The elusive 224/3.7 MerCruiser banger

I've replaced the alternator I added with a 12 volt generator. It was easy to mount inspite of being a big clumsy thing. But the important thing is that it looks old.

 

Doesnt the other side of the housing yhat stays on the toyota engine have a contour that promotes efficient pumping? Im wondering how well this pump will work attached to flat sheet aluminum. Maybe if you used a larger pump for a larger engine mighht move enough water. But man your working it.. better than I can say I havent even started...

 

I seriously hope you post video when the engine is fired.

 

I ran it 20 minutes last summer. don't have video knowhow but may improve

 

I used a 1/4" aluminum plate for strength and to maintain flatness. Many pumps have flat backplates this one did not come with that but lookng at how it is set up, the backplatewas probably flat as a straightedge clears the impeller by about 10/1000" the gasket adds another 30/1000 clearance.

This pump was larger than some I saw on larger engines [the Maxima] so I think it will be ok. Will change to a smaller pulley if it does not pump fast enough.
Or a larger radiator, now that there is room for one.

I spend a little time each day on it. That is how to get it done, do something each day. Tonight I will go down and repair my cracked steering wheel, just a 20 minute job but it is enough to know I did something.

At night before dozing off, I think of what I will do to it the next day. Often this means a detailed sketch, which helps greatly because even if I do it differently, I have at least thought it through once.

dennis

 

here are photos of my generator...it certainly is big compared to an alternator, but it looks old so if it can charge the battery after a start, that is enough. There is a regulator so you know it is real. Near the exhaust I ran the wires in aluminum tubing {conduit style}]. It is really just to make it look funky.

I ran it a few minutes tonight. Its motocraft carb seems better on the mixture than the Rochester 2 jet. It is still runs rich but then it was off of a Ford 289. This engine is 13% smaller, so it would run rich without rejetting. Its steering rack just peeks out from under the flat plate in the 2nd photo.

As you can see I made the radiator hoses by connecting short sections of preformed hoses with copper tubing.

 

What are we using for replacement Timing Chains and Cam bearings...are there any standard issue that are not Mercruiser parts. Ie Forsd or GM crossover parts

 

I believe the timming chains are Ford Parts but I'm not sure about that.

I have bought about 5 or 6 complete cam gear and chain sets used and have yet to find a set that looked worn.

The cam tensioner on several looked like I might want to replace them with new parts.

These engines are seldom high hour engines because they are usually in pleasure boats that are only occasionally used.

Most of the engines that become available come out of boats that have been junked because the hull is not worth fixing or the engine failed due to poor maintainance.

Usually the engine can be rebuilt and sometimes they just need refurbishing.

I recently purchased one that had 2 gallons of water and 5 gallons of wipped water and oil in the crankcase.

We pulled it down to find that everything was standard and in good shape.

I am putting new rings and bearings in it and giving the bores a light hone just to seat the rings.

I cut the water pump extension off of the cam and plug the hole in the front cover and install an external water pump anyway.

This eliminates the inherant weakness of the original Mercruiser design that caused the water to enter the crankcase in the first case.

I also install an aluminum 460 Ford head that eliminates the cast Iron Ford head that is also problematic in a car where the temprature can get higher that the thermostat temp. In a boat the lake is the radiator.

There aren't usually cam bearings in the Mercruiser blocks unless the original casting was out of spec. Those that had factory bearings inserted are as good as the ones that run the camshaft in the casting.

Mercruiser metallurgy is very good and I have yet to see a block that needed bearing inserts for the camshaft.

The "they sayer" and "I've heard" people have much to say about these engines, but except for their complaints about the 3 areas that required maintainance these engines are very high quality robust engines.

The alternator in the Harmonic balancer with a water cooled rectifier/regulator, the camshaft driven water pump seal failures and the cast Iron head on the aluminum block were areas that had to be maintained but they did give good service for those who read and followed the owners manual.

The only reason that Mercruiser stopped making these engines was that 4.2 Chevy V6 engines cost less that the cost to manufacture the 3.7.

That was probably due to the difference in volumn that GM manufactured over the relatively small number that Mercury Marine made them selves.

Being the only inboard engine Mercury Marine made themselves it had some of the outboard features incorperated into the design.

The desire to not have to have a belt driven water pump and alternator was probably a mistake.

The cast Iron head was not a problem as long as the thermostat was maintained and working properly.

When the cooling failed the water cooled voltage rectifier/regulator failed and the head gasket would fail.

The external alternator, water pump and the aluminum head resolve those problems.

Dick

 

hey Dock, I jusplagurized your last post to put on another board where the Merc 3.7 is getting bad mouthed...

 

encswsm,

These engines get bad mouthed all of the time.

Most of the bad mouthers either have had bad experience with them in boats because of poor maintainance or they simply don't know what they are talking about.

I like to correct the weaknesses and build on the strengths with my cars.

These engines are naturals for high torque light weight engines in light weight cars.

I try to use the Mercury Marine Engineers best features along with my own modifications to get reliable performance.

I am not trying to get 300 hp out of 224 cu/in.

If I wanted to get that kind of Hp I would turbo charge these engines.

The 8.8 to 1 compression ratio would lend itself to 6 to 10 lbs of boost and would still be pretty bullet proof.

I just don't need that kind of hp to have a practical Model A sleeper.

The 470 Mercruiser in a well modified Model A chassis with a stock looking Model A body will be extreemly fun to drive and should be reliable.

When I joined my Model A club and started receiving the bullitins I noticed that they often told of 5 to 10 cars going on a 50 mile run and returning with no breakdowns.

That is 250 to 500 miles of Model A travel without any problems.

I soon figured that if that was a red letter day for Model A Fords that I might want to make one that was more reliable.

At the same time I might as well make it perform like a modern car.

I won't ever be able to make one as quiet, safe or comfortable as a new car, but why would I want to.

I don't want to take all of the character away from one of my all time favorite cars.

At the same time I don't want to take a cross country trip and spend hours under the car instead of in it.

And I hate to be stuck in the slow lane on the freeway only to be almost sucked out of my lane by a truck passing me at 70 mph.

Dick
.

 

I think its funny how many people get their panties in a knot whenever someone tries to step oout of the traditional 350 chevy/turbo 350 mold... To each their own!!

 

Anyone put a Jon Kasse BOSS head on one yet.

Blind Elwood

 

I saw a Boss headed one at Jon Kaase's shop years ago. 150 MPH in a dragster.

 

I think that was in HOT ROD many year ago. My brother told me about it.

 

I ran my car yesterday. Its turbo muffler silences the engine very effectively so Dick, if you use that sort of muffler, sounding like a model A will not matter as there is almost no sound. I'd tried a long glasspack and all its only effect was to make it sound ratty compared to no muffler at all. In my barn, the glasspack was much too loud and the turbo muffler about right. Outside it is much quieter.
With the exhaust only a couple feet from me quietness ia a big asset. I have tinnitus and don't want to degrade my hearing by being near a loud exhaust. So I really need a quiet car.
The engine seems to be working well, no knocking yet and only slight wheel spin at half throttle. These narrow tires are going to be limiting but I have a set of extra wheels wide radial tires that don't look as "antique" but should have much more traction.
Randy Dupree's and Dick Carrier's advice helped a lot on deck height. Thanks guys, it worked as so far the engine is running on regular and not knocking in spite of its high compression ratio. [however I don't lug an engine or even load it very hard ].

 

Phil,
I'll dig up some photos of the dragster and post them here.

Steve

 

Awesome. I tried to contact you through your company about 2 years back, without success.
I have a total budgeted to do the Kaase head on mine. Should be even easier than an OE Boss because KAase moved the pushrod more vertical, so it doesn't interfere with teh lifter gallery wall.
Diamond pistons and Manley rods for a 5.4 Ford"mod motor" and an offset ground crank. Lunati very aggressive lobe 220/226 street/RV cam. All ready to go, just budgeting the head

 

After 70 miles my high compression engine simply doesn't knock and it is running on regular low octane pump gas[ ethyl alcohol free].

 

WOW, lots activity since I last visited ~2 years ago. I like your guys enthusiasm for these BIG 4 bangers, not appreciated so much in the boat world, other than Breezeworks. Read thread and you guys sound like very experience engine builders, nice job. I could use some advice. Sorry if long, want to provide enough info, and some deck height specs.

Long story short, 470 in my boat blew #4 piston from what appeared to be water intrusion from typical leaky exhaust/riser... Rebuilt, 0.030 over, head cleaned up, rebuilt, pressure tested and was told everything looked good. Got her together, coolant pressure check, and started right up, Yay. Had little bog/stumble on rev, played around with timing (no light), and thinking my carb rebuild had accel pump delay.. Let it run ~hr doing preliminary checks and decide to its time for water test.

Hit the water, everything going great, runs up to ~3K nice and strong, then ~3200 it starts popping, thinking timing, reach back and retard it a little, not much help, advance a little to see if makes diff, not really. Then I notice coolant overflow bubbling, head to ramp. Blown head gasket...

So thinking bad aftermarket gasket, I get a OEM merc gasket and following merc manual run up to temp and retorque. Pressure checks look good.. Head to the water and same thing.. So now what??? Pressurize cylinders and all 4 leak into coolant ~70 PSI.. Tear it down, and again no noticeable head gasket failure. THATS when I decided check deck and discovered cylinders are ~0.003" lower than deck perimeter.

Take boat up to machine shop and the guy kinda dumbfounded.. thinking there should be more than enough gasket crush.. the spec is actually 0.005, but not sure of thats across entire length or from deck to cylinder. Another boat mech said prob timing, that marine engine timing is more critical, and wasn't too concerned about the 0.003". I'm thinking ~20-30 minutes w/ advanced timing shouldn't blow a gasket, but he said it would do it everytme, and Merc has had several service bulletins regarding revising timing from 8° to 4° and lower compression with thicker head gasket due to poor fuel and blown pisons.. hmmm sounds familiar... Shoulda used a LIGHT, going back out and taking a look, timing mark showed as much as ~15-20° BTDC @ time of point separation, at which time the plug would fire. Gotta say, I'm still little skeptical its just timing, although I never had head gasket issue prior to rebuild and read someelse having similiar issue (0.002") had success 2nd time using OEM gasket and new head bolts. Seen some discussion of bolts up above.

Whats your opinion, TIMING or DECK? Or somehting else, HEAD BOLTS, Compression?

BTW, I noted some discussion regarding deck height.. Here's what I got from Merc manual.

deck height - 10.260" (10.255"-10.265")
Stroke - 3.750"
Rod - 6.605" (6.6035"-6.6065")

Speed Pro ZH535CP40
Compression height 1.752"
Volume +4.20 cc

Stroke/2 + Rod + Compression height = 10.232"
which is 0.023" under min deck height

Although my pistons look to be @ zero.

 

I'd deck it and get it perfect. There is not a lot of margin for poor sealing and yours has leaked since the last work on it.
As far as I can tell, Mercury never found the best deck height for this engine. Mine runs without knocking with tight deck height, however it is not loaded as heavily as a marine engine would normally be. In your case, as long as you have it apart to deck, it would cost little more to put in a set of deeply dished pistons. Then you could run enough more advance to get back some power and make less heat in the process.
Necked down bolts can be torqued enough to stretch and once in the stretch mode should seal better. They can only be used one time before they are thrown away. Fastener fatigue life is another consideration.
Studs have an advantage over bolts in the aluminum/steel surface is not rotating while being torqued,

 

hmm, thats what I thought. I'd really like to believe deck IS within 0.005" tolerance, throw new head gasket on, check timing with light and be DONE; even though I would prefer it to be flat, or even have cylinders 1-2 thou high, to ensure success. Really not looking forward to pulling it out again to get it decked as it should have been the first time. All the above happened ~ 2 years ago, got frustrated, got busy and just let it sit. Now I'm just looking to get this thing running reliably with minimal work and $$. Also little concerned that I may go through trouble and $$ of tearing down a newly rebuilt motor w less then 1hr total run time to re-deck, and still have issues.

Read someone else mentioning dished pistons, makes sense I guess, considering marine load. Might been nice if I started with dished replacements, but not looking to buy more new pistons. Beleive the stock flat-tops were ~8.8:1, doesn't sound too unreasonable. Read several +0.040 - +0.060 flat-top marine app rebuilds.

Thanks for your input..

 

I understand your frustration quite well.
When things seem hopeless it is easy to put a problem on hold.
Insight sometimes comes with time, but the problem does not go away.

The rebuild seems not to have been a success.
There are several solutions to that:
-Sink boat(to punish it) or
-Sell boat at a loss or
-Change motor type or
-Repair motor

 

It's been a wile, but as I remember my Lotus 907, which has drop in wet liners, called for the liners up .010. Lots of sealer around the outside water jackets. Small leak to the atmosphere isn't a big deal and can bu fixed with RTV. Leaks into the cylinder are less easy to live with.

 

Trust me, I considered option #1... just send it down the river and watch it drift away into the sunset as sit back drinking a beer enjoying the view, Or maybe anchor off and have some target practice .. I would pretty much have to donate non-running boat, no real direct replacements w/o changing alot of stuff ($$), so here I am trying to fix it, again, not happy, but hey, it happens. Just getting tired of wrenching, spent weekend under truck.

Is there any other inherent 'issues' with block that you know of that I should look for? Heard of cylinder wobble or head pedestals (head bolt threads) pulling up.

Rich, thats what I was thinking when I found out they were low, seemed high would be preferred, HP import shop in town machines theirs ~0.002 high. I'll probably request at least ~0.002 - 0.003.

Thinking, Just do it Get it running, take it out time or 2, sale, and spend time with kids (reason I've been little busy).

Thanks guys for input, I would love to see one of these in a car.. Any chance I might see one at the NSRA National Street Rod Nationals in Louisville,Ky.

 

The dreaded wet sleeve leak caused problems for me when antifreeze got in the oil, I think it made a jell that would not pump so no oil pressure. That engine I simply replaced ( the bearings survived). Will fix it later, one friend said sandblast it and then put jb weld in the ring land and then bore it so the o-ring will seal. It sounds odd but it just might work. I'll report back later [when I feel like fixing it].

 

Some have reported water leaks on the right side of the block where the block mating surface to the head is narrow. Mine is ok, no leaks perhaps due to using a mercruiser headgasket.

 

Driving my car some 400 miles has shown that the radiator that I used was much too small causing the temp to hover around 240 degrees. There is some saftey factor as it tends to stop running when that hot.
The problem was that a anything larger than a 64-65 mustang radiator is too wide to fit in an 18" body. So when you choose a body, get one with enough room for more than a tiny radiator.

 

You can try running pure glycol propylene. It has a very high boil point and uses a low pressure rad cap.

 

It also has a very poor conductivity. More importantly it does not micro-boil in use, which is how water/glycol coolants do much of their "work".

You know when you put water on to boil, the bottom of the pot starts to release little white bubbles? That's microboiling. If you watch, there are huge amounts of heat absorbed during that time, far more so than the difference between near boil and rolling boil. That pin-point absorbson is what you need, and what you loose with polyproplene.
The science suggests that using that stuff is one of the dumber ideas in automotives, and that any company pushing it could reasonably be brought up on charges...

 

It is not simple.
1. water conducts heat 26% to 57% better than a 50 50 water glycol mix
2. radiators work better at high temperatures
3. "water wetter" seems to work slightly 7% to 15% better than water
4. straight glycol would allow higher temps

5. pressure caps are a huge help in getting to high temps and radiating efficency

15 psi 250 degrees [plain water coolant]
17 psi 254
19 psi 258
21 psi 261
23 psi 264
25 psi 267
27 psi 270
29 psi 273

copper conducts better than aluminum
aluminum conducts better than brass
so the best one would be a copper cored radiator running water and a high pressure cap.

I have a sirocco radiator that i may use as it has good flow and lots of fins.

one other thing, the idea of flow rectrictors is false the only thing they did was lower waterpump pressure against the bottom of the pressure cap. With a flow restricting radiator, the waterpump would build up pressure against the cap. The solution was to get a radiator that flowed better.