Timing a '73 300 inline six

Cliff · 02-13-2008, 06:00 PM

I need to set the timing on my 1973 straight six 300 (4.9 liter) engine. My Ford manual says to see the engine decal for the specs. My engine does not have a decal.

Can anyone please provide the specs for timing this engine? FYI--it has a one barrel carter carb and is a two wheel drive. It is all original--no engine modifications. So, I think that all I need is the original factory specs for setting the timing.

Thanks.

2/17/2008 -- Forgot to mention that my vehicle is a '73 F-250 truck. The original engine was completely rebuilt and I think that is why there is no decal or tag on the engine.

Cliff

ajpletcher · 02-13-2008, 10:57 PM

you dont have a metal tag on the valve cover? or there may be a info tag on the radiator support too.

G O R T · 02-14-2008, 04:23 AM

What vehicle?

jonmark1985 · 02-14-2008, 06:56 AM

10° BTDC

AutoZone.com | Vehicle Selection - Year

Cliff · 02-17-2008, 04:28 PM

It is a '73 F-250 truck.

Thanks.

Cliff · 02-17-2008, 04:32 PM

Today I tired 10 degrees BTDC and the engine dieseled like crazy when I turned it off. I set it at 6 degrees and thought it was fine until I drove it. 9 out of 10 times it is fine but every now and then it still diesels. I don't think the idle is too high. Do you think it could be a worn out carb? The engine was rebuilt recently but it has the the old carb on it.

Thanks for your help.

Cliff

jonmark1985 · 02-17-2008, 06:39 PM

could be a lean mixture

do you run ported or manifold vacuum for your advance?

Cliff · 02-17-2008, 09:39 PM

Sorry, I am not sure what "ported" vacuum is. The vacuum comes off of the carb. Just so I learn something, please explain the difference between "ported" and manifold vacuum. BTW, the carb is a Carter YF one barrel carb with an automatic choke. Don't know if that tells you anything but just thought I should mention it.

Thanks again for your help.

jonmark1985 · 02-18-2008, 05:47 AM

Ported vacuum is sourced from the top of the throttle blade. At idle ported vacuum won't be present.

Cliff · 02-18-2008, 03:23 PM

Thanks. I learned something new.

Ran the truck quite a bit today.

Engine still diesels on me. I think I am going to put a rebuilt carb on it. The cost is about $125 and I already have spent a couple of grand on rebuilding the engine and putting a new clutch. So, I might as well make it run well with a good carb.

I will see if that makes a difference. If not, I am going to concentrate on the timing again. But, if I have a new carb at least I have eliminated one source of the possible problem.

Thanks Jon for your help and the education.

Cliff