The elusive 224/3.7 MerCruiser banger

This is NOT correct!
When cutting a rod journal down by .300" the center line of the rod journal is moved half of that, or .150". Therefore the max stroke to achieve with the 2.2" BBC journal is 4.05". A regrinder I talked with likes to use an 80% rule. So he would only want to offset grind to 80% of the .300", or .240" offset. I believe he could be persuaded to go to a 4" stroke. With a .030" overbore that would be 242 cubic inches.

 

I'm using a weaver three stage dry sump. The only thing you should be careful about with the dry sump is the when it loses pressure the oil goes in to the scavenge. So if you start the engine right away, well, there is no oil. Our answer to this is to put a momentary on the ignition so the engine will turn over go regain pressure then after a set amount of time it will fire up. I personally think the dry sump looks really cool on the engine so thats always another plus.

 

Beck- I shop at Summit Racing quite a bit since the main store is not that far from me. I had been watching a nice Mallory 4 cylinder distributor on the bargain rack for quite a while. It runs off of a coil, not a control box. Once the price got down to where I could afford it, I bought it. Should not be too difficult to mount. Will think about the dry sump. I am still trying to scrounge a belt drive for the distributor, may have to revise if I change the oil pump.

 

Well, does anyone know the stock oil pump flow in GPM?

 

Beck,
I didn't check your math the first time, but you have it right now.
I'm sure your crank guy has his reasons, but the percentage isn't as important as the actual margin for error. I have always been told that .020" is safe. Remember, there are undersize rod bearings for the BBC, too. If you're real brave, you could even go to SBC small bearing rod journals. Could be 1.970" at .030 under!

Now bore the aluminum right out of the cylinders and put in iron wet sleeves and you could have a real BIG 4 cylinder!

 

Why is everyone limiting the stroke to offset-grinding when "add-on"(welded) stroking has been available for YEARS?? As to inches : Weld in the 'deck-closer', bore to use 4.5" L.A. SLEEVE Wet sleeves(common BBC piston size) , then stroke to 4.25, & you have a 270" waiting for a Jon Kaase Head to make some REAL power. (now all I need is the 'cubic-money' to do this project!! LOL!!)

 

Would one weld the factory crank to stroke, or are other options available?

 

Welding the factory crank should be doable. If money were available, one could always check with LA Crankshaft, or SCAT. I have no info on either, but these would be places to start, & if not there, get info on where to go next, as I don't believe MerCruiser 'did' the cranks 'in-house'. If we can find the original vendor, possibly a 'custom' stroke might be available, as a rough 'blank' could have almost any number(within reason, LOL!!) ground on it.

 

You really piqued my interest when you said the 270 CID. Poor mans Offy! Relatively speaking.

 

With the 'right' parts the numbers are certainly there! The OFFY has always set the "Gold Standard" for American 4-cyl engines, at least as far as I'm concerned! (or maybe the "Holy Grail"?)

 

If you look back in this thread, my short block which has been mocked up (assembled w/o rings or final torque values), checked to work, but not yet final assembled or run, uses:
1.968 rod journal diameter, 6.657" length (5.4 mod motor rods)
&
4.40 dia Diamond pistons
to give 253ci

You only run the oil hole away from where it's supposed to be on destroking these cranks. You can tell that from looking at one and poking around, but I have emails from Randy from 5+ years ago confirming that.

When working with another engine family, I had my daily driver (and only insured car) offset ground to increase the stroke 10+% ...and put 50 or 60K miles on it (rust got to it, engine runs fine). You don't mess around with reliability where it gets to be -30*! Point being, offset grinding works.

Never worried about "straightening" or the like. I think that's bogus claims, or some guy getting rammy and not allowing heat to dissipate. And yeah $500-600 is what it takes- not far from being all day.

However, offset grinding cranks makes them "spindly" * thus very sensitive to harmonics. If I were going to rev the heck out of it (or install it in a plane or boat where it sat at 4200-5000 for 5-10 straight minutes) I would *Not* look at any offsetgrind.

This project of mine is going in a light car with a 5spd manual and a conservative driver. Probably will never run in competition.

 

HEI conversion tech guide.

I believe I have my HEI conversion completed on my stock distributor. I talked a little about it in post #1315 on page 44. I didn't figure any of this out. I gathered information to do this online. This takes a little time but it eliminates the points and condenser. The distributor needs to be removed from the motor for this conversion. A complete disassembly and cleanup will be required. I have listed part numbers for new parts. Recycled parts reduce your costs (GM ignition module and coil are easy to find). There are high performance options available for some of these parts at a higher cost.

I used a Chrysler reluctor and pickup. The reluctor (BWD RE2 $6 buy new) is from a V8. I carefully removed every other web. The base ID of the reluctor is slightly smaller than the distributor shaft lobe area which it needs to be pressed onto. I made a fixture to hold the reluctor in a lathe and bored it for a press fit. This fixture was just a piece of pipe chucked and turned to press into the big end of the reluctor. The webs of the reluctor need to be lined up with center of the point cams of the shaft when installing. The press fit is critical. Too loose and it won’t stay in place. BUT you don’t want it too tight either. I had to grab my reluctor with a pliers and turn it a little for proper alignment. If you damage a reluctor web it is junk. Some use locktight, others use JB Weld to hold this joint. I didn’t use either yet, but am considering JB Weld after I have it running.

The original base plate needs to be modified to mount the Chrysler pickup (BWD ME2A $27 my local recycle yard didn't have any) . Remove the points and condenser. Carefully mark the plate on the opposite side as the points were mounted. Drill and tap the plate as needed to mount the magnetic pickup. By mounting opposite of the points location the plate could be converted back to points if desired.

You need to think about the reassembly process to get everything assembled in the right order. After assembly set the reluctor to pickup gap at .008” using a brass feeler gauge.

I wired the pickup to a GM 4 pin module (BWD CBE4P $27). In hindsight I wish I would have used a 7 pin module (BWDCBE15 $55 easy find at salvage yard, vans are the easiest to remove from inside) . I found they handle more current. When using the 7 pin module there are 3 unused pins. The module needs to be mounted on an aluminum plate using heat transfer compound. There are wiring diagrams online. Be sure to wire a ground to the module and the pickup mounting plate.

Initially I had planned to use a Ford E-coil. I changed to a GM coil from a late 90’s truck. Both are easy salvage yard finds. The same coil is used on S/10, Tahoe, etc. The mounts are just different. These coils have a .5 ohm primary. May want to take a good ohm meter to the salvage yard to test. Get the wiring plugs and coil wire too!

The coil wire plug is different on these later style coils. For testing I gently removed the coil plug from the new coil wire and installed it onto my original coil wire. Later I plan to use a universal wire kit to make a new set.

Cut a window in an old distributor cap between the coil tower and a spark plug tower. Mount the base of the distributor in a vise. Wrap a copper wire around 4 spark plug bases and ground to your 12 V batter. Install spark plug wires. Connect the oil pump drive to a drill with a piece of rubber hose. After powering up the ignition, spin the distributor with the drill running in reverse. You should have spark at all 4 plugs. Use a timing light through the hole in the distributor cap check the phasing of the rotor. If it is off adjust the reluctor on the shaft until it is correct. I was lucky and mine was perfect. There is an advance in the distributor. Run it slow and full speed. You should see the phasing change a little. The rotor tip width is enough to allow it to align with and without advance.

When you need a new rotor and cap go to your local parts store and buy one for a 1973 Vega. I used a BWD C167 cap and a BWD D152 rotor from O’reilly’s. It was $17 for the pair. Do not use the caps with aluminum inner parts.

I need to research the spark plugs. I don’t know if the original plugs are the right application any more with more spark energy. The same plugs with a different gap is also a possibility.

In the future I would like to try building a distributorless ignition. I need to figure out an economical remote oil pump first.

 

Me and a buddy is building one of the chev 4 to put in a lightweight dragster. We got all the parts(1 off$) except for the roller cam and we hit a brick wall. after calling 28 different cam manufactures and grinders we found one that said they would build the cam. It's been 3 months now and no cam so I was looking for suggestions from you guys

 

We are having the same problem.

Can you get distributor drive gears to fit your application? That gear material needs to be changed to run a roller cam. Does your distributor gear look like ours? See page 44 post # 1313. Or is your gear the same as a small block? If yours is SBC, they are available.

A cam core can be cut from round stock. The stock is about $100. Machining the cam blank could be expensive. Then most cam grinders can handle the grinding (about $550). Very few cam grinders can put the distributor drive gear on a camshaft core. That leads to a distributorless ignition system, which leads to a remote oil pump, which requires a new or modified oil pan, which leads to $$$$.

The price quote I got was for $4300. That was for 4 cam blanks, with one of those finish ground into a cam. These had the cam gear machined onto them. I had to pass..

Would you share with us the name of the grinder you were using and their pricing?

Since you are in Claremore, go over and ask Hooley for some suggestions.

 

At least were not the only one with cam problems. We are going to run a crank trigger so all we need the dist for is to fill the hole and distribute the spark, I think that's how it goes. We got one quote for 4 cams one ground for 2000.00 a piece and you probably no how that went. Snyder is the one that is supposed to be grinding our cam(900.00$) that we haven't seen yet, Only been 3 months.
My old buddy Hooley was no help at all ask him long ago.

 

Ok. Several days worth of work have been successfully avoided whilst I fill my head w/Mercruiser info. Thanks all!

My questions are this: How wide and long are the oil pan dimensions?
What's the height from the oil pan seam to the top of the deck?
What's the height from the oil pan seam to the CL of the cam?

 

Most of the oil pan is 12.375" wide.
There is a bump out at the right front of the pan for the oil pump. That part is about 14.125" wide.
The pan is about 24.625" long.
From the oil pan mounting rail to the top of the block is about 10.35". (This does not include the head or pan height)
From the oil pan mount rail to the cam is about 6.75"
These measurements were taken with a ruler and are within 1/16".

If you are trying to fit this motor into someplace small it would work to put it in at a 45 deg angle. That would require a pan and oil pickup modification. A Ford V8 intake with one side cut and blanked off would be needed.

 

Thx Beck. My plans are still being formulated. These dimensions help a pile!

 

Piston dimensions & rod selection aside: How far could one conceivable DE-stroke the crankshaft before hitting oil passages & other bad things happening? I see some here have gone to 3.450". Is that the practical limit? Thx all!

 

Let me add this to the above: My potential use could get away w/1.900" rod bearings and still be good on the lower end.

 

Try Redline in Albany Oregon. They treated me very well and did good work quickly. A lot of shops here have them do their cams and cranks.

 

1) Turn the block upside down over waxed paper on a flat surface.
2) pour measured quantity of epoxy into the water jacket.

As heat transfer is important there it is probably best not to fill to much into it.
The main concern I have with epoxy is that it softens with heat, so use a high temp epoxy. As to the epoxy, it should be loaded with aluminum particles to more closely approximate the thermal characteristics of aluminum.

I do not trust a glue joint in tension. In the water jacket it would be in compression half of every strain cycle.

There would be an advantage in having the top of the block Aluminum.
It would machine well (Jb Weld machines well) and transfer heat well.
Attaching the aluminum is the problem as welding involves so much heat that it weakens aluminum. The only attaching process which does not involve much heat is soldering it with a tin solder, but that would not be a strong joint. I think I would
1. cut up some 3/8" aluminum plate to fill in the "C shaped" holes around the cylinders.
2 solder them in place.
3 pour hi temp epoxy in over the plate (from the bottom).
I'm trying to come up with a way to do it without welding to avoid what the welding would do to the block. (It is not a matter of wlding ability as I torch weld
aluminum and have a tig welder for that also)

"Hard Block" is basically a cement, and as such is of use only in compression. (That does not remove it from consideration)

 

Those little screws have very fine threads, go with something coarser to grab more aluminum.
How about a combination of:
1. going outside of the edge and using a bolt with its head on the inside? and
2. studs wherever the metal is thick enough.

 

Well, a few posts back I said I needed a distributor, since I had sold all of mine. Well, today a junk boat followed me home. It was probably a worlds record time for removing a 3.7 from a boat. From the time I backed it into my shop under the jib crane, until the time I pulled the boat out, it was less than 30 minutes, no kidding.

I only used these tools:
9/16" socket on an impact
Sawzall with a wood blade
And lastly a cutoff wheel on a DeWalt cordless grinder.

It was sad. First, I ran the lag screws out of the front motor mount. Then, I took the Sawzall and ran passes vertically on the transom from the top to the bottom, just outside of the Gimbal. I made a cut under the bottom to connect the two vertical cuts. I wrapped a strap completely around the oil pan and started to lift. When the control cables started to hang up, I cut them off lickty-split with the cordless grinder.

The engine and outdrive are fine, the hull is in rather sad shape. Sounds like I should work in a junk yard, but I now have a distributor. Next challenge is to decide how to dispose of the hull. Just thought you guys would enjoy this, a little off of the normal discussion.

 

I plugged the water jacket around the cylinders with molding clay (the kind that won't get hard) then pushed it down about half an inch. Then I coated the new channel with vaseline. I poured in fiberglass resin and before it dried I but some four inch long screws in it up side down. Just gently push on to the clay so they stay standing. Then I let the resin dry and pulled it out. I cut the screws so the didn't stab me and then I carefully traced it on paper. Make sure you measure the distances on the block and on the paper to make sure you are at least close. Then I took the sketch to a water jet shop and had it digitized and cut a little bit over size out of 3/8" aluminum. I ground it and hand fit the plate around the cylinders then once it was flush I used a round 1/4" dye grinder bit to create a welding groove between the block and the plate then between the aluminum cylinder supports and the plate. Then you just tig weld it and fill in the gap. After this we had the block resurfaced. Then you put in the dowel pins and put on the head gasket and trace the ports for the water. I will post a picture in a lil once I get home of the finished product. Heat did not affect anything with my block.

 

Here is my block. It looks pretty nice.

 

Very nicely done!

 

Thanks

 

I currently have my motor set up with a 350 turbo automatic transmission. My setup is for competition. A local engine builder said I can expect to loose up to 1000 rpm through my 4800 stahl 9" torque converter. That is not acceptable to me so I have again been looking at manual transmissions. Weight is also a big issue with me. There is a company that has reproduced the Saginaw 3 speed case in aluminum. I only need 1st and reverse gears, so everything else can be left out. The guy says he can make this into a "shorty" with the tail shaft housing removed. He expects the weight to be under 40 lb, without bellhousing and clutch. All this sounds good to me, BUT I really don't like the idea of cutting 5/8 from the back of the block. I cannot find a mill tall enough to do this.
Does anyone have an easy solution?

 

Beck,

I don't think you need a 'BIG' mill. A Bridgeport with enough spacer would work. How long is the block front to back.
I don't have a spacer on mine but have seen them up to 10" tall. I think that would allow you about 27".

Also, a horizontal boring mill would make quick work of that block. Pretty simple set up for a 'real' machinist. I'd try to find one that a guy could do as a 'government job'. (Case of beer after work)