This may be a little too specific for this particular forum, but the question relates to the cam I am going to install in my 351M.

I have a program called Desktop Dyno, or Dyno2000, and there are some specs in the cam field that are labeled "IVO, EVO, IVC, EVC" and these are ATDC, BTDC and straight. I know about Top Dead Center, but I don't know what these IVO and EVO, IVC and EVC terms are.

The person who gave me this program told me to input the following numbers for my 351m motor and I would like to understand why.

IVO (BTDC) -1.0 IVC (ABDC) 39.0 IVO -1.0 IVC 39.0
EVO (BBDC) 42.0 EVC (ATDC) 2.0 EVO 42.0 EVC 2.0
ICA (ATDC) 110.0 ECA (BTDC) 110.0 ICA 110.0 ECA 110.0

I sonewhat understand this has some relation to setting the cam straight up and also to do with the timing, but I am trying to understand more than just that. Any help is appreciated.

 

Intake Valve Open (IVO)
Exhaust Valve Open (EVO)
etc.

Did they state what the lift value was for the cam timing? Usually either .002 or .050. These numbers are useful for degreeing the cam.

Edit: looking again at the values you posted, I'd say that the numbers are for .050 lift. Do youself a favor and set the cam slightly advanced, maybe 2 degrees.

 

Good answer PC. My question is why should the cam be slightly advanced?

 

Why advance the cam? Two reasons; First is that it helps a little with low-end power. Second it that before very long, the timing chain will stretch a bit and it will end up right were it belongs.

 

Ok, sounds reasonable

 

Yes, they did tell me to set the cam specs at 0.050 lift. The cam I am actually going to use has a 0.513 lift and 268 duration.

 

Those valve openings and closings are for a cam with 218 degrees intake duration and 224 exhaust duration @0.050. The 268 duration refers to the seat-to-seat intake valve timing, the exhaust valve seat-to-seat timing will be longer than 268 degrees. The lift is probably higher than 0.513 on the exhaust valve.

 

BTW, ICA and ECA are

Intake Centerline Angle (110 degrees)
Exhaust Centerline Angle (also 110 degrees)

So your LSA (Lobe Separation Angle) is 110. Good mid-range torque, slightly lumpy idle.

 

Ok, before I put my foot further in my mouth, I'll just tell you the cam I am looking to use.

It is a Comp Cam and the part # is K-32-242-4 and the model # is XE262H.

You're right, it has a 218 duration on the intake side at 0.050 and a lift of .520 on the exhaust side.

 

What are your goals? Sounds like you've already gotten some advice about a cam.

Someone who posted here a while ago was a Ford Technician who worked on some projects. As I recalled, he described building a 400 project engine with OEM parts. As I recall, they used a 75 351M truck cam set straight up (he said it was a pretty decent part), 351C heads, recurved distributor, and rejetted the 2V carb, and got a ton of power. Gotta love making power for cheap.

 

Yea, that sounds like fun.

My goals are to make about 400HP into this engine. It is going in a 78 F150, so I have no interest in racing it or anything like that. I want some real power for regular driving and towing.

I got an article from Hot rod dated June of 1998 where some guys build a 400 with 465ft.lb. or torque and 380HP for under $2k. That is about what my budget is, so I wanted to try to duplicate that.

I have had this truck for 10 years. My dad bought it brand new in 1977 and gave it to me 10 years ago. Unlike the stock 140HP that is came with, I want to notice something when I hit to pedal from now on.

 

I'll bet a guy could get 250hp from a 351M just by retuning.

 

They came stock from the factory with 140HP. The heads aren't worked at all, the cam was around a .190 lift and only a 2BBL carb was used. But it is nice to know that with just a little work, you can get some raw power from them