The elusive 224/3.7 MerCruiser banger

Even when the crank and components are correctly balanced, an inline 4-cylinder also has an inherent imbalance that is generated by the difference in how the pistons accelerate and decelerate at the tiop and bottom of their travel. The bigger the engine, the higher the imbalance forces. A counter-roitating ballancer unit(an many 4-cyl engines have) can greatly reduce the intensity of the vibration. Careful tuned mounting isolation can do a lot to reduce perceived vibration. I always woundered what an old Indy car was like with a 270cid Offy spinning at 6,000+ RPM solidly attached to the chassis.

 

Steve,

If some or all of the magnets are missing Yes the summit balancer is a good idea.

I am assuming that you run a belt driven alternator.

Dick

 

Dick,

Yes it was on the boat when I bought. I pulled the balancer off because I thought the motor was vibrating to much. That's when I noticed that some of the magnets were gone. I removed the rest. Re-installed! It was better. That's when I thought that maybe the balancer needs to be rebalanced or replaced. I also felt because the SBF was mounted in an elastic rubber it might be more effective than something that to me is more like another fly wheel.

Your thoughts,

Thanks Steve

 

I have seen blocks filled with salt or sugar up to the level where the hardblock is wanted,and i have seen epoxy used instead of hardblock.
Let the hardblock get hard,or let the epoxy get hard and wash the salt or sugar out with hot water.

 

4's also shake because there is no overlap on the cylinder firing. You get one power pulse per revolution so the motor torques against the mounts and then gets to rebound the other way a good bit before the next cylinder fires. This is why they wobble around so much at idle. The higher the revs the less you notice it. I got to drive a dirt midget with a Chevy II 153 that was of course solidly bolted to the frame. There was no noticable vibration from the engine.

 

Dawford,

I think you have a good idea with the Buick 3.8 turbo set-up. I have one myself waiting for the appropriate project. Thanks for the kind words about the speedster. Maybe I'll finish one of these days.

Lakester

 

lakester,

I am also thinking that the Buick pull through turbo system can probably be upgraded with one of the new fast spooling turbos.

What I don't know about turbo engineering would fill a warehouse so I will probably get some help from someone who does know how to set it up.

First I have to finish installation of the carburated 470 in one of my projects to work out all of the teething problems that inevitably crop up in any new project.

I have tried to sift through the experiences of others in order to come up with a finished project that will be an example of my ability to combine proven technology with my own ingenuity.

There is nothing wrong with hot rods with small block Ford and Chevy engines but my goal was to create 4 cylinder push-rod engined sleepers.

The best way to achieve that goal is to use light weight vehicles.

I have chosen light vehicles that originally used 4 cylinder engines.

I also used relatively low cost vehicles that were early designs and that appealed to a broad spectrum of people.

It remains to be seen how successful I will be in my quest.

Anyway after getting 2 new knees I think that I will be able to progress more rapidly by next summer.

In the mean time I am still collecting parts for additional projects.

Dick
.

 

The rubber present should dampen resonances, but like vibrating (resonant) systems it is effective ( tuned) to a certain frequency by its weight.
My dampener has always been on my motor so I can't say what it is like running without it, but my motor does not shake around. I'm using chevrolet v6 engine mounts at the side of the motor.
Steve, there are two parts of your feeling vibration:
1. the vibration itself and
2. the transmission of the vibration to your boat's hull.

See if there is anything which allows vibration past your engine mounts:
1. check the integrity of every one of the mounts
2. see if anything solid contacts both the hull and the engine

 

What do you do for a charging system on these motors? In our boat the alternator is water cooled. I also wonder what was the reason Mercruiser went back to the tried and true Chevy II based 4 cylinder?

 

They have been replaced with after market alternator kits that are available on ebay by many of those who still use them in boats.

It is important to use Coast Guard approved alternators as they are fire suppressive in case gasoline fumes are present.

As far as the tried and true 4 cylinder Chevy not many people down grade their boats to the 2.5 of 3.0 chevy because of the alternator problems.

120 or 140 hp just doesn't cut it after having the more powerful 3.7.

Mercruiser sold 250 cu/in chevy six engines that were only 165 hp concurrently with the 120, 140 and 170 to 190 hp 3.7s.

The only reason Mercury Marine stopped making these engines was that they cost more than the Chevrolet V6 that replaced them.

The probable reason that the Mercury Marine engineers built them with the harmonic alternators and the internally driven water pumps in the first place is that they were used to designing outboard engines that were usually drained and flushed after each use.

The basic engine as used in a car is of a very sound design especially when converted to an aluminum head and when the water pump and alternator problems are properly addressed.

Dick

 

dawford,

You're ahead of me, I NEED two new knees and that impairs my productivity, or maybe it's just age that does it and I use the knees as an excuse. I highly recommend Corky Bell's book Maximum Boost as the bible on turbocharging. As I said most of my experience was 30+ years ago and all of it used stone age technology, but you can make good power using a draw-through set-up. It seems to me the Qjet Buick used would be good for this type application. I used a 390 cfm Holley on a 1.8L 4 and it worked pretty well. I was running much higher boost than you plan. I also think your plan is a better one for real world performance. I have been intrigued with the idea of the 3.7 Merc 4, but don't own one and really have never studied one at all. How difficult is it to adapt one to automotive use?

Lakester

 

You need to go back and reread the posts from the actual boat guys. Reread the part about having to retard the ign. These motors were unreliable dogs on the water. Better yet, go sign up on Iboats.com and surf around on that site.

 

randydupree,

You probably have the most experience of any here so I am wondering what you did about the timing chain tensioner.

All of the used ones that I have found in engines are either very worn or cracked.

After installing the timing chain i find that it is fairly tight.

A very successful race boat engine builder friend told me that the 460 Ford engines that he has built did not use any tensioner and that he thought that the 470 would run fine without any tensioner.

He said that when the power was reduced completely the only thing that would happen is that the timing would be retarded slightly but under power it would return to the prescribed advance.

What experience have you had in this regard?

Dick

 

Not sure if this well help but here are some links to free Shop Manuals for this engine.,

URL ., http://www.4shared.com/office/gh-PNxn3/Mercruiser_Service_Manual_8_19.html .,
and forum code., Mercruiser Service Manual #8 1985 to 1989 Merc Marine 4 cyl (Newer 470's).pdf .,

 

ray-jay,

The 470 engine in a boat is like the QuadraJet carburetor and a lot of other things.

For those who understood them they were great for those who didn't they were a nightmare.

On this forum there are those who always see the worst in things and those who see the best in things.

I like to see the best features of things and address the worst features if that is possible.

In the case of the 470 Mercruiser If I ever run one in a Boat I will use an aftermarket alternator and modify it to use an electric or external water pump.

Other than those two things they were high torque engines that were very efficient and reliable.

I have about 10 of them and other than a couple of them that were mistreated they are all easy rebuilds and at least 1/2 of them will be standard bore, rod and crank.

Some of the others are .010 to .030 over now and will require some machining to rebuild.

One of them had been rebuilt and whoever did the rebuild forgot to tighten the bolts on the oil pump plate.

The engine was then run until it threw a rod out through the side of the block.

When I dropped the pan I found 3 of the 4 bolts along with the torn up rod cap in the bottom of the pan.

I don't think that the 4th bolt was ever on the oil pump.

I suspect that the re-builder was probably a home mechanic that had had a few beers before he put the oil pump together and forgot to tighten the bolts and actually left one of them off completely.

Anyway I believe that even that one could be rebuilt after the hole in the side of of the block is welded up and the crank reground.

Dick

 

I converted mine with the helpful instructions on this website.

Randy posted the essential information on what machining must be done to the engine to fit a transmission, how to machine it to keep it from detonating and how to improve its water flow. etc.
Dick made good suggestions for the water pump and balancer.
Phil and "big chief" also provided ideas.
I designed my own engine mount brackets.
the rest bolted together.

 

i used an automotive generator to maintain a desirable [in my case] old appearance. You must use an appropriate regulator. An automotive alternator is quite good. You should get rid of the mercruiser regulator as there is no reason to use a regulator which has to be water cooled. They have one more thing to go wrong.

It is an excellent engine except that you should get rid of its alternator, regulator and water pump. They are not up to standard. An it helps to reduce the deck height unless you have a head with more turbulence.

 

I doubt that would work, but I don't know. Considering that it can cause cooling problems when used just in the lower portions oif the water jackets, I think there would be serious cooling issues if used at the top of the bores on anything other than maybe a drag race engine.

What a race engine builder would do is weld in reinforcement bridges or a complete solid deck. That would require machining the holes in the block straight and round again then installing sleeves with a bigger OD. At that point the limit will then be the second weakest part of the block.

 

The Mercury Marine Engineers probably know as well as anyone how to engineer high performance die-cast aluminum blocks considering their experience in creating some of the highest performance outboard engines in the world.

I just measured the cast in liners in one of my 470 blocks and found that while the total liner measures 6.5" the depth of the water jacket at the sides of the block measures 4.4".

That means that almost 1/3rd of the liner is completely enclosed with casting.

All 4 of the liners are Siamesed together in line front to back.

I cannot see how enough side force is generated to bend four .33" cast iron and aluminum Siamesed liners that are cast solid at the base, only protruding 4.4" above that base and clamped down with a head.

Those who wants to run one of these engines in a practical street car shouldn't worry at all about the water jacket design.

Those who want to run them in anything else should remember any engine will blow if pushed to far.

For street use I think that the more uniform cooling of this design is a benefit and not a weakness.

Dick

 

What you described is a common open deck design. It's hard to imagine the well anchored, tied-together bores flexing, but they definitely do. If starting from a clean sheet of paper it's not the best option. The decks are open because the block can be cast without the need for water jacket cores. If you look down from the top you will see everything tapers in toward the top(called draft). That is so the dies or patterns can easily be removed from the water jacket area in one large piece. The design is about economical manufacturing, not the best way to do the job.

Remember the ZR-1 Corvette engine Mercury built for GM? Those had a lot more problems than the average car engine. If Mercury engineers really are clever they were apparently snoozing on that project. The engine had an open deck block. Among the assorted problems with the engine was head sealing.

I have seen cases of head gasket problems on race engines where there was not an open deck, but just a 2" long water passage in the deck adjacent to the top of the cylinder. I'm not saying these can't work, obviously they can. What I am saying is that in cases where open deck blocks are reliable, real world experience shows they are closer to the edge than other comparable engines.

 

Buddy of mine has two of these engines. Anyone here wanta' buy'em?

 

I found this and the Chevy II thread because I wanted to see what kind of trouble there was in adapting an SBC head to the Chevy II block. Way too much trouble for a street engine and for street use the 153 or the 181 head will work great due to excellent vaporization at low rpm [ non-crossflow ]. Also the 153/181 use the std Chevy bellhousing and flywheel/flexplate. I love KISS.

The 3.7 does use a V8 head which was my original intent but it requires too much custom fab and too much $$$$ for my current energy level.

 

The fact that the Corvette LT5 engine was made by Mercury Marine and not by General Motors in house speaks volumes about their die-casting and building abilities.

I am also building a couple of Chevy 4s to put in Model A Fords.

They have the really good closed top cooling system of the old Chevy 6 cylinder cast iron engine.

The only advantage that I see in using them is that they are an easy fit and the Model A can easily be returned to the ford banger.

Otherwise the extra 85 hp the low end torque of the big bore Mercruiser and the weight savings are hard to beat for the extra cost of the $500.00 aluminum head.

Dick

 

Dick, you've begun a car factory.

 

Hi again from Sweden.

It have been a long time since I wrote here. My work on the car proceds but quite slow. I started to wondering and make plans for the injektion system.

I do have a question like always. Does anybody knows if the petrolpump on the mercruiser is from ford sb/bb, chevy sb/bb or mercruiser? The reson is that I am thinking of using the quite new mecanichal injektion pumps from Race pumps.


Johan

 

Johan, I don't know, but if you find out please let me know, I was thinking of doing the same thing

 

Hi again from Sweden.

I mailed "Race pumps"and asked in what stroke they messured their flow.

quote "The pump flows at .340" stroke the pump flows 450 GPH at 10,000 engine RPMs"

Then I messured the stroke on the mercruiser camshaft and it was 0,23" ruff messured. I think maybe the ford smallblock pump is the closest pump to use. Do anyone have a ford sb camshaft loose to messure the stroke for the pump I would be very happy.

Now I be of to the mountains with snowmobile and ice fishing for a few days.

Johan

 

It doesn't matter the lobe/stroke, it matters the length of arm, and "position in space" of the contact point of arm-to-lobe in relation to the mount flange, and of course the mount flange pattern itself.

 

I used a Chevy fuel pump block off plate on mine.

 

iadr // I know how it works, thats why I want to know the lobe/stroke of the camshaft to calculate if I can use a ford smallblock pump like I think is possible and maybe fit the pump arm in stock location on the camshaft with a new mounting flange.

When I look at pictures it looks like the ford pump have a longer arm. I also going to set up my engine for E85 and 30psi boost so I have to calculate if the pump can deliver the right amount of E85 i need.

Johan