The elusive 224/3.7 MerCruiser banger

I have a boat sitting here in my back yard that has a running 3.7 in it. it is free to the next owner. You can pull it here, I have a hoist, or take the whole boat, I just want the trailer, but I would sell that too. I just hate to scrap a running motor. Message me for details

 

---------------------------------------------------------------------------------------------

The water jacket spider not being welded bypasses the problem of warping the block during welding. Sealing it in place helps the headgasket seal the narrow ledge on the cam side of the engine. Temperatures at the outer edge of the water jacket should be low enough, depending on the alloy, to allow the use of aluminum soldering which, depending on its alloy, melts between 410F and 750 F, and it is much stronger than adhesives. The inner side of the spider runs hotter so I'm still looking for the best solution there.

The idea of running the spider over the block abutments where the hold down bolts are appears to have merit. Milling down the block where the hold down bolts are would allow a straight side rather than having to cut around the bolt hold down abutments. It would also prevent vertical movement of the spider

 

I've made several alternator mounts too. The most recent one allowed the alternator to shake fwd and aft violently. I had to add a brace rearward from the alternator to prevent that. If allowed to, alternators can develop massive vibration from harmonics.

 

One of my engines came to me with aluminum eroded from a headgasket leak and it was resurfaced down to the point where any further removal of metal would have pistons standing above the deck I see no option to removing metal from the piston crown as only one ford rod length (6.6035") is available. Does anyone see other alternatives?

I found that forged piston crowns cut down easily on a lathe, but those I tried would not grind without tearing metal.

 

Cobra Jet 429, Boss 429-T, 460, and MerCruiser rods are 6.605"

Boss 429-S rods are 6.549"

 

dennis g : you do have options of playing with BB Chevrolet rods & grinding the crank to the BB undersize & adjust the stroke to make the rod length work with your pistons, or another way : order new pistons with a shorter "deck-height" to drop them down the bore & cure the projection problem. How much projection are you dealing with?

 

There is a minimum crown thickness that becomes unsafe and compromises piston strength, even in forged pistons. So err to the side of caution.....

 

Thanks guys for the resourceful advice. There is not much to cut down for a clean surface around the bores. My estimate is that 10 thousandths is ample ( I stopped surfacing when I got to the height of the piston crowns ). Silvolite says I must leave 180 thousandths above the top of the first ring so I have several times the margin that I must have to save the block.

Different rods would be a good solution if they were the length I need. Ford rods don't have the available length I need but I've not checked FE series rods. Chevy rods offer more possibilities with crank grinding but as the crank is a good std. crank I'd like to be able to save it for parts if problems arise. I try to keep with parts that interchange, but one can't always do that.

The easy (and cheap) solution is to remove a small amount from the crowns. Either carbide tool bits or tool-post grinding. Forged pistons don't grind well but cut beautifully with a carbide cutter. Hypereutectic alloy pistons are harder and may grind well. We will see what works.

 

They sell pistons with varying compression height if you were buying new slugs

 

When inspecting a used block, watch for erosion of the aluminum at a head gasket leak, It has to be cut away unless you weld more aluminum into the area and then cut it down.

 

Back around page 80 I suggested using bellville washers (conical springs ) under the head bolts.
I checked on available strengths and 250 lbs was the heavy one. Working out the tension on one headbolt from torque etc that came to about 15,500 lbs. the washers are so far below the needed strength that they'd have to be stacked 61 washers high to combine to the needed spring strength.
So it is not a good idea.

 

I think turning the bolt shank down as discussed about a dozen times in the prior pages is the best COA

 

If the shanks of the bolts are rusty, as is common, we can experiment turning down otherwise useless bolts. I did as I had a set with enough rust that some had a diameter of 0.440" at the bottom of the rust. If the threads are corroded, the bolts are just tent pegs. A few years ago bum came along and stole a set of good used headbolts...I think he took them for tent pegs.

 

Something useful for you. Seeing that my engine varied from the one someone kindly provided vector drawings of. I took in a scan of a template that I'd made and inked...I saw it was not accurate so I made a rubbing of my block but did not ink it as I did before. The man at the graphics shop was delighted to see the rubbing saying "that is exactly what I need. It is accurate and precise."
So if you are making a deck filler plate, just make a rubbing.

 

Anyone see this?

https://www.motortrend.com/how-to/b...m_id:fb:mtoo:23:OOtraffic:article:m18-65us:mt

 

It was posted a few pages back. It's a forklift engine built in Kearney, Nebraska. The industrial side of Blueprint Engines built the short block, and BPE finished it off. It's all inhouse and 100% brand new.

 

Just looking through the thread and saw this post. A little late, but hey...

I am not positive about fitment, but the balancer off a 300 I6 may be the same as the 302 and it's 0 balanced. The 250 I6 may also be the same.

 

As previously mentioned, Speedway has a SBF damper that comes with both the 28oz & the 50oz BOLT ON counterweights, & THIS DAMPER IS A BOLT ON FOR THIS CRANK NOSE! Also has threaded holes for crank pulleys... Just leave off BOTH COUNTERWEIGHTS for a "0" balance assembly...

 

I tried because I have a bunch around. The damper isn't offset enough relative to the keyed hub to come anywhere near close to clearing the timing cover. It simply won't work.

I bought a Ford Performance neutral balance SBF damper from some guy in Connecticut who races professionally. The inside diameter steps down for some reason so it doesn't seat. I'm just gonna hit it with the boring head.

 

The alternator stator has mounting bosses on the timing cover which have to be removed. Then a common aftermarket dampener fits. You don't need the mercruiser alternator and regulator as it can't supply enough power for a car.

 

The 240/300 damper still won't fit. The keyed hub sticks out enough to fit the seal and bottom out on the timing sprocket without problem but the body interferes with the whole timing cover because it doesn't offset forward relative to the crank snout as far as the 302 one. You might clear the main face of the cover just barely but you'll still be well into the coolant area. That coolant bolt in the last picture is positioned to hit the internal hub, the rubber and the external hub of the damper and even if the bolt wasn't there the damper still has to go in far enough to hit the boss on the timing cover.

Believe me, if it were doable I'd be doing it because as it stands I'll be cutting the firewall.

The Ford FE uses the same ID/OD for the keyed hub. Someone who has one lying around should do a test fit.

 

Doesn't a 250 dampener work?

 

It may. The 250 is a completely different family of engine.

 

Seeing your photos, The balancer with a pulley for its rim will never fit. It somewhat resembles one used on the little 2.5 liter Mercruiser.
I bought a Professional Products small block Ford balancer see post #267 in this thread it cost $67 from Speedway. It bolted in except for grinding away the protrusions from the front cover that held the alternator stator.

 

Has anyone tried a multi layer steel head gasket?
My machinist claims they will re-seal if needed to.
With our engines, that may help.

 

That thinner balancer is off of a Ford 240. I know because it was installed on it before that picture was taken and went back onto it when I was done. I wasn't expecting it to fit but I originally test fit it weeks ago because I have all manner of 300s and 240s around and if it did fit that would be convenient.

I know about the Professional Products SBF balancer (part #80006). It has been covered many times in this thread. While I could just buy it I'm probably going to bore out the 302/351M damper I already have since it fits other than a step inside the bore.

 

I am using a Cometic multi layer gasket on mine. My only concern was the thin edge at the lifter wall, so I put a bead of right stuff there. I also surfaced the head and block for the proper finish for it. So far no problems but I have not had the car on the road yet.

 

One of your dampeners has a rim pulley which would add the mass of the alternator to the dampener, not a bad idea. I mis-identified it in my post and have adjusted that.

I encountered a strong alternator belt resonance on my tractor last year. I do not know how much the v belt contributed to it, but it was violent enough that I feared it would break the mounts off the alternator. There also was a resonance in one alternator drive on my 2nd 3.7 Mecruiser engine until I braced the alternator better.

 

Thanks, I think it will work well.

 

In preparing an old block today I surfaced the gasket mating surfaces on its front and bottom.
This was primarily to remove corrosion and visible aluminum oxide. Although it may not matter, the surfaces will now be clean and flat and there is less chance of oil wicking out. This is the first engine I thought would benefit from sanding. Maby it was from a submarine. ;0)

Dollar store microfiber cleaning cloths have a nubby surface that collects and holds the small aluminum particles easy removal, even without using oil on the cloth. With no oil on the cloth, the metal particles can be knocked off of the fabric so one can re use it a few times.