Camshaft Opinion

Dear Skoczek,

          I am involved with building an engine and we went through this in January.  We had  specs for a custom cam and discovered that actual cam blanks for hydraulic cams were very scarce.  A significant effort finally located a cam manufacturer with blanks and after a six week wait for them to complete the orders in front of us, we finally had the cam.

           I am not fluent nor adroit with cam specs translated to ordinary understanding, but the lift does seem rather high.  Also the scarcity of on-the-shelf cams may possibly have motivated Comp Cams to recommend what they have available.

          I would suggest getting another opinion.  Try Jones Cams.  They're old school and do custom cams.  They also provide camshaft recommendations without charge.  You could compare what they recommend with the Comp Cam spec card.

                    http://jonescams.com/street-performance/

         Now is the time to  put on the proverbial brakes and make sure that you have the cam you want, although be prepared that obtaining it may be challenging and cause some delay in completion of the engine build.

                Warmest regards, Chuck Engles

Thanks Chuck!  I contacted JonesCams and they are putting together a profile for me.  I really appreciate your feedback.

When I was spec'ing my cam about 10 years ago, Comp Cams recommendation also was the biggest lift cam.  When I questioned the tech about the specs, he just kept telling me, "Trust me! I've been doing this a long time.  This is what you want.  You won't be happy with anything less."  And he just kept repeating the same line like a broken record when I asked for more information about why he recommended those specs, or specifics on driveability and vacuum.  I wouldn't trust Comp Cams to recommend a custom camshaft.

Interesting. It's going to idle around 850 and have about 14 inches of vacuum.

For a street car it is close to a MAX cam. I'm running three  CompCams in three different engines.

The one in my Pantera is the solid lifter, .606 lift and 244° @ .050. It is border line liveable on the street. If it was an everyday car, it would be too hot,

Your 230° intake duration is going to make yours rather civil.

Here's the thing though. With that lift you are going to need more than "average/normal" maintenance. Mostly you should change out the valve springs periodically for safety. They aren't going to be 30,000 mile items.

You may experience push rod and rocker arm related failures as well?

It is going to have VERY decent off idle torque and power, a HUGE mid range and scream in the upper rpm's. Likely this is what the "tech" told you and if so,  he's right.

I can vouch for the CompCams tech information. It is largely accurate.

180's in a Pantera are "tuned" for 6,700 to 6,800 rpms'. You can change that a little by playing with step tube design of the primaries or enlarging or decreasing the ID of the pipes but not drastically. The engine will turn way more then that but you may experience a flat spot right there or seem like you are suddenly pushing a stack of bricks up a hill so really the lift of that cam is PROBABLY unnecessary? With Cleveland heads right around .588" actual lift is where they seem to max out.

A .624 lift is getting up there with the 8,000 rpm engines and with hydraulic lifters, that is somewhat of a contradiction since those are likely somewhere around a 7,200 rpm float. At least that's where mine did?

Cams being what they are you need to run them in YOUR application to see if they are filling the requirements. In that sense, the results are unpredictable since YOUR interpretation MAY vary from the theoretical predictions.

One additional comment here. George's cam profiles are similar to the stock CJ cam with more lift.  A 113° center line cam is something generally you would do with an exhaust that has issues. The PORT itself, not necessarily the back pressure of the exhaust system AFTER the port.

An example of that would be the Ford FE series. It has a lousy exhaust port design regardless what FE series it is (all the exhaust ports are the same) which generally speaking you can't fix. As a result it doesn't respond well to 110° center lines and most builders recommend a 113 in that case.

The stock iron Cleveland head has a lousy exhaust port also. It was so bad that for Pro-stock racing it was radically sectioned and a 1" aluminum bar was added that corrected the port flow to almost straight up. Now I don't know the cam profiles that someone like Nicholson was using but it might have been even more radical then a 106°? Maybe a 104 with a ridiculous lift around .800?

The 110° in your cam won't hurt anything in the engine but the engine just won't be able to take full advantage of it. So with iron heads you CAN do what George did and go to a 113 and calm the engine down without loosing any power.

IF you were using something like one of the Ford aluminum "high port" heads the exhaust port configuration in them can take advantage of the 110. That just means that you will be able to get more horsepower out of the exhaust side of the engine. Maybe another 35 to 50 hp?

To say that aftermarket cam grinders don't know what to do with a Ford "Cleveland" style valve configuration is just not true. Chevy brought out the "mystery engine" in '63 and it's cylinder head was the basis for the "Big Block" Chevy head. They have similar port configurations, BUT an aftermarket cam profile with 110 centers is for an Ford Cleveland head that has had it's exhaust PORTS "corrected".

The issue with the Ford Cleveland iron production head is the bad exhaust ports.

Thanks everyone, all good information!  I thought maybe the intake duration may make the lift they chose to make more sense.  All my knowledge about cams is theory based, I have no working experience at the moment.  I'm thinking I'll probably keep with this cam, mostly because waiting another 2 months for core supplies to possible come available will set back the build, especially since every step of this build seems to cause a domino effect in needing another upgraded parts that may or may to be available due to supply chain issues.  Thanks again for all the insight!

@Skoczek posted:

Thanks everyone, all good information!  I thought maybe the intake duration may make the lift they chose to make more sense.  All my knowledge about cams is theory based, I have no working experience at the moment.  I'm thinking I'll probably keep with this cam, mostly because waiting another 2 months for core supplies to possible come available will set back the build, especially since every step of this build seems to cause a domino effect in needing another upgraded parts that may or may to be available due to supply chain issues.  Thanks again for all the insight!

It would be great if you let us know what the final results turn out to be once you are up and running and dialed in?

Absolutely!  I wish all posts like this had a beginning and an end.  

In my opinion that is too much overlap and lift for a 4V Head.

The big intake valve is angled more than, for example a Big Block Chevy, I think. So Overlap has a bigger effect on a cleveland with 4V heads. GeorgeP has written a lot about this here in the forum.

And because the Intake port flows so much more than the exhaust port (see link below), I would make the split between intake and exhaust duration bigger.

https://www.speed-talk.com/for...=10300&highlight

You can also see that the flow numbers flatten around .550 lift, so more lift won't bring much power but increase friction and stress on the valvetrain.

I went with 226° Intake, 236° exhaust, 113° LSA and lift is around .540 intake and .560 exhaust ( I don't recall the lift exactly).

The 180s surely dont make much backpressure, I have no experience with them.

This is just my opinion, hope this helps and as always: sorry for my bad english!

Those flow numbers are about what I have seen as well.

The cam application does depend on what you have done to the heads though.

The original heads have a built in "torque ring" just under the seat. They were originally put into the 70 Boss 302 heads because of "customer complaints" on the '69 Boss 302's with the 2.21 intakes as being sluggish.

I don't have any flow numbers on the  heads with the "competition" cut under the valves and can't get any of my friends with flow benches to comment on if there is an improvement or detrimental effect on that modification but my A3 heads flow 330 @ .600 and were built without the torque rings.

Even so the flow numbers will not indicate IF the engine can use the additional flow to make more power. It's entirely possible that the additional flow only makes more power at above useable rpm's  of the engine.

My information shows maximum flow at between .570 and .580.

As you point out and as I had mentioned, the issues with the iron heads generally stem from the exhaust port configuration.

The OP's cam is also a roller which uses a little different criteria and shows different results at different rpm's. They typically provide more low end torque then flat tappet cams can.

The overall timing of that cam is not radical and so what if it has more overlap? It isn't going into an automatic transmissioned car and isn't being used on an individual runner intake manifold.

Personally I think that it just would run just as well with about .025 to .030" less lift. Probably .570 to .580 would be about what to aim for which would be much kinder on the valve train components.

I have never heard of a "perfect cam profile" anyway. It just depends on what you find acceptable and not acceptable, which means you have got to run it and find out if and where you made a mistake in judgement. You can always change it for a better solution.