The elusive 224/3.7 MerCruiser banger

I had 3 four bolt main Cleveland blocks at one time. I bet those caps would fit the 3.7. Wished I'd kept them now!

 

Bruce, My bearing were replaced in 06 by the date on the back of them. They had to be Merc bearings as all the tangs were in the right places. All mine were full groove bearing. The Cleveland bearings are haft groove, so more support on the lower haft. There are Cleveland bearings available that are full groove, if you want them. The advantage of full groove is you send oil to the rod bearing full time. Haft grooves send oil to the rod bearing only when the crank hole comes to it. Rather then buy the more expensive Merc bearings, I cut the 4 caps for the Cleveland bearings. The thrust cap has the tang in the right place.
If you were to buy two sets of Cleveland bearings, you use only the top hafts in both the upper and lower. No need to cut the caps then.
Hope that makes sense.

 

The fixture for narrowing or chamfering the bearings is just a scrap piece of alum that I bore in the lathe to what the rod housing size is, Squared off so the bearing sits square. The first ones I made just had a window for the tang to stick in, but was to hard to get them back out. So I cut the slot to slide the first bearing in then the other one. I also cut hack saw slots around it and have a hose clamp to hold it all tight when cutting. Works great! In my case I narrowed the bearing .040 to get them out of the radius of the crank.

I forgot to add my crank is a cast crank. I did not lighten it as I had planned, just going to run it as it is. I will rebalance it, as moving the stroke should have affected the balance. It was $200 to have it stroked.

 

CNC, I will pull some Cleveland caps out and see how the compare, but as I remember they were not the same.

 

Ok, thanks for the leg work. Then others that are curious may get to know as well!

 

CNC,
It looks like Cleveland caps will fit. But the Merc caps are taller at the bolts by .250. Plenty of beef in the block to drill for the outer 3/8 bolts the Cleveland cap uses. Of course the rear cap can not be used unless you want to make up a new rear seal system. Also a line bore will be needed too.
Some one asked about main studs, I don't have any Cleveland studs on hand and I can tell you that if using the Cleveland caps 351W main studs will work. If using the stock Merc caps, 351W long head studs will work as main studs just fine.

 

Dennis,
I think I get it but,
If you were to use 2 sets of Cleveland bearings, wouldn't you wind up with a full grooved assembly?
Same as a Mercruiser bearing.
I see the value of having the plain shell on the bottom half, so adding a second notch to the cap makes sense.
If you can live with a fully grooved bearing it makes more sense to use the ones made for the Mercruiser.
Here is what I found:

The Clevite MS1741P is fully grooved and is made for the Merc, Pricing at Summit - $57.99
Clevite MS101P is the half grooved Ford Cleveland bearing - $97.99
These are comparable to each other.

Does the perception that the Merc bearings are more expensive come from buying them from Mercury?

However, there are many more choices for Cleveland bearings.

I'm sure that someone has poured over the bearing specs and not found any other bearing that would fit directly and provide the 1/2 groove, but maybe.............................

 

Yes if using two upper sets of Clevelands you would end up with the same full groove as Mercury bearings. My bearings are Clevite MS1010P. I believe Federal Mogul has 3/4 groove bearings with you want a little more oiling to the rods.
As a side note the Cleveland caps are cut from the factory with both tangs locations.
Big Block chevy bearings are a close fit for the mains, but of course the thrust does not work.

 

Thanks for the pics of the main caps. I am thinking of making some torque/honing plates for this engine. Anyone here use one yet or been thinking about it?

 

In the passed I just used a 460 torque plate on the Merc blocks.

 

Yeah, I knew they would work but didn't know how available they were to people. I know some guys are using aluminum heads, and then comes the debate of whether they prefer an aluminum plate or the traditional heavy steel plate if they are using an aluminum head.

 

I was always told the plate should match the head used. I have used both on the same V8 block, one on each side once and really couldn't pick up a difference with a bore gage.

 

Yeah, its 6 of one, half a dozen of the other. On a 4 bolt per cylinder engine I have seen little if any difference. Aluminum is definitely easier to make and easier to carry around.

 

It has been posted about abnormalities in the casting of our motors. I am seeing the same thing here. I had to do some piston modification to my motor and noticed the cylinder wall of my motor is way out of whack.

Look at the difference in the thickness of the steel sleeve between the top and bottom. There isn’t much left at the top. This motor is bored .060” over.

 

Beck,
This won't help your situation, but hopefully it will help some of the other guys, especially those that are boring the original sleeves completely out.

I developed a CAD drawing so that we can have plates cut by Laser, Water Jet or some other means. Since the blocks are not consistent I worked from the two engines I have here and made the drawing so that the part can be modified to fit at assembly.
This is a very basic plate that can be used to locate a boring bar or modified to reinforce the existing barrels. To use it as designed, it does require machining a recess in the block. This can be done a Bridgeport with a bit of fooling around. I suppose it could be modified to fit around the bolt bosses, but it might be better to make a dedicated plate. This block has a split cylinder and barrel, so those will eventually be machined completely away.



This is not my original idea. I combined what @beck did with what @Chris Nichols did.

I got a quote from a Laser shop, but when I asked him to quote me a price for 3/8" material instead of 1/4", the price was 50% higher. When I asked if I could supply the material, he 'No Quoted' me. Too bad because I have enough of that to make 15 or 20 plates.

This plate is simple enough that I can make it on my mill. I just wish my DRO was a bit more reliable. Since this is a long term project for me, I will keep trying to find someone to cut the plates at a more reasonable cost.

I will try to make a drawing for a plate more like the Honda guys use. It's not that hard, but time consuming for a guy that doesn't have a good handle on CAD

 

Use a different cutting shop if they act that way. One near me suggested ways to reduce the cost and buying my own material was one of his suggested options. His charge for aluminum was not unreasonable.
For that kind of cutting they need to work from a vector file. A DWG file is one example of a vector file a DXF file is another vector file. the problem when working from raster files (pdf, tiff, jpeg and more ) is that they are pixilated. magnify them and you can see that at high magnification. When they are converted to vector files they often become double lines which causes confusion in the laser cutting equipment so it stops cutting a line and cuts a circle. The local cutter took the time to show this to me and he did not charge me for the half hour he spent on me.

 

Beck, You do have plenty of aluminum and the other cylinder there for support. The only problem would be if it gets thinner as it goes down and the cast iron starts peeling. Should be a good block for sleeving. If seen before boring that cylinder could of been offset a bit to keep some thickness there.

 

Bruce, I like your plate idea and was looking at something similar. I only have the one block so I can't play with it. I ordered pistons for it today, when they get here I can get on with getting mine assembled.

 

GM Coolant Suppliment part # 3634621 was used in the Northstar engines before the coolant leak problem was elimiated by changing the headbolt design ( changed from fine to coarse thread and ?). The suppliment is supposed to be Bar Leaks gold. two pellets per gallon of coolant were used but there are conflicting reports on this in the caddy forums. This may help our engines seal.

 

Dennis,
The drawing I posted is a DWG file. I had to scan it and make it a JPG to post it here. I also have it in DXF but the Laser guy couldn't open that one.

Once I get a plate made, I will take it to an Automotive Machine Shop to get an opinion as to whether to install the plate and then bore it for sleeves all at once. Or, bore the existing sleeves out and then install the plate for final sleeving. The Bridgeport has a maximum quill travel of 5" and the cylinders are 6 1/2" long. It can be done by boring to the maximum depth and then raising the table the extra 1 1/2". You can raise the table after every pass of the boring bar or bore the first 5" all the way out and then raise the table and repeat the process. Either way, it is a lot of extra work.

This block will be wet sleeved, but if it wasn't cracked, I would attempt to leave the aluminum barrels in place. I love this stuff.

 

Bruce,
I know what a JPG is but after that I have no clue! I'm a manual Bridgeport guy! But I do have a friend with Plasma and access to water jet stuff, he would know. I have boring bars here and won't try to do boring on the Bridgeport, but it does have that DRO to keep things right.
As for the plate, I think I would install the plate then bore for sleeves. Is your block cracked like Dennis G's? Crack running down the bore? How big do you plan to bore it? If not going to a 4.600 bore I think I would offset bore it in your Bridgeport to expose the aluminum, weld it up, install the plate then bore it for regular sleeves.
If you cut everything out for say for a Darton wet sleeve, then put the plate on, that's a lot of air to cut to get the top in inline with the bottom. I was never a fan of a Darton sleeve even though I have put in a few in Honda's. I was always afraid of the seal at the bottom. Which brings me to another point, how much do these blocks move around under load? How much do they move with heat expansion?
I mocked up my timing chain yesterday, none of my chains were very tight. I know there are under size chains available, but was that chain tensioner in there to take up heat expansion? I know the head will swell .007 or so from hot to cold on the valve leash. My aluminum rods will grow .001 to .0015 bearing clearance when hot. How much does the Mercruiser block grow?
My engine will be going in a street car and will need to be able to cruise for at least 40 to 100 miles at a time.

 

Rodeck and Donovan aluminum blocks need .005" additional deck clearance, not sure if the die cast Merc block has the same expansion rate or not. Also aluminum rods need .010" more deck clearance than a steel rod.

 

I have not dealt with this company but it sounds like they have some good parts for us. There in Canada so I don't know what their pricing will look like to us.
https://www.propowerengines.ca/contacts.htm
Here is a comment that Dave from there put on another site; "We sell a true roller timing set that does not need the tensioner. it was not a hard part to come up with but our shop does maybe 20-30 of these little gems every year and replacement parts were getting impossible to get. Cams and timing sets and selected other things we have developed over the years make building these engine simple and more reliable."
From the appearance of their site it looks like they do some high performance work there, so may be just what we need.

 

Lots of things to consider. Dennis, I think you are right about installing the plate first and then boring the sleeves out. hadn't thought about welding the crack in the aluminum barrel. It is pretty wide and extends down the cylinder about half way.

It has been over 40 years since I sleeved a block, so I'm not up to speed on what all the latest equipment can do. I planned to remove the aluminum barrel completely, leaving the iron exposed to the water. Sealing at the top and bottom will be critical. The final bore will probably be 4 1/2". With a sleeve of 1/8" wall gives a bore in the block of 4 3/4". I think that in this case the plate should be welded in the block.

 

Two sets of Cleveland bearings would indeed yield one set of Mercruiser bearings.
I just use Mercruiser bearings.

 

A narrow o ring at the bottom is usual for a wet sleeve so is corrosion if plain water is used rather than an antifreeze mix. With an o ring at the bottom, the top end of the wet sleeve in my Allis Chalmers engine fits into its deck. In a Mercruiser, the metal at the base of the cylinder would be the total support against the force of the head on the cylinder. Chris did it, it works.
(I used an Allis Chalmers engine before changing to the far superior Mercruiser)

Welding distorts metal so it is critical to bore after welding.
Welding the cylinder involves several problems:
- weld the thin cast iron and there is potential for the aluminum of the cylinder to become a useless little puddle down somewhere else.
- the limited access in there makes welding difficult
- There is so little metal to work with
one good thing though, you could fill it with Argon and work in that.
I'd avoid it, it is much easier to find a different block than to fix a broken one.

 

Timing chain tensioner: not available new for many years. Used ones work ok. It would not hurt to make one either a spring thing or a hydraulic one. You can mold the rubber "shoe" ( get recap rubber from a recapping shop force it into a mold and cook it at 350 F in a toaster oven.) It will be entertaining and less frustrating than some of our other problems. Teflon can be bought in blocks and made into a "shoe"for the chain to slide on. Maby you can cut an entire tensioner out of an engine in a junkyard.

 

I talked with Locktite/Henkel/Permatex today about sealants for the edge of the block. I found that #515 is for Iron and the slower curing #518 is for aluminum. The problem was that copper in the aluminum was causing the sealant to set up before the parts could be assembled.
We discussed the difficulty of applying a .003" thick sealant rtv bead and concluded that it would be difficult to do with precision. The original gasket beads were silk screened onto the gasket according to Mahle.

 

https://www.engineeringtoolbox.com/linear-thermal-expansion-d_1379.html
here is an online calculator for thermal expansion It works in either metric or english system data just don't mix them together. Just plug your numbers in.

the problem in finding how much an engine expands is that it does not expand perfectly evenly because it is not at an even temperature throughout but you can assume that the front of it is a little below the coolant temperature. The expansion is directly proportional to the length of the part being considered. the expansion is at different rates for different kinds of metals. Aluminum expands faster than Steel so the timing chain would tighten as the engine warms but You would never notice it as the timing chain is a loop its length is twice that of the aluminum parallel to the chain and since aluminum expands about twice as much as steel does you'd not see much diference in the chain's tightness as the length and expansion factors roughly cancel. So don't worry about growth with temperature. Wear is another issue so when possible I use chain tensioners.

 

On Facebooks Mercruiser 470 Racing Group there is a post about making a tensioner using hard white plastic (UHMW). If we purchase a chain that fits correctly (post 2453 above) the tensioner is eliminated. That is the best solution. If Pro Power Engines chain set comes with a top sprocket, which I expect it does, it solves a major problem by eliminating the tensioner.

Many pages back there was a discussion on timing chains. We discussed using an undersized 460 timing chain. It is available in undersize to fit line bored motors. The 460 bottom sprocket interchanges. The top sprocket doesn't interchange. The 460 timing chain can be purchased with the bottom sprocket having 3 keyways to help when degreeing the cam. I expect that Pro Power Engines has put together the right parts from these and located a top sprocket mfg.

I keep referring back to the SBC. It never used a tensioner. However, the 470 is harder on the timing chain than the V8. Because the 4 cylinder has half as many power pulses as the V8 everything ratchets more. Several years ago I had a Cummins 4bt powered pickup truck. I couldn't get fast enough rear end gears. I contacted Gear Vendors about an overdrive. I was told their unit wouldn't survive behind that motor because of the ratcheting action of the big 4. After saying that, I wouldn't hesitate to run a good fitting timing chain without a tensioner.

If were into a total effort build there is another option. The Mercruiser has the camshaft located very slightly closer to the crank than the BBF. Most of the Merc cams run directly in the aluminum block. The following won't work if you have one of the blocks that already has cam bearings installed. The cam bearing has a big enough OD that the blocks cam bore can be offset bored to the same distance as the 460 block. After that modification it uses the 460 timing set, except for the top sprocket. However this modification will require shorter pushrods. This modification needs to be done after any crank line boring of the block, since that moves the crank centerline slightly higher in the block and closer to the cam.