Lakes ????

[Squirtin Thunder]

Do you know if the '91 7.5L EFI (460) had a retard cam timing????
Thanks
Jim

[Squirtin Thunder]

OK the deal is my water pump is leaking and if I am going that far I was thinking of gaining a few extra hp by bringing the timing strieght up. It only has 451,000 miles on the engine and the water pump is original. I thought these things last forever?????????
Jim

[LakesOnly]

Compared to what engine?
In 1972, Ford effectively retarded the cam timing 8 degrees (by advancing the cam chain's crank gear by 4 degrees).
http://www.reincarnation-automotive.com/early-straight-up-crank-sprocket.jpg
http://www.reincarnation-automotive.com/late-retarded-crank-sprocket.jpg
Whether or not this applies to the computer-controlled FI motors is not known by me, but comparing its crank gear to the photos above will answer your question...I would think probably the later set.
LO

[Squirtin Thunder]

Believe it or not I have called about three dealers and they all say that they have no idea. They just replace them if needed. This is my first '91 that I have even thought of changing the timing set on. I usually deal with older ones. At the dealership that I worked at in NC all I saw were the GM ones, Black Pontiac GMC, imagin that right.
Thanks
Jim

[LakesOnly]

...water pump is leaking and if I am going that far I was thinking of gaining a few extra hp by bringing the timing straight up.
Jim
Jim, the cams on the later engines are ground differently...for a different power curve and so if you put the earlier timing set in with your 1991 smog cam, you will lose about 500 rpm top-end power (when compared to an early engine with the early set). Low end response will be improved, though.
LO

[hondajoey]

I was told on a fuel injected motor you need to put the timing in the factory location thats is where the Computer is calibrated for, i changed a cam in my 350chevy with TBI and changed the timing set and the summit rep advised me to leave it in the strait-up location due to knock sensors.

[Squirtin Thunder]

Yes if it had knock sensors that could be true but the knock sensorf will know if it it knocking at 20degs advanced too.
Lakes
This truck has 3.55 gear in it the highest it has ever seen is 4000rpms. and with the 33" tall tire it would help a bit, to be a little advanced I believe.
Put it this way the truck in overdrive turns 1900rpms at 75mph or so.
In town the thing is chugging along. I do think the reson it has lasted me so long was that the gears are so high and that FORD has one hell of a base 460 (7.5L).
Thank you
Jim

[Squirtin Thunder]

Well I found that the '91 F250 7.5L (460) came from the factory with a double roller timing set and they are straight up. I did show signs of wear, after 451,000 miles I guess its OK !!!! The cylinder presure is still at 162psi average. Now that is eather the Valvoline Dura Blend or just one Hell-of a Engine Ford made. It is still hard to believe though. But the water pump sucks it should have lasted forever. This is my first water pump replacement on this truck.
Jim

[058]

Only 451K?....just getting broke in. Be sure to take it back to the dealer for its 500,000 mile service. :D

[MudPumper]

You guys forgot...........JETBOAT

[Squirtin Thunder]

I just got back from test riding my F250 Land yaht. It handled the chop well. The holeshot is much better. That 2 degs advance was the ticket. Thanks Lakes and Steelcomp for the help.
Jim

[LakesOnly]

I just got back from test riding my F250. The holeshot is much better. That 2 degs advance was the ticket. Thanks Lakes and Steelcomp for the help.
Jim
My Pleasure. You just advanced your valve timing events by 8 degrees. Now your intake valve closes sooner (relative to crank orientaion) and you have greater dynamic compression ratio as a result. :cool:
And by the way, it works on all engines! Y'all keep it in mind when you're dialing in rpm range for your jet pump, or something like that.
LO
p.s.: You guys with non-computer controlled ignition systems: Remember to check your ignition timing and re-adjust as necessary after this modification!

[LakesOnly]

Well I found that the '91 F250 7.5L (460) came from the factory with a double roller timing set and they are straight up.
Jim
Oops, did I miss something here? The double-roller part is no surprise, but the timing is zeroed? Did you change your cam chain or not?
(Whatever the case, my above post remains true when this modification is made.)
LO

[Squirtin Thunder]

Lakes,
It was a big surprise to me. All the old BBFs I have delt with are that way, 4degs retarded that is. But with the RPM range of this truck it will help on the big hills and in town racing from stop light to stop light. And of course pulling that super unheavy Sanger Custom Sprint with the Little BBF up the Tahatchapis. Or towing those GM vehicals back from where ever they broke.
Thanks
Jim

[Squirtin Thunder]

Steelcomp watcha lookin at???
Jim