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LOW budget engine not working well....HELP!

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jberenyi:

--- Quote from: Cliff Ruggles on August 02, 2021, 10:00:04 AM ---
Another possibility is that there is a vacuum leak someplace.......

--- End quote ---

As noted earlier we have a lean condition.  Cupping the airhorn raises the rpm.  After changing the mixture screws from 5 turns out to 8 turns out the roughness got better.  Probably 90% there.  I plugged all vacuum sources and sprayed all gasket areas with starter fluid and no change.  We don't have a vacuum leak.

jberenyi:
"Do I have to wait for the engine to break in due to a lower compression till the rings seat?"
No. Should be no difference

So your saying an engine with 10 miles on it has the same compression as when it has 1000 miles on it?  Really?

"one month ago my friend let the oil get low and spun a bearing "
Why would the engine oil go low on a good engine?

I can't account for someone's lack of checking their oil. 

"While at it we ground the valves and put new seals in"
When you say we I hope you mean a Professional

Yes.

"The cam is the same one when I bought it."
A used cam?

Original used cam as noted in my thread above.
 
"I don't understand why the carb has a rough idle"
Have you ever thought it might not be the carb. Why was the carb fine before the motor was taken apart?

That's the $50,000 question

 
"Vacuum is about 15Hg at 1000 rpm"
Maybe you should be checking your engine repairs / valve job.

I don't question the valve job.  I do question how long it will take the rings to seal though.  BTW when the idle was at about 650 to 700 it was 10Hg if I remember correctly.

Mudsport96:
Bump your timing to 16 degrees btdc and see gow it reponds.

jberenyi:

--- Quote from: Mudsport96 on August 02, 2021, 01:53:45 PM ---Bump your timing to 16 degrees btdc and see gow it reponds.

--- End quote ---

At 14 deg she's doing fine.  At 2800 rpm she pulls in at 36 deg with vacuum cannister blocked.  I don't think I want to go any higher than that.  When Clifford did my disty he also made sure the cannister was correct.  Lately I've done a fair amount of study how the idle metering circuit works and IMHO I think I don't have enough manifold vacuum to pull fuel up the idle tube on through to the down restrictor.  With having the cylinder bores professionally honed and new rings maybe we have to wait for full break in to happen so we can get the increased vacuum like it had before.  Looking at all the variables this is the only thing I can come up with other than the valves being jacked up which I know is not the case.

Cliff Ruggles:
How much manifold vacuum did the engine make before the "rebuild"?

There is not going to be any improvement in engine vacuum based on ring seal.  If it was done correctly the rings were sealed as good as they will ever be a few minutes after you fired up the engine. 

Did you change the timing set?

If so what did you use?

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