To cam or not to cam...the debate continues...

[CobraSix]

okay...I finally got my timing cover off. Is it just me or is it easier to do in a car then on a stand?

Anyways...I'm starting to get the "while I was at it"s. Here is what I've got and plan to do:

Offy 3-1V with Autolite 1100s
Cliffy 6-2 Dual Exhaust
Port divider
Pertronix Coil (already in).
Dual Roller Timing Chain.

I have my trial engine torn down to the point where only the pistons, crank, and cam are left in the block. I know this is a perfect time to replace the cam. Should I?

I'm obviously looking for more performance...but my car is a nearly daily driver (at least 4 times a week during the summer) so I want a very streetable car.

Should I change my stock cam?
What degree should I go?
What companies (besides Cliffy) has some? (any links would be great).

Thanks,
Slade

 

[Anonymous]

Yes, replace the cam.

Comp, Crane, ISKY, Clifford, and a few other assorted dealers sell cams for these engines.

Probably a Comp 252 would be best if you don't want it at all rough and it will still get better perf then the stock junk. Or an ISKY 256 cam for a lil more wild. 8)

Most people use a Comp 260 or equivalent though it can be a bit soft off the line with an auto or a tall gear.

www.iskycams.com
www.compcams.com
www.cranecams.com
www.summitracing.com for the comp cam.

 

[MustangSix]

For a daily driver I'd pick either the Comp 252 or Isky/Crane equivalent. Add electronic ignition. But I'd skip the triple carb manifold and install a YF. RBS, or DGV instead.

 

[CobraSix]

Unfortunatly, I already have the manifold and the Head mods are in progress when I get some time.

I already have electronic ignition and a hotter coil.

I'll look at the 252 cams. Right now I have the 2.77 3Spd...but next winter will be putting in a T-5 so hopefully the gearing will be a little better.

Slade

 

[CobraSix]

I just got done re reading Falcon Six.

It seemed to imply that you do not want a performance cam and a roller rocker 1.6:1 lift as well.

Is this due to the increased lift and increased duration may cause the pistons to hit the Valves?

ALso...if I do not want both mods...which one is preferable?

Thanks.

Slade

 

[Guest]

The 252 is pretty close to stock. I'd at least jump up to the Comp 260 or Clifford 264 to help handle the extra breathing you'll get with the triple combo.

Al

 

[CZLN6]

Howdy Slade and All:

The caution on using 1.6 rockers with a higher than stock lift cam is to avoid piston/ valve interference.

Most cam manufactures advertise gross lift using stock rocker ratios. Also on a stock type log head any lift more than about .450" is wasted, and counter productive as it takes energy/hp to operate, as the head simply can't put to use any more flow.

If you measure and pre-fit I would guess that you could use 1.6 rockers with a 252H cam. But I would question the wisdom behind it. If you're going to a performance cam buy the lift you want in the cam and save the cost of the roller rockers. The decision might be if you're doing a complete rebuild add a performance cam. If your bottom end is in good shape, and you want a little more flow, go with the 1.6 rockers. They are a simple bolt on and add about .030" lift in a later model 200 with a stock cam.

 

[CobraSix]

I did some more reading:

From the Comp site...there 260 cam provides .440 valve lift over the stock .348.

By upgrading to a 1.6 roller rocker...my valve lift only goes from .348 stock to like .378.

So, would I really need a 1.6 roller rocker set up? Especially since the cam seems to be the cheaper, and all around better upgrade...right?

Slade

 

[CZLN6]

HowdyBackSlade:

Right!

The only reason to add roller rockers and a high lift performance cam would be for extreme performance or bragging rights. If you intend to run sustained high rpm/speeds roller rockers are a great durability item, reducing friction and side load on the valves. If it's bragging rights, you'd have to remove the rocker arm cover every time you wanted to get it up. Kinda takes the thrill out of it.

If I were in your shoes, I'd go with the Comp 260H with a standard trans, or the 252H with an auto. If that doesn't do it for you, you could always add the roller rockers later.

Adios, David

 

[MustangSix]

I dunno, Al. I think the 252 is a good bit stronger than a stock cam. The duration @.050 is over 200 degrees vs about 185 for a stocker. Also, lift on a stock cam is only .368" lift - pretty wimpy vs .4oh -something for the 252.

 

[Guest]

What do I know

Ize jest a hacker :roll:

Al

 

[CobraSix]

I think I'm going with Comp Cam.

I can get the complete kit for $272. That is the 260H cam, lifters, pushrods, timing set, valve springs, valve locks, and valve seals.

Much cheaper then the 1.6 Roller rocker sets that I've seen.

Slade

 

[Anonymous]

Question here!!

How close is to close?? (valve to piston clearance) IIRC I had .0115 .00115

one hundred and fifteen thousandths between the valve and the piston before I installed my roller rockers.

I'm not concerned about it because I've never had any problems but, whats the optimum clearance??

Thank's,

Doug

 

[CZLN6]

Howdy Doug:

Most "Experts" recommend .012" on the 200/250 stock dished piston. Stock type cast pistons don't grow as much as forged, when heated to operating temperature. .0115" is right in the ball park. If you used 1.5:1 roller rockers you will not have a problem. It you used 1.6:1 rollers you just lost all valve to piston clearance and then some. Best hope that some of you measurements were a little short.

Clearance is critical when; time and wear set in loosening everything up a bit, valve float occurs (heaven forbide), carbon builds up, high rpm is sustained and things get hot and grow.

I hope that helps without scaring you to much.

Adios, David

 

[MustangSix]

Are you guys maybe a decimal place off? one hundred fifteen thou is .115 not .0115 (eleven and a half thou).

 

[Anonymous]

Jack, I get confused easily :roll:

David, Thats a little scary but I've had no problems yet...Blocked decked to 0, HSC flattop pistons, head milled .040, steel shim headgasket, 272H cam and 1.6 roller rockers.

Hopefully my measurements were off quite a bit.....

Thank's,

Doug