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Discussion Starter #1
Since I posted this and this Ive done the following:

Removed all lines from the vacuum tree - no difference.

Removed the PCV line from the carb and sealed it - no difference

Removed the vac advance from the carb and sealed it - no difference (since has been put back as it was)

Gone around the intake manifold gasket with carb cleaner - no difference

Gone around the carb gasket with carb cleaner - no difference

Turned the dist. from pointing forwards to the point where the vac adv line touches the rad pip - from 9 inches at idle to 14-16 at idle. The problem here is that it isnt stable above 1500 (doesnt sounds quite right, not sure how to describe it). This is most likely due to the timing now being shot to hell. Im pretty sure its not a vacuum leak on the engine. Any pointers from here?
 

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I read your other posts......someone suggested checking your power brake booster, have you done this? You mentioned your brakes were getting worse, maybe the diaphragm is shot in your booster. Mine was bad, causing a very rough idle.
 

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Discussion Starter #4
The booster isnt connected to the manifold at all any more. Nor is the transmission. Or anything that draws vacuum. The booster probably is on its way out, but theres also the underlying problem of low vacuum.
 

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Discussion Starter #5
That site is really great! Im not 100% sure about what category mine falls under, but based on that site its either worn rings, or timing/ignition problems combined. Im going to change the plugs and see if I can get my hands on a timing light tomorrow.
 

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What shape is the motor in? What's the milage? Ypu've seem to have checked a lot of things and no one has mentioned a timing chain. I think you've got a worn chain and skipped a tooth.
 

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Discussion Starter #7
The motor seemed to be in good condition when I got it, no idea about milage. Looked to have been somewhat recently rebuilt, but the car was a daily driver. Thanks for the idea of the timing chain. Ill look into it.
 

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A quicky way to check; put a timing light on, rev the engine a liitle and release. If the timing bounces all over the place, the chain is worn. If it advances and retards smoothly in relation to rpm, it's ok.

My bet is a worn chain.
 
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What compression readings are you getting. Also, are you hearing any noise from the lifters. Your vacumn readings are way low and you are likely looking at either rings or valves as the source of the problem.
 
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Any backfiring through the carb under acelleration? If so, I'd pull the valve covers and observe the ammount of travel each rocker arm has. Could be a wiped lobe on the cam. I once had this problem, and my 6-71 blower was only giving me 3 lbs of boost and the pop off valves were going nuts. Pulled off the blower and then it was backfiring into the carb under acelleration. New cam and lifters fixed it. If no backfiring, maybe a burned or bent valve. Do the compression check!!
 

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Since you've done all the standard checks and you were able to get the vacuum up to 14 with a maxed out advance I suspect the timing chain has jumped a tooth. You will need to pull the cover and check the cam timing alignment. /forums/images/icons/frown.gif
 
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