Author Topic: No performance  (Read 17828 times)

Offline adams18

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Re: No performance
« Reply #15 on: January 31, 2011, 06:23:13 pm »
What are all the ways oil could get into the combustion chambers?

Offline beastie_3

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Re: No performance
« Reply #16 on: January 31, 2011, 07:01:01 pm »
bad valve seals is one. Cracked heads or cracked block,

Offline beastie_3

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Re: No performance
« Reply #17 on: January 31, 2011, 07:01:39 pm »
How much oil do you have in the cylinders?

Offline adams18

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Re: No performance
« Reply #18 on: January 31, 2011, 11:44:07 pm »
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.

Offline adams18

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Re: No performance
« Reply #19 on: February 01, 2011, 01:24:44 am »
Could drilling and tapping for threaded rocker arm studs have cracked the heads?

Offline screamin86

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Re: No performance
« Reply #20 on: February 01, 2011, 01:55:52 am »
Did the machine shop do the drilling and taping?
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Offline adams18

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Re: No performance
« Reply #21 on: February 01, 2011, 02:15:36 am »
No. I did the drilling and tapping.

Offline adams18

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Re: No performance
« Reply #22 on: February 01, 2011, 03:42:53 pm »
The top compresssion ring has a chamber. Does that go up or down?

Offline 1979C20

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Re: No performance
« Reply #23 on: February 01, 2011, 03:46:34 pm »
The top, and middle ring's cambers should be facing towards the top of the piston.
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

Offline adams18

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Re: No performance
« Reply #24 on: February 01, 2011, 04:04:42 pm »
Do you think the threads of the rocker arm studs could be leaking oil into the compression chambers?

Offline 1979C20

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Re: No performance
« Reply #25 on: February 01, 2011, 04:27:28 pm »
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?
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

Offline adams18

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Re: No performance
« Reply #26 on: February 01, 2011, 04:29:47 pm »
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

Offline beastie_3

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Re: No performance
« Reply #27 on: February 01, 2011, 06:28:08 pm »
I dont know if it was asked or stated, but is it one cylinder, or many?

Offline adams18

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Re: No performance
« Reply #28 on: February 01, 2011, 07:36:30 pm »
all cylinders had oil and all pistons were black with carbon

Offline 1979C20

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Re: No performance
« Reply #29 on: February 01, 2011, 07:59:04 pm »
The angled edges of all of the plugs should be facing the top of the cylinder, despite the markings. Thats where your problem lies.
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