1987 Ford Corsair Carb Problem ?

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jamie2666

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Nov 23, 2019
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18
Vintage Ford 460s were notorious for timing chain wear. The rest of your issues are likely carbon build up and/ burned valves.
Thanks Donn. I was hoping since it had relatively low mileage for the year, 50,000 miles, that maybe the timing chain wouldn't be the issue. But I'll look into it! Would that cause both low idle and high idle ? I've read a worn chain can cause a rough idle. I should have mentioned too that the low idle is only in drive after driving for a bit.....if you switch it into neutral or park then the idle is fine. But, like i mentioned, sometimes at a stop light, in drive, the idle is way too high....and other times normal. But thanks again!
 

jamie2666

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Nov 23, 2019
Posts
18
You were given some good advice in your related thread here:


Based on what you describe about the idle, my vote is for the timing chain acting up.
Thanks! I probably should have combined the EGR thread with this one. Sorry! I thought that was a separate issue.
 

TheBar

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Jun 25, 2018
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Timing chains or burnt valves don't case intermittent problems. Vacuum leaks can and there are many places where leaks can occur besides the vacuum lines. Get a vacuum gauge on it when it idles rough. Click here to diagnose your engine.
 

jamie2666

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Joined
Nov 23, 2019
Posts
18
Timing chains or burnt valves don't case intermittent problems. Vacuum leaks can and there are many places where leaks can occur besides the vacuum lines. Get a vacuum gauge on it when it idles rough. Click here to diagnose your engine.
Thanks again. Next up is to buy a vacuum gauge, that page is very informative. You're probably right with the vacuum leak or some sort of vacuum problem. When I put the new carb on I had to eliminate some of the vacuum lines as the old carb had two fuel bowl vents and the newer carb didn't. Although this intermittent idle issue was present before I swapped carbs. I have thought about completely de smogging it just to get rid of all the extra lines in there and air pumps, etc. and clean up that engine bay a bit. Internet seems to be split on whether that should be done or not though.
 

donn

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Nov 8, 2009
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One other thing to check. The distributor. The advance plate can freeze up which will cause your problems.
 

Old_Crow

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Nov 20, 2016
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Mt Laguna, California
I have thought about completely de smogging it just to get rid of all the extra lines in there and air pumps, etc. and clean up that engine bay a bit. Internet seems to be split on whether that should be done or not though.

Sort of depends on which state you call home. In Arkansas you can get rid of all that stuff and even cut off the catalytic converter. I wouldn't try it in California, at least if you plan on renewing your tags.
 

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