worn valve stem

Why would you want to cover a pretty engine like that? You are going to have a helmet on so just use ear plugs!

I like what I read all around, the first round should be pretty stout. The TW heads are an investment but should be least risk in terms of quality and performance, they are gonna run good with whatever cam profile you throw at them in either a stock 351 or stroked 302 setup.   Pcm pyramids may run into the valve covers with those heads due to the higher valve cover mounting surface- one set of mine did and one didn't – a little angle added to the manifold mounting surfaces or an extra gasket cures that with minimal pain.   Upside to the raised valve cover is that you should be able to fit the rockers under the stock height covers no problem, although the scorpions can be a little fat and may need a little relief on a corner or two.

I would think you could run a 75-95 hp bump on the 351w conservatively propping for 5100-5300.    I would just degree in the cam and run it straight up to start, perhaps adjust after if you feel you are either slower out of the hole than you think you should be or if you are running out of breath a bit too soon on the top.

Round two throw a single plane, roller cam, and some balancing at a 10.0 cr 331 and I would suspect you would drop just a bit of pitch on the prop and have full power band improvement of at least another 25+ hp. Depending on the weight drop and the prop design you might not even want to drop the pitch any – but I would still cam it for 5500-5600 and prop it for 6k for all round snap and sound. Not that you couldn't shoot higher if you were feeling randy.   

A used aluminum 1:1 pcm transmission would be a complete score on the weight reduction front if one happens to roll by - no experience with the 1:1 but the 1.23:1 has proven to be very reliable.   

Obviously exhaust manifolds other than pcm would save you a bunch of weight as well – possibly with the loss of a little performance as I do like the pcm manifold design for a stock manifold. The pcms sound better with some intake work if you feel like wearing a respirator for a few hours, Don't know if they are any faster after but they sound faster. Same advice if you find some commanders, which are wider but on a 302 block should be no wider than a set of pcms on a 351 block.   

Now you don't need this guys engine... however he doesn't really want to sell it with the transmission anyway -

https://miami.craigslist.org/pbc/bpo/d/jupiter-marine-engine-58-pcm/6804324314.html

Shortblock is in the basement..

Great friend with a mini-excavator made it a precision operation






Before i pull the trigger, what main and rod bearings would you men suggest?

at first glance, i see Sealed Power CP-Series Rod Bearings 83380CPA and Direct Replacement Series Main Bearings 5078M

This is odd, the #3 piston's extra dish is machined differently..

KENO wrote: GottaSki wrote: Oh my, I hadn't considered that it was incorrect from a repair long before i got it I'll take some closeup pictures, for posterity. Plus its fall, what else we going to discuss Remarkably little wear on the rocker, but it feels as if the original profile is slightly worn. May be a day or so Where are those pictures for posterity?

We know you know how to post pictures so "where are those pictures for posterity" so the world can see what your original problem was?

Tom,
With the valve stem issue and now the different piston, it looks like someone put that engine back together with Ken's left over parts!!

GottaSki wrote: Oh jeeze yes! Wish i could get better focus

And here I was hoping to see a picture of the "short" exhaust valve next to a normal one on the workbench or some explanation of what the problem was found to be.

After more pondering and estimating, Unless I stumble upon a fresh built 331 shortblock cheap, I suspect phase two becomes a bit steep to get to the 440# engine, without going to stock 3" stroke 302 which could be a little weak against a strong slalom tug . Expenses are shortblock and stroker kit, roller cam, lifters, pushrods, and proper distributer.

However, if one used a 351W oil pump on a 302 block, couldn’t one then keep the 351 distributor and its larger diameter hex drive??

Now I’ve been long pondering a third lightweight engine option. I’m not going to do on this to this boat, but hey, if someone wanted to do similar, why keep it to myself?

The scenario involved switching brands to the LSx platform, sometimes thats enough to dismiss it for some.

Now, a used, all-aluminum (except rotating mass and sleeves), 440# engine 290+hp seems could be had somewhat cheaply. (Plus add exhaust manifold weight - common to all options ) and be equivalent to a dieted, well Aluminized, 302 based sbf. At almost half the cost of a built up propr fresh bore 331 sbf.

Plus, upgrades are just a cam and springs away.

Here is the scenario.

1)     The LSx platform takes the chevy bellhousing pattern, minus one bolt not used. B/W bellhousings with top mount starter can be sourced used
2)     A $40 0.400” flywheel spacer returns the flywheel to its expected location
3)     Align, machine and tap the flywheel to accept the damper
4)     One would need a proper marine chevy starter
5)     Transmission mounts unaffected.
6)     An aluminum carbureted intake and standalone spark controller can be had for $700
7)     A 2003-2005 LM4 is an overlooked LSx style engine from a Trailblazer EXT or Envoy X, I’ve seen three on craigslist this week, entire vehicles for $600.
8)     The LM 4 is an aluminum block engine 5.3L with 3.62” stroke
9)     The LM4 has a peculiar cast pan, with a tunnel through it for a front axleshaft. However contrary to the LM7, it has a front sump, and likely advantageous for the engine tilt, though mid-sump would be best I suspect.
10)     Fresh main and rod bearings, just because.
11)     Engine mounts: if chevy small-block to LS, adapter plates are available cheep
12)     Engine mounts: if Ford Windsor to LS, consider the LS engine has engine mount holes very centered on the block much like the sbf, and not forward on the block like the typical chevy small block. This means the boat’s ford mounts cradle system is unaffected, and with some modest fabrication, one crates front mounts
13)     Thermostat system – I think a solution is out there - havn't looked
14)     Since intake valve lift and duration is only 191 degrees and 0.460”, A better but still truck-oriented camshaft reportedly wakes these engines up well beyond stock 290hp it appears, all else is there, heads, 9.5:1 compression. It does have smaller intake valves than the L33, but not prohibitively so.
15)     The LM4 does not have VVT like some later models of LS, reducing complications.
16)     Lift is limited to 0.500 but LS6 springs then permit .550 lift.
17)     Lastly, Exhaust manifolds.. Some options are starting to come down, the lowest price point of cast aluminum pyramid manifolds ive seen is from Marine Engine depot #612663 @ $1050. Hardin has some #620-32941 at $1300, and word on the street is that Crusader has a cast aluminum set for 900, but have yet to confirm parts list numbers
18)      Also, ive seen multiple sources suggest the LSx exhaust pattern is a carbon copy of the Ford Cleveland, that could open some options.


In the pursuit of a very lightweight engine for cheap, this could very well be a cool project for the hobbyist

Have you considered 393 kit or 408 would need some clearance ....I know Eagle and Scat kits were reasonable when i looked at it

similar but your making more power. . aluminum isnt the greatest option if your in a raw water situation to combat corrosion. sure you save some weight but xyz boat also designed around that weight now you change the handling some..

GottaSki wrote: Where the original excess valve clearance came from would be nice to find from there, seems it was just hammered into submission at least 23 of its 37 seasons or more.

Any chance that the pressed in rocker stud has pulled out a bit?

I think you wouldn't actually be disappointed in the pull of a stock 302 bottom end with those heads, an intake, and a roller cam.    I am a best a hack of a slalom skier so that might be where my experience falls apart but I ran my 83 Ski Nautique for a couple years with a 302/gt40ps/edelbrock performer/mild edelbrock flat tappet cam and it was a solid 47.3 mph boat . I also was running a lot of time weighted for wakeboarding at the time and that relatively mild 302 was better than a stock 351w in every way.

Worst case pitching down the the prop a half inch would stiffen up the pull at the expense of a few more rpm.

A junk yard bottom end (preferably with roller lifters ), some gaskets, and a craigslist intake is about all it would take to find out. If the experiment failed you could sell off the 302 shortblock and intake likely for what you paid.   

The ls engines are all pretty spectacular - might be a stainless header available that could be flipped upside down - add a bit of a downturn and weld a water box around them - take a little talent but maybe not so much money.

rosconole wrote: Some things I think that have been failed to be mentioned is 302 is 8.2 deck height , 351 is 9.2 or 9.5 . Changing motor mounts, dizzy,...among other things   I would agree if you can get a roller block and put get a cam would be the most bang for the buck.

No motor mount changes with the 302 vs 351 - distributor for sure as noted above -

The Two major Engine Bearing manufacturers in the USA are Clevite or Federal-Mogul/Sealed Power. Either one should serve your purpose.
Make sure your oil clearances are correct. Rods and Mains in a boat I would hope to stay between .002 and .0025. Larger clearance will cost you some oil pressure at idle.

GottaSki wrote: I see, so with competent heads, a smartly chosen roller cam could bridge much the gap in cubits. Good idea Joe, I'll would check a rocker stud, but, being an '82 or '81 casting, its the pedestal type head.

Can you get a RR roller cam for a 302 ???

I pulled a pressed in stud up on my original heads. They are not reliable. Screw in studs or at least pinning the press in type is the answer. Screw in require milling the bosses down and then tapping for the studs. Milling machine is best way. If you have to pay for all that work (not being able to do it yourself) then aftermarket aluminum heads may be a route to go. Performance and light weight

Could be 28 oz or 50 oz balance depending on year. Here is cost effective combo for poor mans stroker kit guys use;

Scat 3.850 crank , stock lenght 351w rods, stock type 302 pistons, early 351w heads.