Yes, I overhauled my first Y in 1959.

The mushroom on the Y is larger than diameter of lifters of even the Chrysler Corp. engines. This aids in its ability to handle more agressive ramps.

The concern with the Y is the small stem verses the dia of the head and the possibility of flexing/fracture at that juncture.

I do know of one Y built with the agressive ramps I want. It worked OK.

Don,

You do understand the The Y has mushroom lifters, the ramp cannot be as newer roller lifter ramps can be due to the fact you would break the head of the lifter or it would dig in to the ramp severely accelerating the wear of these components, not to mention wear the lifter guides.

The program you are using to do your calculations may not be adding into the equasion that the Y is a solid mushroom lifter only, so ramp angle is limited on these.

55 Vicky & customline

58 Rack Dump, 55 F350 yard truck, 57 F100

59 & 61 P 400's, 58 F100 custom cab, 69 F100, 79 F150, 82 F600 ramp truck, 90 mustang conv 7 up, 94 Mustang, Should I continue?

Blew it, fat finger, didnt proof read, 380 horsepower.

If building an engine from the ground up, then I agree, a bigger cam, and different pistons, and such is a good decision. I interpreted the original post as implying that these are necessities, rather than options.







If the airflow stalls, then you still have more to gain, new heads or old. It is when it drops off that you have no more to gain. Lets just say hypothetically that the heads peak at .400" lift but the flow does not drop off significantly until after .500". A cam with .500 lift should produce more power, even though it peaks at .400" because the valve will be open at or beyond the point of maximum flow for a longer time.



I think you will be able to get away with a bigger cam. Mine's 226 @ .050 and I get 15.5inhg at idle - and it's a copy of an old cam. If it were me, and I was spending all this money, I'd shoot for well over 300hp. We've seen that 280 can be achieved with iron heads with ease.


Lawrenceville, GA

I mispoke in the above post, I also raised the compression ratio to 10.2 and used Thunderbird specfic headers with the 214/220 .500 lift cam. This yielded outputs in the 280 HP range. (edit 380 HP)

Remember I was able to very nearly duplicate the results of Ted's engine with this soft ware (hp peak was within 2, peak rpm off by 500 rpm).

Please, I said optimize. Camshafts with profiles generated in the 50 and 60's have been vastly improved on. I suspect most of the cams offered for the "Y" have a direct lineage to those cams probably because the stock heads needed mods at rather modest valve lift.

This is not a new head issue, this is an issue with most Y cams.

Using the software to experiment a gain of 30 HP can be gained by increasing lift from .400 to .550 with the new heads based on Ted's engine. The old heads may not gain very much if the airflow gains stall at lifts above .400. Please remember the new heads peak at .550 valve lift.

As to reliability, pushing the limits by raising acceleration rates on the valve train can lead to lubrication failures at the cam/lifter interface. Lifts of .500 are common and reliable with longer duration cams. As the duration shortens and acceleration to achieve the lift increases reliability becomes more marginal.

The test results of the EMC engine should be very revealing. the higher lift cam used on this engine and the added displacement should really test the new heads.

The soft ware is not an absolute but it is a strong indicator of directions to take during an engine build.

Don,

I agree entirely that modern valve timings have improved. The faster and wider a inlet can open the better the VE of an engine. This is the advantage of overhead cam that because of a lack of valve train weight the faster you can open the inlet because of reduced inertia.  This not only increases the time a valve is open at it's maximum it also optimizes the ram effect and uses the pressures that occur in the inlet port when closed.

The new heads don't affect any of the currently available valve train componentry. You have avenues to explore where, you can as you say, either choose to grind your own cam or use an existing can with hi ratio roller rockers.

I like higher lift cams I've had a few engines where either the existing cam or the one I've chosen is of relatively modest duration but of higher lift than other cams that are available from other companies. I think it tends to broaden the power band. Some of these engines have felt as though they are bigger than they are.

Lift can be at odds with one of my other preferences reliability. All machines are a compromise of function over use.  

Grizzly (Aussie Mainline)

Don: I'm a bit surprised at your conclusions. I gotta agree largely with Charlie, bill & griz. First your comments that all sorts of changes are needed to optimize the heads.. Ted got well over 50 H.P. with no changes other than timing & jetting! And over 20 lbs Ft of torque also. And the Cams you are talking about are likely all for roller valve trains. Not "Y" compatible. I'd say that John Mummert has done a superb job with the heads. They stand very well on there own...

Paul

Grizzly, I hope not all of the new cam research has not been wasted. Todays camsfafts have much more agressive lift rates to give more area under the lift curve. There is a lot of hype in selling cams,but developing as great as area possible with out exceeding the limits of the valve train is the name of the game. Think of a valve opening event. The area under a square wave is a lot greater thana modified sine wave that is achieveable using a cam and solid or hydraulic flat base lifter. A roller can more closley approach a square wave. Stock class racing cams deliberately induce valve float to attain more performance. There are a lot of sublities th be addressed in cam design.

Two of the good things to come from Mumert are a better single 4 manifold and these heads. It adds to the range of parts that are already available as either vintage or new items. The thing with both of these items is that they address part of the design inefficency of the originial design, breathing.  The heads do not address anything other that porting, combution chamber (both shape & size) and the other funtions of a over head valve head.

New cam design revolves around the use of either roller lifters or overhead cam construction. The head has nothing to do with this as it doesn't address any of these functions. Although I do conceed that there will be developments in line with the release of the heads.

I would be disapointed if the heads didn't fit abroad range of applications as a potential customer I don't see myself at ether end of the range and would like the freedom to build an engine around what I need and want.  

Grizzly (Aussie Mainline)