The elusive 224/3.7 MerCruiser banger

Moroso (brand) grout (cement) type filler is overwhelmingly the most popular with e drag race engine builders I know.
It is said you can fill an already finish (final) machined and honed block,

 

Information I have seen online states that this filler is a repackaged steel reinforced grout that is used to "bed" heavy equipment. Online information states the exact brand and type. It is available in 40 or 50# bags. I went to my local lumber yard and ordered a bag. It was there the next day. The price was about $40. So - I have a full bag in the garage, but am hesitant to use it. It is one of those "no going back" moments.
My block is finish machined already, which added to my concern. I have seen a video of a block being short filled that was already assembled.

 

Beck,
I'm thinking that you have gone to a lot of trouble and expense to have a LIGHT WEIGHT engine, now hesitant to fill it with iron filings.
I like the idea of aluminum chips. How important it is to get all the coolant cleaned off is debatable. Could you just bake it off in an oven?
Do you fill the block with chips and pour your binder over the top? Or, do you mix the whole mess together and pour that in? Would think the viscosity would be pretty important in the first case.
I might try to find someone that makes magnesium chips. I've had some here in the past and couldn't wait to get them out of the shop after I had a pyrotechnic experience. I might know where you could get a bunch. Shipping should be cheap, but insurance might be high.
How about carbon fiber?
Is polyester resin lighter than epoxy?
How does heat affect any choice of materials?
Does the binder actually have to adhere to the interior surfaces of the block?
You didn't say whether you tied the upper end of the bores together with a plate, assuming that you did not.
Sorry, more questions than answers, but I think this stuff is fascinating. Please keep us posted.

 

For ideas on chip cleaning, look here

http://www.practicalmachinist.com/vb/general/how-do-you-clean-cutting-oil-coolant-off-parts-257436/

 

My concern about using the iron impregnated filler is the possibility of corrosion. Iron and aluminum don’t like touching one another. When corrosion occurs it could break the filler in that area and possibly make more pressure in the block. I believe the filler should be the same material as the block to keep expansion rates as close to the block as possible. That would rule out the magnesium and carbon fiber.

I would want the chips clean. Epoxy bites very well to aluminum making a strong bond. With the coolant on the chips I doubt that bond would be very strong. This same thought continues to bonding the filler to the block and cylinder walls. It would lock all the parts together. If the epoxy glues the cylinders to the outer block surface everything would become very rigid and strong. The top of the block wouldn’t be as strong as those that have plates welded to the surface, but the strength would be there full cylinder length. I have not welded mine. That came up here after I had my blocks machined.

I also wondered about when and how the aluminum chips would be added. I guess that is dependent on their size. Very small chips or aluminum powder could be added to the epoxy before pouring in. Larger chips would probably need to be put into the block and then the epoxy added. I envision this happing in layers, put chips in ½” thick and add epoxy until they are covered. Then repeat until the fill level is reached. A vibrator may help remove air bubbles. Rodding the mixture would be a minimum for removing trapped bubbles. If epoxy is heated it thins making it flow easier, but heating also speeds the cure time.

Epoxy or polyester should both handle temperatures that a short run time motor would see. There isn’t flow like a water coolant, but temp shouldn’t get too high. I just like the epoxy bond better than the polyester, and I have epoxy available.

 

http://www.enginebuildermag.com/2014/07/cracking-block-fillers/

 

I have been procrastinating about the decision to fill or not fill the block for a few months now, delaying the progress of my motor build.

Hard Blok and Moroso block filler are both mixed with water. Phil34’s links author likes the Hard Blok but disliked a grout product that was mixed with water. I’m confused! I had previously read Phil34’s link but had forgotten about it. Thanks Phil.

Here are some online examples of the grout (Masterflow 885) I was referring to. (I understand that just because I read it online doesn’t make it true.)

http://classracer.com/classforum/showthread.php?t=66499&page=4

http://speedtalk.com/forum/viewtopic.php?f=1&t=43498&start=15

When I did online research before I believe I read that the Moroso product is this grout repackaged.
REMEMBER - I read this online – That doesn’t make it true. I have no 1st hand knowledge.

Since my machine work is completed I may be better off not filling the block. I don’t want to distort the bores. If the motor doesn’t work out for competition use, it would still be useable for another project.

My intended usage has maximum weight limits. I am having serious problems getting my tractor light enough. I need to eliminate all the weight I can. This could be a way to save a few pounds, hopefully not at the expense of an blown motor.

 

iadr: Like you, I'd prefer not to mill .625 off the block bellhousing flange, using instead the Jeep bellhousing and longer-input-shaft Mustang SN95 T-5, probably the V-6 version for the ratios.
How did well did that combo work out for you?
Thanx!
Eddie

 

Mark: avgas labeled 100/130 approximates 96 octane automotive fuel. Its octane rating is 100 (lean) and 130 (rich). It is close to what Mercruiser engines originally ran on. There is possibility that jet changes will be needed. Another option is E85 which is mostly ethyl alcohol (E85 octane rating is 100 to 105 ).
Changing fuels requires adjustment of timing and different jets...you might get by briefly by pulling the choke partway closed ( that will of course restrict the air entry). I can not over emphasize the importance of running a reasonable fuel to air ratio as a hot engine burning lean will use its pistons as fuel...and run out of fuel and compression. I strongly believe in monitoring fuel to air with a wide band oxygen meter as it is far cheaper than replacing pistons.

 

It would be easier. and saves $200 in machining. does it all fit?

 

The distortion comes from the volume change on curing of epoxy or cement. I reasoned that with more aluminum in the water jacket, less distortion takes place. I used solid blocks of aluminum with a thin layer of epoxy holding them in place.
Another thing to consider is that as metals have their individual coefficients of expansion it is better to have compatible expansion taking place in the water jacket. At least cement does not soften with heat as epoxy does.

 

Dennis G. Thanks for all the help. The Impeller on the out drive I replaced, had all the fingers torn off. I thought I had them all, but that was not the case. I found more pieces when I looked. Also I went back to the jetting the Carb came with, as opposed to the suggested setup by Edelbrock tech guy I talked to. He thought it would need smaller jets and suggested the kit they sell for the 4.2 V6. The timing checked out exactly at 32 degrees at 2200 rpm. Ran really well, and did not over heat! Thank you again. I will try some different jetting and if anyone is interested will report. Unfortunately mounting an O2 sensor in a wet exhaust is not an easy thing to do. But I am certainly open to suggestions. Also unfortunately there is no vacuum port anywhere. So I am at this point anyway, stuck with reading the spark plugs.

 

I just went with the 93 octane I had. I did not hear any pre-ignition, but I don't hear too well anymore. I did however find 100 octane Sunoco up in Sarasota. I will try some and see if it helps.

 

Aluminum reacts with cement to make tiny hydrogen bubbles which prevents shrinkage.

 

Because of fuel changes, plug reading is different from how we used to do it. I suggest you look it up as an accurate description is critical. It does sound as if you are ok. Late timing causes an exhaust to get really hot. Be careful with small jets. Jet a little rich and be safe. There are cylinder head temperature gauges that work with a sensor fitting under a sparkplug. Ultralights use them. Mercruiser intake manifolds have a vacuum port atop the rear half of the manifold.

 

Doing up a second engine, I noticed that its starter had a fat rounded nose. I had to cut DEEP grooves into it to get it to fit into the bellhousing I'd already cut to fit a newer Mercruiser starter with a more tapered nose that requires less cutting of the bell housing.

 

A geared starter like this is a much better choice as you save about half the weight of the older starters and the bell housing does not need to be modified.
The car engine should turn clockwise as seen from the front and as the starter faces the opposite direction the starter would therefore turn clockwise as seen from its output end. I don't know if cw in the illustration refers to the engine as it should or the starter.

 

Several problems will arise when trying to fill an open deck block design. One is that this block is die cast, and is much more flimsy than a sand cast engine block is, especially with an open deck. Many other early engines were also designed like that and also had similar failure prone issues, such as the aluminum Slant 6 Chrysler block. One Slant 6 guru who has raced the Slant's successfully for many years has tried a multitude of remedies to try to tame the aluminum block version, but has never found an adequate solution that has ever worked well for very long. He has filled blocks using many different concoctions such as with molten aluminum, Hard-Blok mixed with aluminum shavings and other fillers, but nothing has solved the issue of head sealing for very long.

Regardless of what the manufacturers claim, filling will distort a block, and should only be considered at the beginning of the machining process, not as an afterthought, or you will just have to repeat those processes again especially with flimsy blocks like these. The Honda guys figured this problem out almost 20 years ago with their open deck 4 cylinders, and now reaching over 1000 HP with them is common place and has eliminated the deck sealing problems completely. I had one of these blocks sent to me from another Slant 6 guy to make and incorporate the "Honda solution" to it, but he soon abandoned the aluminum block idea and went back to the iron blocks. It would be easy to apply that "Honda solution" to these Merc blocks though, and can extend their life even under more extreme conditions, considering that the head gasket failure issue is normal to them even in stock trim.

Looking back at the beginning of this thread, just ask Randy Dupree if his Bonneville engines we filled. I don't think you will be getting close to what he made with his engines HP-wise, but maybe he can give you some input on whether to fill or not to fill the block. At the least, if you do try to fill your machined block, if it was honed with a torque plate, you will have to re-torque one to the block as the filler cures to replicate the cylinder stresses. And you still may have to re-hone depending on how much the block moves when its poured.

 

CNC-DUDE,

Glad you're on here and talking from your experience.

I'm not fan of filled blocks but I can see the benefit in certain situations. My interest in these engines would be for street use and therefore would require coolant.

Do you have a web site detailing your products?

 

I do a lot of one-off prototyping for enthusiasts and racers as well as pattern making and aluminum casting of my own products. I think the Merc engine has a lot of potential above and beyond what has already be accomplished with it. Maybe some would like to help push it to the next level as far as product selection ie. intakes or other products. I can contribute a lot in the way of design engineering and 3D modeling and casting ideas. Not trying to self promote, many guys here are equally capable and able if they choose to be.

 

CNC-Dude, You talked about the "Honda solution" to these blocks, but you didn't elaborate on what that was. Please tell us about it.

I have decided not to fill the 2 blocks I am not working on. The distortion issue and the dedicated "race" motor use convinced me.

I am having bearing clearance problems. My crank was .010 - .010 under when I disassembled the motor. It cleaned up with just a polish, but is slightly undersize. I bought a set of .010 under bearings. When assembled with Plastigauge it indicates that I don't have enough clearance (.0015 to .002"). At first I thought it was my main bearing set. It was an ebay purchase. Inside the taped box was a piece of masking tape with X15 on it. I wondered if that was a .0015" over the .010" bearing.
Next I tried the rod bearings which came direct from a motor supplier to me, so they are what the box says. I have the same problem with the rods, not enough clearance.

I miked the crank. It measures what the shop told me at .0115" undersize. I'm confused. My mike has not been calibrated recently. I have always sent my motors out for rebuilds. I wanted to do these myself for a "pride of building" and make sure things were right. Maybe I'm not qualified, or maybe a shop would have just put it together like this.

 

Sure, it basically boils down to a machined support that fits around each cylinder at the deck and in between the inside walls of the water jacket at the top of the deck. Its a one piece part that wedges itself around the top of each of the cylinders and varies in thickness from 1/2", 3/4" or 1" depending on how much support you think you'll need. You could even drill and tap holes thru the side of the block to maintain a redundant retention setup if you want to, and may be a good idea. Being a custom part you can tailor it to your needs with circulation holes to match the head.

 

1 to 3 thousandths is supposed to be the clearance on the mains and rods. If what you wrote said that you have 1.5 to 2 thousandths you are gold, assemble it. If it is less than 0.9 thousandth polish it a bit and measure as you go.
I saw a worker use hand held belt sander on a crankshaft spinning in a lathe. It looked easy and came out smooth. He'd done it a lot though.

 

Where did you get those clearance specs from? (I like those better than mine)
The clearance spec I have seen is .0007 to .001" per inch of bearing.
Using that dimension with our 2.75" mains the spec is .00193 to .00275" clearance.
Using that dimension with our 2.50" rods the spec is .00175 to .00225"clearance.
Since my motor is more of a competition piece I was wanting to go on the large side of the clearance.
If I ran tighter clearances I would use lighter weight oil. That is the trend in new cars, and in some of the racing circuits (NASCAR), to gain some fuel economy and a little more power.
I borrowed a dial bore gauge today. Using that with my micrometer I should be able to get a more accurate measurement of what I truly have.

 

My figures are from the Mercruiser Inline Engines shop manual. Your figures are more precise , but leeway is built into them. Like the guy who asked how is your oil pressure? I said "fine" and he sanded the crank with what seemed like wild abandon (while I looked on worried) but he'd polished (sanded) thousands of cranks. I thought "who was I to complain?"
Yes, your choice of larger clearances seems like a good idea, but these engines are built for boats and they run hard all day long.

Specifications copied from my manual page 221:
main bearing clearance:
production: 0.0009" to 0.0031"
service: 0.001" to 0.0035"

main journal allowed taper:
production: 0.0002"
service: 0.0005

main bearing allowed out of round:
production: 0.0002"
service: 0.0005"

rod bearing clearance:
production 0.0009" to 0.0031"
service 0.001" to 0.003"

rod journal allowed taper:
production 0.0002"
service 0.0005"

rod journal allowed out of round:
production 0.0002"
service 0.0005"

 

More help needed.

I am working toward crank instillation. I don’t know which direction the side seals of the rear main are installed. The rubber is pyramid shaped with the point cut off. Both sides have a grove. A metal stake goes into the grove on one side.

I have 2 problems. Which direction does the rubber go in, and which side does the stake go in?

I am guessing that the narrow end of the rubber goes toward the bearing cap and the stake goes in on the cap side.

 

In answer to a question that I ask back on page 59.

From the Mercruiser manual Chapter 10, page 274
There is a diagram used for ring gap location. When talking about the top ring gap it states.
(The top ring gap goes toward the )“Starboard or camshaft side of piston with hole located in oil ring groove.”

Chapter 10, page 275
"Make sure the pistons are correctly installed on the connecting rods. The rod bearing tangs should
be on the same side as the hole in the piston oil ring groove."

Putting these 2 together the bearing tang side of the rod goes to the camshaft side of the engine.

There is a pad on the top of the rod at the piston pin. This pad is on the opposite side of the bearing tangs. Therefore the pad at the top of the piston faces away from the camshaft side of the block.

I have a mock up motor that was previously rebuilt elsewhere. The rods in my motor are installed opposite of what this says. Either I have interpreted it wrong or the previous rebuilder didn't get it right.

All of the motors that I have taken apart have been previously rebuilt using oversized pistons. All of my pistons have holes on both sides in the oil ring grove. It seems odd that the original piston would have had a single hole on only 1 side.

 

Don't really think it matters, many other engine have similar side seals and the pins swell to seal to expand it against the cap and block. So either way you install it, it will seal against those surfaces equally as well whichever way you orient it.

 

OK. The crank is in my 1st motor. Installing those rear main side seals is a pain! On the 1st attempt one slid out slightly so I had to do a re-do. Driving the pins in was the hardest part. I bent the 1st one, and had to straighten it. The 2nd was better, but still no fun. They didn't want to go quite all the way in. I had some .015" shims so trimming to length went pretty easily. I'm happy!
I need to order another gasket set to get my 2nd motor caught up.

 

It is easy to damage the seals if the pins cut through the seals instead of pushing the seal tight .
If you got them fully in it is a success. They can be frustrating. My pins bent also so I pulled my seals and coated them with a flexible locktite flange sealant and pushed the pins in as far as they permitted me and trimmed them off. My first engine seals fought me less (but they were new).
Logic says that a round pin works best in a round hole.