Carter YFA Alaska Bound?
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Senior User
Joined: Jun 2001
Posts: 121
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From: S.E. Alaska
Carter YFA Alaska Bound?
I changed my intake and exhaust manifold gaskets on my 84 unemisioned 300 with carter yfa manual choke. Ran the same as before, with low vacuum (like 12-15). When I went to adjust the air/fuel mixture the vacuum gauge wouldn't move through the whole range of adjustment! The engine is tired and I'm getting some blow by. What would cause the air/fuel adjustment to be worthless through the whole range? I'm heading for Alaska and would like to get it sorted out before. Thanks.
Elder User
Joined: Apr 2004
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Things that also effect vacuum, ignition timing, leaks at power brake unit or a bad check
valve, pcv valve. carb screws loose. Since you say adjusting the carb does no good is the engine idle speed correct. Take a good look at the carburator first. Also does the reading go up after you race the engine.
valve, pcv valve. carb screws loose. Since you say adjusting the carb does no good is the engine idle speed correct. Take a good look at the carburator first. Also does the reading go up after you race the engine.
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Senior User
Joined: Jun 2001
Posts: 121
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From: S.E. Alaska
If I rev it the vacuum goes up to about 20 under full load (after zeroing first). I adjust it with the brake booster and vacuum advance disconnected and timing set at 10 degrees. There aren't any screws loose and all vacuum ports are capped securely. I got it to adjust maybe 1" of mercury through the full range of adjustment but the vacuum at idle is still only 13". The gaskets are all new and secure. I checked the manifolds for any leaks and they are fine. The PCV valve is functioning as it is oiling the air cleaner lightly. The only thing I can think to do now is check compression. It will pull stumps in 4-low, but I think that is more a function of gearing than an indicator of potential power.
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Senior User
Joined: Jun 2001
Posts: 121
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From: S.E. Alaska
I am driving up to Prince Rupert and then taking the ferry to Wrangell in Southeast, it actually gets colder here in southern Utah than Wrangell! I lived outside of Fairbanks for four years and it was block heaters or wait until summer there. I'll have to check the temp's through BC but I dont think I'll need one skipping the Yukon Territory and the Interior of Alaska.
I'll try advancing the timing with the vacuum gauge on. What criteria can I use other than spark plug color and knocking/pinging to know when I have it right?
I'll try advancing the timing with the vacuum gauge on. What criteria can I use other than spark plug color and knocking/pinging to know when I have it right?
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Senior User
Joined: Jun 2001
Posts: 121
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From: S.E. Alaska
I just went out to check the timing for the fourth time in three months and lo and behold NO MARK. Fixed the timing and voila! 4 more inches of mercury! It's getting 17 plus now on the vacuum gauge at over 3000 feet which translates to over 20 at sea level. Good enough! Thanks for recommending timing! Had my head in too far I think! Runs a lot better as you can imagine!
