CVZ-18 hull rebuild has begun!

[Plugcheck]

Yes, they probably do let some water in compared to not having them, but I figure it's a boat, you must allow water some way to get out.  It seems to always find a way in.  At TI meet, my boat filled with enough rain water that I'm sure the tank had some under it, but the channel let it all back out.

[Scott in nh]

I could end up changing my mind, but this is where my thinking currently is:

A self bailing Boston Whaler has an inner and outer hull.

Between them is filled with foam and there is no way for water to get in so there is no need to allow a way for water to get out.

That is how I want my floors to be, with the exception that the bilge area will have a pump rather than being self bailing.

Everything will be glassed in and cavities will be foamed.

[dorelse]

I could end up changing my mind, but this is where my thinking currently is:

A self bailing Boston Whaler has an inner and outer hull.

Between them is filled with foam and there is no way for water to get in so there is no need to allow a way for water to get out.

That is how I want my floors to be, with the exception that the bilge area will have a pump rather than being self bailing.

Everything will be glassed in and cavities will be foamed.

Boston Whaler's are all OB's if I'm not mistaken.

[thedeuceman]

I totally agree with the enclosed foamed space's being sealed, but if there's air space on anything I've done I always put a drain.
I see your point about not putting the access covers in until you may need them, I did plan that on my 1900 but chickened out at the end and put them in anyway.
Just my 2 cents


Sent from my iPhone using Tapatalk

[Plugcheck]

     Just an opinion, but boats, cars, aircraft, and all have flex to them.  Add to that many of us have dug countless pounds of wet foam out of the recesses of our beloved crafts tends to favor the pessimist in me.  Any compartment sealed up will eventually leak in time, but that's really just an opinion.  I hope your plan works well, it certainly has possibilities, maybe seal an electronic moisture sensor(s) in those sealed compartments and check their conductivity over time.   The stuff not seen is usually what creeps up to get us.

[Scott in nh]

I appreciate the discussion!

I'm no expert - mine is just an opinion too.

From the factory the foam got wet because the poorly located (too high) drain holes let water in and most but not all of the water out IF the bilge was dry, if not it soaked in water.

when the holes got plugged up, more water was trapped.

The holes they drilled as drains were not sealed and the wood structure soaked up water too.

The fiberglassing they did was not intended to waterproof compartments and didn't....

[Scott in nh]

Update: there isn't enough room under the floor for the rear tank fittings, they require the extra room provided by an access cover.

So I will install new front and rear access covers and I also put a drain hole in the rear bulkhead behind the tank.

I will put a drain plug in to prevent water from getting in, but allow a way out if required.

Both the areas to the left, right and in front of the gas tank are glassed in, sealed and foamed to prevent water intrusion and will not have drains.

I still have to cut/install the flooring over the gas tank and build up the motor mounts, but then I will be done with all of the structural repairs!

[Scott in nh]

Happy New Year everyone!

So I did not get much past my last post before work travel and the weather put the hold on hull work for the winter.

I do have the engine in the basement and want to finish getting that ready.

While there hasn't really been any project creep, the project itself has been more time and work than anticipated, so I have gotten to the point where I want to make sure the engine is as good as possible (within my budget constraints) before reinstalling.

I have heard this motor run briefly, but never operated it on the water.

Last summer I did a compression check and found 7 of the 8 cylinders to be great (140 - 150 psi).

Cylinder 8 was a little soft and seemed to be leaking down.

The motor had sat for 1 - 2 years and I do not know how much it ran before that, so I pickled it with Marvel mystery oil and let it sit for the last 6 months.

I have not redone the compression test, but am looking for opinions based on the possible outcome.

1) the compression comes inline with the other cylinders - should I consider it good to go and install/run it as is or?

2) still soft - I will probably do a leakdown test and my assumption is that it is likely getting past a valve.

If so do I:

     2a) Take both heads off and have them professionally rebuilt (~>$500?)?

     2b) Clean/inspect/hand lap valves/check valve guides reinstall (<$100 gaskets and supplies)?

     2c) buy reman iron heads (~$550)?

     2d) buy new GM Performance iron Vortec heads (~$350 heads, ~$150 for vortec intake manifold)?

     2e) other?

If I go the Vortec route, will my exhaust manifolds still fit? What about distributor and other accessories that go through or mount to the new manifold?

Should I pull the timing cover and inspect and or replace timing gears/chain?

Should I replace the water pump just because?

Should I replace all external gaskets just because (no current sign of leaks)?

[Plugcheck]

      Sitting at the crossroads of what choices to make for the engine.   Most of us have been there, budget is a restrictor, but I've learned that the CVZ is simply not as performance based of a hull as I had originally expected.   May be due to my hull prep, restoration work, or simply the base design.   Most folks get low to mid 50's with the 898 package, the CVX-18s get into the upper 50's with the 260.   My best so far was 64mph with a 388 ci SBC with Vortec top.   So this should give you a bit of info to help decide.  I actually may take the 260 from my Timi and put in the CVZ, and use the 388 in the Timi. It would probably take 500+ hp to push the CVZ into the 70's, takes a lot less to push a Timi there.   Now I assume you are considering the 898 which is a SBC 305.   Nothing wrong with a tear down and inspection, but I'd air up that low cylinder and determine what is causing the issue.  You can even just plug the air compressor to that hole just be aware it may want to push the piston to BDC.  Listen for air leakage, in the intake, exhaust, and crankcase(just listen at the oil fill).    You could also go back to the leak down test, and add some oil to the cylinder, if the readings pick up, then its the ring seal.  If not, likely a valve or head gasket.   A bit low on a leak down is really not too pressing an issue, you could likely run for years that way.
As for going Vortec, certainly possible, but somewhat money wasted on a 305.  Could probably find a decent running 5.7 Vortec engine and go down that road.   You could easily gain 100hp going that way.  Heck, Tim just sold his complete Merc 260 for $1000 I believe, and no one has shown up yet to get it, not sure if that deal fell through.  Good time of year to find boat/engine deals.   Bottom line, the 305 is a good motor, just don't expect stellar performance, if its broke, go another route.  If it were me, I'd either run it as is, or tear down and inspect/clean. A gasket set for SBC are common and inexpensive.  A valve job should not be that expensive for a set of stock heads, do some shopping.   

[Scott in nh]

Thanks Michael,

I should have pointed out that the boat came with a 350 engine, but had the 2 bbl carb/manifold from the original 305.

The "story" is that they bought the engine off a guy who was going with a BB for more power, but that it was good.

I put center rise exhaust manifolds on it (one of the logs was cracked) and an Edelbrock 4 bbl intake (but haven't purchased a carb yet).

[Scott in nh]

Assuming the testing described above shows a problem with the head, I am leaning toward either the cheapest - home cleanup and lapping of the valves, or toward the Vortec heads because of the low price from GM performance (which would mean I have a brand new Edelbrock intake for sale that has already been painted black).

If I go that far, I might go with a new Comp Cam marine cam and lifters too.

[Jason]

I agree with Mike, if the 305 runs good as is use it. If you have to put money and effort into it, especially a Vortec swap which is probably the best route, put your money into a 350.

[Scott in nh]

I agree with Mike, if the 305 runs good as is use it. If you have to put money and effort into it, especially a Vortec swap which is probably the best route, put your money into a 350.

Hi Jason, my bad, I should have noted right off that the engine in question is not the original and is a 350.

[Plugcheck]

      Yes, having an LT bottom end 350 does change the perspective a bit.  Converting to Vortec is worthwhile, but I believe it may be more an asset on a street engine using a camshaft that can take advantage of the Vortec heads higher flow characteristics.   Not saying its not a good swap, its what I run, and several others do as well, but the power output will be less than the same engine in street trim.   A mild shave, 3 angle valve job, electronic ignition, and a decent intake with 4 bbl should push that 350 into the 275-300 HP range in marine form which is technically the limit of the alpha drive anyways.  The CVZ hull will perform admirably with that level of power, and reliability and fuel economy will be acceptable unless your into the 4 bbl all the time.  I suppose what I'm driving at is that if your current heads are functional and rebuildable, and you have a LT 4bbl manifold then you would save a bunch going that route.  The vortec route, your dropping $800+ to make the conversion.  Or maybe you have a great line on Vortec heads I haven't heard about?  Summit has them for about $330.00ea  Got mine from the boneyard and had them worked, still cost about $500 before I was done.

[Scott in nh]

$314 each delivered is the cheapest price I have found for new Vortec heads (Amazon).

Rem LT heads (I am using your terminology and assume these are the std. port heads) are $399/pair and another $50 to upgrade to 2.02 x 1.60 valves (Aerohead Racing) - are the bigger valves worth it?

Looking for advise, but my assumption going into this topic was I would see where the air is going and (assuming it is a valve) fix the head myself.

If I find a crack or other reasons not to clean up these heads, going with the Aeroheads is the next cheapest solution - if I do, are the bigger valves worth it? Or would it be worth the extra $3-400 for the Vortec heads/manifold?

Is going up a notch in cam specs worth doing?

[Plugcheck]

       Do some sniffing around, you should be able to find a decent set of heads for SBC for cheap.  The larger valves(2.02) would be a waste since our engines just don't see the RPM a street engine would.  As for camshaft, you really can't go too radical in a marine application as too much overlap will suck water in from the wet exhaust.  A good RV/torque type camshafts seem to work best.   Unless the current cam is flat, I'd probably stick with it for now.  Most cams are stamped on the end, you never know till ya look, or get out the degree wheel and dial indicator and map it your self.  Engine building has always been a "sky is the limit" kinda deal, but with some research you'll find the engines with impressive figures don't seem to last long in marine applications.  If your stock heads are sound you can get them rebuilt in the $200.00 range, double that approximation if you need new guides.   Sounds like you know your way around an engine, pull them apart and look them over.   Keep everything organized.  You can always take them in in parts which is what I do, and I ask to get them back in parts. Saves a lot of labor when all they do is tank, inspect, and grind.   I like to lap and check, clean up flash, port match, set spring heights, etc.....

[DL-North]

New guy here, but have a lot of years working in engine development.

Hand lapping a valve is a waste of time, if you have a leaking valve. It won't remove enough material to make a seat round again.
Spend the money to have it ground.

Dan
and I'd probably not spend much time or money on a 305


 

[Plugcheck]

I don't lap to create a seal, only to check the margins. 

[Scott in nh]

So if the larger valves aren't worth it, is there any real advantage to port matching and seat blending the heads?

Looks like I will do another compression check this weekend. if it is better i will leave it be, if it leaks down I will strip down and investigate.

If the heads are repairable I will, if not I will replace them with remanufactured heads of the same specs.

Probably stay with the stock cam, but might go to this Comp Cam:

COMP Cams Comp Cams Xtreme Marine Hydraulic Flat Tappet Camshafts
Xtreme Marine Hydraulic Flat Tappet Camshaft
Chevy Small Block 262-400ci 1955-98
Lift: .447"/.462"
Duration: 256°/262°
Lobe Separation Angle: 112°
RPM Range: 1000-5000

I have an Edelbrock manifold and will likely go with an Edelbrock marine carb

I have the stock distributor, but will replace the points with Hot-Spark electronic module

I have added new center rise exhaust manifolds

If the heads come off I will also replace the timing cover/water pump/oil pan gaskets to avoid any leaks and allow for inspection (might do this anyway).

I don't want to spend a ton of money, but I have money to spend and I want a turn key reliable motor with good performance.

[carlsoncvx18]

I would check compression find out where the leak is , if there is one.

Running a stock motor should give you in the mid 50 range.

If it is the heads that are the problem and you want to spend a little more money vortec heads and the cam you mentioned is what I am running in my cvx 18. That cam is the same as the old 327 /350 hp cam. 

Been running that combo for 5 yrs with no problems other than outdrive issues which I have had plenty of.

Good luck