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#1
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360 engine assembly questions
I am re-assembling my fresh 360 motor using the summit rebuild kit with hyperutectic speedpro pistons and moly rings. It didnt come with any specs on ring gap. I calculated a gap of .032 since I plan on running a little nitrous. Do the top two rings get the same gap or is it just the top ring.
Also I dont understand how the oil ring is assembled. Cant figure how the center oil ring connects together. What is better engine oil then assembly lube or assembly lube then engine oil on the cam, crank, rod journals? Is it best to install the headgasket dry or with a sealer? Thanks that should keep me busy for a while. |
#2
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according to "High performance Mopar" Magazine, Jan 2001, compression ring end gap should be .010-.020 & oil ring .015-.050! Hope this helps ya!
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#3
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Rings
The oil rings are three piece. The waffle ring goes between two very thin rings. Watch your gap placement in relationship to the others on each ring land. They must not line up with any other gap.
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#4
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how does the "waffle" ring connect together?
For ring gap, I still dont know for sure if all rings get the same gap, even the small oil rings, ....... or is it just the top ring that does. bore is 4.030 Also are there any rubber seal tabs that go into the rear cap as part of the rear main seal/cap install. The gasket kit came with two tab seals in a small envelope, cant figure out what they are for. |
#5
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waffle ring
or expander the ends just butt together do not overlap.then roll bottom oil scraper in and roll top one in with gap on opposite side.next rings will have a dot or something on them that goes up.regular engine motor oil only smeared on sides of piston and clamp down ring compresser,Did you wipe down cylinders with clean lint free cloth and motor oil yet?Make sure the rag comes out clean.That shows you there is no honing stone residue left in there.If the pistons and rings came as a set and your machinist is any good at all,end gap should not be an issue.does not hurt to check.For extra added measure I like to pour a nice puddle of oil on top of the piston when you are done to see if the end gap is good.still oil after a couple hours good sign.If it runs right past you better pull that one out and look things over again.The only thing more fun than building motors is sex.And sometimes I wonder about sex.
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#6
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seals
The 'Open' part of the rear seals goes "IN" toward the center of the engine. In other wise words ...the split goes inside. Easy to mess up this one..just think about it blocking oil from coming out the front side and remember (if you are like me...poor guy!) you have the engine and bearings upside down on the engine stand.
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#7
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seal
when you install the rear main seal, try to offset the mating ends just a little, reduces the chance of oil leaks, the ring manufacturer should have included a sheet with the rings for showing gap placement and clearance
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#8
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I understand the actuall rear main seal install. Is the two seal halves the only seal that goes in under the 5th main cap. The reason I ask is one engine book I have said something about rubber ends that are needed on the side of the cap.
The rings did not include a spec sheet at all. Just one paper showing the top or each ring........nothing on end gap. |
#9
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seal
The rubber ends were attached to MY seal..They fit in the small channels on each side of the block on the outer edge of the surface where the cap sits,..
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#10
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Re: waffle ring
Quote:
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#11
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I promise
I will get it right this time,just gimme one more chance!
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#12
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Re: I promise
Quote:
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#13
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the supplied seal was just a 2 piece half circle. No ends to it. I hope it is correct, because it is in allready. Dont remember any end seals when I tore it down. Was told that the 318 has the end seals.
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#14
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seals
They are trapazoid shaped if you look at them from the ends...
They fit in the cut outs on the block surface on each side of the rear main cap...at least on my 87-360 block anyway. |
#15
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dude, questions are nice, but its not a way to rebuild your engine post by post. buy the book "how to rebuild your small block mopar" read it cover to cover, then rebuild your engine along with the book. you'll learn alot more in the process that way. i wish you luck, and horsepower.
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#16
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Let me try to be of some help.
What you are trying to compensate for with piston clearance and ring gap is HEAT! Sure, the cylinder bore expands with increased heat, but the aluminum pistons expand at a much greater rate(about 3X as much). But the piston doesn't expand at a uniform rate. The top of the piston expands much more than the skirt. That's the reason the flat(top) of the piston is several thousands(.000") larger than the skirt. The difference between the dimension on the skirt and the top of the piston depends on the type of aluminum used, the design of the forging/casting and the ultimate use of the piston. The reason for ring gap is the same, to compensate for heat that is absorbed by each individual ring. The top ring gets the hottest since it is exposed directly to combustion temperature-it needs the most gap. The second ring gets a lot of heat as well-but it's not exposed directly to combustion heat and the piston has an opportunity to absorb some of the heat by the time it gets down to the second ring. This absorption of heat continues for the oil expanded ring. Under ideal circumstances, the piston clearance AND ring gap would be almost ZERO at operating temperature. But, if the clearance is too tight,the pistons will gall in the bore(or worse, sieze in the bore). The same is true for rings(but they usually break-very, very bad). You don't want too much clearance because that allows combustion pressures to go through the ring gaps and get down into the oil pan. This creates blowby, does funny things to oil, generally loses power, etc. Now, with all this explanation- I really can't help you with specific ring gap recommendations. I don't have any experience with nitrous(and use of nitrous creates a lot of heat in the combustion chamber. I can tell you on our engines(serious race engines on gas only) the ring gap is .018" on the top ring(gas ported pistons) and .014" on the second ring. I suspect that same relationship should be maintained when using nitrous. If the top ring is .032", then the second ring should be around .024". If you use this gap, non nitrous operation will be plagued with blowby. Again, I don't know; but, I would not use that much gap unless I was planning to use a LOT of nitrous. I would start with .024" on the top, about .018" on the second ring. But, that is my thought only. Hope I haven't confused everyone too much! |
#17
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I have that book....that is what I am using, but they are building a 318 in it and the question I had was on the rear main seal which is differant from the 360. Also the picture of the rear cap in the book is differant from what I have on my 360. thats why I was confused.
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