Big inch four: Mercruiser 470/485

Yeah, that's the guy, kind of a ... newb. The deal occured right around the time Randy and I exchanged emails. But he's sold it again, to someone going to make soem sort of pulling contest machine with it.

 

BTW, my crank is not prepared for a pilot bearing/bushing.

 

What's the bore/stroke, i need to know for a top secret insane project

 

Not 100%, but I believe it is 4.36" bore (stock 460) and 3.75 stroke.

I am now 100% on the bore. http://kb-silvolite.com/spistons.php?action=details&S_id=333

 

Yes I'm the newbie. Randy sold them to a guy on the 460 Ford forum and he sold them to a guy that pulls in the "mini rod" class tractor pulling. I found out about these engine through his ad and was really intrigued by them. This thread has been very informative, I have a short block and turbo 350 trans mocked up for my model A.
Thanks John

 

No direspect intended by the Newb crack, John. I meant the guy you describe in your post as "the guy on 460 Ford.com". He had ideas of turboing and 700-100hp, but didn't know basics... IMO, anyway.


Still hoping for a pic of the Boss headed one.

BTW, Jon Kaase's lastest Engine Masters Contest winner has a super trick damper on the nose of the crank made by the guy who ran a Boss-Headed one in a rail at one time... everyone keeps poping back up after a while.

 

No disrespect taken, Mike at 460ford.com purchased some nice parts from Randy but it wasn't going to be cheap or easy to do what he wanted to do.
I keep researching these posts for info and it's good someone pops back up.
Thanks John

 

I had a pair of the 488 with Rochester 4 bbl's in my old 32ft flybridge boat. It was a slug, but got good fuel mileage compared to a pair of BBC's. Lots of torque.

 

I recall seeing one a 53-55 Studebaker at Bonneville years back, was that your car Randy ? We had no clue what it was except seeing the 460 type head so I asked the guy what it was and he told me.

 

Has anyone come up with a roller lifter/cam setup for one of these? I'm putting a pair together and trying to convince myself that if I had a good roller cam I could tolerate running a mildly worked production iron head.

 

This motor sounds like it could be a good foundation for a pretty stout piece but I think that you will need to go with the after market aluminum head and then pretty much fab everything else, header, intake, altenator mounts and a special water pump. I would bet that it could easily be bored and stroked to over 250 cu. inch but one thing you need to remember: Fours are shakers!Especially big ones! It will really be important to make sure that the thing is mounted in or on good rubber motor mounts, no engine plates bolted to the frame. I would bet that with an aluminum after market head, good intake and exhaust and bored and stroked to around 250 cu. inches you could see a very driveable 300 hp with lots of torque, but I'll bet you will have $10,000 in it be for you can say "Bobs your uncle"!

Rex

 

The issue with shaking is mainly the secondary imbalance of a 4 cyl... and that is defined by reciprocating mass multiplied by how far the reciprocating mass is thrown. Sounds obvious, but here's how it breaks down: with infinitely light components, you'll have no vibration. Or, with an infinitely long rod, you'll have no vibration. So, a light rod and piston help, and a long rod helps.
Someone will say, any time you make 80+hp per firing, it'll be rough. Well, there are lots of little 120 inch turbo cars making that with a few aftermarket tweaks, and they are creamy smooth.
So, it's hardware related and it's isolating the engine.
I'm thinking a subframe, and possibly filling the subframe with a liquid- oil or antifreeze, about 90% full. Probably won't, just try it the easy way first.

I can have four rods and the crank done for them for 440-580, .030 bore pistons for ~110each, gasket set is cheap. Head-wise what is the best bang for the buck is the TFS or Kaase SCJ aluminum heads. Those are, all up, to your door ~$900. Regrind the cam with as much of a reduction in LSA and gain in lift as the grinder feels he can put on the core with good durability- $200 at most. Fabbing a manifold is not for everyone, but cutting half a Victor... or as someone pointed out halving a factory EFI, is a good starting point. Can you spend money doing this, yes. Not entirely needed though.

 

I'm sending a cam out Monday for a regrined I will let you know how it turns out.

 

What cam grinder did you go with?
What's your "aim" in terms of duration/lift/lobe sep angle?

My project got delayed yet again as the place I was renting got foreclosed on, so I had to move on short notice (landlord had 90days, but he didn't tell me until 21 days before d-day)

 

Steve Demos 279 Meadow Ln Jefferson GA. 30549 706 367 2417 He has done them before about 2 weeks turn around. cobrahd557

 

I'm building one with 6.920 alum rods 30 over SCJ heads reground cam custom intake 650 holley It will make 350 400 Hp

 

Tim,
How much compression are you running?
What vehicle are you running it in?

 

hot rod johnny is correct! i would be happy to never see one of theese again! IT WAS A GOOD IDEA POORLY EXECUTED IVE WORKED ON TONS OF THEESE AND HATE THEM WITH A PASSION! WE ONLY REFER TO THE AS "HERMAPHERDITE" JUST MY OPINION

 

I will be running 12to1 compression with 110 race gas in 3/4 size dragster.

 

Tim,
How's the engine coming along?

 

for what its worth, found a few in the Tampa area:

http://tampa.craigslist.org/pnl/boa/1311088655.html

 

Does a mercruiser 470 engine require external balance or not? It will matter if I replace the marine alternator with a fluid dampener.
[A member of this thread used a 351 ford viscous dampener so I checked a catalog and a 351 ford was said to have 28 oz balance correction in the dampener. I thought the Mercruiser was neutral in external balance.]
Clearly I'm confused. :0)
Dennis

 

Neutral. All 4cyl are by definition neutral balance- short form is they depend on the other cylinders which are travelling opposite for their balance action, which isn't quite complete. It's a little more complex than that, but in a sentence that's a pretty good summary. When a machine shop sets it up in the machine, a 4 Cyl crank isn't balanced with bobweights on it either.
I didn't re-read the thread as far as the use of an aftermarket Ford dampener you cite, but a number of Ford balancers use a bolt on weight, because Ford used both 28oz-in and 50 oz in calibrations, and aftermarket rotating assemblies for the same block are often neutral, so the balancer usually comes with interchangeable/removable weights. Mystery solved.

The OE Mercruiser balancer is a better one than anything Fluidampr has ever made- a little ugly, but a good balancer. Partly its advantage is in weight- this motor design needs a heavy outer ring on the dampener, which the OE one has...

 

I am contemplating the stock compression ratio being 8.8:1 and the engines knocking without the timing retarded 2 degrees.

The fix is said to be a dished piston, but I've not seen anyone say the dish volume that worked best. I've found pistons with volumes of 0cc [stock], 11cc , 15cc, 22cc and even more for pickup truck pistons.

Suggestions welcome.

 

In the original application (marine use) they knock like a can full of rocks on a paint shaker unless you pull the timing back or reduce the compression. Retarding the timing tended to over heat them which tended to crack heads and/or at least push head gaskets to failure. The reason these motors tolerated the over proping/heavy boats they tended to be installed in (when new) is because they had good gas....the gas quality dropped like a rock and these motors suffered worse than most. Remember, your lugging a hot motor on crap gas with a detonation prone combustion chambers....boat motors under load is similar to that of being on dyno full time....they don't get much of a break when the boat is under way. If your putting this is motor in a car with reasonable gears then thats a whole different situation and THAT set up could tolerate more compression.

I'm assuming your OEM Mercruiser pistons were flat tops? Which head casting to you have?

Two common 460 dishes we've used for boat motors are .180" deep and .230" deep. BTW.....with a flat top piston, 0.038" gasket, .020" down the hole and a 97cc chamber your still well over 9:1 compression ratio. Do the math. Lots of these heads were on the tighter side (closer to 92cc's) and the pistons sometimes weren't .020 in the hole....all of which raises compression. 8.8:1 is the number in the book but real world numbers suggest differently....and real world performance and actual use backs the fact up that these motors -as delivered and in the original intended use- have too much compression with the flat tops.

One word of caution. You need to use original Mercruiser head gaskets. No Sierra, no aftermarket, no HP stuff....you need original Mercruiser head gaskets, a good fresh head surface and a block with no dips, warpage and hopefully no nimrod with a "cookie" on a die grinder came anywhere near the block sealing surfaces.

 

I'm not sure what "truck" pistons would have the correct pin height- none as far as I know...?

BigChief is the expert here, no doubt.

Strictly looking ahead at my project, I don't see why, in a swap into a passenger car use, with a well set up radiator, that the stock compression should be a problem, in fact it should be ideal or even just a touch low if using a significantly larger regrind cam. I usually close up lobe separation as much as I can, 114-115 is OE. I'd doubt the core would go to 108 area, but that's what I'd want.
Also I'm going with an aluminum head with better designed chambers, so that's at least equiv to 0.5 or 0.75.

This is the second time I've been told about the importance of the Mercury brand gasket. I suppose some good glue- the Caterpillar stuff comes to mind- might serve some of the same purpose, if put on the problem area (lifter valley to head water passages, Big Chief?).

 

Thanks, but I'm no expert. My buddy who owns/runs a local engine machine shop/marina is. I'm just remembering all the stuff we did to these motors over the years.

I'm fairly certain all 460 pistons have the same (nearly) compression heights (either 1.77 or 1.76" depending on application). The Mercruiser slugs are at 1.755". All close enough to work well in either application....always do a mock-up to double check all clearances.

Yes, your correct in your assumptions about the OEM (or more) compression ratio in an automotive application. All is good. We use gaskets dry or sometimes cement them to one surface. We always use Mercury Marine glues, goops and gunks as recommended in the service manual and have never had any of these motors turn into leakers.

 

I manufacture an alternator conversion kit using Delco 10si or 12si alternator. Goes right on front of block. CNC machined and mig-welded. Does away with that crank stator thingie real quick! Email me for more info.. [email protected]

 

hey there was reading some of these posts and found some great info on the merc 470 aka what ever what ever engines half of 460. i have a boat with two of these engines. i know you guys use these in hot rods but any info on these would be helpful this thread is a few years old but what the heck. anyone know what auto chevy 4 banger the distributor came from. what engine did the timing chain and gears come from. any parts for these engines that i can not go through the vampires to get. what mods can i do fuel inj?electronic igintion, have the protronix stuff can i use something else to work the advance and curve. i have the 165 hp 2 bbl thanks