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73-87 Chevy _ GMC Trucks
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No performance
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Topic: No performance (Read 17844 times)
adams18
Newbie
Posts: 37
No performance
«
on:
January 30, 2011, 02:09:51 pm »
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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bobcooter
Junior Member
Posts: 788
1979 Scottsdale C-20
Re: No performance
«
Reply #1 on:
January 30, 2011, 03:26:23 pm »
Did all of the pistons have oil on them? Did it smoke throughout the RPM range?
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'79 C-20, 350/400, 3:73 gears, 9 leafs and a headache rack
Favorite Quote, "Good judgement comes from experience. Experience comes from poor judgement."
TexasRed
Junior Member
Posts: 727
Re: No performance
«
Reply #2 on:
January 30, 2011, 05:01:37 pm »
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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adams18
Newbie
Posts: 37
Re: No performance
«
Reply #3 on:
January 30, 2011, 09:27:57 pm »
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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1979C20
Senior Member
Posts: 1659
Kyle Taulton.
Re: No performance
«
Reply #4 on:
January 30, 2011, 10:13:32 pm »
Before you installed the rings on the pistons, did you check the gap in the rings with a feeler gauge?
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1979 SCLB C20 Q-jet 350 SM465 14b F.F. 4.10 G80
1989 GMC Suburban V2500 TBI350 TH400 4in lift 35's 14b SF
adams18
Newbie
Posts: 37
Re: No performance
«
Reply #5 on:
January 30, 2011, 10:40:46 pm »
yes, i gapped them
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1979C20
Senior Member
Posts: 1659
Kyle Taulton.
Re: No performance
«
Reply #6 on:
January 31, 2011, 12:03:31 am »
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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1979 SCLB C20 Q-jet 350 SM465 14b F.F. 4.10 G80
1989 GMC Suburban V2500 TBI350 TH400 4in lift 35's 14b SF
adams18
Newbie
Posts: 37
Re: No performance
«
Reply #7 on:
January 31, 2011, 02:10:10 am »
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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1979C20
Senior Member
Posts: 1659
Kyle Taulton.
Re: No performance
«
Reply #8 on:
January 31, 2011, 02:18:45 am »
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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1979 SCLB C20 Q-jet 350 SM465 14b F.F. 4.10 G80
1989 GMC Suburban V2500 TBI350 TH400 4in lift 35's 14b SF
adams18
Newbie
Posts: 37
Re: No performance
«
Reply #9 on:
January 31, 2011, 02:27:26 am »
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?
Logged
1979C20
Senior Member
Posts: 1659
Kyle Taulton.
Re: No performance
«
Reply #10 on:
January 31, 2011, 02:32:00 am »
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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1979 SCLB C20 Q-jet 350 SM465 14b F.F. 4.10 G80
1989 GMC Suburban V2500 TBI350 TH400 4in lift 35's 14b SF
adams18
Newbie
Posts: 37
Re: No performance
«
Reply #11 on:
January 31, 2011, 02:37:01 am »
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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adams18
Newbie
Posts: 37
Re: No performance
«
Reply #12 on:
January 31, 2011, 02:41:41 am »
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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1979C20
Senior Member
Posts: 1659
Kyle Taulton.
Re: No performance
«
Reply #13 on:
January 31, 2011, 02:51:27 am »
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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1979 SCLB C20 Q-jet 350 SM465 14b F.F. 4.10 G80
1989 GMC Suburban V2500 TBI350 TH400 4in lift 35's 14b SF
TexasRed
Junior Member
Posts: 727
Re: No performance
«
Reply #14 on:
January 31, 2011, 09:44:22 am »
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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No performance