Timing carb set 300 6cyl

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1968_ONEHUN
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Timing carb set 300 6cyl

Post by 1968_ONEHUN »

I'm on the look out for a manual,but does anybody know the timing set up #'s and the initial air screw adjustment for a 1979 300 6cyl .Is their anywhere on the net for this info???
1968 F-100 Custom Cab
300 6cyl 4spd


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re: Timing carb set 300 6cyl

Post by FORDification »

The timing should be set to about 10 degrees BTDC....you can fine-tune it from there for best performance.

As for the idle mixture screws, the suggested method is to individually screw each one in until the engine starts to run a little rough, back it out until the engine just smooths out again, and then run it back in about 1/2 turn. That's the way I've always done it, anyway, FWIW.
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ChiefRedcoles38
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re: Timing carb set 300 6cyl

Post by ChiefRedcoles38 »

Keith, isn't there a difference in timing between a automatic and manual trans for that year? I don't have my info handy.
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muchtomydelight
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re: Timing carb set 300 6cyl

Post by muchtomydelight »

there is usually a 2* difference between auto and manual timing- i assume for drivability reasons.
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re: Timing carb set 300 6cyl

Post by FORDification »

I don't have my book handy either....the one I have here that covers that year doesn't cover trucks. :(
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willowbilly3
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re: Timing carb set 300 6cyl

Post by willowbilly3 »

My experience on anything built in the 70s is that base timing is just a rouigh guidline anyway since gasoline has been totally reformulated since then. Also the 79 is a nightmare of vacuum controls and the vacuum advance has at least a couple things that need to be checked ot just bypassed if you don't have to have an emissions test. One is the thermostatice vacuum control, probably in the thermostat housing. This only allows vacuum advance after the engine has warmed up. It may be a combination valve that has more than 2 hoses running to it and controls other things too. Then there will be a vacuum delay in the line too, usually these dodn't go bad. If you can locate the ported vacuum on the carb, you can just run a hosew directly to the distributor and bypass all that stuff. I am not sure if they were still using the dual vacuum distdibutor on 79s or not but that adds a bunch more hoses. You can just eliminate the secondary vacuum stuff all together. Then time it at 10 and if it pings back it down to 8. I do all my timing with a dialback light and would be lost without it. You can check the vacuum and mechanical advance with it and you need to know if that stuff is working or not. It also has a tach which makes setting idle ect. easy.
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1968_ONEHUN
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re: Timing carb set 300 6cyl

Post by 1968_ONEHUN »

all the smog stuff has been taken off by a previous owner.All I have,is a vac line from the dist to the bottom of the carb.I am not even sure yet if the vac adv. is working or not.How do I find out ????
1968 F-100 Custom Cab
300 6cyl 4spd


If it ain't broke,what the hell, fix it anyways !
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willowbilly3
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re: Timing carb set 300 6cyl

Post by willowbilly3 »

suck on the hose with your mouth when the engine is idling. You should hear the engine speed up.

I was just reading my last post. Geez I need to remember to proof read, what a bunch of typos.
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re: Timing carb set 300 6cyl

Post by NM5K »

Also, should see the timing advance when you give it gas. "Using a timing light". One thing about the port on the carb....make sure you are on the correct metered port. Mine has two or three ports total. The only correct port for vacuum advance is the one that has no vacuum at idle, "or very little", but increases as you give it gas. The other ports give full vacuum at any speed. This will mess up the advance operation big time if you connect to one of the "regular" vacuum ports. MK
1968 F-250 / 300 six / T-18
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