The elusive 224/3.7 MerCruiser banger

A front shot I took of Doug's engine. This is a mock up engine. Most of what you see is a one of a kind piece.

 

I have been slowly working on my motor. I have it down to the block with crank, rods, pistons, and cam still assembled. All of my bores have stains in the walls. #4 has a few small spots I can feel with my fingernails. So time to bore, right? Nope. It is already .030 over. Apparently there was a rod issue in the past. My rods are stamped as normal on disassembly. None are in order and I have two #2 rods. I inspected the bearings on the rods and mains. All look super except #1 rod bearing which has a few scratches. I didn't mike the crank.

My current plan is to take a chance. I am going to hone the cylinder walls and put on new rings. I will add some clearance to the piston skirts and open up the ring gaps. I need to machine new intake reliefs in the pistons too. That should be a real pain to figure out. My plans are to run without coolant, with boost on alcohol. This poor little motor is a ticking time bomb.

They make pistons that have reliefs cut for the stock head AND P51/ Super Cobra Jet. Does anyone have one to measure the relief location and depth?

Does anyone have a good running motor with a reground cam? I am looking for cam suggestions.

 

I intend to run a powerglide transmission. I don't have it yet but used a turbo 350 to mock up. Everyone is saying that there is a 5/8" bellhousing difference. When I measured my converter to flexplate distance I needed a .730" spacer. I did allow for the converter pulling forward .100". This was using the flexplate from post #1189 on page 40. I have those spacers cut. I still need to make a support for the center of the torque converter. I hope to cut the Mercrusier coupler and add a sleeve onto it, since it's OD is not big enough. Using that will give me the right bolt pattern, but could be a problem chucking in the lathe.

I don't know what I did wrong or if this combination just measures out differently.

I was told tonight by a knowledgeable source that the auto trans won't work for my application. He also wants me to put a LOT more boost to it. His tractor has a 3208 Cat V8 (640 cubes) converted to alcohol with 100+ psi boost.

 

They make a fuss about centering the oil pump. I just accepted it.
Sounds like the sleeves you will make would work.
It was just expedient to do what i did.

 

..........
The 5/8" is for a manual transmission* and its bellhousing.
from the specs I saw(and posted in this forum years ago) I think the automatic IS different.
Your measurements fit what I remember (a spacer being needed for the automatic). Don't mill your block .

* I used a Saginaw.

 

[QUOTE="beck,

Does anyone have a good running motor with a reground cam? I am looking for cam suggestions.[/QUOTE]

Redline Cams in Albany Oregon reground the Mercruiser cam for me. I was quite happy with their work. It was a very mild cam but that was better for me. That cam wore out so I put in a new cam close to the Mercruiser profile. I did not like it used more fuel and the engine knocked more easily.
Pay close attention to have the lobe centerline like Randy advised (115 degrees). I think I posted the cam cards here a couple years ago.

 

That reference was for a clutch pressure plate not a flexplate.

 

What is inside the water cooled exhaust manifold?


I removed the outer walls using a grinder and mill. A grinder with a cut off wheel roughs it in best. It weighed 41 lb when I started and is 20 lb now.
I wondered if it would work for a turbo manifold. The outlet is a little small but could be adapted.
There is a lot of rough casting around the ports and bolt bosses.
This looks pretty crude compared to the one in post # 1203 above and another that was posted some time back.

 

The other header is on page 4, post #113 from turboclubnorth.

 

Big block ford headers are easier cast iron If you want cast iron. I make mine up from steel tubing and they are still ok after 5 years (I keep high temp header "paint" on them).

 

Beck;

Had you ordered your starter off of Ebay yet? If so, please advise your thoughts on quality and fitment. I have been trying to source it on my end and not having much luck. Have spoken with Powermaster and they are drawing blanks also.

Craig

 

I purchased a starter from Quality Power. You can access them direct or through eBay. The price is the same, $260 including shipping.
I held the starter into position, but have not bolted it on. It looks correct.
Without engaging it, I am unsure of tooth engagement.
It looks like all the other high torque mini starters out there.

 

I had ordered a starter from Quality and the deal went as it should. This morning, I took the engine down off the shelf and installed the starter. I am pleased to see that the side of the starter it is not extending out past the bellhousing. I cranked the engine over and the flywheel engagement was good and it ran very quiet, possibly quieter than the stock unit. One thing I am not sure that I like is that the pinion drive only extends slightly past half way into the ring gear. Watching it spin, every time the engine came up on compression, the drive backed off a little. My concern, maybe unfounded, is that this could lead to a stripped pinion or premature drive failure.

My first thoughts are that I could cut maybe .100" off the crankshaft flange, this would give a much better tooth contact. The only other issue I have is the original unit was attached with through bolts. I am running a New England style bellhouse and through bolts are not possible. I may tap and stud the existing bosses or figure something else out.

 

My original starter was attached with bolts. My motor is tapped. I rebuilt the stock starter and cannot figure out how the bolts were inserted into the starter. I could not get them out.

 

My understanding is the (and this is from memory and may be wrong) International pickups with V8's from the 70's have starters that should bolt up without modification.

 

tjm73 is correct : check back in the thread ; they're noted.

 

I just found 2 NOS 3.7 timing covers, let me know if anyone needs them.

 

Dennis g : suggest using studs instead of bolts ; they will align the starter automatically, & the nuts & lock-washers will be much easier to install! My motor was already tapped & studded when I got it & that's how I know that it's easier to work with than trying to hold a heavy starter lined up while trying to insert a couple of bolts into a very tight location!

 

Good suggestion. Mine had studs so no issue at all as the new starter went right on.

 

stuck bolts can be removed in a press. penetrating oil may help

 

A few years ago someone posted photos of a 3.7 in a Dirt Late Model stock car engine that looked a lot like this one. Would anyone know what shop built it ?

 

I just took my intake manifold off and found it was quite loose and had caused mixture problems. The studs and nuts were safety wired so it could not come off, so the problem was that I made that gasket from 1/8" cork/rubber which sealed but compressed with use. Don't use cork for the intake manifold gasket without frequent re-torquing. Since writing the preceding, I made a much harder fiber gasket Mr gasket 77C material and got a huge cloud of white smoke out the exhaust. The 77C material is 1/16" thick and seems not to have sealed as my ford head is 24 thousandths narrower than the block.

 

Mercruiser used Ford heads. Ford drilled their intake manifold mounting holes at both 90 degrees to the flange surface and also some at roughly 45 degrees to that flange surface. The 45 degree holes are useless. Mercruiser supplemented the holes at the bottom of the manifold by having a row of holes on the block which also mount the intake manifold. Relative movement between the block and head will disrupt the sealing of the intake manifold and would push the intake manifold away from the head.

I wonder if a way to fix this difficult situation might be to drill holes for the "missing" studs a bit to one side of the angled studs. I tried this on an Allis Chalmers head and found the head far too thin for an extra threaded connecter.
Although cast iron heads are heavy, the metal can be quite thin.




So if any of you has solved this I'd like to hear about it.

 

I recently flow-tested the two water connections from my Mercruiser intake manifold to my Ford head. The front one has to make a very tight right angle turn to miss the distributor and therefore flows much less than the rear connection does. (I'd guess 75% less flow)
If you are making a single connection, make it at the rear. You have the option of going through the water jacket of the intake manifold from there if you want a heated manifold. This is even an option with a stock Mercruiser modified Ford head with its glued in water connection at the front.

 

Hey guys. So I just came across this thread while doing some research. Well I would like to share that I have one of the 3.7 engines with a BOSS 9 head by Jon Kaase. The engine has a 4.000 inch stroke with a 4.440 inch bore. We had the crank off set ground to use big block chevy 6.800 rods. We are planning on using two 52mm IDA EFI fuel injection bodies from CB Performance. We are expecting to get about 400 horsepower naturally aspirated. I am happy to share photos and answer any questions if you guys are interested.

 

oh, hell yes.
r

 

I just ordered a head like pictured in the 1203 post, a Trick Flow A460.
I had an email conversation with Charlie Evans, a noted BBF builder. Talking about the 3.7, he warns, "
The problem that I am told, is that pretty quickly they can make more power than the block can handle. So be advised."
I hope I am not going to put all of these pretty little pieces together into a motor and wind up with ugly, bent and broken pieces.

Any news from the rest of you Mercruiser 3.7 guys? It has been quiet here for a while.

 

OK. 2 new posts while I was typing mine...

Tell us more about the Boss 9 headed motor.
How did you get to a 4.440 bore. Whose sleeves?
What kind of cam? I am researching a solid roller. The post 1203 motor has one. It looks like the first one would cost about $1k. They would get cheaper after that if using the same grind.
I am not a Ford guy normally so I don't know if there is a width problem using the BBC rods. More information please. Maybe a photo too?

 

We too are researching a cam. The cam is currently at Crower getting cam doctored. There is no clearance issues with the 6.8 rods but of course you have to regrind the crank. We are currently having JE pistons make a set of custom pistons and they will be done in about two weeks. We designed our own sleeves and had advanced sleeves made for it. I will have pictures posted later. I just got my account so still figuring things out.

 

Just let me know if you guys want to see anything specific. Figured this would be a good little set of starting pictures