Need advice, ready to buy cam

[addo]

Stock 250 cam specs?

It's dual profile; think the intake is about 252° advertised duration. Maybe an extra 6° on the exhaust. Not sure on the lobe separation. I measured 221 thou lift on the intake and 229 thou on the exhaust but you need to multiply that by the nominal rocker ratio. Cam timing is reasonably described as "retarded".

BTW, I think you need the JP5608 timing set if you want a multi- adjustable one. May be worth checking with Az.

 

[CZLN6]

Howdy Ronn and All:

Recess is over!

On the stock 250 cam my research says, it is rated at 256 degrees, with .245" lift at the cam for a total lift with 1.5:1 rocker arms of .368". It is a straight up cam, but the corresponding timing gear, for the last few years of production ('72 - '80) retards it by 4 degrees. If you were to use this cam, you would be wise to use an earlier ('69 - '71) straight up timing set.

A straight up cam that's retarded is not the same as the dual pattern cams AzMike has. A retarded cam steals from one side to help the other. A dual pattern cam uses two different profiles, varying duration profile and lift. In the stock OEM 250, retarding the cam timing, was done to help the low rpm range at the expense of the top end. It also improved idle quality and emissions. For a vehicle weighing close to 4,000 lbs, with an automatic, and a 2.79:1 gear ratio, choked down with EPA stuff, it may have been the right thing to do. For your circumstances, it is not.

I have never seen duration or lift specifications at .050" for this cam, but I'm betting at .050" it would be lower and later.

If you're going to spring for new valve springs and expect to see the high side of 5 grand frequently, consider the '66 - '68 289/302 spring. They are Part #212-1165 At NAPA. They have a 2" free height and are rated @ 60# open and 175# compressed. Be sure to stay below a seat pressure of 100#.

Another stock choice would be the exhaust valve springs from a '73 - '78 302, rated at 80# open and 200# compressed. The NAPA part # is 212-1059.

Adios, David

 

[Ronn]

Cool, so the 60# springs will or are the same dimensions as the old? Basically drop in? Maybe a shim to get around 70#?

Well depending on how well the engine was balanced, I would like to see if going into the 5K realm is doing anything but sounding sick lol. my current stock as stock gets inside the block 250, does'nt produce anything past 3800.

 

[CZLN6]

Howdy Back:

Yes, both of the NAPA springs listed above have a 2" free height and are the same diameter as the 200/250 OEM springs.

Note- even though FoMoCo used the NAPA #212-1059 springs on the exhaust side, I'm suggesting it can be used on either the exhaust or the intake side with no problems.

The key to going past 3,800 rpms is the total engine package. Building a strong short block with the right cam for the job is the foundation.

Adios, David

 

[Ronn]

Thank you very much. I am now going to order the cam tonight, and pick up the springs monday. I can't wait to get done and running. This project has been in the making for over 4 years now :roll: But with yall helping, this should be decent when done.

Doing some of this is going to help me determine exactly what to use when I rebuild the 250 I'm yanking out. That one will have more work done than this though. And with the Argie heads coming...and even the aussie, supercharging, and after market multi point injection kits.....oooowee and about $5K later I should have a screamer. But then again, for 3500 I could have a new crate tickford turbo'd 250 dual overhead cam 300+ HP......you know 8)

Thanks again

 

[Ronn]

I just bought the cam. Same as we talked about cept 110 degree lobe.

I'm gonna go ahead and use a higher stall convertor. Although this cam says it's good from 1600 and thats what I have now is a 1600 stall, but as we know, or at least as much as I know. is that you want to be a couple hundred past and also the looser slush won't transmit as much shake from the engine to the wheels. But transmit rubber to the pavement is fine

I have a feeling this will all come together. Thank you.