camshaft on the 200 & 250 6 cyl

[Anonymous]

I have a '67 Mustang cpe w/the sprint package. Bought it from the proverbial "little old lady"(car has 23,980 documented original miles).
This lady never drove the car more than a few miles a day. Engine never broke in properly so am now rebuilding it. Crank needs turning, cam is shot, cylynders will hopefully not need reboring just deglazing.
Here's the big question can a camshaft from the later 250 cid be used in the 200 cid? 250 cam stock has a little more lift and duration than the stock 200 cam.



p.s. I am also going to install a dura spark ditributor to get rid of points and condenser worries.

 

[CZLN6]

Howdy My:

Yes, the cam can, but the cam gear is no interchangeable. The big difference, other than a slight difference in lift and profile, is that a cam for a 250 has reliefs ground in the shaft to clear the longer stroke swing of a 250 engine.

We are still researching this, but it appears that FoMoCo retarded late model cam timing in two ways; with the 250 they retarded the cam timing by changing the location of the key way. With 200s they seem to be changing the cam, itself. This would be true for parts after '72.

Also know that- a stock, late model cam with a 256 duration and .368" lift is not the same as an aftermarket cams profile. The 252 duration cam from Comp cams, with .425 lift will have a much more rounded profile, giving more duration and lift at say .050" and all the way through the profile. All Aftermarket grinders have cams in this range. The added lift will be a plus for any engine and, as long as the lobe centers are 110 or more, you should have good vacuum for an automatic and low end performance.

Also check with Mike at Ford Six Performance Parts for what he might have along these lines. Most likely the price of an aftermarket cam and gear will be close to what a stock piece will be.

Adios, David

 

[Anonymous]

Does this mean i'll have to change the cam gear depending on what the donor engine was for the dura spark unit that i have?

 

[JackFish]

On the Fairmont302 board a fellow mentioned he had just put a 250 cam in his 200. I asked for a bit more info and he replied:

What are the specs on the cam? Is it just a stock 250 cam?

Reply

Recommend Message 4 of 7 in Discussion
From: MSN Nickname49pjm Sent: 2/24/2006 1:37 AM
Yeah, it's a stock 250 cam from NAPA. I got the info out of that book the Falcon Performace Handbook. It's .30 over and balanced, and I put a Pre- smog Carter RBS.on it. I'm going to re-torque eveything this week end and start playing with the timing and the carb. I'm going to drive it back and forth to work. Sure beats a Jap econo box. Later Pat.

 

[CZLN6]

Howdy Back:

No, your distributor gear drive should be compatible with any aftermarket cam and with a 250 cam if you chose to go that way.

Comparing your stock cam to a later 250 cam- know that your cam has 252 degrees of duration and .348" of lift. The 250 cam has 256 degrees and .368". These cams are rated off the seat, not at .050". The rating at .050", like most aftermarket cams are rated is much more indicative of the profile. If you were to compare a stock type cam to an aftermarket cam with the same duration specs, looking at a lobe from the front the stock cam would appear to be a sharply pointed egg shape. The performance cam would appear to be a fuller egg shape. That's the difference. There's more to it than just the numbers.

You can easily make up the .020" difference in lift between the 200 and 250 cam by back cutting the intake valves or adding 1.6:1 rockers. If your stock cam was in good shape and you just wanted a little more, I'd say, "Sure, just add the high lift rockers". But since you're going to change cams you might as well step up to a real difference.

Adios, David

Adios, David

 

[Anonymous]

Looking at the spec stock 200 is .348 lift intake & exhaust with a duration @.050 lift of 178 degrees intake and exhaust. The stock 250 specs out at .368 lift intake/ehaust and duration @ .050 Intake 184 degrees/ Exhaust 185 degrees. Talking 252's and 256's is advertised duration and looks cool on paper but has no bearing on the reality of how the cam will truly perform.