hydraulic cam for 2v heads

hydraulic flat tappet or hydraulic roller tappet $$$?

Well that is the ultimate question and one that I was also going to get you to touch on, the pros and cons. I was thinking of a flat tappet from a money point of view. I was thinking this route was better for me because I have the correct length push rods,using ford racing roller rocker arms, and may not have to up grade the valve springs from what I have now. If I go roller,then complete valve train will need upgrading.And how important is it having the valve spring seat cups? should I upgrade?
In comparing a flat tappet to a roller camshaft, both the same spec, would the roller produce a flater torque curve, or would it just flat out make more power all around over the flat tappet.I'm not building a race engine just one for the street but looking for that torque kick and as you put it, good street manners.But I'm thinking from the reliablity point of view, the flat tappet is the better way ( I'm worried about the roller needle bearings failing).
Your opinion on this is very welcome, thanks Mark

Hydraulic roller valve train having the same capabilities as a flat tappet valve train requires more valve spring force, and of course that means in the long run a faster wearing valve train. Hydraulic roller valve train is more expensive. Hydraulic roller tappets operate with a tremendous amount of side thrust friction that is not found with flat tappets. Using roller tappets does not mean the motor can use any oil, because the distributor drive gear still needs ZDDP.

In regard to the angst that exists regarding flat tappet cams and premature lobe wear, my best advice is to never make a decision based on fear, that's irrational. I go round and round with younger guys debating this issue. In their minds there is some mysterious force at work that makes flat tappet cams fail unpredictably. But decades ago we installed flat tappet cams in our motors and never thought twice about the possibility of premature failure. If flat tappet cams fail prematurely today there is an understandable explanation for this. I think it must boil down to either (1) an oil issue (lack of ZDDP); (2) a QC issue, i.e. the parts were not made of the same materials used decades ago or were not heat treated properly; or (3) a performance issue, meaning the flat tappet lobes of our street cams today have faster lift rates, require more spring force, and therefore wear like race cams did decades ago. So my solution is (1) to use the right oil, (2) to custom order the cam requesting the cam grinder's best heat treating and best lobe polishing, and to use the best lifters possible, and (3) to avoid using the highest lift rate camshaft lobes or excessive valve spring force. Taking those steps should get a person a cam that is at least as durable as the cams we purchased off the shelf decades ago.

In regards to performance, comparing the profile of a hydraulic roller tappet lobe with the profile of a hydraulic flat tappet lobe both having the same advertised duration, the hydraulic roller tappet lobe will have less duration at 0.050” but more valve lift. We can make a powerful motor with either type of camshaft, the hydraulic roller cam simply substitutes valve lift for duration at 0.050". Lifting heavier valve train components (i.e. the roller lifters) faster and higher is the reason the hydraulic roller cam tends to negatively impact the high rpm capabilities of a motor. I do not consider the hydraulic roller tappet as having more potential than a hydraulic flat tappet in a street motor application. Ultimately both technologies have limits, increasing flat tappet duration will hurt drivability, but increasing roller tappet lift requires more and more valve spring force with an increase in the rate of valve train wear.

I go back and forth in trying to decide which type of cam to install in my next motor. Although I like roller cams, I think today's hydraulic flat tappet camshaft lobes offer the better balance between lift and duration. I believe that balance is exemplified by the 3 Cleveland friendly hydraulic flat tappet grinds I offer to folks.

Cobra Jet camshaft
Grinder: Bullet Cams
Intake: Lobe #H275/318
Exhaust: Lobe #H285/324
-----------------------------
275°/285° advertised duration
280° average duration
Exhaust valve opening = 80° BBDC
Intake valve opening = 25° BTDC
50° overlap
Exhaust valve closing = 25° ATDC
Intake valve closing = 70° ABDC
------------------------------
225°/235° duration @ 0.050
0.550"/0.560" valve lift
115° lobe separation angle
Int lobe mathematic centerline = 112.5° ATDC
Ex lobe mathematic centerline = 117.5° BTDC


Boss camshaft
Grinder: Bullet Cams
Intake: Lobe #H285/324
Exhaust: Lobe #H295/324
-----------------------------
285°/295° advertised duration
290° average duration
Exhaust valve opening = 85° BBDC
Intake valve opening = 30° BTDC
60° overlap
Exhaust valve closing = 30° ATDC
Intake valve closing = 75° ABDC
------------------------------
235°/245° duration @ 0.050
0.560"/0.560" valve lift
115° lobe separation angle
Int lobe mathematic centerline = 112.5° ATDC
Ex lobe mathematic centerline = 117.5° BTDC


¾ Race camshaft
Grinder: Bullet Cams
Intake: Lobe #H285/324
Exhaust: Lobe #H295/324
-----------------------------
285°/295° advertised duration
290° average duration
Exhaust valve opening = 81° BBDC
Intake valve opening = 34° BTDC
68° overlap
Exhaust valve closing = 34° ATDC
Intake valve closing = 71° ABDC
------------------------------
235°/245° duration @ 0.050
0.560"/0.560" valve lift
111° lobe separation angle
Int lobe mathematic centerline = 108.5° ATDC
Ex lobe mathematic centerline = 113.5° BTDC

The 3/4 race cam is simply the Boss cam with narrower lobe centers. It offers a lopier idle, less manifold vacuum, a narrower power band, but a steeper torque curve and higher peak numbers. It may get you around a track (on track tires) faster, but on the street or a winding mountain road I would prefer the boss cam.

-G

Custom ground solid flat tappet camshaft

Grinder: Bullet Cams
Intake: Lobe #F285/355
Exhaust: Lobe #F295/358
-----------------------------
285°/295° advertised duration
290° average duration
Exhaust valve opening = 85° BBDC
Intake valve opening = 30° BTDC
60° overlap
Exhaust valve closing = 30° ATDC
Intake valve closing = 75° ABDC
------------------------------
250°/260° duration @ 0.050
0.585"/0.590" net valve lift (0.029" lash)
115° lobe separation angle (camshaft degrees)
Intake lobe mathematic centerline = 112.5° ATDC
Exhaust lobe mathematic centerline = 117.5° BTDC

This was the cam spec you gave to mustangjp for a solid lifter engine with 2v heads. Would you likewise increase lift on a hydraulic cam grind for an engine with 2v heads or should I just stick with your hydraulic boss camshaft grind.
One last question, what do the lobe numbers mean #H295/324, H285/324, are they Bullet Cams blank camshafts for grinding?

Lastly just wanted to say I enjoyed reading your cleveland buildup stickys, great detailed information on an engine I think is special in ford engine line up. Thanks Mark

Besides what George recommends on cams, do not lose sight of the fact that "little bitty 2-V heads" carry larger ports and valves than any stock SBC. They will work just fine in anything short of racing for money. I know of one Pantera running Aussie 2V heads and a hydraulic cam that was clocked at a Nevada open road event at 182 mph, right on the rear bumper of a 750-horse race-prepped Viper (to his great surprise).
It's just that the more showy 4-V heads had big-block-sized ports and valves in comparison to the much more streetable 2Vs.

I may be misinterpreting what I read and see about the 2v heads but what I see is the intake ports have terrible line of sight to the valve.

They positively go the wrong way.

The exhaust port is very resrictive.

The dyno tests I have seen show that any lift over .500" with those heads is a waste because they absolutely stop flowing right there at .500".

182mph is very impressive and the car probably wouldn't go any faster with better heads but maybe the time spent waiting to get there would have been more...interesting?

Performance is relative I suppose, and everyone has a different perspective on what is performance.

The 2v heads aren't my choice to invest anything into.

quote:

Originally posted by ski:

Would you likewise increase lift on a hydraulic cam grind for an engine with 2v heads or should I just stick with your hydraulic boss camshaft grind.

A solid flat tappet lobe can open a valve at a faster rate than a hydraulic flat tappet lobe, therefore the solid flat tappet version of this cam has a little more net valve lift than the hydraulic flat tappet version. Although the advertised duration specs and event timing specs are identicle, they are actually using two completely different lobes.Just compare the duration at 0.050" specs and you'll see the solid flat tappet cam has more "area under the curve" as they say.

The amount of valve lift of the hydraulic flat tappet version of this cam is a characteristic of the lobes I've chosen, it can't be altered unless we specify completely different lobes or expensive rocker arms with a lift ratio higher than 1.73:1. I chose these lobes because they possessed several key characteristics and I wouldn't change them. The valve lift is adequate ... especially for 2V heads. An unported iron 2V intake port hits a brick wall in the air flow curve around 0.400" lift.

Opening the intake valve 0.560" is actually quite a lot, Ford's first racing cams for the 351C only had 0.589" net valve lift, so this hydraulic street cam is just shy of that amount.

quote:

Originally posted by ski:

One last question, what do the lobe numbers mean #H295/324, H285/324, are they Bullet Cams blank camshafts for grinding?

Bullet cams has a catalog of hundreds of lobe profiles to select from, the lobe numbers are simply their way of identifying each profile. My spec provides enough information to them to grind the camshaft, just copy & paste it.

quote:

Originally posted by ski:

Thanks Mark

you're welcome

Thanks for the comments guys. I actually do have a set of 4v heads but have not been happy with them for the street. I have both styles to choose from but I think my cam choices have let me down so I thought of asking someone with more experience. Thanks again and can't wait to try your boss spec camshaft George. Thx Mark

A 351C with 4V heads, 10:1 compression, the Cobra Jet cam, Blue thunder manifold, 750 cfm carb properly jetted, and a dialed-in ignition will have plenty of pep at low rpm, good street manners. The proper gears (and torque converter if applicable) finish off the combination.

The 4V heads are tuned for 7000 rpm, its up to the rest of the combination to fill in the bottom end of the powerband. This is just opposite of the situation with other motors.

-G

I'd go with the 4v heads, provided they are the quench chamber and not the open chamber.

Use port stuffers. It will have plenty of punch.

Any of the cams GP suggested will work fine. They are on the mild side and they won't get your panties all in a bunch.