The elusive 224/3.7 MerCruiser banger

I think a car distributor from a junkyard would be all of it... and an adapting ring so the mounting diameters match.

It cranks on well now ( about like a 289 v8) so a turbo would do nice things. You need lots of combustion chamber turbulence and the heads you are using may do that for you. I'm using the stock Iron head and aside from its weight it is ok ( with a zero decked block) I get turbulence that way so it doesn't detonate.

 

I was just poking dawford for getting way OT

Actually, I wouldn't consider this motor a good candidate for a turbo due to the open deck block. The Chevy II 153 or the marine 181 would be a better bet probably.

Anyway, back to your dist. What rpm are you turning at your normal cruise speed ?? Often this is well under the rpm where the adv is all in resulting in a motor running with FAR less advance than it wants.

 

The problem is that your points plate is probably screwed to the dist body. Going to be hard to have a movable points plate unless they used an existing dizzy [ which would have been smart but sounds unlikely ]. I haven't kept up with modern ign control boxes. I wonder if you could get an MSD or other box that would help with some adv options ?

 

2000 rpm at 62mph advance is 33 degrees then 37 when it is all in at another 1000 rpm.

define "open deck block" I've changed the deck ht on mine and all that keeps the piston off the head is the head gasket. It is zero decked [.037 inch clearance].
dennis

 

problem was, that aluminum oxidation kept the two out of contact at times ended in many mysterious engine stoppages with hot engine. Now cleaned and screwed down tightly.
They used a chevrolet points distributor

ps I have a big old Ray jay turbocharger

 

that is why I suggested finding an appropriate old* 4 cylinder chevy distributor.

* an appropriate one which is probably old as these were made in the 70's.
[not an appropriately old one]

 

Open deck means the cylinders are free standing and not tied into the perimeter of the block. See the pic below.

 

Maybe you could see what other marine engine uses the same PN for a replacement dist then we could determine what pass car dist to look for.

 

Here are some interesting pictures from another forum.

These pictures are posted on page 4 of the Thread.

http://www.yellowbullet.com/forum/showthread.php?t=415635&page=4

Notice that this engine uses the Mercruiser 2 barrel intake.

ray-jay Randy Dupree ran over 12 to 1 compression ratio and never had head gasket problems on the cylinders.

He had water problems when he used Ford head gaskets instead of Mercruiser head gaskets but the water leak was in the area of the push rod gallery and it was solved by using the Mercruiser gasket.

I do not intend to use more than 6 to 9 lbs of boost if I use the Buick turbo and dished pistons at just over 8 to 1 compression.

The 3.0 Mercruiser is 43 ci/in less and doesn't have the cross flow head that the 3.7 mercruiser has and it is heavier to begin with.

It also has to run 9.5 to 1 compression to get 140 hp.

After turbo charging it I would probably not get the same Hp as I get with the 4 barrel carbed 3.7 unless it is boosted above good reliability.

There are several people using turbo chargers on the 3.7 but most of them are out for total performance.

I am looking for modestly good performance with good reliability.

Anyway check out the pictures.

The first 3 pictures are from another post but they are also interesting.

The second 3 are from the above posted site.

Dick
.

 

The 470 distributer a 153 chevy with a bushing pressed on the body so it fits the merc. block.
I made an adapter and used a V8 chevy distributer in one of my engines,it was way taller than the Merc. dist and the body of the V8 dist, was above the intake runner.
The dist. gear and oil pump drive fit right on the chevy dist.

I may still have that dist.
I will look..

 

Dawford, you are right, for a ghetto turbo setup you will be fine.

 

IT SEENS THAT ALL OF THOSE WHO SAY THAT THE MERCRUISER 470 BLOCK DESIGN IS FLAWED MIGHT NOT KNOW WHAT THEY ARE TALKING ABOUT.

Clint Neff runs this dragster quite well.

The 1,400-pound altered sports a replica 1923 Ford T body mounted on a 125-inch wheelbase 2001 chassis from Neil & Parks in Burlingame, Kan. The 254-inch four-cylinder engine is based on an aluminum block that a MerCruiser inboard boat engine in 1985.

David From who built the engine in 2010, used the block because its favorable 4.900 bore spacing accommodates the Ford E-460 Pro Stock aluminum head.

With a Comp Cams cam, Australian-made Motec fuel injection, and MSD ignition, the engine puts out 625 horsepower. It is sent through an Ace clutch and 2.98 low-gear Liberty transmission to a Strange 12-bolt drop-out rearend with a 5.86 gear. The launch RPM is 6,600-7,000, and the revs are 9,600 at the shifts and the finish line.

The best times for the car are 7.78 at 168 on an 8.41 index.

See below:

http://www.competitionplus.com/drag...and-his-little-racecar-looking-at-big-picture

Dick
.

 

They probably filled the block at the very least. That's common even on iron block motors used for high rpm drag racing.

 

I'm almost sure that they used Hardblock in that engine.

The beautiful part of using these engines in my light weight street cars is that I don't have to get 625 hp or 9500 rpm.

I'll be happy to get between 200 and 300 hp at 5000 to 6000 rpm in an engine that I can drive across the country at 1800 to 2200 rpm.

My ultimate goal is to drive to Hershey and a few other Eastern and Mid Western Show/Swap Meets from So. Cal..

Dick
.

 

What works in a dragster of race car doesn't necessarily work in the "real" world. Regardless of what some have done or gotten away with, open deck blocks trade strength and stiffness for ease of manufacture. That's just how it is. They tend to have sealing problems, especially when leaned on. There have been some decent open deck engines. The bottom of the bartrel is probably the 4-cyl Vega and the early 4.1L Cadillac V-8. At the other end of the scale, the Porsche 944 Turbo was a decent open deck engine. But....... it went through several generations of more and more expensive head gaskets to cure sealing issues. Increases in boost were limited by how long the engine needed to last between head gasket changes.

Even long water slots in the deck can limit head sealing. Race blocks for open deck engines normally have a closed/solid deck. There is a reason why industrial engines don't have open decks.

Not trying to dismiss anyone's opinion, just trying to keep things in perspective.

 

Can Hard block be put in a water jacket to fill just the top of it?

 

Randy's reference to the Chevy 153 {chevy 2} distributor is valuable. I just checked and they are available for a little over $30 [rebuilt]. It would probably pay for itself in reduced fuel consumption. There is very little room around the distributor but it looks as if can be rotated so the vacuum part is outward pointing away from the engine .

 

dennis,

I though about that some time ago and decided that I could be done by heating the block enough to match the temperature of melted paraffin (125 to 165 degrees).

Then by filling the void from the bottom up with melted paraffin using a funnel to avoid letting the paraffin touch the sides where the Hardblock has to bond with the aluminum.

I would leave the paraffin down 3/4' or so from the top and then pour in the Hardblock.

Paraffin dowels could then be set vertically onto the paraffin before it completely cooled to allow the paraffin to later be melted out.

The paraffin dowels are called sprues in lost wax casting.

I would put them every where that the head gasket has a water hole.

The Hardblock could be left down 1/2 to 1" down from the top to allow water to cool the head gasket seal.

If there was a concern about hot spots on the cylinder bore double sided tape could be used to hold half round or square paraffin sprues to the wall every so often to allow water contact to be more uniform.

After turning the block over and heating it to melt tie paraffin out the tape could be removed with a narrow chisel

I was also wondering if JB Weld couldn't be used in place of the Hardblock cement although it might not transfer the heat as well as the Hardblock.

It might bond better with the aluminum casting. A thin layer of JB top and bottom might seal the cement better.

All of this is unnecessary unless you intend to produce gigantic hp.

For a street machine or a real driver this would be overkill.

Dick
.

 

You could do it like the Honda guys with a plate.

 

By the time you count the cost of the points and condenser the price is even more attractive

 

Here's Sarge Nichols engine being run in on the Self Racing dyno , http://www.youtube.com/watch?v=fMkBqwY4b-w&feature=related

 

What kind of fly wheel fits the crank of the 470 mercruiser.

 

I have a boat with this engine runs great but I feel it vibrates too much a certain rpms. It has the original balancer with the magnets removed and an after market alternator..

My question is would a ford sb harmonic balancer help with this. Any suggestion.

Thanks Steve

 

dawford,
Thanks for the reply on the manifold,, I had found a complete motor on craigslist for 300 and thought it was out of my range,, should have snatched it up. I have moved on to more important things, ie, kitchen cabinets--need I say more? Thanks again, I will be watching this thread. Babyearl

 

While not the lightest option, if you are looking to make a lot of power from 4-cylinder and do it reliably the best option is milling one bank off a V-8 race block and capping things off as needed. Of course that requires a custom flat/180 degree crank, special cam, and suitable intake. My friend's race engine shop and done several with very good results.

 

Dawford,

You asked about the effect of boost on a vacuum advance distributor. From my experience, there is no effect. The vacuum can advances the timing when it sees vacuum, as the vacuum goes away the timing returns to the normal centifugal. On a turbo 4 banger I built 30 years ago, I never had problems with the vacuum advance. It was a draw through set up (I call them stone age) but it worked well sometimes and not so well others. When they're on, better tighten your seat belt. IF you can maintain a proper air/fuel ratio, 14.7 lbs of boost equals double the normally aspirated HP. Maintaining the air/fuel ratio is hard, especially with a draw through set-up, but that's what water injectors are for. Hope you guys have fun with them.

 

lakester47,

Thanks for the kind words earlier and I like your lakester.

I think that I will be using the early Buick pull through turbo with a Buick tuned QuadraJet.

They apparently maintained an acceptable air/fuel ratio in the 3.8 Buick V6 and were fairly reliable.

I am figuring that the Buick 3.8 is pretty close displacement wise to the Mercruiser 3.7 and that the GM engineers probably had it pretty close to optimized for a low boost pull through system.

You said that 14.7 lbs of boost equals double the normally aspirated hp.

I am thinking that about 7 lbs of boost would yield a sufficient boost while not adversely affecting the reliability of the engine using the Ford performance connecting rods.

I am not concerned about the valve train or bottom end as they are very robust anyway.

I Figure that the normally aspirated engine that I am building should produce 225 hp and with 7 lbs of boost I figure that it should produce over 300 hp.

Thanks for the information on the vacuum advance distributor.


boston#2,

Look for a zero balance Mustang flywheel. The ones that I have either came with zero balance or were the type that had the removable weights.

The early Mercruisers had long crank studs that went through the flywheel and through the engine coupler had usable ford flywheels that were drilled for a 10" clutch.

The later one could probably be used but they would have to be drilled for the pressure plate.

If you are going to use a T-5 or other manual transmission you will have to either have the crank drilled for a throw out bearing or you will have to have one made to install in the flywheel.


seacastle,

The Mercruiser harmonic balancer that is on there is heavier and better than the sbf balancer.

The best way to avoid the harmonic vibration is to not run your boat at that speed.

It's kind of like the guy who goes to the Doctor and asks what to do about the pain in his arm when he lifts it over his head. The Doctors says don't do that.

In a car if you want to cruse at a certain speed for a long time the problem can be avoided by shifting gears.

Four cylinder engines are inherently out of balance.

Most modern 4 cylinder engines over 2.5 liters have an additional balance shaft to make them balance.

The Chevy 2.5, 3.0 and the Mercury Marine 3.7 use heavy cranks and flywheels in an attempt to moderate the harmonic imbalances of the engines and large bearings to minimize the inherent stress on bearings that the vibrations cause.


Dick
.

 

I was going to use the merc alternator as a balancer but the magnets started falling out. So I used an aftermarket harmonic balancer[like Dick's] instead, and it had a pretty set of degree marks to time the engine.
It works, I'd not call the engine exceptionally smooth, but vibration is not a problem with it.

 

While we say zero balance sbf a Ford 250 six has the same crank pattern and ring gear and is zero balance.

 

Thanks for all the info. I understand the big fours vibrate, however I'm wondering if the merc balancer is "out of balanced" because the magnets fell out. You can see it was originally drilled out to balance. I assuming that was done after the magnets were installed. I just want to eliminate that the balancer isn't making things worst. Summit Racing has one for $76. Does anyone know of a less expensive part?

Steve