl by adding two little cans to each side of the bowl, I searched around to find a picture but I can't find it all that comes up is bowl extensions that you need to drop the mainjet down. these just add capacity and everything else stays the same. I was going to put them on my dirtbike but now I can't find them rrr!! Might work for your chopper too if you run out of fuel in the bowl when you get on it hard!! We used to paddle a windsurf board without the sail 3 of us on it we would take it off shore and in the channel in the intercoastal waterway making everyone mad, When we came in from offshore people would be freaking out because it was like we came out of nowhere, people would be like do your parents know what you are doing, I am calling the beach patrol, We would run carrying that giant board it wasn't easy!!