The elusive 224/3.7 MerCruiser banger

How about taking new head studs/ bolts and cuttong the centers down to A smaller size leaving a shoulder on the bolt when you cut it to help with location?

 

You only require two dowels to locate the head, then all the head bolt shanks can run big clearance to the holes through the cylinder head.
These two dowels can be simple hollow sleeves, and fit around two of the head bolts.
They align the gasket and head during assembly, and stop any slight creepage with heat cycling.
Nothing fancy, and quite easy to do. Many engines already use hollow dowels as standard for the cylinder head, gearbox, and bellhousing bolts..

 

It is the most conservative way, and it is very easily done ( just duplicating the present bolts in a stud format). I think it is mandatory if using studs which exceed the minor diameter of the stock bolts.

The bolts being considered are Ford parts designed for a cast iron block. They may not be optimal for the expansion rates of the aluminum mercruiser engine. Single use necked down fasteners of a completely different(much smaller) diameter may work better as they would be stretched more strongly. The caution is that their use would have to be logged and they would then be discarded after a given number of fatigue cycles. Also, they would be installed only once and then discarded on any engine teardown.

 

My merc engine came with two hollow dowels in it aligning the head. They are adequate for alignment on assembly but I'd trust them for nothing more than that as they look so frail and they do not engage deeply.

And yes, there seems to be a lot of room around its headbolts. So they would not seem to contribute much to alignment. I wonder if this was to allow for sloppy manufacturing tolerances?

 

That, and to allow for the slightly different rates of expansion of head and cylinder block.

 

I always try to do what the experts do.

As far as I am concerned the Mercury Marine engineers knew what they were doing.

Consider the fact that these engines are ostensibly 1/2 of a 460 Ford V8.

Now double the 190 hp they produced in their QuadraJet configuration and you get 380 hp.

Thats not bad at all.

Then consider that many of them were installed large cabin cruisers two at a time.

An aquaintance of mine had a boat set up like this. He said that he would go deep sea fishing with it and run full throttle at 4800 rpm for 5 or 6 hours steady.

He never had any trouble and had over a thousand hours on the boat when he sold it.

Mercury engineers put head bolts in the engine that would not pull out of the aluminum block while at the same time secure the cast iron head well enough to insure good seal.

The head to block failures were usually caused by over heating that caused expansion problems or expansion problems that caused over heating problems.

This is the reasion that I suggest installing aluminum heads.

In their original configuration the 3" fresh water inter cooler was insufficient for warm water running. The 4" was much better.

If the coolant was changed occasionally and the thermostat watched they worked very well.

But at best the cast iron head on the aluminum block could be problematic.

Anyway the things I am doing are to take off all of the boat hardware, replacing the head, the exhaust manifold, the water pump, the flywheel, the harmonic ballancer and the alternator.

I will retain the carb and intake, he necessary bolts and gaskets and the front cover minus the waterpump and pump cover.

I have yet to read where the headbolts have been a problem except where the builders are going way beyond the bounds of reliability.

I would guess 300+ hp. Again that would equal 600 hp in a 460 V8s.

When people tune an engine for 600 hp they have to do a lot of things.

The good news is that even though the bottom end is a 2 bolt it has a stronger crank than most V8, and very large crank and rod bearings.

Getting even 300+ hp out of the bottom end should not cause any problems at all.

Dick

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Volkswagen had problems with the cylinder studs pulling out of their alloy crankcases. They had boosted the displacement of their 1200cc engine to 1600cc without changing much.

The studs in use at the time (on the 1600 engines) were heavy ones. Sometimes they broke, more commonly they pulled out. They solved that by reducing the diameter of the center of the bolt and leaving the end diameter unchanged. The new smaller studs stretched in service in the manner of a spring.
A side by side comparison of the studs shows a radically reduced diameter on the new studs. An alternative solution to pulled studs is increasing the diameter of the threaded ends, this is commonly done to most aircooled vw engines when rebuilding.
(Those VW cases are old now and have suffered from fatigue. It was designed as a low output, lightly built, easily replaced engine which was not expected to have a long service life.)

I do not know if any of the above applies to our mercruiser engines but designs are usually involve compromises.

If Mercruiser had used purposely designed studs for the 470 rather than Ford headbolts, the argument against their fasteners would seem weaker. The bolts may be fine in this application. If there is a history of them pulling out, breaking or possibly sealing poorly it would argue for improved fasteners.

We do know that the threaded parts of the Mercruiser blocks will wear as their bolts are turned. Thus a stud is superior to a bolt as it maintains a tight fit in the block. It is reasonable that the stud must duplicate the bolt's dimensions to be equivalent.
Without special knowledge we can only be guessing beyond this point.

I came cross a nice set of bolts and used them. If I had studs, I would have definately used them instead.

 

Hey Dick,
I take it that most 460 internal components would work? Like new improved Connecting rods and modern minimal skirt pistons. Im planning on rebuilding mine as modern as possible. Thanks

 

dennis g,

Years ago I built a VW 1756 I believe that I ran in a 69 VW bus. It went good untill I got from Cerritos, Ca. to Long View Wa.

I was passing a Cadillac on a grade when I looked in the rear view mirror to pull back into my lane and everything dissapeared in a cloud of smoke.

I had it towed to the local VW dealer who said that his mechanics were on strike.

When asked if he could recomend someone he said that there was a hippie who ran a vw shop but that he didn't recommend him.

It turned out that the Hippie knew more than the supposed VW speed shop mechanics that put the engine together for me.

He put in case savers in the new cases to insure that the top end and big bore dodn't pull the cases apart again.

The case savers were installed by drilling thru the original stud holes and thru the split case seam into the opposit case.

He then installed the case savers which were similar to helicoil thread inserts and extra long studs that reached from the head thru the case and into the opposite case.

That way the tension on the studs actually pulls the cases together instead of apart during the power pulses.

Anyway we don't have 2 cases to deal with but if the threads ever got worn they could be helicoiled.

The threads on the Mercruiser bolts are 1 1/2" long and because the bolt shaft is smaller than the threads they could go deeper into the hole in the block which is 2" deep.

Normally a bolt should be threaded 1 to 1 1/2 times its diameter deep.

In this case they extend 1 1/4" thru the aluminum heads that I have.

That's 2 1/2 times the thread diameter.

encswsm

If I gave anyone the impression that I am any athority on these engines, I'm sorry.

I am just sharing some of my thoughts based on information acquired on this forum and from the Mercruiser Service Manual.

The Ford pistons and rods work and some of the bearings but you should look at some of the other HAMBers for a list of the ford parts that work.

When I first got started collecting parts I bought some con rod bearings and when I tried them I found that they were just slightly too wide to fit the crank throw.

Others have suggested that they can be turned down to work but I will just use the Mercruiser parts for the rods.

Anyway we all learn together.

As stated before, I do not want to sacrifice reliability for power so I am staying conservative.

225 hp in such a light package is equal to 7.55 hp/lb in a 1700 lb car.

If you install a 550 lb engine in the same car you will need about 251 hp to get that same ratio.

That means that the 200 less lbs equal hp saved in the overall picture.

I don't know how much these modern dual overhead cam engines weigh when all of the peripherals, wires and computers are added but I doubt that lb for lb many of them can match the torque and hp of the 470 without sacreficing reliability.

And none can match the fun factor of surprising friends after they look at the simple appearing installation.

I also understand all of the technology of these engines because the technology is older than I am.

If I used one of the new engines and had injector, sensor, ignition or computer problems I would have to find someone willing to work on a hot rod.

Most dealers won't touch one of their engines when it has been installed in a hot rod.

Dick

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They certainly should work. While you are making it modern, it is worthwhile to weld an oxygen sensor bung in the exhaust manifold as a tuning aid for the carb. All you need is the oxygen sensor and a voltmeter reading from 0 to 1 volt.

 

I'm using the quick reply box, because that's what this is relative to some posts.

The Mercury engines probabaly didn't feel they had much choice but to use the head bolt size the heads were machined for already when they got them from Ford.

Rather than cut down any existing studs, I would use prepared studs in a smaller size coupled with a reducing insert in the block. I have an email from Time-sert. The studs I have in mind are from a Cummins diesel as used by Dodge truck. Granted those engines use a higher number of studs "per bore", but it proves they can handle stress, despite being much smaller.

As for the crank dimensions, the mains are 2.75 which is smaller than most all V8's except the SBC & 302/289 Ford. A 351W, for example uses 3", as do most all big blocks, if they don't use 3.25.
The main bearings are identical to a 351C excpet they have the tang in a different spot. If it was Cleveland bearings you tried, they are not so much wider, as just not sitting in the right spot when installed as is.

 

iadr,

If it is my post that you are referring to about the bearings, I tried 460 rod bearings and found that when I started tightening them down they locked up.

One reason that I think that the crank is strong is that the connecting rod throws only have to be 1/2 as wide as they are on a V8 yet the crank is just as long.

When you see a 470 crank you will notice that the counter weights are about twice as wide as they are on the V8.

This means that the crank is going to be considerably stiffer than most V8 cranks.

And certainly stiffer than the smaller displacement 4 cylinder engines.

The proof of their stiffness has been demonstrated by their durability in boats where they are run in Dyno pull type conditions for hours on end.

I have 3 used crankshafts that I bought that measure standard and look almost like new.

The mains are similar to a 351 Cleveland V8 but only have to contend with 4 cyinders, 5 mains and the very stiff crank.

Randy Dupree gurdled the bottom end on his but he was probably getting well over 500 hp to run the Maxton mile at 170 mph.

He said that the cast crank was preferable to the forged crank because it handled the vibrations better.

Mercruiser probably came to the same conclusion because only the first 470s produced had the forged cranks.

Dick

 

That sounds familiar, my crank locked up on tightening before I had the engine align honed. It was off only a tiny amount, but that was enough.

 

http://www.breezeworks.net/cgi-bin/...forum=1&searchSort=dateDESC&ReturnPage=Search

 

Hi group. I was looking at the engine and was wondering if anyone has cut the water pump drive shaft off of the camshaft . Then blanked the hole where it passes through the waterpump housing/timing chain cover then put the front cover of the water pump back on and use the existing nozzle to put water into the engine using a detached water pump the nozzle mounting plate has three holes arranged in a triangle that shouls let you clock the pump in at least six different positions... or how about re drilling the backing plate for the toyota pump to sit where the nozzle sits? Just wondering..

 

I cut the camshaft water pump extension and plugged the hole but didn't use the water pump cover.

By removing the pump cover you reduce the length of the engine by about 2 inches.

See page 24 of this thread, Post #464 and 467 to see how I am handling that.

Dick

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dennis g,

Back in your post #581 you mention welding a bung for an oxygen sensor into the exhaust manifold.

The Ford side dump manifold comes with holes for 4 oxygen sensors.

I think that since I am using the stock Mercruiser carb and Manifold I won't have to do much tuning of the fuel ratio.

But if I do what will I look for as far as a good reading ?

Dick

 

Between 0.3 and 0.7 volt. It is a sudden change and it happens over a very small mixture range.
Lean would be under .3 and too rich would be over .8
The voltage for a reasonable fuel/air mix hunts between .3 and .7
Both the.1 to .3 range and the .7 to .9 ranges are not too sensitive[within the range]

 

Although I'm using a stock manifold and carb. The mixture is off so far that smoke is on my car body near its exhaust.
I have opened the merc rochester carb its insides are nice, float level set the specified way, but it is way rich, even with #69 jets
I thought the power valve might be sticking, but it moves and looks ok. Bought other jets but have not yet tried them.
[ I also bought a plate adapter to use my autolite carb that I know to be good in case the Rochester is stubborn. ]
At present, I'm doing a suspension replacement on it so I'm wrapped up in that.

dennis

 

I haven't kept up to speed with this thread but noticed your last thread. I've got oodles of experience with these engines in boats, and thought you might want to know that if you use a "regular" thin fuel pump gasket instead of the Mercruiser approximately 1/4" - 5/16" thick gasket, the pump pressure becomes way too high and causes the float valve to blow off it's seat and essentially flood and dump gas. I've had customers change multiple carburetors only to be humbled by this info.

Cool engine, have fun with it.

 

Thanks Jason, that could be a "life saver" [for a carb at least].

I'm using an electric pump and a pressure regulator. I will set it lower before re-jetting. I'd much rather re-jet than get innovative with the float level. [I did on one Yamaha with an odd two throat carb that was a difficult for me to work on, so I changed the float level to lean it out...and it was very effective. Difficult to control, but it worked. As I said, I much prefer changing jets. If that fails to get it I'll change the powervalve. And if I still can't get it lean enough, I'll try another carb for a while.
Dennis

 

All this, is why I much prefer EFI on almost anything these days.

 

Factory EFI bought with motor is indeed good. Carb setups are also good and have the advantage of being much easier to setup from scratch. [I've never setup EFI from scratch but have some parts for a Lumina TBI as it is something that might work on a mercruiser. I'd think it would be easier to do for a boat than on a car because of the need for compensating for the varying loads in automotive operation. ]

 

Dennis, it is all vastly more simple than you probably realize.

Forget about trying to adapt an existing factory EFI system.
That is going about it the hard way.
Just buy an aftermarket fully tunable engine managemant system, hook up the sensors that come with it and follow the installation instructions. It will start and run very first attempt, and it will be much more drivable and better mannered than any carb.
No more flat spots, stumbles, bitchiness when cold, or excessive richness.

If you are on a limited budget, Megasquirt is what many people recommend. If you want the very best, I can recommend Autronic.

These systems have many advanced features that are not even possible with a carb, and with a lap top computer they are MUCH easier to tune.
No more spending money on jets, air bleeds, springs, pump cams, gaskets, floats, and all the rest. Once it is on the car, you can play around with the tune without having to keep buying extra small parts, and the engine will start and run much better hot, or stone cold.

 

Warpspead: I looked megasquirt up and found good information. But what would we do to get a distributor signal for the ECU? I know that an HEI distributor conversion is out of the question as it is far too big for the space available. Other Ford and GMC distributors were mentioned, but I don't know enough about them. Or would it need to be a crank signal system?

 

Dennis, there are two different ways to go about this.

Remove all the guts from a Mercruiser distributor, so you are left only with the body and main shaft. Then fit either an optical or magnetic pickup which is locked solid to the shaft. There is no advance/retard here, it must be locked solid.
It will require two output signals, one giving four output pulses per distributor shaft revolution (to fire each plug) usually set at around 60 BTDC and a second signal that gives only one output pulse per revolution to tell the computer which is number one plug, usually around true TDC number one cylinder.
But check the instruction manual for this.
These two digital signals will be used by the engine management unit to fire both the plugs and injectors, and to measure engine rpm.

The other way is to steal a whole intact distributor from another four cylinder EFI engine that already has all these features, and adapt the drive gear so it fits the Mercruiser block and cam dive gear.

Now this new "distributor" may not have a rotor button or distributor cap on top, just a very small body containing the electronic pickup bits. These are often called a CAS or Cam Angle Sensor, (not a distributor). And it will be quite small.

The engine management unit will then be able to drive four ignition coils, one per plug.

No more points, no more rubbing block, no more rotor button or distributor cap.
The ignition will be ultra reliable, require no constant "retiming" and will work very well.

The other sensors are a manifold pressure sensor, and two temperature sensors. One is water temp, the other inlet manifold air temperature. And that is ALL YOU NEED.

The computer will measure engine rpm and inlet manifold air density, and adjust spark and fuel, including full warm up and acceleration enrichment. It is all a lot simpler to install than many guys expect for what it does.

 

If I can ever afford to do it, what I would like would be to fit four fuel injectors and four throttle bodies right onto the cylinder head. That would give the absolute ultimate in throttle response fuel economy and drivability.

 

So then we'd run a coilpack with this injection system? Any special interface for it?

 

There are two basic choices with most EFI systems, depending on what features the engine management unit you end up buying actually has.
1/ Use a single ignition coil and associated igniter module, with a conventional rotor button and distributor cap. Many factory 1980's EFI cars were like this.
2/ Take four ignition outputs from the engine management unit, and drive four coil on plug ignition coils. Most current model factory cars now use this system.

When you initially program your engine management unit, you tell it how many cylinders are there, and how many ignition coils there are going to be. It will then provide the correct ignition outputs at the correct times to fire your plugs. This also works on strange engine configurations like V twins and radial aircraft engines with odd numbers of cylinders.
It is just a case of telling the ignition software what to do.

 

And my computer just suffered from a near death experience at my hands