First engine rebuild

[LAC_STS]

Re: First engine rebuild

How do I tell of the bock does need bored? There was a small amount of oil leaking past the rings. I could see it when I turned the engine over by hand with the heads off.

And almost all of the spark plugs had oil on them.


But I wiped the cyl walls off and felt them with my fingers and they feel smooth. I can't find any rough spots. So I assume the oil was coming from the rings being bad. I'll take pics of the pistons and rings and post them when I get home.


I'd rather not have it bored if I don't have to as it will add alot of cost to this.

 

[coheej]

Re: First engine rebuild

Have the machine shop measure the wear (or taper) in the cylinders. Mercruiser from what I read says .003 or in some cases less is the maximun taper before boring. Some people will rering a block without boring up to .005". The cylinders even though they are very smooth could be worn. When you look at the cylinder wall, if you can't see an angled crosshatch pattern then it needs bored also. If you bore it you will need new pistons. Replace the rings even if you don't bore.

 

[LAC_STS]

Re: First engine rebuild

The angled cross hatch your talking about is a x in the cyl walls right? Where about should it be? Towards the top or the bottom? I dont recall seeing any of them.

 

[coheej]

Re: First engine rebuild

The crosshatch is an X pattern. The angle between the lines should be about 45 degrees. This pattern should cover the entire cylinder, but as it wears it will start to dissappear at the top first right wear the top ring stops. This is what causes the taper. The rings are seated tightess at the top of the cylinder where the compression is greatest; so they wear most at the top and tapers down the cylinder wall. You need the crosshatch for oil retension.

 

[GLENN M]

Re: First engine rebuild

if your gonna rebuild it,throw out pistons cam lifters timing chain,oil pump,bearings,take to amachine shop have them grind crank,resize rods,press new pistons on,hot tank block,install new cam bearings,frost plugs,and they will usally install crank,and pistons in block eliminating tricky part for you for areasonable price,it cost me about 550 ayear ago of course i paid for parts.differance in stroking is price for a scat crank and machine work price on yours you need pistons anyway,no substitution for cubic inches i vote stroke it

 

[6meter]

Re: First engine rebuild

The crosshatch was done with a cylinder hone. At the very least it needs to be honed again. But I would have the machine shop measure it first.
Oil on the cyl walls is normal. You want it there. Its for lubrication of the rings. Motors are supposed to burn a little oil. Motors that burn to much oil, smoke and foul plugs, indicates a mechanical problem. Generally the rings, which you will replace, or valve guides and seals, which the machine shop should check. And while they're at it, grind the valves too. Keep asking.
You could swap cranks and they would know what size bearings will go with it.

 

[LAC_STS]

Re: First engine rebuild

Ok everyone so I am hoping to get the engine and parts taken down to the machine shop sometime this week.

Ive hbeen really busy and haven't had the chance to get it down there we will be able to continue my education here. Lol


I have been reading here and there still about all this.

I do have a question though. I numbered all of the main and rod bearing caps. I couldn't find the punch set I have so I used a sharpie marker.

Well for one the rod bearing caps are still marked but the main bearing caps the number has come off. And I read somewhere that your supposed to mark which direction the caps go on. Like a L on the left side of the engine so they all go back on the same way. I didnt do this.


So what do I do about the now not numbered main caps? And does it really matter about the direction on the rod caps?

I see caps for sale so maybe do I have to buy new caps now?




Much thanks as always!!!

 

[GLENN M]

Re: First engine rebuild

all gm main caps have arrow cast in pointing which way. it is crucial they go exactly where they were,or you will have to have block align bored,pistons all have arrows point to front of block.rod caps have to be resized anyway so mark them and send it all to machine shop.theres no room for error no second chances every mistake will cost you money.if you cant find the right tool put it on hold till you find it. first thing before you start get a how to sbc book read good luck

 

[Fishermark]

Re: First engine rebuild

first thing before you start get a how to sbc book

Yep. Like this one by David Vizard:

Your local library may even have a copy. It's good to ask questions here, but much of what you are asking is basic stuff covered in the book. Not "busting your chops" - but with the book you will get some good info that you can clarify with questions here.

Just saying.

 

[Fishermark]

Re: First engine rebuild

A more specific one is by Dennis Moore - Small Block Chevy Marine Performance. The Broward County Library has a copy. The Miami Beach Library has a copy as well.

 

[proshadetree]

Re: First engine rebuild

It is good that you are asking questions and are wanting to rebuild your own engine. Kind of a dying art these days with so many affordable alternatives. look forward to your progress.

 

[LAC_STS]

Re: First engine rebuild

ok thanks everyone.

I have another question.


To make it a stroker, I have to have it bored 30 over, but what other machine work is needed?

Im probably wrong but doesnt some work have to be done to the bottom end of the engine to give clearance for the stroker crank?

 

[Aloysius]

Re: First engine rebuild

Boring and stroking are unrelated.

There are bottom end clearance issues using a stroker crank.

for a first engine, keep it REAL simple.

 

[LAC_STS]

Re: First engine rebuild

Oh, I was refering to earlier in the thread where others were saying if it had to be bored to make the engine a 383 stroker.

There are bottom end clearance issues using a stroker crank.

But that answers my question.


Im not saying Im gonna do it just asking. First step is to take it down to the machine shop and let them check everything.

 

[proshadetree]

Re: First engine rebuild

Most 383 kits require you to use 400 balancer and flywheel adding to your cost. Also for a marine engine it just is not worth it. An automobile will see seat of the pants gains marine has to make big numbers before you feel it. And if you are worried about cost it will drive up the price.

 

[Dakota47]

Re: First engine rebuild

Just make sure they go back on the same rod they came off of.. comprenda ..

 

[coheej]

Re: First engine rebuild

So what do I do about the now not numbered main caps? And does it really matter about the direction on the rod caps?

I see caps for sale so maybe do I have to buy new caps now?




Much thanks as always!!!

If the arrow to the front is not visable, look at the main cap and block. Both will have a notch that the bearing tang goes into. The notch will be on the same side of the motor for both.

If the main caps are mixed up, you might ask the machine shop to bore gage the main bores to see if the correct order can be determined.

The direction of the rod caps is like the main bores, the bearing tang notches go together. Also on a sbc the rod caps will not fit correctly if reversed. It will be obvious that it's not right.

If the caps and rods are mixed up even if you have them resized, they will not be accurate without a lot of grinding on the parting surfaces. Also the side of the cap and rod will not be in perfect alignment. If you sand on the sides to correct this, you will have some rods thicker than others and your side clearance may be too large.

Also, you cannot just buy new main caps without having a line bore or align hone done on the block

 

[redjmp]

Re: First engine rebuild

IMHO you should forget about a 383 and just build a stock 350. A 383 will cost more and would require re-propping and/or re-gearing further adding to the cost. If you had a boat for it that felt under powered, then it would make sense but you don't even have a boat to put this in. Any motor that has worn enough that there is a pronounced ridge at the top of the cylinders and doesn't have any visible cross hatching left, will be out of round and tapered and will need a rebore. You need to decide what you want this motor for before spending a dime more on it. If you plan on waiting till spring when the improperly winterized boats with cracked blocks start showing up on craigslist so you can find a great deal on an otherwise decent boat, and only want do a quick re and re in hopes of reselling for a quick buck, then don't bother doing all that work to it at all! Just enough that it will run well enough to get sold... If your cylinders dont have any deep grooves, then just give them a quick hone and install some new rings. The crank could do with a polish but not imperative though. Rod jornals seem ok at first glance with normal bearing wear and only 1 iffy main. So long as there are no burrs then I would just slap it together with new bearings even .001 undersize and flog it. Even things like the oil pump, timing chain components, cam and lifters, unless totally shot, I would just reuse. Or just wait until you have a cracked motor and pick the best parts from both motors. I would have the shop boil everything and make sure no crap in the oil passages or cracks. Now if you plan on keeping the motor then you need to decide what its going into before deciding 350 vs 383. And then the easiest would be to get a complte rebuild kit online for about $400 complete with cam, lifters, pistons, rings, bearings, oilpump, timing set, and gaskets. Have your shop bore the block and polish the crank before as they can the tell you what oversize pistons/rings and undersize bearings you will need to order...

 

[LAC_STS]

Re: First engine rebuild

I took the block and stuff down to the machine shop today.

The guy was really cool and he checked every bore with the bore gauge and said the bores were good. He said just a hone is fine and he said it hasn't been bored before.

He said the crank has been ground 20 already so he would swap me with a better one for $25 extra.

To finish disaseemling the block, clean (boil), hone, swap crank, install new cam bearings, install new brass freeze plugs, and check all of the rods is gonna be $275.

It'll be done in a couple days.

 

[RogersJetboat454]

Re: First engine rebuild

Sounds like a good deal.
Is he going to do any crack checking? Is he going to check the alignment of the mains?