318 Dis-assemble & Assembled 1st time

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bschubarg

bschubarg

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This is my first attempt to rebuild a engine. Any engine for that matter.

I am in the process of tearing down the 318 since it is burning oil and lacks all kinds of power. I added a small cam, intake and carb and even gears, but it was obvious that what really was needed was to fix the oil burning and low compression. One of the cylnders registered a 125 psi cranking pressure. The rest where in the 140's to 155 psi. An that was before the abuse I put on it.

Anyways, after teardown, I noticed the entire pass. head covered with oil in the combustion chamber and all plugs oil fouled. The other side looked good.

However all top rings I measured had a gap of .05 or more. Is that correct for a factory ring or are these rings just another sign of abuse and wear?

I have pics of everything that I have disassembled including piston tops and chambers if that helps.

So what caused just one side of the blocjk to burn oil like that and what other measurements should I do to help determine what happened. Or do I just skip this and go right to the rebuild?
 
Just to start with The vent cap on the pss side let's the oil fall back down to the oil
pan and if it was pluged up or someone put after market valve cover's on and did not vent the oil would hold on top and your valve seal's let oil in your combustion chamber.
see if the drain hole's are restrickted and this would slow flow of oil down out of your head's.I would have the head's cheacked and cleaned.A bad valve will give you low compretion,How did your head cascket's look when you removed them?
I am sure someone will get to you soon with more exp.
 
Oil on the combustion chambers comes from 3 places. Either the rings let it by, it leaked past the valve seals because of bad seals and/or guides, or it leaked into the intake port from the intake gasket. It's very rare that PCV would introduce enough to keep a single chamber wet. I suppose possible, but rare IMO. If your rings have .050 end gaps, it's because the bores and rings are worn. Normal and fresh engiens will have anywhere from .020-.030" depending on a lot. Brand new rings have .018-.025ish. Maybe more depending on pistons. your leak down isnt too bad. I'd be looking at the stems of the intake valves. If they are wet with oil, or covered with black coal looking gunk, you need the heads redone. Post pics if you can...
 
Upon close examination after reading Moper's post, it is indeed the intake gasket. I can see where the trace of oil in each intake port making it's way to the combustion chamber. It would of been unusual if the valve guides were worn on just one side using the factory valve train.

Oh, one other thing I forgot to mention. I am running Magnum heads on a LA block. This time I am going to tap and thread the oil gallery that leads to the heads from the deck surface just for insurance...

Anothing thing that I am kinda baffled. The piston from the factory lies 0.085 in the hole. So I figured that these are probably 8.5 pistons. I bought the Sealed Power PN285 pistons with a compression height of 1.741 thinking that I would get a boost in compression. Would you beleive that from the factory for a '85, the compression height is..... yep.... 1.741. Time to look into a new set of pistons. I am not about to go thru all this just to wind up with the same kerosene burning quench...
 
The top two rings are compression rings and control just that. If you are getting oil past the pistons it is from the oil (bottom) ring.

I had one of my first motors I rebuilt use oil in one cylinder upon removing that piston I found that when I installed the oil rings on that piston I did not notice that the seperator had overlapped and wasn't "butted" causing the oil rings not to have enough tension. This lead to the oil consumption.

Chuck
 
What you are finding is not the piston's fault. It's more than likely the block machining from the factory. When an engine is rebuilt, it is normal for the shop to mill a little off the decks to make them "flat". But if you start from the factory machining, you may be way tall to begin with. This is not a dimension most shops check during a stock type rebuild. The term "square decking" means the deck surfaces are not only flat, but set to blueprint height and parallel to the crankshaft's centerline. As for pistons, if you have stock replacements already, they will work fine. But you won't get as much compression. Keith Black has a couple of modern hypereutectic pistons that are designed to address the lack of compression. I usually run them at "0" deck and use the gasket and chamber size to set the compression ratio. On the magnum swap, I would also do this. Aside from tapping and plugging (really not needed..the head has no port in it. So the head IS the plug). Whne you are assembling, install the heads using an old set of gaskets. Lay the intake on the shortblock, and closely examine the intake port flanges and head flanges. Put a light behind the engine, and site down the gaps from the front. If you see light, or the intake doesnt "settle" in and seal off the lower edge, you need to mill the intake or the intake flange of the heads a little to have it fit properly. Leaks at the bottom opf the ports are usually the result of poor intake fitment. If you had to pry the intake to start bolts, or had issues starting the bolts with your fingers, you had intake fitment problems.
 
That is exactly what my problem was in the first place. Fitting the intake was such a huge chore that I thought I had the wrong intake to begin with.

I went so far as buying a Crosswind Professional Intake thinking that the factory intake from the original LA style just didn't fit well with the new Magnum heads.

I could lie the intake between the heads and there would be about a .020 gap between each intake surface on the manifold and the heads. SO my solution was to double up on the intake gaskets. What was I thinking.....?

Anyways, I am reconsidering the piston choice and looking at the KB's 167 with a Compression height of 1.81.

The block is completely disassembled and next stop is the machinist to bore it 0.030. I'll partially assemble it to get what I need to achieve zero deck. I was going to mill the necessary surface of the deck to achieve zero deck with the PN285 pistons I have now. But that might be too much metal when the compression height is 1.74 and they sit 0.085 in the hole....
 
try looking at a set of pistons from the 68-70 era, these were higher in comp ratio at the outset, and with some 302 or magnum heads you should come to around 9.5 to one cr.
 
I'd look at the KB pistons. They should be balanced, but you'll spend close to the same money on milling a lot, then milling the intake or heads, then buying pushrods and shims..etc. its cheaper and better to just put the right ones in if at all posible/
 
The assembly is coming along fine. I took some of the advice given to me, per ususal and made some changes to the build. Also attached are some pics of the project.

Like a waddling politician I went back and forth to what the project should entail. One of the senior members here mentioned on a thread that you stick to the best plan. Making changes during mid-stream(waddling) makes for a longer and more expensive build. I learned from their mistakes and came up with a build after some conferring with members here and stuck to it... finally.

It was going to be a "rebuild" at first, but hearing horror stories about rebuilds... I went ahead and spent the extra $ to get a performance rebuild including align boring, square decking, torque plate boring and +/- 2.0 gram balance on the assembly.

I also took Moper's advice and bought KB 167 pistons and zero decked them with my Magnum heads. I was going to go the route of a 360 crank and get pistons for the 318... but in the end, I think I saved myself some $ and also stuck to the orignal plan.... without deviating.

I home ported the magnums, nothing fancy, more or less a clean up. Pics attached.

The rest of the plan is to use the cast iron intake 4BBL from an 1985 Police Dippy. I don't think there would be much a difference b/w using an aftermarket and this stocker. A Rochester Q-Jet 750 CFM. 1 5/8" Hedman Headers. The camshaft is the Summit Racing venerable .441/.441 @ 218/228 duration @0.050. It has been suggested by the author of the "How to build a Mopar small block stroker" to use a cam that favours the exhaust since the ports do not flow well.

The differential is a 3.55 with a Detriot Trak Lok.

Any ideas or advice as to how I am proceeding so far. And please, don't mach the M-Body 5th Ave. Besides, it has something many of you A-bodies don't have.... a hood ornament!

318_port.jpg

318_internals.jpg

318_pull1.jpg


318_port.jpg


318_internals.jpg


318_pull1.jpg
 
Aww man..you use GOJO?? ;)

Looks good so far. But...you will need the Magnum heads drilled for the LA intake pattern to re-use that intake. The Quadrajet (aside from being GM...) has some good points. Parts are easy to find, so is tuning knowledge. I think you and your hood ornament will be happy with the results.
 
The heads have been drilled and tapped to accept the LA styled intake. I borrowed a jig that has been circulating the country to perform the conversion. Worked out well.

I chose the Q-Jet 'cause I am the most familiar with them. Love the idea of really small primaries and large secondaries. Biggest problem has been keeping them filled with fuel. But I also installed a Carter Electric Fuel pump to solve that.

My goal is to get a good broad torque band from 2000-5000rpm with a peak HP of 325 @5500.

My compression ratio should be around 10.7-10.9. I am thinking of getting the valves ceramic coated or possible the chambers to thwart detonation. I have heard several times that the excellent quench and design of the Magnum heads allow these compression numbers if you use 93 octane. But I would hate to run it only to find out that the C/R is too high.
 
You should be able to squeak past. But a coating can't hurt.
 
KB-silvolite.com has a dynamic compression ratio calculator. Go plug your numbers in (you'll need the cam card) and the rod length is 6.123. If you have higher than 8.5:1 dynamic compression, you may be in the detonation threshold. Now is then time (before it's all done) to adjust if needed.
 
moper said:
KB-silvolite.com has a dynamic compression ratio calculator. Go plug your numbers in (you'll need the cam card) and the rod length is 6.123. If you have higher than 8.5:1 dynamic compression, you may be in the detonation threshold. Now is then time (before it's all done) to adjust if needed.
Click to expand...
That is why I like you so much. We often on the same page. Just don't get anyu ideas about swapping wifes. 'Cuase I just might say yes....

I did that already with calculating the Dynamic Pressure. It wasn't pretty.
I attached a copy of the output. Any ideas on how to get to the 8.1~8.5 ratio?
comp_ratio.jpg


comp_ratio.jpg
 
You are going to have a real hard time with the comp ratio above 11 if the calculator is correct. You might want to see if you can get it below 10, or go with aluminum heads. I always had a detonation problem with my 318 Magnums in the past. You can also mill the pistons down to get a little less comp.
 
How paniced are you right now? Like crazy disappointed? Like what kind of a j_rk would tell me to do that??

Your input for the pisont dome should be a positive number, and it's 5ccs.
Here's what it should read...

Static of 9.9:1, dynamic of 8.5:1

That's a great cheapie unleaded street engine.

;)


edit: Oh, and if you can convince her to leave...I wont need yours. I might even finance and build a 418 for you...lol.
 
yeah, you would think so, but I failed to mention a very important point. Now i guess I will have to divulge it here.

You see, I lied. I had plans on going with the KB167s, but then came along a great price on a set of KB399s. Got so excited that I bought them and handed them to my machinist who had planned on putting on the KB167s.

My requirement initially, called for zero deck. I fogot to change that requirement after the purchase of the KB399s. Not his fault.

So now I have a short block with the dome sticking out of the hole.

There has to be a way, other than tearing down, removing the pistons, shaving the dome and then re-assemble to get a more tolerable c/r for the street and 93 octane.

Now I am thinking of going with a set of 360 heads with the huge chambers....
Damn!
 
You LIED!!!

that would be an issue then...lol. You could simply poull the rods and pistons and have the domes milled off them too. That's the easiest way really I think. And it can be done with the rods attached if their careful. As the crank will be heavier, it shouldnt affect the balance much at all.
 
Things have changed....The block is back and once again, breaking the rules, I have decided to go with the KB167s and went with a custom hydraulic roller.

It is Easter and while the kids are looking for eggs in the easter egg hunt I decided to go online and ask a quick question that has me stumped.

Upon re-assembling the block, ie valve train, I have installed the camshaft and now ready to put on the "dog bones" on the rollers, but when I put on the retainer that mounts to the inside of the block with three small bolts, there is a 1/4 gap between the retainer that holds the "dog bones" and the block itself. It almost looks like there needs to be three spacers, one for each bolt. When I dis-assembled the block myself, I didn't recall any spacers. Is there a trick? Am i missing spacers, Or do I have to bend the retainer to make it fit?

Any insight would be helpful, and by the way, Happy Easter!
 
I dont recall there being any spacers in there. Just the height of the bosses on the cam tunnel. And there is a little space there, to allow the dogbones to follow the lifters thru the entire cycle.

Happy Easter BTW ;)
 
Is it possible that I have the dog bones upside down. Currently I have it situated as the raised center pointing towards the intake manifold. Is it possible that the dog bones are suppose to be place where the center is a bit lower than the top edge of the lifter boss? I got to find me some pics....
 
I think you have them on right. Raised part up...It's been a while for me tho.
 
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