The elusive 224/3.7 MerCruiser banger

One of the things I am going to make a cylinder girdle for the deck side of the block if that's what you are meaning.

 

Yep - good, I’ve seen them for Hondas and such; it seems like they would help this motor especially under boost.

 

I agree, it should help further this engines potential with forced induction and help take it to many levels above its current ability.

 

I already have a merc 170 that is locked up but I'm pretty sure I can free it up. However, I have the chance to get a running 165 mercruiser? Does anyone know if this is the same block that can use the 460 bbf head and has the chevy bell housing bolt pattern? I see most gaskets and parts swap with the 165/170/190 but I hadn't heard of the 165 in this forum post.

 

Unique122s ; If you pull-up "picture: Mercruiser 165" It would appear that it is an entirely different motor, starting with being a 6cyl......

 

There is also a Ford based one, I don't have manual out so can't tell if anything unique on it

 

The one 165 mercruiser I'm looking at is a 4 cyl 224 cid, firing order on tag reads1-3-4-2 . I would have know it wasn't the same block if it had been a 6 cyl. Kinda hard for a 460 head to fit on a 6 cyl block. When I look up gaskets for the 170/190 it also usually says 165 so that is why I was wondering where this 165 mercruiser fit into this elusive big bore 4 banger.

 

MY BAD!! There is a MerCruiser 165 "Banger" : it is a 2bbl version(as was the 170), where the 190 was a 4bbl(mine came with a Quadrajet), & the basic parts schematics show them being in the same family. The problem is that there also is a MerCruiser 165 - 6cyl shown when you pull up "pictures: MerCruiser 165"! I sometimes think MerCruiser just want to confuse us to the point that we just open our wallets & bend over!!!

 

LOL, totally agree with you there is so many different nomenclature for the same motor. Like my earlier posting stated I have a 170 aka 2bbl but if I could pick up a running 165 and I can still upgrade the head and fit a chevy tranny I think I'll just grab it. Guess I will have to take some measurements and see if I can get really cheap. After a few tweaks either 165 or 170 I doubt I'll know any difference anyway in that small volvo.

 

I don't go on hamb much. But I am working on putting a 78 470 in a 80 pontiac sunbird. Notching the oil pan tomorrow, so far using a tall throwout bearing with washers welded to it. Will add more detail later. Dreams are to break 10.50 on the quarter n/a with a kaase boss 9 head. Well heck gonna add details now. Get a extended pilot bearing, drill the crankshaft only 5/8" deep, and make sure you buy a roller it will last longer, so pilot is taken care of. The cheap ebay 460 driver side header cleared with some bashing. Look on ebay for the cheapest ones you'll see what I'm talking about. Now back to the clutch, I'm not 100 percent yet if my funny bearing will work, but with a big stack of washers welded on and the whole bearing on the saginaw's collar I see no issue. The flywheel, I have the early one, Google the 78 flywheel and then a 90's one, the later one has a big opening. Anyway, some local guy charged me $120 to drill and surface it. Gm 10.4" clutch with a 11.625 bolt circle puts it right on the edge. The flywheel also only goes on one way and has a crazy small tooth count like 137 teeth iirc. Thats all I can think of sharing right now. Also it's huge compared to the 2.5 tech4 that came out. I'll try to remember to share more and come back. But this thread got me motivated.

 

That's COOL!
This thread has been needing a shot in the arm for awhile. Keep it coming.

 

Notching the oil pan. Got to see the crank. It's a 78 and it's cast. Pretty big on the inside. H body gm cars have a center link that loves to get in the way. I expected it with a full sump oil pan, well 2 sump one in the back and front with a valley that connects. No windage tray either, and I will see some oil starvation on hard braking when all the oil goes to the front. So future holds blocking off the front sump building onto the rear one and a windage tray because the crank throws a lot I imagine. But the breaks suck anyway so hopefully I don't have too bad of oil starvation.

 

Pictures. It's a pita to upload them. Crappy and I apologize. Tomorrow I will have one where it's welded in and sitting perfect. Well we all know how that goes, we'll see.

 

I've been working on a pattern to cast a front cover that will use a dodge slant 6 water pump. They are aluminum and cost around $30, should fit well and be around the right volume for this size motor. The question I have anyone know for sure the correct coolant flow, most of the hoses were gone off the motor when I bought it. The original pump appears to pull water from the front of the intake and by the picture above into The front of the block. The design I am working on would be pulling coolant from the front of the block instead, not sure if that will be a problem? The stock head looks to have a water outlet added to the front, I have a aluminum aftermarket head I will use guess I will have to modify that as well

 

The intake definitely needs water. Mine will be set up in the same way my 2.5 was. Too complicated to explain but will allow for my heater core. There isn't much wrong with the water pump either. Just repair it as soon as it starts to leak. I honestly would just keep my in block system until I have to go electric.

 

You first need to confirm the direction of rotation for the Mercruiser water pump. This will help show the water flow path. Many applications other than automotive, such as industrial and marine, often have reverse rotation water pumps, so adapting an automotive water pump wont work on them. How is the Mercruiser pump driven? I don't see a drive belt in the pic above to turn the water pump, so it may not turn the same direction as a water pump in a car will.

 

It's a centrifugal pump so it pulls water in from the center and throws it out. The impeller has straight blades and turns cw.

 

Noe to CNC-Dude : The original MerCruiser waterpump is driven internally off the end of the camshaft : the alternator is part of the Harmonic assembly : originally there are no belts. When we add a pump, alternator, & Harmonic balancer(internally balanced[no balance weights]sbf fits) & add a pully to drive the accessories, if the motor is the std rotation, it all "works"! Just make sure you haven't picked up accessories for a "serpentine belt" motor, as some of them ARE reverse rotation.

 

I'm just signing in to say hi. It has been a wile for me. I have another project going that has halted my 3.7 for a while. I do hope to return to it in the not so distant future.

CNC-Dude, Do you have any ideas on making the front web stronger? I haven't run mine yet, so I am going off of hear-say. I am told that is where they tend to break under heavy load. From looking at the block, that does look pretty thin.

 

I'l take a look at it. Short of making a main girdle or main straps, those would be an economical plan A.

 

Is it possible to use a spacer to put a flywheel 5/8" further off the back of the engine rather than cut the block? You could make the OEM flexplate/flywheel super light by cutting out material as it would only act as a starting ring and you could use the original starter. That would make all other parts regular service parts and easily replaced/serviced if need be.

 

No. It would also move starter ring 5/8" further away from starter. It is possible to have a flywheel made 5/8" thicker that takes a chevy to ford pilot bearing in it for a Ford manual trans. If you cut the middle of the engine side you can get it down to 40# if you like.

 

I think he’s talking about basically two flywheels back to back, the inner one skeletonized to just a starter ring, the outer one interfacing with the clutch. In theory it should work; up-thread (this is from memory) there is described one of these engines in a modern rock-crawler (Suzuki?) and the extra flywheel weight was a plus to keep it from bogging so easily.

 

Yes this is what I was talking about. The starter "flywheel" would be nothing more than an independent starter ring leaving the other true flywheel to handle the tire spinning duties.

A 5/8" thicker flywheel would be heavy than a dead donkey!

 

I'm planning on trimming the back of the block on mine, project has been sidelined for a bit.The idea I have in mind is to cut the majority of the 5/8" with a sawzall or cut off wheel or whatever it takes to get close, then cleaning up the last bit with a v.s. router and carbide bit mounted on the flywheel while the crank is still in the block. this way the back of the block will be perfectly square to the crank.

 

I keep coming and going and watching and thinking about this thread since starting it more than 10 years ago. I really like the idea of a simple T-bucket with this engine. The other day I had a thought and it took me down this rabbit hole again.

The 3.7 Mercruiser bellhousing bolt pattern is nearly the same as the Gen-1 smallblock Chevy. The one roughly shaped like a barn roof. The 3.7 bellhousing mounting flange is 5/8" deeper than needed to use the GM bellhousing without modification to either the block or the bellhousing. The accepted modification is to trim the flange on the block. But what if that wasn't the only way to go? What if you couldn't find a shop that could trim the block? What if you don't want to cut the block and you do want to run a manual transmission? Specifically a T5 overdrive?

I think I may have come up with a no maching required way. Well, a no machining the block or modifying a bellhousing way. Now this is not a fully formed, fully vetted idea. This is in it's infancy.
To maybe do this, the following would be needed.

1.) Gen-1 pattern bellhousing with the common Muncie/Saginaw pattern. These are listed online as being 6.29" for depth with a 4-11/16" (119.1mm) diameter retainer hole. The retainer diameter is 4.685" (118.9mm). A small cover plate would need to be added to fill the starter hole on the bellhousing too.

2.) Ford '83-'93 5.0 V8 World Class T5. These have a 7.18" input shaft length, are 10 spline and have a 1.0625" diameter input shaft. The bearing retainer is 4.909" (124.7mm) in diameter.

Since the bellhousing is 6.29" deep and the 3.7 block is 0.625" deeper than required, we can treat the bellhousing as if it were 6.29" + 0.625" in total depth. So it's equal to being 6.915" deep. Now the input shaft of the '83-'95 Mustang 5.0 T5 is 7.18" in length. Taking the T5 input length and subtracting the 6.915" depth leaves a difference of 0.265" (6.75mm). A spacer will be needed to compensate for this difference.

At this point two things are needed. First, is the custom 0.265" (6.75mm) thick adapter plate that has both the Muncie/Saginaw pattern and the Ford T5 pattern. Now a 0.25" spacer may suffice. The difference being a scant 0.015" which may not matter. I would envision the adapter would bolt to the face of the T5 and then the the T5/adapter combo would bolt to the GM bellhousing. Second, the throwout bearing would be 0.625" from where the clutch fork should be due to the extra flange height of the 3.7 block so a 0.625" throwout bearing spacer would also be needed to ride between the throwout bearing and the clutch fork.

Why the '83-'93 Ford 5.0 T5 specifically? Simple. It is highly supported by the aftermarket and Ford built tons and tons and tons of cars with them. The biggest possible gripe is the rearward shifter placement. But that gripe is moot now. Modern Driveline released a forward mount tailhousing specifically for the Ford T5. Straight bolt on that uses any of the dozen or so Mustang aftermarket shifters. Moves it up just like it it is on the S10 T5's.

 

That's a hell of an idea. Hmmmmm.........

 

I've been thinking the same thing but using the water pump from a 1960 thru mid 70's Ford 200 CI six. Smaller profile and has only one outlet for heater hose. Or from early 2300 Pinto.

 

Pulling water from the front of the block WILL cause issues. Here is a diagram from Mercruiser for coolant flow. The intake does not need water flow if used in automotive applications. Imagine the intake connection going to lower rad outlet, port from head goes to upper rad outlet. You will need to install a thermostat in the upper hose somehow. If you will be modifying an aluminum head have it machined for a thermostat housing.

 

It's way too new for the HAMB, but I was looking at a BMW electric water pump the other day for this engine. Water flow on demand independent from engine rpm.