Cam Shafts

[wade]

hey guys i have a 72 bronco roadster i just biult it has a fresh 302 in it , i just found a 351 winsor for it that i want to build, can any body tell me what kind of cam shaft to go with. I want the 351 to lope, but not to wild, and with my new cam do i have to change valve springs.

 

[BigNasty]

Before saying anything about what to go with.. can you get the casting #s off the block, or do you already know exactly what vehicle and year it came from?

The casting # on mine is just above the starter.

You can get all the lope you want with a factory lift rate on the cam with just getting one with a longer duration. Depending on how old the engine is, hoiw long since it was rebuilt etc would be the determining factor for myself with whether or not to get new springs for a stock lift replacement. If recently rebuilt and low miles, no, I wouldn't change the springs. ( I dislike loping.. the last big lift cam motor I built, I used Rhodes lifters to make it idle glass smooth /emoticons/[email protected] 2x" width="20" height="20" /> )

But if it has been a while or high mileage since its last build, yes, I would change the springs just to ensure they are all strong.

If going with a higher lift cam (any higher at all that is) then yes, new springs as they will need to be closely matched to the cam (spring return rates) to ensure the valves don't float (not fully closing from weak or slow springs) which will limit your rpms and power.

And with new springs, new keepers need to be used, may as well change the valve seals since you'll have the springs off, new timing chain, rotating the engine by hand, possibly using cly in the cylinders to make sure there will be no valve slap (if going with an overly large lift) new rockers may be needed with a higher lift cam also as the factory rocker slots may be too short and cause the rocker to act like a pry bar and pull the rocker studs out of the heads ( I had this happen on my 351w.. the fellow that rebuilt it used the factory rockers on a high lift cam and it resulted in all the studs being forced out of the heads)

 

[wade]

I am completely rebuilding this engine, like boering it out, getting the heads machined, getting springs checked and valves replaced.

I was told if you go with a high lift cam you might have to change springs, however I was also told if you go with a duration of around 268 to 272 you won't have to change the springs. Would this duration give me a definate lope? The lope that I am looking for is a lope that will be dependable on the engine, the engine #09ae-6015-ed15.

 

[Seabronc]

Wade, I don't mean to sound harsh or like a wise guy, but I suggest that you at least go out and buy a couple of books on the subject. That way you will have a better understanding of what you are doing. You will find some pretty good books at Borders or Barns & Nobel, etc. on the subject of Ford engines and the effects of what you would like to do. Also, I seem to understand you are having the engine rebuilt. If so, the rebuilder should be a great source. It's not like their first engine is it? Most rebuilders will do it to factory spec unless you tell them what you want and that is the best time to make the internal changes. Believe me, if they rebuild, they also build performance engines.

Good luck,

>-

 

[BigNasty]

Are you sure the first number is an 0 ? and not a C ?

Also look at the heads, at the plugs, are the plugs the large thread base?

If so, it sounds like a generic 1969 351w (knowing the year makes it a lot easier to find and buy the parts )

As for the springs, since you are rebuilding anyways, change them to match the cam as different lifts and durations will need varying spring strengths and rates.

The duration you posted "duration of around 268 to 272" will give a nasty lope and will most likely give you problems towards vaccuum and running good, especially in the mud and on trails.

Check out this chart on durations and effects and needs of engines, it might give you a better idea of what you want to do.

http://engineparts.com/Motorhead/techstuff/cam.html

The biggest question is, are you rebuilding it or is a shop doing it for you?

 

[wade]

I am biulding it, i built my 302 and its awesum, but this 351 is just for fun, i talk to some engine biulders and they say a diration around 268 would be perfect, but after looking at your chart i see their wrong. sorry the first letter is a D not an O, the spark plugs threds are very small. thanks for giving me some insight, you seem to know what your talking about. I can put to gather an engine not a problem, but when talking high performance i need to ask lots of quetions.

 

[Seabronc]

Sorry Wade, didn't get that from your original post. Any way, if this is to be a street engine, it is suggested to select a cam that gives you the best torque between 2500 and 4500 RPM. Also for street a cam a lobe seperation of between 108 to 114 degrees. The lower sepertion will give you more of a lope where up near 112 will give the smoothest running. Below 108 will give poor streetability. It is also sugggested to keep your lift profile under .500 in. lift to keep from beating the crap out of the valvetrain and to prevent problems with valve to piston clearances.

Good luck,

>-

 

[Guest_Toby the Dancing Bronco]

One of the things you need to consider when selecting a duration on a cam is the type of transmission you are running. A manual doesn't care about duration, but an auto does. More duration=less vacuum. Back before I found dirt, I liked the .500 lift/310 duration 114 overlap grind infront of a Ford Toploader. Lots of power, sound and snap. There are ways to get around the vacuum issue for an auto, but you can accomplish the same type of performance you want by trusting your machinest in a speed shop! Almost every cam manufacturer carries whole kits of lifters, springs, retainers and keepers. This is a good and inexpensive way to make sure all your parts go together. Have fun!

 

[wade]

Hey Wade here I found a cam what do you guys think of this cam, its a comp cam. 218-226 493-512 this is diration and lift Im also getting springs, retainers and locks to match.