SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: che77y on March 28, 2015, 07:23:42 PM
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So I got my block back from the machine shop today, noticed a few things worthy of questions, first off I had them put on forged .030 over slugs on, I know u need a rod heater to pop those pins out but the end of the rids at the pin look maybe a lil over heated? Check out the blueing did they weaken my rods? on that also is my clearance from piston to bore gunna b a lil bigger for a forged piston? I also have the main oil restictors for the mains and I will b using a stock oil pump seeing the high pressure ones rob a few ponies input on other things I may need to do? Thanks guys
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Did you take the pistons and have them do the bore for the pistons you are using? That's important. Any shop will
bore the block to the pistons that are being use. The blueing I don't see a problem with. I have to ask reading that you are building a 455 is that does the shop you are having do you work know the 455 motor?
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So I got my block back from the machine shop today, noticed a few things worthy of questions, first off I had them put on forged .030 over slugs on, I know u need a rod heater to pop those pins out but the end of the rids at the pin look maybe a lil over heated? Check out the blueing did they weaken my rods? on that also is my clearance from piston to bore gunna b a lil bigger for a forged piston? I also have the main oil restictors for the mains and I will b using a stock oil pump seeing the high pressure ones rob a few ponies input on other things I may need to do? Thanks guys
The rods look perfect to me. No problem.
As for the clearance from piston to cylinder wall. The technical answer is no. The piston to cylinder clearance would be tighter on a forged piston than a cast, but more importantly, the clearance needs to be proper for a marine engine.
So I guess your statement is right for the wrong reason.
GT
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Did you take the pistons and have them do the bore for the pistons you are using? That's important. Any shop will
bore the block to the pistons that are being use. The blueing I don't see a problem with. I have to ask reading that you are building a 455 is that does the shop you are having do you work know the 455 motor?
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yes he's done a few, and yes I gave him the pistons to bore to. I'm not sure how well he knows them it was a virgin motor and hadn't been opened up before. Is there some key specifics of the olds that must be done diff besides the usual obvious? I've put a few chevys together
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The rods look perfect to me. No problem.
As for the clearance from piston to cylinder wall. The technical answer is no. The piston to cylinder clearance would be tighter on a forged piston than a cast, but more importantly, the clearance needs to be proper for a marine engine.
So I guess your statement is right for the wrong reason.
GT
ok GT looks like I have some info to look up I've done car motors but never a boat motor, why the difference?
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ok GT looks like I have some info to look up I've done car motors but never a boat motor, why the difference?
Think about it this way.
The marine engine is under a huge load as compared to a car motor. That creates a ton of cylinder heat and oil temperature. At the same time, they are running with very cold cooling water and you want cool temperatures mainly because of the untreated water.
The pistons will expand at or greater than they normally would, whereas the block would stay cold and not gain the thermal growth.
So the piston could technically hot seize or the rings could bite and pop the top right off of the piston.
Depending on piston material and type, the clearance needs to be wider.
Hope that all makes sense.
GT
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Ok that makes sense seeing I have no closed cooling system I have heard about hot pockets of air trapped inside when someone dummies down the gate valve to raise the temp. I'll b getting a thermostat kit too btw. So I suppose the question here should be how much extra room did he leave me? And if he bored for a standard auto setup for my pistons can this ruin my whole build? I guess I'll call him Monday and see if he has the numbers I don't have a snap gauge and mic at the moment but will be getting all these tools very shortly
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Think about it this way.
The marine engine is under a huge load as compared to a car motor. That creates a ton of cylinder heat and oil temperature. At the same time, they are running with very cold cooling water and you want cost temperatures mainly because of the untreated water.
The pistons will expand at or greater than they normally would, whereas the block would stay cold and not gain the thermal growth.
So the piston could technically hot seize or the rings could bite and pop the top right off of the piston.
Depending on piston material and type, the clearance needs to be wider.
Good that all makes sense.
GT
.
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I have to say it out loud.
If you want a thermostat kit, I say go for it. But don't think that they actually "control" the engine temp. They control the outlet temp. Which is different.
A proper thermostat kit involves a a block mounted automotive style water pump. Are you at all familiar with how the water flows through a block? If you did, you would understand where I am going.
GT
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I have to say it out loud.
If you want a thermostat kit, I say go for it. But don't think that they actually "control" the engine temp. They control the outlet temp. Which is different.
A proper thermostat kit involves a a block mounted automotive style water pump. Are you at all familiar with how the water flows through a block? If you did, you would understand where I am going.
GT
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I have an idea but I'm not a scientist on the subject.
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I have an idea but I'm not a scientist on the subject.
Neither am I.
That being said. Restricting the water leaving the block until it gets to a certain temperature is fine, as long as the water within the block and heads is moving and homongenous.
With the regular thermostat kit found virtually anywhere now, the water simply is slowed, not circulated.
The water flows from the water pump holes through the block, to the rear of the heads, from the rear of the heads to the front of the intake manifold. There are some small holes in the gasket along the way, but for the most part, that is the travel of flow.
In an open system, the easiest way to totally control the temperature is a water pump style system like what is found on an I/O.
Don't get me wrong, the stat kits help and I have used them with some success, but be warned, they are not fool proof.
With the stat kit, the front two cylinders will run extreme cold with the hottest combustion chamber temps. Not a real good recipe for longevity.
With a true open, limited flow system, everything is pretty cool. Also making everything consistent temperature wise from one cylinder to the next. As long as the engine is built right, it will run forever.
GT
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Neither am I.
That being said. Restricting the water leaving the block until it gets to a certain temperature is fine, as long as the water within the block and heads is moving and homongenous.
With the regular thermostat kit found virtually anywhere now, the water simply is slowed, not circulated.
The water flows from the water pump holes through the block, to the rear of the heads, from the rear of the heads to the front of the intake manifold. They're are some small holes in the gasket along the way, but for the most part, that is the travel of flow.
In an open system, the easiest way to totally control the temperature is a water pump style austen like what is found on an I/O.
Don't get me wrong, the stat kits help and I have used them with some success, but be warned, they are not fool proof.
With the stat kit, the front two cylinders will run extreme cold with the hottest combustion chamber temps. Not a real good recipe for longevity.
With a true open, limited flow system, everything is pretty cool. Also making everything consistent temperature wise from one cylinder to the next. As long as the engine is built right, it will run forever.
GT
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word GT, I was under the impression that the Stat kit helped reg the temp w/o restricting flow too much. Whole diff world w boats I'm starting to notice. I looked up some things on the subject of piston clearance and there is a general rule about expansion I'm calling him Monday and if I hafta have him open it up a lil then that's what's gotta happen I do want to build it right so it does last forever. As far as the cooling stuff goes sounds like there's some splitting hairs here to get the best of all worlds. And to think I ran this motor a season in stock form before pullING it out of my old hull. Although my rpms were under 4k and I only kept a load on for 2 min max at a time haa