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Tech Talk => Engine Mechanical / Electrical => Topic started by: Kyle700 on October 18, 2013, 04:42:05 PM

Title: Chevy 350 flat at full throttle
Post by: Kyle700 on October 18, 2013, 04:42:05 PM: Engine runs pretty good up to full throttle then flattens out, makes more noise, little louder, little rougher, but doesn't go any faster...? It is a 76 chevy 350, with several owners before me, I am not sure of its history (of course).

Also, it has oil leaking from the oil pressure connection. It has the copper tube, any ideas to seal it?

Thanks!
Title: Re: Chevy 350 flat at full throttle
Post by: Kyle700 on October 18, 2013, 06:32:12 PM: The end of the oil pressure line that connects to the nipple on the block has a "bulb" on it. Can I cut it off and put a compression fitting on it?
Title: Re: Chevy 350 flat at full throttle
Post by: JBASHAM on October 18, 2013, 06:43:55 PM: There's a ton of factors that come into play as far as engine performance. Have u checked ur timing? Is it advancing properly? U don't know the history, maybe it's bone stock n that's all the cam has to offer. Oil line issue- cut it of with tubing cutter n put new compression fitting on. Hope this helps. Jake

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Title: Re: Chevy 350 flat at full throttle
Post by: GT Jets on October 19, 2013, 10:07:06 AM: JBASHAM is spot on.
It sounds to me like you're all out of motor, what you are describing sounds like a textbook description of valve float and a worn out jet pump.

More info is required to know exactly what's going on.

What rpm does the mouse turn?
What hull speeds are you seeing?
Can you describe the noises?
What's the oil pressure at speed?
Have you pulled a plug to see if there is something going on with carburation?

Basically, get the oil leak fixed using the above method, make sure there is good oil in it, document what you are seeing, hearing, smelling and check the tune.

You simply cannot take a stock small Chevy and expect it to turn 5000 rpm without some good parts and pieces.

Good luck, don't get discouraged. Small blocks can kick some ass if the setup is right.

GT

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Title: Re: Chevy 350 flat at full throttle
Post by: Kyle700 on November 13, 2013, 03:56:31 PM: 1. RPM's, don't know. (Yet) Tach not working, checked all connections, tight still not working. Time to trace wires.......
2. Hull speed probably high 35-40.
3. Noise, hard to describe other than "Bogging"
4. Oil pressure, not sure will check next time out.
5. Have not pulled plug out (yet)

Thanks for the suggestions, I will get into them soon.
Title: Re: Chevy 350 flat at full throttle
Post by: Kyle700 on November 13, 2013, 04:25:20 PM: The tach is actually stuck and 1000-1100 rpm's, even when key is off.....
Title: Re: Chevy 350 flat at full throttle
Post by: SoCalPSD on November 13, 2013, 10:46:13 PM: What carb you tuning, had the same issue. Turned out my secondary's circuits were clogged with crap.

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Title: Re: Chevy 350 flat at full throttle
Post by: Kyle700 on November 14, 2013, 10:49:53 AM: It has a Qudrajet on it that came off a good running engine that was converted to fuel injection. Sounds quite possible.......

Thanks
Title: Re: Chevy 350 flat at full throttle
Post by: Bigblockchevy on November 14, 2013, 01:51:51 PM: Problem number 1

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Title: Re: Chevy 350 flat at full throttle
Post by: SoCalPSD on November 14, 2013, 03:53:36 PM: Ditch it for a Holley. So much easier to rebuild and clean.

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Title: Re: Chevy 350 flat at full throttle
Post by: Kyle700 on November 14, 2013, 05:12:32 PM: What size Holley for a chevy 350? Something to consider....
Title: Re: Chevy 350 flat at full throttle
Post by: Chad krieger on November 14, 2013, 08:11:52 PM: If it was me a 650 works great for my truck.

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