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?? Tune Up Specs. Slightly Modified 240 ??
Posted: December 16, 2008, 7:11 pm
by samdog66
I have a 1966 F100 with a 240.
The PO installed a 2 barrel Holley carb, a Clifford intake man., a Unilite dist. and headers.
What spark plug should I use?
What should the Gap be?
What should the timing be set to?
THANKS, Samdog.
Posted: December 16, 2008, 7:31 pm
by foghorn
As far as plugs i only use motorcraft and the gap stays the same as stock. If you havent changed the timming put a light on it and see just where it is first. Then i would call the PO and ask him if he remembers what it should be set at. When i did my intake gaskets i wish i would have checked the timming before i took it apart. I have it back to close but it still back fires a lil bit. So im still tweaking it a lil at a time till i get it right. Then im gonna see just where it is and mark it permently.
Foggy 
Posted: December 16, 2008, 8:16 pm
by Gary Seymour
I would start at 10 degrees initial advance without the vacuum advance. Bump it up if it doesn't ping on accelleration. Back it off a bit if it does. I was told you are better off with timing a little advanced from stock, if the engine can run hard without pinging. Pinging or predetonation is a kiss of death to an engine.
Posted: December 17, 2008, 8:13 pm
by samdog66
I have had this truck for about a year. It runs good except for hesitation when I accelrate in 2nd or 3rd.(three on the tree). Last week I changed the plugs. 5 out of the 6 were black. One was like new. The gap on the five black ones was .030+/-. The one clean plug was .036 +/-. The chilton manual says gap should be 0.32.
Any ideas? Thanks,Samdog.
Posted: December 17, 2008, 10:02 pm
by foghorn
Well IMO i would go with the 0.32 as the book says. With electronic ignition the plugs dont wear out near as fast as with points. I had a 1977 ranchero GT some years ago and did the first plug change at 75,000 and the plugs still looked like new.
Foggy
Posted: December 18, 2008, 10:17 am
by Truckfarmer2
If that is electronic ignition, you should be able to open the plug gap up to about .042".
Posted: December 20, 2008, 11:01 am
by needmoretime
I have the same engine with electronic only and run 42-44 on a stock plug. You can go one step hotter but do not try and run a new late model style plug that was degigned for fi. They cannot take the fuel/oil from an older engine IMO. You will be throwing away good money.
WK