The elusive 224/3.7 MerCruiser banger

I put a gallon of oil in my engine this evening and ran the oil pump with a drill motor for a few minutes & then set static timing. Will run the engine on a test stand soon. It shouldn't be long but one can never tell.
I've decided to use copper tubes for attaching the coolant hoses as their I.D. is larger than any alternative connection.

 

Here's a couple of pictures of the intake I started building

 

Anybody know how much meat is in the cylinders of the Mercruiser block? How much can it be safely bored ? I can get a good block that has been bored .030 over already and has surface rust that needs to be cleaned up.

What oversize pistons are available ?

Tom

 

Silvolite .020 .030 .040 & .060 pistons are listed by Summit, but I've not called to check [1-800-517-1035]
My engine isn't open so I can't measure how much metal there is for overboring but I'd go ahead and get the block if it is cheap.[and it should be]

 

Thought I'd show a simple little alternator mount I made today. a 4" channel welded to an angle, then cut down form the base and a couple of flat pieces make the belt tensioner.
One more piece will be added to the tensioner to take the load(which isn't much) off of the adjusting screw. It fits well and is light.
The crossdrilled block is part of a toyota adjuster and makes adjustment very convenient.

The greenish wood is a test stand it is now mounted on.

 

Tom, that's a problem that's plagued my project. I am very much "land-locked" where I live and getting a core motor was hard. I did not know the one I got by going on an 1200+ mile trip, was 0.030" over already, until I tore it down.
Worse, the reason I got it ("free" aside from the trip which was an adventure/vacation anyway) was that piston skirt had broken off and the rings got dragged around without support ... so the one bore is pretty scratched. It needs another .040 to be perfect. I am advised that as a real world compromise I would be better off to take my block another .020, .025 (4.41 or 4.415, 50 to 55 thou nominal) and leave some of the bottoms of the deepest scratches alone.
If the hone job is done right the scratches will not wear the rings, and the pressure escaping is pretty much nil, given the time x area we are dealing with in a running engine.

I am told, but would like real world back up, that the aluminum backing to the cast in liners apparently doesn't have all that much strength (I'm looking at building for ~330 lbs-ft of torque). Even if it never "breaks" it flexes and gives blow by under full throttle & load.

There are a few 4.405 rings (TotalSeal, Mahle, & some piston maker had a listing) which are a file fit for a 4.40. If you are getting custom pistons, they can do them at whatever size you need. So, although 4.405 is 0.045 over, you can do that....if you are doing custom.
Mahle also make a series of 4.40 bore rings for Harley based custom bikes and for them, they do do 0.010, 0.020, .030, and 4.44. I am trying to source these for my project, and will post here with what I hear back.
I know Randy had thick "diesel" sleeves put in his block, but the machine shops local to me say typical thin wall sleeves for an Ford 460 iron block are not practical for this block design.

Bottom line is: 4.36, 4.39, and 4.44 are the common sizes for Ford460 Iron block pistons. The latter size is likely too extreme.
To find something in between 4.39 and 4.44 in a "on-the-shelf" piston, is not going to happen...
This is to the very best of my knowledge of having worked in the automotive industry for over 20 years and researched this project casually for 2 or 3 years,

 

oooo... velly nice

Late model FI head I see... That should be a really good head for this project. If I were not going aftermarket, that would be #1 on my list.

BTW, if you are interested in taking it to the next level, talk to Scott at Reincarnation in Washington state- he's done some very successful port jobs on those heads. For V8's, they get over looked because there is not carb-flanged manifold that can easily be adapted to the subtly raised ports.
The ports are real high velocity designs, but the small area can limit you if you start looking for big HP/RPM. Scott can help there. Super smart guy (he's done porting for several Engine Masters contest engines, and 460 OE iron is his #1 specialty)

 

Report sent.

 

silvolite pistons for the Ford 460 in the following oversizes .030 .040 and .060 are in stock and available from Summit, I checked by phone a few minutes ago.

 

I was told by a man who raced a Boss headed mercruiser in a dragster they would only take 0.030". So I would say no to 0.060"

 

I had reservations on going more than .030 over on a block such as this. I decided that this is a project that I never would complete, so I'm throwing in the towel so to speak. If anyone in the Detroit area woud like a good block already bored .030 over that has surface rust, PM me for the contact info where you can buy it for $75.

Tom in Detroit

 

I had Scotty do a cam and dizzy for my 460 awhile back and have talked to him about the fuelie heads, I subscribed to his web site a few years ago. He finished third at the Engine Masters in 2006. There are a bunch of good people on the 429/460 forums...
Thanks John

 

Request For Advice:
My starter spins the Merc fine when the plugs are out, but when they are in, the engine will not turn over. The battery is ok [I even connected two in parallel but that was the same]. The starter appears to be new and is the mercruiser starter.
This engine is zero decked and has flat-top pistons. Compression is higher but I did not expect it to be so much more difficult to crank.
I'll have the starter checked, but I'm wondering if I have to go to a geardrive starter.

Any ideas?
Dennis

 

dennis,

The starter is only having to compress 1 cylinder at a time so a healthy starter should turn it over unless you are running diesel type compression.

If your starter is bad it is time you got a Hi-Torque International scout starter on ebay for 235.00 delivered.

They have a 1.9hp high speed perminent magnet motor with a 4.44 to 1 gear reduction.

They will handle a 392 ci International V8 and 13 to 1 compression ratio.

Unless there is something really wrong with your engine they should turn it over very well.

A 9 tooth starter gear on a 157 tooth flywheel gives you a 6.33 to 1 ratio times the 4.44 starter ratio gives you over 28 to 1 ratio.

That times 1.9hp equals over 52hp not counting losses.

I think that you altered several of the stock components, pistons, deck height, pushrod length etc.

Make sure that nothing is touching (valves to Piston or piston to head clearence) before putting fire to it. The starter problem may be a blessing in disguise.

Dick

 

Measure the voltage right at the terminals of the starter motor while it is cranking (or trying to crank).

If there is eight volts or more, your battery is fine, and the starter just does not have the cajones to do the job, or there is something wrong with that particular starter.

If the voltage ar the starter terminals drops to way less than eight volts, check your battery and wiring. There is just not enough power getting to the starter.

 

Thanks, I was too suprised to be able to think clearly enough to do that yesterday.

 

Thanks Dick: Nothing internal touches, it goes around and around with the plugs out.
But I did deck it and change to a cam that builds more cylinder pressure so it will be harder to crank.
If mine is not up to the job, I'll go with a reduction drive starter. The motors on them are smaller than on the direct drive starters so they will need much less current. Their torque is multiplied by the gearing, but their horsepower stays the same.

 

It cranks! The trouble was paint under the starter mounting...I sanded it & cleaned with thinner & sander more. compression is 160psi with new rings so It will be ok.

 

Mine is running!

I put 20 minutes for cam break-in on my engine at what turned out to be 3000-4000 rpm when I got a tach running. It has a very nice "yowl". I LIKE it.

Advice?
1. Use lockwashers or locktite or safety wire wherever you can. These motors "thrum" with secondary harmonics when they run, even when closely balanced [0.2 gram] as mine is.

[I had several bolts back out, but that was completely my fault for having them under-torqued and using no locking device]

2. I used a bucket & a water hose instead of a radiator and found a tablespoon of scale from water passages in the head in the bucket. Scale like that would plug passages in a radiator.
I may run a coolant filter for a while.
I used a coolant filter on my mustang until it removed the abundance of casting sand that was left in the engine water passages. It was a success and no longer plugs radiators.

 

Video! Video! Video!

 

tjm,

If you want to hear a 470 run try YouTube "1985 470" there is a good startup of a mercruiser 470 out of a boat.

It sounds great and I am hoping that I can get it to sound something like a Model A Ford.

I may try a cutout hooked up to a model A muffler to fake out people at a signal.

I don't endorse street racing but don't mind a little off the line suprise, just to shake up the forign roadsters.

There is one guy on YouTube that built a boat and claims 360hp out of his 470. I don't know what he did to get that.

With the Procomp heads out of the box, the stock cam and the 750 QuadraJet I expect to get a reliable 220 to 230 hp.

Plenty for a Model A Ford.

.

 

Link?

Either he's deluded (aka "on crack" lol) or has a build I'd be very interested in. Probably the former...

 

That sounds about right.
If you want more than that, a very mild blower setup would be my choice.

 

I think either that or nitrous is a good choice as you do not have to have either operating all the time so it is all easier. I only have one motorcycle that has huge power and almost no torque, I hate it, so I've not run it in 30 years. Others [with both torque and rpm] I run regularly. Thats why this mercruiser appeals to me.
The ones on "you tube" have enough of a model A sound that it will pass for one of them. I was running mine at high rpm and it did not sound like a model A, it was running twice as fast and had a short megaphone exhaust.
The merc scared the cat too, she ran faster than my wife ever saw her move. The cats eyes were open so wide they looked like headlights. Poor kitty.

 

Sorry, I do not know how to do that, My still camera is supposed to be capable of that, but I've no idea of how to do it. An I'm still putting nuts back on that shook off.

 

Smaller horses I guess.

 

I'm still looking for the guy on youtube that built the boat and calims 365hp out of the 470.

But Randy Dupree was getting more than that when he went 187mph on the salt with a destroked 470.

Someplace there is a formula for Hp vs MPH on the salt. It depends on a lot on weight, rolling and wind resistance and a lot of other factors but this formula is based on outcomes and averages.

Taking speeds and Hp to calculate how many Hp it takes to get to a certain speed using data from actual runs and averaging them.

I have seen the video 2 times when I wasn't looking for it, now I can't find it. I will sooner or later and I'll post the name of it.

.

 

A good rule of thumb for n/a is 1 Hp per inch at 6,000 rpm.
224 Hp from a very well built and tuned 470 at 6,000 rpm is not an unreasonable expectation.

To get 360 Hp from 224 inches, might require around 9,000 rpm to 10,000 rpm normally aspirated.

I am sure it is possible, but most of us probably could not afford it. And even if we could, it would probably be totally undrivable on the street, and not last very long.

 

Mercury engineers got 190hp at 4800rpm with a cast iron head with 2.075 intake valves and standard ports.

I think that these engines with 2.19 inch intake valves and large ports will get the 220 to 230hp at less than 5500 rpm.

I won't be running them all day long at 4800 like some of them were in boats so an occasional run to 5500 or 6000 probably won't hurt.

It will depend on if any vibration or harmonic is set up at the higher rpm.

I'm trying not to mess with too much on them as I have great respect for the Mercury Marine Engineers who designed them.

They run their outboards at very high rpm for sustained periods of time with great reliability.

The same engineers designed this engine using many off the shelf Ford parts to keep the cost down.

They got more out of them than they did out of their Chevrolet 165hp 250 6 cylinder engines.

They got great reliability out of them if the proper maintainence was followed.

The problems with design were the alternator inside the harmonic balancer and the water pump on the front of the cam shaft.

I am eliminating both of those problems and focusing on the easy improvements that should improve the performance while not negatively impacting reliability.

I have at times improved things to death and don't want to do that with these projects.

I want to drive these cars as I would any modern car and not have to worry about breaking down in the middle of nowhere.

.

 

I just ran across a boat dealer who said "thats a good old motor" referring to the 470. He explained that he ran his at 5500rpm and got very good power. He later went on to turbo it beginning with 8psi boost and he increased that but said "if you boost it too far, it will let you know". He said that his boat passed all the others [small block v engines] with a wide speed margin.

So Dick, I think your power projection is reasonable. Be sure to get one of the late high power output cams for it.