These are the very things that have kept me form ordering one of these cams. The jerk is a serious consideration but even more is a too agressive lift (forgot the exact terminology) acceleration. I once spent a week trying to decipher a cam design manual that was not written for a beginner. EAP has genaric (mild, and agressive) lift rates as well as well over the nose inputs for the cam profile. I believe, altho I have not tried it, you can put in specified acceleration profiles. I understand where you are coming from on lobe centers but a lot of the old FE HP grinds were on wide lobe centers and the newer designs favor wide centers, probably due to emissions regulations. I have not played much with changing lobe centers, I'll give it a try.

Don, I would be very hesitant to use a cam lobe designed for a flathead engine in a rocker arm engine. While I have never Cam Doctored a flathead lobe I have checked many overhead cam lobes and they would be very ugly in an OHV engine. An OHC valvetrain is just a flathead turned upside down. With no rocker arm, the lobe must be very aggressive to generate even .350" valve lift in a reasonable duration.

Without the weight of a rocker or pushrod the designer doesn't need to be very careful about jerk and rapid acceleration changes. Some of worst cam designs I've ever seen were from late model Japanese ATV's. No way you would want to use them in a pushrod engine.

With regard to lobe separation, we recommend 108 for engines with headers, 110 for engines with fair headers or very good dual exhaust and 112 for restrictive exhaust. I'm not a hugh fan of wide lobe separation cams such as 112 or more. Generally, low RPM power suffers particularly if the engine also has low compression. Exhaust will also noticeably louder under full throttle.

http://ford-y-block.com 

20 miles east of San Diego, 20 miles north of Mexico

Don has a strong point! If we could have a roller cam and lifters for Y, the world would not be the same again.... Count off friction losses, cam wear etc...

Just my opinion, but...

 Seppo from Järvenpää, Finland
www.hollowheads.net (just click the hole in the head to proceed)

John: The cam profile used in the engine referenced was one generated for flathead Fords. The reason I have not ordered one of these is I am not sure how good that profile is. It may be very good, but even if I purchased one, and had a cam doctor profile run on it, I am not knowledgeable enough to determine the "goodness" of this profile. I know some excellent local engine builders but these guys rely on the cam companies to design and supply them with compatable parts. I tried Comp Cams but they did not want to go out of their way for a one off oddball engine.

The EAP program will evaluate valve train stability if the componet weights and cam profile is entered.

John: For your amusement I mailed you the EAP files on my proposed build. This is not for max horsepower, but for a strong week end driver. If I get to radical on the Tbird my life will be in peril from the wife. I have turned too many cars into race only, so have to keep this one gentle. This build will have to take a bit of time to complete due to finances. I will dyno it, so we will see how realistically electrons build an engine.

I could have worded my question better I knew that springs were designed for different cams. So the heads can handle up to .520 delivered.

Thanks

Grizzly (Aussie Mainline)

Grizzly, the springs on the site are listed by seat pressure but we sell them based on valve lift. The VS65 is for stock cams, VS95 for .450" lift, VS105 for .480" lift and VS115 for cams up to .520" valve lift. These springs can be used with any appropriate cam and fit common retainers with 1.060" inside step (except VS65).

The springs in the new heads will handle up to .520" lift but are not the same as the VS115.

http://ford-y-block.com 

20 miles east of San Diego, 20 miles north of Mexico

John,

On your site you have a range of cams. These are referenced to a spring. Firstly what cam are the springs, that are sold with the heads, designed for and Secondly do you offer other springs for specific builds? 

Grizzly (Aussie Mainline)

While it is true that the Y-Block's 1.00" lifter face allows the possibility of more aggressive cams with higher lifter velocities at some point the attachment of the stem to lifter face becomes a concern. If a person is considering a high velocity cam lobe a few things will help the lifters live:

Light weight valves and retainers. Titanium will greatly reduce the component weights and valve spring tension required to keep everything under control.

Well designed cam lobe. Some designs are harder on parts than others with the same basic specs.

Sufficient valve spring pressure. Nothing will break lifters quicker than weak valve springs.

Higher lift is harder on parts. Longer duration is easier on parts.

Keep in mind that better cylinderheads will make the same power at lower compression ratios and with smaller cams.

http://ford-y-block.com 

20 miles east of San Diego, 20 miles north of Mexico

Yes, one "Y" with very aggressive ramps was documented in YBM a while back. And the builder has been on this site on occasion. However, I don't know if that was a street engine & if it has been run enough to prove reliable. J. Mummert has indicated that he feels the Y lifters are somewhat fragile. I don't know what he bases that on, but unless someone proves him wrong, I'd be inclined to go with his observations..

Paul