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Engine Assembly


Guest Locutus

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Guest Locutus

I know that you need to put some kind of lube on the cam, crank, rods, etc, but what do you do for the pistons? Do I just use oil to get them in and then prime the oil pump before the first start, or do I need to put lube on the piston walls as well?

 

Mike

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Guest super280z

Mike,

 

how's it goin? well im pretty sure you dont need any kind of lube on your pistons for startup. you did out oil on them when you put them in right? i have heard of people dumping a little marvel mystery oil in the intake before startup. but i personally dont think it matters. if your using chrome moly rings they need that extra heat at the first startup to form to the cyllinder walls. icon_smile.gif hope to hear its running soon.

 

p.s. i gave in and bought the JTR manual. icon_rolleyes.gif oh well..

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Mike,

I've heard of people doing it both ways...some have smeared a thin layer of engine oil on the walls of the bores, but the rings will 'seat' quicker if installed dry. My Father, who races Trans Am type formula cars overseas and has been building V8 for decades, installs them dry and he also says that if the ring gaps and bearing tolerances are CORRECT at time of installation, no 'break in' time is necessary. He has often built an engine the night before a race and laid into it to 7000RPM, without any problems. Obviously if the cam is new then you want to keep the revs up around 2000 RPM for 'break in'.

Tim

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Guest Anonymous

For what it's worth, my old high school shop teacher had us dip the assembled piston into 30W oil up to the rings just before assembly... seemed like a good idea at the time...

 

Tim

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Guest Locutus

Well first off let me tell you guys what this motor is for. Its a Mercruiser 140 inboard. For those of you who don't know boats this essentially a GM engine, its a 4 cylinder that is more or less 1/2 a V8. It is basically the same engine used in 4 cyl Novas and Chevy II of the early 70's except is has a 4" bore and marine grade gaskets. I am rebuilding it and I am nearing completion but I wanted to be sure I was doing this right as far as the pistons were concerned. Tonight I am probably going to put the pan on oil filter and prime the pump to make sure I have good oil pressure before I go and put on all the accesories. Any other ideas or steps you guys can recommend?

Boat parts are infinately more expensive than car parts so I would hate to screw up now and have to buy more gaskets etc.

 

 

Mike

 

[ August 18, 2001: Message edited by: Locutus ]

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What's different about the gaskets? I noted some oil on my block while pulling the $%#! T56 and while I'm pretty sure it's the valve covers I'm curious. If "marine grade" is better it might be worth the money.

 

BTW - who was the dim bulb who thought only 4 valve cover bolts was enough? C'mon that's silly... icon_rolleyes.gif

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Guest Locutus

I don't know about all the gaskets, but I do know that the head gasket is made to resist salt water that may be used for cooling as well as the water pump gasket. As far as vavle cover gaskets go I do believe they are rubber gaskets for my particular motor. I think the Mercruiser 350 valve covers are slightly different then regualr 350, I also think the heads are far different because of the water flow is thru the stern drive and out the exhaust.

 

Mike

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quote:

Originally posted by Montara22:

For what it's worth, my old high school shop teacher had us dip the assembled piston into 30W oil up to the rings just before assembly... seemed like a good idea at the time...

 

Tim

 

That's what several books I have said to do also. The only thing that bother me about this is getting the combustion chambers all carboned up when that stuff burns off.

 

One thing I like to do is get a roll of white, non-patterned paper towels and automatic trans fluid and wipe the cylinders down until a clean paper towel with fresh liquid on it comes out of the cylinder without a trace of grey on it. This gets all the metal and honing grit out of cylinder wall surface.

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BLKMGK,

I've heard that the new silicon based cover gaskets with the anticrush steel inserts in the bolt holes work very well...much more expensive than the paper or cork gaskets, but in the endevour to make sbc motors oil tight, it's probably well worth it.

Tim

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Guest Anonymous

What pparaska said/wrote about cleaning the bores should be your main concern for good longevity of your motor.

Also flush out all oil galleries etc, with kero or something then blow air through with a compressor to make sure theres a minimal amount of metal particles left behind.

If your rings are properly gaped it isnt totaly necessary to oil the bores up, but i still do because it doesnt hurt to be on the safe side.

Also its worth changing your oilfilter after run-in and seeing how much gunck it has picked up, it can be a bit of a shock when you split one after 500 km and its fairly black. icon_eek.gif

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Guest Locutus

I used brake cleaner and an air compressor to blow out all passages etc. To be honest everything was very clean. The motor had been recently rebuilt but the moron's that had it let it sit in the rain for weeks so the cylinders had rust on them, and there was water in the oil pan. So I tore it down to check to make sure nothing else was rusted and honed the cylinders to get the rust off(it was only on the surface thank god), and since it was tore down I replaced all the bearings, rings and gaskets. I cleaned everything with brake cleaner and blew out the oil passages, and made sure they were free of any contaminates. The crank turned very freely torqued down to specs. When I added the pistons I did dip them in fresh oil to make installing them easier. With the pistons on it is harder to turn the crank but I believe that to be because of the drag with the pistons not being lubricated yet. Am I right in assuming that?

 

Mike

 

[ August 19, 2001: Message edited by: Locutus ]

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Yeah, even lubricated, the piston rings add friction to the rotating assembly. If you are using hypereutectic pistons, you may notice that they have tighter clearances than forged units and will be harder to turn in theory. Happy rebuild! icon_smile.gif

 

Davy

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I've got silicone valve cover gaskets now with a metal frame inside. I thnk they're still leaking though - grr! Don't think I'm willing to put more pressure on them with these aluminum heads etc. Will see how they work out when the motor is running again. This may be spooge left over form the previous gaskets and th ework done on the car. Going to have to Simple Green the entire engine bay darn it. Yick! Flat black holds oil...

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