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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: adams18 on January 30, 2011, 02:09:51 pm
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I have a 78 Chevy short wide 4x4 that i rebuilt the engine in, and it doesn't have anything near the amount of power it should have. Its a 33970010 casting block bored .030 over with the rotating assembly balanced. KB pistons that require the thin compression rings. Hastings rings. stock heads with a 3-angle valve job and .020 valvespring shims. roller rockers with tapped rocker arm studs. a professional products power+plus hurricane intake manifold and a reman'd holley 650 mechanical double pumper. The cam grind is CS 268H-10 from Comp Cams. it has .454 lift, 268 duration at .006, and 110 degree lobe separation. It also has a cloyes true dual roller timing chain.
My first problem with the engine was that the intake manifold was leaking water into the lifter valley. I noticed this during the break-in period. so I pulled the intake and put a new set of gaskets in. but it still leaked. finally figured out that when the engine would heat up, the intake bolts would loosen up, so i tightened them up when it was warm, then put a pressure tester on the radiator and it seemed to be fixed.
Next/main problem with the engine was that it had no power until it got wound up, it smoked, and the plugs were always oily. The timing was set up, and the carb was tuned in, but still no power until 4000 rpm. There are maybe 50 miles of run time on the engine so far. I originally thought that my problem was that the rings didnt seat right during break in, or the heads were bad and somehow letting oil into the cylinders. So i pulled the engine and started the tear down. When i pulled the heads, the cylinders were covered in oil and the tops of the brand new pistons were completely black and wet with oil.
Any Ideas what the heck is wrong with this engine? I know this is going to be hard to diagnose without seeing the engine or hearing it. Ask me some more questions about it, because i know i probably didn't give enough information.
Thanks for the help !
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Did all of the pistons have oil on them? Did it smoke throughout the RPM range?
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As a corollary to the above, if I'm understanding correctly, you rebuilt this engine? Did you clean the bores after the honing? I've smoked a set of rings that way. That honing process leaves a lot of fine grit.
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Yes, I rebuilt this engine and I did clean the bores before assembly. All of the pistons had oil on them, but the number 4 piston was a lot cleaner than the rest. not alot of carbon on it. and no, i believe it only smoked at idle. just on the passenger side. i thought that the number 4 cylinder might be getting water from somewhere because it was so much cleaner than the rest of the cylinders and there was only smoke coming from the passenger side, but i was running straight water, which wouldnt explain the smoke
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Before you installed the rings on the pistons, did you check the gap in the rings with a feeler gauge?
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yes, i gapped them
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Are you sure you got the right rings? And, did you use 30w break in oil? Are you sure the rings are on the pistons in the right order?
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I used a break in oil and eos. and i'm pretty sure the rings are in the right order. I went to hastings and ordered standard .030 over rings, but they wouldnt fit in the ring lands of the pistons, so i went back and found the rings that fit into the KB pistons. I talked to acouple people at hastings and they said the rings i have now are the right ones. The one thing i thought was that i might have put all of the compression rings in upside down? but would i have still had good compression? I did a dry compression test, and i came up with good numbers on every cylinder.
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Upside down piston rings would still make compression, but it would not "scrape" the oil off.of the cylinder walls properly. Which would call for the oil on the pistons. You may have installed the #4 pistons rings right side up, equalling the clean piston. When installing rings, there is either an indentation, dot, or writing specifying the size bore on ONE side of the ring, usually at one of the ends of the rings. You install the rings with the with the marking toward the top of the piston. And, I can only assume you know how to install the bottom ring? You cant get it upside down. Also, when you installed the rings, did you line up the gaps in a line? That is incorrect. Allways stagger the gaps of the rings, 5 gaps, so one gap every 60°.
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I did stagger the rings, and are you talking about the bottom compression ring or the oil rings? I pulled the number 1 piston and the dot on the bottom compression ring was up, so thats right. but ill have to pull another piston to see how i put the top ring in. the top compression rings do have a chamfer in them. but do the chamfers go up or down?
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(http://t0.gstatic.com/images?q=tbn:QfCPXKgaCABvtM::www.ellweinengines.com/jezus2/jezus2.htm&t=1&usg=AFrqEze7LJrHIFO9mYQ9dCgRe9pRmFjv0g) this is how the rings should look installed. you install them from the bottom to top, one of the really thin ones, no specific direction, bottom of the bottom grove. Then the one that looks like a bike chain, no specific direction, middle of the bottom grove, gap 60° off. Really thin one, top of bottpm grove, no specific direction, gap 60° off. Then the fatter of the solid rings, marking facing top of the piston, on the second grove, gap 60° off. Then lasty, the skinnier of the solid rings, marking facing the top of the piston, on the top grove, gap 60° off. I hope this helps and solves your problem. Also, after finding oil in the block, did you flush fresh oil through the block, turning the oil pump with a drill? You dont want to spin a bearing from the oil. And, the angled edge of the rings, also the side with the marking, faces up.
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thanks for all the help. and do you mean water in the block? i did prime the oil system before i broke the engine in, but i havent since.
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but if my problem wasnt coming from the rings, what else could it be? could it be a warped or cracked head?
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You said your intake was leaking water into your lifter valley. When you get any water im your oil, its smart to flush the oil/water out of the block. Drain it, put Bout 2 and a half quarts of oil in it, spin the oil pump for a good 5 mins, drain again. Id do that until just oil comes out. No milky color. I had to flush about 20 quarts through my block. Due to, leaking head gasket, and leaking intake twice when I first put the engine in. as for the warped head, im not sure. Could be? Coud also be you valve grind. Your valves may bot be seating correctly, oil leaking through,the head, through the valves, and onto your pistons? I dont know for sure.
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I think it maybe the rings. Staggering isn't really necessary. I mean, you're running something like 150+ psi on that, they're gonna turn, and stagger themselves, probably within the first minute of running.
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What are all the ways oil could get into the combustion chambers?
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bad valve seals is one. Cracked heads or cracked block,
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How much oil do you have in the cylinders?
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It was just a thin coat on the cylinder walls and piston, but definitely visible. I used Teflon valve seals when i built the engine. Cracked heads seem like a reasonable explanation though. The heads I used had had a rough life, not to mention that they have thin casting and are prone to cracking, but i used them anyhow because they had a 3 angle valve job. I also had the heads and block magnaflux crack tested before I built the engine and the machinist told me there were no cracks.
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Could drilling and tapping for threaded rocker arm studs have cracked the heads?
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Did the machine shop do the drilling and taping?
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No. I did the drilling and tapping.
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The top compresssion ring has a chamber. Does that go up or down?
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The top, and middle ring's cambers should be facing towards the top of the piston.
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Do you think the threads of the rocker arm studs could be leaking oil into the compression chambers?
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Personally, I dont know. I dont really know the mechanics of the heads. Just know how to build the engine. I would take the heads to a machine shop and have them inspected, maybe they can find any oil leaking problems. Did you check all of your rings? Can you get a picture of a piston with the rings on? And pictures of the cylinders?
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yeah, i can get pictures of those. I looked at my rings again, and both of the rings had the chamfer towards the bottom of the piston. Even with the dot on the second compression ring facing up. both chamfers were down
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I dont know if it was asked or stated, but is it one cylinder, or many?
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all cylinders had oil and all pistons were black with carbon
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The angled edges of all of the plugs should be facing the top of the cylinder, despite the markings. Thats where your problem lies.
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so the marking on the second compression ring was just to distinguish between top and bottom compression rings?
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From Hastings Website
CORRECT COMPRESSION RING INSTALLATION Back
Ring installation instructions are placed in every set of piston rings Hastings Manufacturing Company produces. These instructions should be read each time before the piston rings are installed on the pistons. Listed below are the general rules for the installation of various types of compression rings.
Rings having a "pip" mark or dot on the side of the ring must always be installed with the "pip" mark or dot towards the top of the piston.
Rings with a bevel on the inside diameter but no "pip" mark or dot must be installed with the bevel towards the top of the piston.
Rings with a groove in the outside diameter and no "pip" mark or dot must be installed with the groove toward the bottom of the piston.
* Rings having no dots, bevels, or grooves can be installed either way.
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I've figured out that it was the rings that were causing the smoke. Would the rings also cause the engine to act retarded? stumbling when i hit the gas and only having some power at higher rpms? Thanks for all the help
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Okay, I guess I wad backwards on the angled edge, but i was correct on the marking going up. Im not sure about the power aspect could be the oil robbing it of power, but it could also be carb, tuning, timing problems.
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would a backwards fuel filter hinder performance?
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would a backwards fuel filter hinder performance?
lol. yes
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Let me rephrase it. How much would it hinder performance, since you obviously know everything.
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Let me rephrase it. How much would it hinder performance, since you obviously know everything.
Flip it around and see for yourself
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I pulled the engine.
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Well don't get snippy and you'll receive a better explanation.
Depending on the filter you will have varied amounts of restriction of the fuel flow, and the filter will plug up and be useless sooner. Some have almost a check valve effect where you wouldn't get enough flow to do much more than idle. Either way it can be hard on a fuel pump and you would most likely have a significant decrease in performance. That, however, would not contribute to the other problems you're having, so you didn't pull the engine for nothing. Performance-wise, when you get it all back together put the filter in the right way, dial in your idle mixture and timing, and check for vacuum leaks.
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Thanks. haha I really do appreciate all the help you guys are giving me. Its just frustrating that this fresh engine that i took my time building, making sure things were right, doesn't run.
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I'm sure you'll get it figured out, and it will be worth it when you are done 8)
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When I first put my motor in my truck, I had no oil pressure. Found out I had forgot a plug on the back of the motor under the driver side head, and the one above the oil filter. Pulled the head off, plugged the hole, plugged the one above the filter, reused the head gasket and put it back together. Still no pressure. Had to pull the engine out and call the machine shop. They put a metric sized plug in one of my oil passages and blocked the oil flow. Got it back together, into the truck, and got water in my oil. Replaced the head gasket I reused, flushed about 6 quarts through the block and tried again. Water in my oil. Replaced the intake gaskets, flushed another 6 quarts. Water in my oil again. Replaced the intake gaskets again and made sure I put a thick bead of silicone around the water ports and flushed oil through her again and finally got the leaks fixed. Ridiculous. Some times things just go wrong. You'll get it figured out.
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I'm getting new rings and putting it back together. Hopefully it runs this time!!
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Let us know!
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Bought rings and gaskets this morning!
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Do you think the threads of the rocker arm studs could be leaking oil into the compression chambers?
Were the intake ports and the back of the intake valves also oily? Did you use any thread sealant on the rocker studs?
The oil problem needs to be sorted out obviously, but no power until 4000 rpm could simply be due to a poor combination of parts. For example, you have a race-type single plane intake bolted to low performance smog heads? Compression ratio? What was your ignition timing? What are you goals for this engine?
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My goal for the engine was for it to be an agressive driver. Overall timing at 32. CR around 10:1, I'm not sure. It has stock rods with KB231 pistons, stock deck height, no head milling. I used red loc-tite on the rocker arm studs. As of now, I'm thinking I'm going to try and find a set of vortec heads and an intake that fits my needs alittle better. I'll have to check on the intake ports and valves to see if there was any oil.
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Now I am assuming what you have now are smog-era square chamber heads? This is correct, right? 9:1 compression (with stock 76cc heads and flat tops) is more like it and that's on a zero-decked block. I think if performance is important, you should look for better heads (you can't go wrong with vortec heads on a street 350). Also, unless you are prepared to give up considerable low end output for what may not be a very considerable gain in top end, I would look more closely at a high rise dual plane intake such as the Edelbrock Performer RPM.
I think these books could be of great use to you:
http://www.amazon.com/David-Vizards-Build-Horsepower-Design/dp/1934709174/ref=sr_1_1?ie=UTF8&qid=1304994119&sr=8-1
http://www.amazon.com/Build-Chevy-Small-Blocks-Budget-Performance/dp/1932494847/ref=sr_1_3?ie=UTF8&qid=1304994119&sr=8-3
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Thanks! Haha The funny thing is, I own those books. :/ That helps alot though. I think I'll head for some Vortecs and a Performer.